kernel-ark/mm/hugetlb.c
Mel Gorman d833352a43 mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables
If a process creates a large hugetlbfs mapping that is eligible for page
table sharing and forks heavily with children some of whom fault and
others which destroy the mapping then it is possible for page tables to
get corrupted.  Some teardowns of the mapping encounter a "bad pmd" and
output a message to the kernel log.  The final teardown will trigger a
BUG_ON in mm/filemap.c.

This was reproduced in 3.4 but is known to have existed for a long time
and goes back at least as far as 2.6.37.  It was probably was introduced
in 2.6.20 by [39dde65c: shared page table for hugetlb page].  The messages
look like this;

[  ..........] Lots of bad pmd messages followed by this
[  127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7).
[  127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7).
[  127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7).
[  127.186778] ------------[ cut here ]------------
[  127.186781] kernel BUG at mm/filemap.c:134!
[  127.186782] invalid opcode: 0000 [#1] SMP
[  127.186783] CPU 7
[  127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod
[  127.186801]
[  127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR
[  127.186804] RIP: 0010:[<ffffffff810ed6ce>]  [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160
[  127.186809] RSP: 0000:ffff8804144b5c08  EFLAGS: 00010002
[  127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0
[  127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00
[  127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003
[  127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8
[  127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8
[  127.186815] FS:  00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000
[  127.186816] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0
[  127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0)
[  127.186821] Stack:
[  127.186822]  ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b
[  127.186824]  ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98
[  127.186825]  ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000
[  127.186827] Call Trace:
[  127.186829]  [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80
[  127.186832]  [<ffffffff811bc925>] truncate_hugepages+0x115/0x220
[  127.186834]  [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30
[  127.186837]  [<ffffffff811655c7>] evict+0xa7/0x1b0
[  127.186839]  [<ffffffff811657a3>] iput_final+0xd3/0x1f0
[  127.186840]  [<ffffffff811658f9>] iput+0x39/0x50
[  127.186842]  [<ffffffff81162708>] d_kill+0xf8/0x130
[  127.186843]  [<ffffffff81162812>] dput+0xd2/0x1a0
[  127.186845]  [<ffffffff8114e2d0>] __fput+0x170/0x230
[  127.186848]  [<ffffffff81236e0e>] ? rb_erase+0xce/0x150
[  127.186849]  [<ffffffff8114e3ad>] fput+0x1d/0x30
[  127.186851]  [<ffffffff81117db7>] remove_vma+0x37/0x80
[  127.186853]  [<ffffffff81119182>] do_munmap+0x2d2/0x360
[  127.186855]  [<ffffffff811cc639>] sys_shmdt+0xc9/0x170
[  127.186857]  [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b
[  127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0
[  127.186868] RIP  [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160
[  127.186870]  RSP <ffff8804144b5c08>
[  127.186871] ---[ end trace 7cbac5d1db69f426 ]---

The bug is a race and not always easy to reproduce.  To reproduce it I was
doing the following on a single socket I7-based machine with 16G of RAM.

$ hugeadm --pool-pages-max DEFAULT:13G
$ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax
$ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall
$ for i in `seq 1 9000`; do ./hugetlbfs-test; done

On my particular machine, it usually triggers within 10 minutes but
enabling debug options can change the timing such that it never hits.
Once the bug is triggered, the machine is in trouble and needs to be
rebooted.  The machine will respond but processes accessing proc like "ps
aux" will hang due to the BUG_ON.  shutdown will also hang and needs a
hard reset or a sysrq-b.

The basic problem is a race between page table sharing and teardown.  For
the most part page table sharing depends on i_mmap_mutex.  In some cases,
it is also taking the mm->page_table_lock for the PTE updates but with
shared page tables, it is the i_mmap_mutex that is more important.

Unfortunately it appears to be also insufficient. Consider the following
situation

Process A					Process B
---------					---------
hugetlb_fault					shmdt
  						LockWrite(mmap_sem)
    						  do_munmap
						    unmap_region
						      unmap_vmas
						        unmap_single_vma
						          unmap_hugepage_range
      						            Lock(i_mmap_mutex)
							    Lock(mm->page_table_lock)
							    huge_pmd_unshare/unmap tables <--- (1)
							    Unlock(mm->page_table_lock)
      						            Unlock(i_mmap_mutex)
  huge_pte_alloc				      ...
    Lock(i_mmap_mutex)				      ...
    vma_prio_walk, find svma, spte		      ...
    Lock(mm->page_table_lock)			      ...
    share spte					      ...
    Unlock(mm->page_table_lock)			      ...
    Unlock(i_mmap_mutex)			      ...
  hugetlb_no_page									  <--- (2)
						      free_pgtables
						        unlink_file_vma
							hugetlb_free_pgd_range
						    remove_vma_list

In this scenario, it is possible for Process A to share page tables with
Process B that is trying to tear them down.  The i_mmap_mutex on its own
does not prevent Process A walking Process B's page tables.  At (1) above,
the page tables are not shared yet so it unmaps the PMDs.  Process A sets
up page table sharing and at (2) faults a new entry.  Process B then trips
up on it in free_pgtables.

This patch fixes the problem by adding a new function
__unmap_hugepage_range_final that is only called when the VMA is about to
be destroyed.  This function clears VM_MAYSHARE during
unmap_hugepage_range() under the i_mmap_mutex.  This makes the VMA
ineligible for sharing and avoids the race.  Superficially this looks like
it would then be vunerable to truncate and madvise issues but hugetlbfs
has its own truncate handlers so does not use unmap_mapping_range() and
does not support madvise(DONTNEED).

This should be treated as a -stable candidate if it is merged.

Test program is as follows. The test case was mostly written by Michal
Hocko with a few minor changes to reproduce this bug.

==== CUT HERE ====

static size_t huge_page_size = (2UL << 20);
static size_t nr_huge_page_A = 512;
static size_t nr_huge_page_B = 5632;

unsigned int get_random(unsigned int max)
{
	struct timeval tv;

	gettimeofday(&tv, NULL);
	srandom(tv.tv_usec);
	return random() % max;
}

static void play(void *addr, size_t size)
{
	unsigned char *start = addr,
		      *end = start + size,
		      *a;
	start += get_random(size/2);

	/* we could itterate on huge pages but let's give it more time. */
	for (a = start; a < end; a += 4096)
		*a = 0;
}

int main(int argc, char **argv)
{
	key_t key = IPC_PRIVATE;
	size_t sizeA = nr_huge_page_A * huge_page_size;
	size_t sizeB = nr_huge_page_B * huge_page_size;
	int shmidA, shmidB;
	void *addrA = NULL, *addrB = NULL;
	int nr_children = 300, n = 0;

	if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) {
		perror("shmget:");
		return 1;
	}

	if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) {
		perror("shmat");
		return 1;
	}
	if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) {
		perror("shmget:");
		return 1;
	}

	if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) {
		perror("shmat");
		return 1;
	}

fork_child:
	switch(fork()) {
		case 0:
			switch (n%3) {
			case 0:
				play(addrA, sizeA);
				break;
			case 1:
				play(addrB, sizeB);
				break;
			case 2:
				break;
			}
			break;
		case -1:
			perror("fork:");
			break;
		default:
			if (++n < nr_children)
				goto fork_child;
			play(addrA, sizeA);
			break;
	}
	shmdt(addrA);
	shmdt(addrB);
	do {
		wait(NULL);
	} while (--n > 0);
	shmctl(shmidA, IPC_RMID, NULL);
	shmctl(shmidB, IPC_RMID, NULL);
	return 0;
}

[akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build]
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:50 -07:00

3173 lines
82 KiB
C

/*
* Generic hugetlb support.
* (C) William Irwin, April 2004
*/
#include <linux/list.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/mmu_notifier.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
#include <linux/bootmem.h>
#include <linux/sysfs.h>
#include <linux/slab.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/tlb.h>
#include <linux/io.h>
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
#include <linux/node.h>
#include <linux/hugetlb_cgroup.h>
#include "internal.h"
const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
unsigned long hugepages_treat_as_movable;
int hugetlb_max_hstate __read_mostly;
unsigned int default_hstate_idx;
struct hstate hstates[HUGE_MAX_HSTATE];
__initdata LIST_HEAD(huge_boot_pages);
/* for command line parsing */
static struct hstate * __initdata parsed_hstate;
static unsigned long __initdata default_hstate_max_huge_pages;
static unsigned long __initdata default_hstate_size;
/*
* Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
*/
DEFINE_SPINLOCK(hugetlb_lock);
static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
{
bool free = (spool->count == 0) && (spool->used_hpages == 0);
spin_unlock(&spool->lock);
/* If no pages are used, and no other handles to the subpool
* remain, free the subpool the subpool remain */
if (free)
kfree(spool);
}
struct hugepage_subpool *hugepage_new_subpool(long nr_blocks)
{
struct hugepage_subpool *spool;
spool = kmalloc(sizeof(*spool), GFP_KERNEL);
if (!spool)
return NULL;
spin_lock_init(&spool->lock);
spool->count = 1;
spool->max_hpages = nr_blocks;
spool->used_hpages = 0;
return spool;
}
void hugepage_put_subpool(struct hugepage_subpool *spool)
{
spin_lock(&spool->lock);
BUG_ON(!spool->count);
spool->count--;
unlock_or_release_subpool(spool);
}
static int hugepage_subpool_get_pages(struct hugepage_subpool *spool,
long delta)
{
int ret = 0;
if (!spool)
return 0;
spin_lock(&spool->lock);
if ((spool->used_hpages + delta) <= spool->max_hpages) {
spool->used_hpages += delta;
} else {
ret = -ENOMEM;
}
spin_unlock(&spool->lock);
return ret;
}
static void hugepage_subpool_put_pages(struct hugepage_subpool *spool,
long delta)
{
if (!spool)
return;
spin_lock(&spool->lock);
spool->used_hpages -= delta;
/* If hugetlbfs_put_super couldn't free spool due to
* an outstanding quota reference, free it now. */
unlock_or_release_subpool(spool);
}
static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
{
return HUGETLBFS_SB(inode->i_sb)->spool;
}
static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
{
return subpool_inode(vma->vm_file->f_dentry->d_inode);
}
/*
* Region tracking -- allows tracking of reservations and instantiated pages
* across the pages in a mapping.
*
* The region data structures are protected by a combination of the mmap_sem
* and the hugetlb_instantion_mutex. To access or modify a region the caller
* must either hold the mmap_sem for write, or the mmap_sem for read and
* the hugetlb_instantiation mutex:
*
* down_write(&mm->mmap_sem);
* or
* down_read(&mm->mmap_sem);
* mutex_lock(&hugetlb_instantiation_mutex);
*/
struct file_region {
struct list_head link;
long from;
long to;
};
static long region_add(struct list_head *head, long f, long t)
{
struct file_region *rg, *nrg, *trg;
/* Locate the region we are either in or before. */
list_for_each_entry(rg, head, link)
if (f <= rg->to)
break;
/* Round our left edge to the current segment if it encloses us. */
if (f > rg->from)
f = rg->from;
/* Check for and consume any regions we now overlap with. */
nrg = rg;
list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
if (&rg->link == head)
break;
if (rg->from > t)
break;
/* If this area reaches higher then extend our area to
* include it completely. If this is not the first area
* which we intend to reuse, free it. */
if (rg->to > t)
t = rg->to;
if (rg != nrg) {
list_del(&rg->link);
kfree(rg);
}
}
nrg->from = f;
nrg->to = t;
return 0;
}
static long region_chg(struct list_head *head, long f, long t)
{
struct file_region *rg, *nrg;
long chg = 0;
/* Locate the region we are before or in. */
list_for_each_entry(rg, head, link)
if (f <= rg->to)
break;
/* If we are below the current region then a new region is required.
* Subtle, allocate a new region at the position but make it zero
* size such that we can guarantee to record the reservation. */
if (&rg->link == head || t < rg->from) {
nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
if (!nrg)
return -ENOMEM;
nrg->from = f;
nrg->to = f;
INIT_LIST_HEAD(&nrg->link);
list_add(&nrg->link, rg->link.prev);
return t - f;
}
/* Round our left edge to the current segment if it encloses us. */
if (f > rg->from)
f = rg->from;
chg = t - f;
/* Check for and consume any regions we now overlap with. */
list_for_each_entry(rg, rg->link.prev, link) {
if (&rg->link == head)
break;
if (rg->from > t)
return chg;
/* We overlap with this area, if it extends further than
* us then we must extend ourselves. Account for its
* existing reservation. */
if (rg->to > t) {
chg += rg->to - t;
t = rg->to;
}
chg -= rg->to - rg->from;
}
return chg;
}
static long region_truncate(struct list_head *head, long end)
{
struct file_region *rg, *trg;
long chg = 0;
/* Locate the region we are either in or before. */
list_for_each_entry(rg, head, link)
if (end <= rg->to)
break;
if (&rg->link == head)
return 0;
/* If we are in the middle of a region then adjust it. */
if (end > rg->from) {
chg = rg->to - end;
rg->to = end;
rg = list_entry(rg->link.next, typeof(*rg), link);
}
/* Drop any remaining regions. */
list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
if (&rg->link == head)
break;
chg += rg->to - rg->from;
list_del(&rg->link);
kfree(rg);
}
return chg;
}
static long region_count(struct list_head *head, long f, long t)
{
struct file_region *rg;
long chg = 0;
/* Locate each segment we overlap with, and count that overlap. */
list_for_each_entry(rg, head, link) {
long seg_from;
long seg_to;
if (rg->to <= f)
continue;
if (rg->from >= t)
break;
seg_from = max(rg->from, f);
seg_to = min(rg->to, t);
chg += seg_to - seg_from;
}
return chg;
}
/*
* Convert the address within this vma to the page offset within
* the mapping, in pagecache page units; huge pages here.
*/
static pgoff_t vma_hugecache_offset(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
return ((address - vma->vm_start) >> huge_page_shift(h)) +
(vma->vm_pgoff >> huge_page_order(h));
}
pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
unsigned long address)
{
return vma_hugecache_offset(hstate_vma(vma), vma, address);
}
/*
* Return the size of the pages allocated when backing a VMA. In the majority
* cases this will be same size as used by the page table entries.
*/
unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
{
struct hstate *hstate;
if (!is_vm_hugetlb_page(vma))
return PAGE_SIZE;
hstate = hstate_vma(vma);
return 1UL << (hstate->order + PAGE_SHIFT);
}
EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
/*
* Return the page size being used by the MMU to back a VMA. In the majority
* of cases, the page size used by the kernel matches the MMU size. On
* architectures where it differs, an architecture-specific version of this
* function is required.
*/
#ifndef vma_mmu_pagesize
unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
return vma_kernel_pagesize(vma);
}
#endif
/*
* Flags for MAP_PRIVATE reservations. These are stored in the bottom
* bits of the reservation map pointer, which are always clear due to
* alignment.
*/
#define HPAGE_RESV_OWNER (1UL << 0)
#define HPAGE_RESV_UNMAPPED (1UL << 1)
#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
/*
* These helpers are used to track how many pages are reserved for
* faults in a MAP_PRIVATE mapping. Only the process that called mmap()
* is guaranteed to have their future faults succeed.
*
* With the exception of reset_vma_resv_huge_pages() which is called at fork(),
* the reserve counters are updated with the hugetlb_lock held. It is safe
* to reset the VMA at fork() time as it is not in use yet and there is no
* chance of the global counters getting corrupted as a result of the values.
*
* The private mapping reservation is represented in a subtly different
* manner to a shared mapping. A shared mapping has a region map associated
* with the underlying file, this region map represents the backing file
* pages which have ever had a reservation assigned which this persists even
* after the page is instantiated. A private mapping has a region map
* associated with the original mmap which is attached to all VMAs which
* reference it, this region map represents those offsets which have consumed
* reservation ie. where pages have been instantiated.
*/
static unsigned long get_vma_private_data(struct vm_area_struct *vma)
{
return (unsigned long)vma->vm_private_data;
}
static void set_vma_private_data(struct vm_area_struct *vma,
unsigned long value)
{
vma->vm_private_data = (void *)value;
}
struct resv_map {
struct kref refs;
struct list_head regions;
};
static struct resv_map *resv_map_alloc(void)
{
struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
if (!resv_map)
return NULL;
kref_init(&resv_map->refs);
INIT_LIST_HEAD(&resv_map->regions);
return resv_map;
}
static void resv_map_release(struct kref *ref)
{
struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
/* Clear out any active regions before we release the map. */
region_truncate(&resv_map->regions, 0);
kfree(resv_map);
}
static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
if (!(vma->vm_flags & VM_MAYSHARE))
return (struct resv_map *)(get_vma_private_data(vma) &
~HPAGE_RESV_MASK);
return NULL;
}
static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
set_vma_private_data(vma, (get_vma_private_data(vma) &
HPAGE_RESV_MASK) | (unsigned long)map);
}
static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
set_vma_private_data(vma, get_vma_private_data(vma) | flags);
}
static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
return (get_vma_private_data(vma) & flag) != 0;
}
/* Decrement the reserved pages in the hugepage pool by one */
static void decrement_hugepage_resv_vma(struct hstate *h,
struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_NORESERVE)
return;
if (vma->vm_flags & VM_MAYSHARE) {
/* Shared mappings always use reserves */
h->resv_huge_pages--;
} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
/*
* Only the process that called mmap() has reserves for
* private mappings.
*/
h->resv_huge_pages--;
}
}
/* Reset counters to 0 and clear all HPAGE_RESV_* flags */
void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
{
VM_BUG_ON(!is_vm_hugetlb_page(vma));
if (!(vma->vm_flags & VM_MAYSHARE))
vma->vm_private_data = (void *)0;
}
/* Returns true if the VMA has associated reserve pages */
static int vma_has_reserves(struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_MAYSHARE)
return 1;
if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
return 1;
return 0;
}
static void copy_gigantic_page(struct page *dst, struct page *src)
{
int i;
struct hstate *h = page_hstate(src);
struct page *dst_base = dst;
struct page *src_base = src;
for (i = 0; i < pages_per_huge_page(h); ) {
cond_resched();
copy_highpage(dst, src);
i++;
dst = mem_map_next(dst, dst_base, i);
src = mem_map_next(src, src_base, i);
}
}
void copy_huge_page(struct page *dst, struct page *src)
{
int i;
struct hstate *h = page_hstate(src);
if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
copy_gigantic_page(dst, src);
return;
}
might_sleep();
for (i = 0; i < pages_per_huge_page(h); i++) {
cond_resched();
copy_highpage(dst + i, src + i);
}
}
static void enqueue_huge_page(struct hstate *h, struct page *page)
{
int nid = page_to_nid(page);
list_move(&page->lru, &h->hugepage_freelists[nid]);
h->free_huge_pages++;
h->free_huge_pages_node[nid]++;
}
static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
{
struct page *page;
if (list_empty(&h->hugepage_freelists[nid]))
return NULL;
page = list_entry(h->hugepage_freelists[nid].next, struct page, lru);
list_move(&page->lru, &h->hugepage_activelist);
set_page_refcounted(page);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
return page;
}
static struct page *dequeue_huge_page_vma(struct hstate *h,
struct vm_area_struct *vma,
unsigned long address, int avoid_reserve)
{
struct page *page = NULL;
struct mempolicy *mpol;
nodemask_t *nodemask;
struct zonelist *zonelist;
struct zone *zone;
struct zoneref *z;
unsigned int cpuset_mems_cookie;
retry_cpuset:
cpuset_mems_cookie = get_mems_allowed();
zonelist = huge_zonelist(vma, address,
htlb_alloc_mask, &mpol, &nodemask);
/*
* A child process with MAP_PRIVATE mappings created by their parent
* have no page reserves. This check ensures that reservations are
* not "stolen". The child may still get SIGKILLed
*/
if (!vma_has_reserves(vma) &&
h->free_huge_pages - h->resv_huge_pages == 0)
goto err;
/* If reserves cannot be used, ensure enough pages are in the pool */
if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
goto err;
for_each_zone_zonelist_nodemask(zone, z, zonelist,
MAX_NR_ZONES - 1, nodemask) {
if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) {
page = dequeue_huge_page_node(h, zone_to_nid(zone));
if (page) {
if (!avoid_reserve)
decrement_hugepage_resv_vma(h, vma);
break;
}
}
}
mpol_cond_put(mpol);
if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
goto retry_cpuset;
return page;
err:
mpol_cond_put(mpol);
return NULL;
}
static void update_and_free_page(struct hstate *h, struct page *page)
{
int i;
VM_BUG_ON(h->order >= MAX_ORDER);
h->nr_huge_pages--;
h->nr_huge_pages_node[page_to_nid(page)]--;
for (i = 0; i < pages_per_huge_page(h); i++) {
page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
1 << PG_referenced | 1 << PG_dirty |
1 << PG_active | 1 << PG_reserved |
1 << PG_private | 1 << PG_writeback);
}
VM_BUG_ON(hugetlb_cgroup_from_page(page));
set_compound_page_dtor(page, NULL);
set_page_refcounted(page);
arch_release_hugepage(page);
__free_pages(page, huge_page_order(h));
}
struct hstate *size_to_hstate(unsigned long size)
{
struct hstate *h;
for_each_hstate(h) {
if (huge_page_size(h) == size)
return h;
}
return NULL;
}
static void free_huge_page(struct page *page)
{
/*
* Can't pass hstate in here because it is called from the
* compound page destructor.
*/
struct hstate *h = page_hstate(page);
int nid = page_to_nid(page);
struct hugepage_subpool *spool =
(struct hugepage_subpool *)page_private(page);
set_page_private(page, 0);
page->mapping = NULL;
BUG_ON(page_count(page));
BUG_ON(page_mapcount(page));
spin_lock(&hugetlb_lock);
hugetlb_cgroup_uncharge_page(hstate_index(h),
pages_per_huge_page(h), page);
if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
/* remove the page from active list */
list_del(&page->lru);
update_and_free_page(h, page);
h->surplus_huge_pages--;
h->surplus_huge_pages_node[nid]--;
} else {
enqueue_huge_page(h, page);
}
spin_unlock(&hugetlb_lock);
hugepage_subpool_put_pages(spool, 1);
}
static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
{
INIT_LIST_HEAD(&page->lru);
set_compound_page_dtor(page, free_huge_page);
spin_lock(&hugetlb_lock);
set_hugetlb_cgroup(page, NULL);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
spin_unlock(&hugetlb_lock);
put_page(page); /* free it into the hugepage allocator */
}
static void prep_compound_gigantic_page(struct page *page, unsigned long order)
{
int i;
int nr_pages = 1 << order;
struct page *p = page + 1;
/* we rely on prep_new_huge_page to set the destructor */
set_compound_order(page, order);
__SetPageHead(page);
for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
__SetPageTail(p);
set_page_count(p, 0);
p->first_page = page;
}
}
int PageHuge(struct page *page)
{
compound_page_dtor *dtor;
if (!PageCompound(page))
return 0;
page = compound_head(page);
dtor = get_compound_page_dtor(page);
return dtor == free_huge_page;
}
EXPORT_SYMBOL_GPL(PageHuge);
static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
{
struct page *page;
if (h->order >= MAX_ORDER)
return NULL;
page = alloc_pages_exact_node(nid,
htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
__GFP_REPEAT|__GFP_NOWARN,
huge_page_order(h));
if (page) {
if (arch_prepare_hugepage(page)) {
__free_pages(page, huge_page_order(h));
return NULL;
}
prep_new_huge_page(h, page, nid);
}
return page;
}
/*
* common helper functions for hstate_next_node_to_{alloc|free}.
* We may have allocated or freed a huge page based on a different
* nodes_allowed previously, so h->next_node_to_{alloc|free} might
* be outside of *nodes_allowed. Ensure that we use an allowed
* node for alloc or free.
*/
static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
{
nid = next_node(nid, *nodes_allowed);
if (nid == MAX_NUMNODES)
nid = first_node(*nodes_allowed);
VM_BUG_ON(nid >= MAX_NUMNODES);
return nid;
}
static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
{
if (!node_isset(nid, *nodes_allowed))
nid = next_node_allowed(nid, nodes_allowed);
return nid;
}
/*
* returns the previously saved node ["this node"] from which to
* allocate a persistent huge page for the pool and advance the
* next node from which to allocate, handling wrap at end of node
* mask.
*/
static int hstate_next_node_to_alloc(struct hstate *h,
nodemask_t *nodes_allowed)
{
int nid;
VM_BUG_ON(!nodes_allowed);
nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
return nid;
}
static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
{
struct page *page;
int start_nid;
int next_nid;
int ret = 0;
start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
next_nid = start_nid;
do {
page = alloc_fresh_huge_page_node(h, next_nid);
if (page) {
ret = 1;
break;
}
next_nid = hstate_next_node_to_alloc(h, nodes_allowed);
} while (next_nid != start_nid);
if (ret)
count_vm_event(HTLB_BUDDY_PGALLOC);
else
count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
return ret;
}
/*
* helper for free_pool_huge_page() - return the previously saved
* node ["this node"] from which to free a huge page. Advance the
* next node id whether or not we find a free huge page to free so
* that the next attempt to free addresses the next node.
*/
static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
{
int nid;
VM_BUG_ON(!nodes_allowed);
nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
return nid;
}
/*
* Free huge page from pool from next node to free.
* Attempt to keep persistent huge pages more or less
* balanced over allowed nodes.
* Called with hugetlb_lock locked.
*/
static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
bool acct_surplus)
{
int start_nid;
int next_nid;
int ret = 0;
start_nid = hstate_next_node_to_free(h, nodes_allowed);
next_nid = start_nid;
do {
/*
* If we're returning unused surplus pages, only examine
* nodes with surplus pages.
*/
if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) &&
!list_empty(&h->hugepage_freelists[next_nid])) {
struct page *page =
list_entry(h->hugepage_freelists[next_nid].next,
struct page, lru);
list_del(&page->lru);
h->free_huge_pages--;
h->free_huge_pages_node[next_nid]--;
if (acct_surplus) {
h->surplus_huge_pages--;
h->surplus_huge_pages_node[next_nid]--;
}
update_and_free_page(h, page);
ret = 1;
break;
}
next_nid = hstate_next_node_to_free(h, nodes_allowed);
} while (next_nid != start_nid);
return ret;
}
static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
{
struct page *page;
unsigned int r_nid;
if (h->order >= MAX_ORDER)
return NULL;
/*
* Assume we will successfully allocate the surplus page to
* prevent racing processes from causing the surplus to exceed
* overcommit
*
* This however introduces a different race, where a process B
* tries to grow the static hugepage pool while alloc_pages() is
* called by process A. B will only examine the per-node
* counters in determining if surplus huge pages can be
* converted to normal huge pages in adjust_pool_surplus(). A
* won't be able to increment the per-node counter, until the
* lock is dropped by B, but B doesn't drop hugetlb_lock until
* no more huge pages can be converted from surplus to normal
* state (and doesn't try to convert again). Thus, we have a
* case where a surplus huge page exists, the pool is grown, and
* the surplus huge page still exists after, even though it
* should just have been converted to a normal huge page. This
* does not leak memory, though, as the hugepage will be freed
* once it is out of use. It also does not allow the counters to
* go out of whack in adjust_pool_surplus() as we don't modify
* the node values until we've gotten the hugepage and only the
* per-node value is checked there.
*/
spin_lock(&hugetlb_lock);
if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
spin_unlock(&hugetlb_lock);
return NULL;
} else {
h->nr_huge_pages++;
h->surplus_huge_pages++;
}
spin_unlock(&hugetlb_lock);
if (nid == NUMA_NO_NODE)
page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
__GFP_REPEAT|__GFP_NOWARN,
huge_page_order(h));
else
page = alloc_pages_exact_node(nid,
htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
__GFP_REPEAT|__GFP_NOWARN, huge_page_order(h));
if (page && arch_prepare_hugepage(page)) {
__free_pages(page, huge_page_order(h));
page = NULL;
}
spin_lock(&hugetlb_lock);
if (page) {
INIT_LIST_HEAD(&page->lru);
r_nid = page_to_nid(page);
set_compound_page_dtor(page, free_huge_page);
set_hugetlb_cgroup(page, NULL);
/*
* We incremented the global counters already
*/
h->nr_huge_pages_node[r_nid]++;
h->surplus_huge_pages_node[r_nid]++;
__count_vm_event(HTLB_BUDDY_PGALLOC);
} else {
h->nr_huge_pages--;
h->surplus_huge_pages--;
__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
}
spin_unlock(&hugetlb_lock);
return page;
}
/*
* This allocation function is useful in the context where vma is irrelevant.
* E.g. soft-offlining uses this function because it only cares physical
* address of error page.
*/
struct page *alloc_huge_page_node(struct hstate *h, int nid)
{
struct page *page;
spin_lock(&hugetlb_lock);
page = dequeue_huge_page_node(h, nid);
spin_unlock(&hugetlb_lock);
if (!page)
page = alloc_buddy_huge_page(h, nid);
return page;
}
/*
* Increase the hugetlb pool such that it can accommodate a reservation
* of size 'delta'.
*/
static int gather_surplus_pages(struct hstate *h, int delta)
{
struct list_head surplus_list;
struct page *page, *tmp;
int ret, i;
int needed, allocated;
bool alloc_ok = true;
needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
if (needed <= 0) {
h->resv_huge_pages += delta;
return 0;
}
allocated = 0;
INIT_LIST_HEAD(&surplus_list);
ret = -ENOMEM;
retry:
spin_unlock(&hugetlb_lock);
for (i = 0; i < needed; i++) {
page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
if (!page) {
alloc_ok = false;
break;
}
list_add(&page->lru, &surplus_list);
}
allocated += i;
/*
* After retaking hugetlb_lock, we need to recalculate 'needed'
* because either resv_huge_pages or free_huge_pages may have changed.
*/
spin_lock(&hugetlb_lock);
needed = (h->resv_huge_pages + delta) -
(h->free_huge_pages + allocated);
if (needed > 0) {
if (alloc_ok)
goto retry;
/*
* We were not able to allocate enough pages to
* satisfy the entire reservation so we free what
* we've allocated so far.
*/
goto free;
}
/*
* The surplus_list now contains _at_least_ the number of extra pages
* needed to accommodate the reservation. Add the appropriate number
* of pages to the hugetlb pool and free the extras back to the buddy
* allocator. Commit the entire reservation here to prevent another
* process from stealing the pages as they are added to the pool but
* before they are reserved.
*/
needed += allocated;
h->resv_huge_pages += delta;
ret = 0;
/* Free the needed pages to the hugetlb pool */
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
if ((--needed) < 0)
break;
/*
* This page is now managed by the hugetlb allocator and has
* no users -- drop the buddy allocator's reference.
*/
put_page_testzero(page);
VM_BUG_ON(page_count(page));
enqueue_huge_page(h, page);
}
free:
spin_unlock(&hugetlb_lock);
/* Free unnecessary surplus pages to the buddy allocator */
if (!list_empty(&surplus_list)) {
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
put_page(page);
}
}
spin_lock(&hugetlb_lock);
return ret;
}
/*
* When releasing a hugetlb pool reservation, any surplus pages that were
* allocated to satisfy the reservation must be explicitly freed if they were
* never used.
* Called with hugetlb_lock held.
*/
static void return_unused_surplus_pages(struct hstate *h,
unsigned long unused_resv_pages)
{
unsigned long nr_pages;
/* Uncommit the reservation */
h->resv_huge_pages -= unused_resv_pages;
/* Cannot return gigantic pages currently */
if (h->order >= MAX_ORDER)
return;
nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
/*
* We want to release as many surplus pages as possible, spread
* evenly across all nodes with memory. Iterate across these nodes
* until we can no longer free unreserved surplus pages. This occurs
* when the nodes with surplus pages have no free pages.
* free_pool_huge_page() will balance the the freed pages across the
* on-line nodes with memory and will handle the hstate accounting.
*/
while (nr_pages--) {
if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1))
break;
}
}
/*
* Determine if the huge page at addr within the vma has an associated
* reservation. Where it does not we will need to logically increase
* reservation and actually increase subpool usage before an allocation
* can occur. Where any new reservation would be required the
* reservation change is prepared, but not committed. Once the page
* has been allocated from the subpool and instantiated the change should
* be committed via vma_commit_reservation. No action is required on
* failure.
*/
static long vma_needs_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
if (vma->vm_flags & VM_MAYSHARE) {
pgoff_t idx = vma_hugecache_offset(h, vma, addr);
return region_chg(&inode->i_mapping->private_list,
idx, idx + 1);
} else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
return 1;
} else {
long err;
pgoff_t idx = vma_hugecache_offset(h, vma, addr);
struct resv_map *reservations = vma_resv_map(vma);
err = region_chg(&reservations->regions, idx, idx + 1);
if (err < 0)
return err;
return 0;
}
}
static void vma_commit_reservation(struct hstate *h,
struct vm_area_struct *vma, unsigned long addr)
{
struct address_space *mapping = vma->vm_file->f_mapping;
struct inode *inode = mapping->host;
if (vma->vm_flags & VM_MAYSHARE) {
pgoff_t idx = vma_hugecache_offset(h, vma, addr);
region_add(&inode->i_mapping->private_list, idx, idx + 1);
} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
pgoff_t idx = vma_hugecache_offset(h, vma, addr);
struct resv_map *reservations = vma_resv_map(vma);
/* Mark this page used in the map. */
region_add(&reservations->regions, idx, idx + 1);
}
}
static struct page *alloc_huge_page(struct vm_area_struct *vma,
unsigned long addr, int avoid_reserve)
{
struct hugepage_subpool *spool = subpool_vma(vma);
struct hstate *h = hstate_vma(vma);
struct page *page;
long chg;
int ret, idx;
struct hugetlb_cgroup *h_cg;
idx = hstate_index(h);
/*
* Processes that did not create the mapping will have no
* reserves and will not have accounted against subpool
* limit. Check that the subpool limit can be made before
* satisfying the allocation MAP_NORESERVE mappings may also
* need pages and subpool limit allocated allocated if no reserve
* mapping overlaps.
*/
chg = vma_needs_reservation(h, vma, addr);
if (chg < 0)
return ERR_PTR(-ENOMEM);
if (chg)
if (hugepage_subpool_get_pages(spool, chg))
return ERR_PTR(-ENOSPC);
ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
if (ret) {
hugepage_subpool_put_pages(spool, chg);
return ERR_PTR(-ENOSPC);
}
spin_lock(&hugetlb_lock);
page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
if (page) {
/* update page cgroup details */
hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h),
h_cg, page);
spin_unlock(&hugetlb_lock);
} else {
spin_unlock(&hugetlb_lock);
page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
if (!page) {
hugetlb_cgroup_uncharge_cgroup(idx,
pages_per_huge_page(h),
h_cg);
hugepage_subpool_put_pages(spool, chg);
return ERR_PTR(-ENOSPC);
}
spin_lock(&hugetlb_lock);
hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h),
h_cg, page);
list_move(&page->lru, &h->hugepage_activelist);
spin_unlock(&hugetlb_lock);
}
set_page_private(page, (unsigned long)spool);
vma_commit_reservation(h, vma, addr);
return page;
}
int __weak alloc_bootmem_huge_page(struct hstate *h)
{
struct huge_bootmem_page *m;
int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
while (nr_nodes) {
void *addr;
addr = __alloc_bootmem_node_nopanic(
NODE_DATA(hstate_next_node_to_alloc(h,
&node_states[N_HIGH_MEMORY])),
huge_page_size(h), huge_page_size(h), 0);
if (addr) {
/*
* Use the beginning of the huge page to store the
* huge_bootmem_page struct (until gather_bootmem
* puts them into the mem_map).
*/
m = addr;
goto found;
}
nr_nodes--;
}
return 0;
found:
BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
/* Put them into a private list first because mem_map is not up yet */
list_add(&m->list, &huge_boot_pages);
m->hstate = h;
return 1;
}
static void prep_compound_huge_page(struct page *page, int order)
{
if (unlikely(order > (MAX_ORDER - 1)))
prep_compound_gigantic_page(page, order);
else
prep_compound_page(page, order);
}
/* Put bootmem huge pages into the standard lists after mem_map is up */
static void __init gather_bootmem_prealloc(void)
{
struct huge_bootmem_page *m;
list_for_each_entry(m, &huge_boot_pages, list) {
struct hstate *h = m->hstate;
struct page *page;
#ifdef CONFIG_HIGHMEM
page = pfn_to_page(m->phys >> PAGE_SHIFT);
free_bootmem_late((unsigned long)m,
sizeof(struct huge_bootmem_page));
#else
page = virt_to_page(m);
#endif
__ClearPageReserved(page);
WARN_ON(page_count(page) != 1);
prep_compound_huge_page(page, h->order);
prep_new_huge_page(h, page, page_to_nid(page));
/*
* If we had gigantic hugepages allocated at boot time, we need
* to restore the 'stolen' pages to totalram_pages in order to
* fix confusing memory reports from free(1) and another
* side-effects, like CommitLimit going negative.
*/
if (h->order > (MAX_ORDER - 1))
totalram_pages += 1 << h->order;
}
}
static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
{
unsigned long i;
for (i = 0; i < h->max_huge_pages; ++i) {
if (h->order >= MAX_ORDER) {
if (!alloc_bootmem_huge_page(h))
break;
} else if (!alloc_fresh_huge_page(h,
&node_states[N_HIGH_MEMORY]))
break;
}
h->max_huge_pages = i;
}
static void __init hugetlb_init_hstates(void)
{
struct hstate *h;
for_each_hstate(h) {
/* oversize hugepages were init'ed in early boot */
if (h->order < MAX_ORDER)
hugetlb_hstate_alloc_pages(h);
}
}
static char * __init memfmt(char *buf, unsigned long n)
{
if (n >= (1UL << 30))
sprintf(buf, "%lu GB", n >> 30);
else if (n >= (1UL << 20))
sprintf(buf, "%lu MB", n >> 20);
else
sprintf(buf, "%lu KB", n >> 10);
return buf;
}
static void __init report_hugepages(void)
{
struct hstate *h;
for_each_hstate(h) {
char buf[32];
printk(KERN_INFO "HugeTLB registered %s page size, "
"pre-allocated %ld pages\n",
memfmt(buf, huge_page_size(h)),
h->free_huge_pages);
}
}
#ifdef CONFIG_HIGHMEM
static void try_to_free_low(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
int i;
if (h->order >= MAX_ORDER)
return;
for_each_node_mask(i, *nodes_allowed) {
struct page *page, *next;
struct list_head *freel = &h->hugepage_freelists[i];
list_for_each_entry_safe(page, next, freel, lru) {
if (count >= h->nr_huge_pages)
return;
if (PageHighMem(page))
continue;
list_del(&page->lru);
update_and_free_page(h, page);
h->free_huge_pages--;
h->free_huge_pages_node[page_to_nid(page)]--;
}
}
}
#else
static inline void try_to_free_low(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
}
#endif
/*
* Increment or decrement surplus_huge_pages. Keep node-specific counters
* balanced by operating on them in a round-robin fashion.
* Returns 1 if an adjustment was made.
*/
static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
int delta)
{
int start_nid, next_nid;
int ret = 0;
VM_BUG_ON(delta != -1 && delta != 1);
if (delta < 0)
start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
else
start_nid = hstate_next_node_to_free(h, nodes_allowed);
next_nid = start_nid;
do {
int nid = next_nid;
if (delta < 0) {
/*
* To shrink on this node, there must be a surplus page
*/
if (!h->surplus_huge_pages_node[nid]) {
next_nid = hstate_next_node_to_alloc(h,
nodes_allowed);
continue;
}
}
if (delta > 0) {
/*
* Surplus cannot exceed the total number of pages
*/
if (h->surplus_huge_pages_node[nid] >=
h->nr_huge_pages_node[nid]) {
next_nid = hstate_next_node_to_free(h,
nodes_allowed);
continue;
}
}
h->surplus_huge_pages += delta;
h->surplus_huge_pages_node[nid] += delta;
ret = 1;
break;
} while (next_nid != start_nid);
return ret;
}
#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
nodemask_t *nodes_allowed)
{
unsigned long min_count, ret;
if (h->order >= MAX_ORDER)
return h->max_huge_pages;
/*
* Increase the pool size
* First take pages out of surplus state. Then make up the
* remaining difference by allocating fresh huge pages.
*
* We might race with alloc_buddy_huge_page() here and be unable
* to convert a surplus huge page to a normal huge page. That is
* not critical, though, it just means the overall size of the
* pool might be one hugepage larger than it needs to be, but
* within all the constraints specified by the sysctls.
*/
spin_lock(&hugetlb_lock);
while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
if (!adjust_pool_surplus(h, nodes_allowed, -1))
break;
}
while (count > persistent_huge_pages(h)) {
/*
* If this allocation races such that we no longer need the
* page, free_huge_page will handle it by freeing the page
* and reducing the surplus.
*/
spin_unlock(&hugetlb_lock);
ret = alloc_fresh_huge_page(h, nodes_allowed);
spin_lock(&hugetlb_lock);
if (!ret)
goto out;
/* Bail for signals. Probably ctrl-c from user */
if (signal_pending(current))
goto out;
}
/*
* Decrease the pool size
* First return free pages to the buddy allocator (being careful
* to keep enough around to satisfy reservations). Then place
* pages into surplus state as needed so the pool will shrink
* to the desired size as pages become free.
*
* By placing pages into the surplus state independent of the
* overcommit value, we are allowing the surplus pool size to
* exceed overcommit. There are few sane options here. Since
* alloc_buddy_huge_page() is checking the global counter,
* though, we'll note that we're not allowed to exceed surplus
* and won't grow the pool anywhere else. Not until one of the
* sysctls are changed, or the surplus pages go out of use.
*/
min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
min_count = max(count, min_count);
try_to_free_low(h, min_count, nodes_allowed);
while (min_count < persistent_huge_pages(h)) {
if (!free_pool_huge_page(h, nodes_allowed, 0))
break;
}
while (count < persistent_huge_pages(h)) {
if (!adjust_pool_surplus(h, nodes_allowed, 1))
break;
}
out:
ret = persistent_huge_pages(h);
spin_unlock(&hugetlb_lock);
return ret;
}
#define HSTATE_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
#define HSTATE_ATTR(_name) \
static struct kobj_attribute _name##_attr = \
__ATTR(_name, 0644, _name##_show, _name##_store)
static struct kobject *hugepages_kobj;
static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
{
int i;
for (i = 0; i < HUGE_MAX_HSTATE; i++)
if (hstate_kobjs[i] == kobj) {
if (nidp)
*nidp = NUMA_NO_NODE;
return &hstates[i];
}
return kobj_to_node_hstate(kobj, nidp);
}
static ssize_t nr_hugepages_show_common(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h;
unsigned long nr_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
nr_huge_pages = h->nr_huge_pages;
else
nr_huge_pages = h->nr_huge_pages_node[nid];
return sprintf(buf, "%lu\n", nr_huge_pages);
}
static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t len)
{
int err;
int nid;
unsigned long count;
struct hstate *h;
NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
err = strict_strtoul(buf, 10, &count);
if (err)
goto out;
h = kobj_to_hstate(kobj, &nid);
if (h->order >= MAX_ORDER) {
err = -EINVAL;
goto out;
}
if (nid == NUMA_NO_NODE) {
/*
* global hstate attribute
*/
if (!(obey_mempolicy &&
init_nodemask_of_mempolicy(nodes_allowed))) {
NODEMASK_FREE(nodes_allowed);
nodes_allowed = &node_states[N_HIGH_MEMORY];
}
} else if (nodes_allowed) {
/*
* per node hstate attribute: adjust count to global,
* but restrict alloc/free to the specified node.
*/
count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
init_nodemask_of_node(nodes_allowed, nid);
} else
nodes_allowed = &node_states[N_HIGH_MEMORY];
h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
if (nodes_allowed != &node_states[N_HIGH_MEMORY])
NODEMASK_FREE(nodes_allowed);
return len;
out:
NODEMASK_FREE(nodes_allowed);
return err;
}
static ssize_t nr_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return nr_hugepages_show_common(kobj, attr, buf);
}
static ssize_t nr_hugepages_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
return nr_hugepages_store_common(false, kobj, attr, buf, len);
}
HSTATE_ATTR(nr_hugepages);
#ifdef CONFIG_NUMA
/*
* hstate attribute for optionally mempolicy-based constraint on persistent
* huge page alloc/free.
*/
static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return nr_hugepages_show_common(kobj, attr, buf);
}
static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t len)
{
return nr_hugepages_store_common(true, kobj, attr, buf, len);
}
HSTATE_ATTR(nr_hugepages_mempolicy);
#endif
static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h = kobj_to_hstate(kobj, NULL);
return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
}
static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t count)
{
int err;
unsigned long input;
struct hstate *h = kobj_to_hstate(kobj, NULL);
if (h->order >= MAX_ORDER)
return -EINVAL;
err = strict_strtoul(buf, 10, &input);
if (err)
return err;
spin_lock(&hugetlb_lock);
h->nr_overcommit_huge_pages = input;
spin_unlock(&hugetlb_lock);
return count;
}
HSTATE_ATTR(nr_overcommit_hugepages);
static ssize_t free_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h;
unsigned long free_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
free_huge_pages = h->free_huge_pages;
else
free_huge_pages = h->free_huge_pages_node[nid];
return sprintf(buf, "%lu\n", free_huge_pages);
}
HSTATE_ATTR_RO(free_hugepages);
static ssize_t resv_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h = kobj_to_hstate(kobj, NULL);
return sprintf(buf, "%lu\n", h->resv_huge_pages);
}
HSTATE_ATTR_RO(resv_hugepages);
static ssize_t surplus_hugepages_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
struct hstate *h;
unsigned long surplus_huge_pages;
int nid;
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE)
surplus_huge_pages = h->surplus_huge_pages;
else
surplus_huge_pages = h->surplus_huge_pages_node[nid];
return sprintf(buf, "%lu\n", surplus_huge_pages);
}
HSTATE_ATTR_RO(surplus_hugepages);
static struct attribute *hstate_attrs[] = {
&nr_hugepages_attr.attr,
&nr_overcommit_hugepages_attr.attr,
&free_hugepages_attr.attr,
&resv_hugepages_attr.attr,
&surplus_hugepages_attr.attr,
#ifdef CONFIG_NUMA
&nr_hugepages_mempolicy_attr.attr,
#endif
NULL,
};
static struct attribute_group hstate_attr_group = {
.attrs = hstate_attrs,
};
static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent,
struct kobject **hstate_kobjs,
struct attribute_group *hstate_attr_group)
{
int retval;
int hi = hstate_index(h);
hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
if (!hstate_kobjs[hi])
return -ENOMEM;
retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
if (retval)
kobject_put(hstate_kobjs[hi]);
return retval;
}
static void __init hugetlb_sysfs_init(void)
{
struct hstate *h;
int err;
hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
if (!hugepages_kobj)
return;
for_each_hstate(h) {
err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
hstate_kobjs, &hstate_attr_group);
if (err)
printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
h->name);
}
}
#ifdef CONFIG_NUMA
/*
* node_hstate/s - associate per node hstate attributes, via their kobjects,
* with node devices in node_devices[] using a parallel array. The array
* index of a node device or _hstate == node id.
* This is here to avoid any static dependency of the node device driver, in
* the base kernel, on the hugetlb module.
*/
struct node_hstate {
struct kobject *hugepages_kobj;
struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
};
struct node_hstate node_hstates[MAX_NUMNODES];
/*
* A subset of global hstate attributes for node devices
*/
static struct attribute *per_node_hstate_attrs[] = {
&nr_hugepages_attr.attr,
&free_hugepages_attr.attr,
&surplus_hugepages_attr.attr,
NULL,
};
static struct attribute_group per_node_hstate_attr_group = {
.attrs = per_node_hstate_attrs,
};
/*
* kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj.
* Returns node id via non-NULL nidp.
*/
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
int nid;
for (nid = 0; nid < nr_node_ids; nid++) {
struct node_hstate *nhs = &node_hstates[nid];
int i;
for (i = 0; i < HUGE_MAX_HSTATE; i++)
if (nhs->hstate_kobjs[i] == kobj) {
if (nidp)
*nidp = nid;
return &hstates[i];
}
}
BUG();
return NULL;
}
/*
* Unregister hstate attributes from a single node device.
* No-op if no hstate attributes attached.
*/
void hugetlb_unregister_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
if (!nhs->hugepages_kobj)
return; /* no hstate attributes */
for_each_hstate(h) {
int idx = hstate_index(h);
if (nhs->hstate_kobjs[idx]) {
kobject_put(nhs->hstate_kobjs[idx]);
nhs->hstate_kobjs[idx] = NULL;
}
}
kobject_put(nhs->hugepages_kobj);
nhs->hugepages_kobj = NULL;
}
/*
* hugetlb module exit: unregister hstate attributes from node devices
* that have them.
*/
static void hugetlb_unregister_all_nodes(void)
{
int nid;
/*
* disable node device registrations.
*/
register_hugetlbfs_with_node(NULL, NULL);
/*
* remove hstate attributes from any nodes that have them.
*/
for (nid = 0; nid < nr_node_ids; nid++)
hugetlb_unregister_node(&node_devices[nid]);
}
/*
* Register hstate attributes for a single node device.
* No-op if attributes already registered.
*/
void hugetlb_register_node(struct node *node)
{
struct hstate *h;
struct node_hstate *nhs = &node_hstates[node->dev.id];
int err;
if (nhs->hugepages_kobj)
return; /* already allocated */
nhs->hugepages_kobj = kobject_create_and_add("hugepages",
&node->dev.kobj);
if (!nhs->hugepages_kobj)
return;
for_each_hstate(h) {
err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
nhs->hstate_kobjs,
&per_node_hstate_attr_group);
if (err) {
printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
" for node %d\n",
h->name, node->dev.id);
hugetlb_unregister_node(node);
break;
}
}
}
/*
* hugetlb init time: register hstate attributes for all registered node
* devices of nodes that have memory. All on-line nodes should have
* registered their associated device by this time.
*/
static void hugetlb_register_all_nodes(void)
{
int nid;
for_each_node_state(nid, N_HIGH_MEMORY) {
struct node *node = &node_devices[nid];
if (node->dev.id == nid)
hugetlb_register_node(node);
}
/*
* Let the node device driver know we're here so it can
* [un]register hstate attributes on node hotplug.
*/
register_hugetlbfs_with_node(hugetlb_register_node,
hugetlb_unregister_node);
}
#else /* !CONFIG_NUMA */
static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
{
BUG();
if (nidp)
*nidp = -1;
return NULL;
}
static void hugetlb_unregister_all_nodes(void) { }
static void hugetlb_register_all_nodes(void) { }
#endif
static void __exit hugetlb_exit(void)
{
struct hstate *h;
hugetlb_unregister_all_nodes();
for_each_hstate(h) {
kobject_put(hstate_kobjs[hstate_index(h)]);
}
kobject_put(hugepages_kobj);
}
module_exit(hugetlb_exit);
static int __init hugetlb_init(void)
{
/* Some platform decide whether they support huge pages at boot
* time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
* there is no such support
*/
if (HPAGE_SHIFT == 0)
return 0;
if (!size_to_hstate(default_hstate_size)) {
default_hstate_size = HPAGE_SIZE;
if (!size_to_hstate(default_hstate_size))
hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
}
default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
if (default_hstate_max_huge_pages)
default_hstate.max_huge_pages = default_hstate_max_huge_pages;
hugetlb_init_hstates();
gather_bootmem_prealloc();
report_hugepages();
hugetlb_sysfs_init();
hugetlb_register_all_nodes();
return 0;
}
module_init(hugetlb_init);
/* Should be called on processing a hugepagesz=... option */
void __init hugetlb_add_hstate(unsigned order)
{
struct hstate *h;
unsigned long i;
if (size_to_hstate(PAGE_SIZE << order)) {
printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
return;
}
BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
BUG_ON(order == 0);
h = &hstates[hugetlb_max_hstate++];
h->order = order;
h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
h->nr_huge_pages = 0;
h->free_huge_pages = 0;
for (i = 0; i < MAX_NUMNODES; ++i)
INIT_LIST_HEAD(&h->hugepage_freelists[i]);
INIT_LIST_HEAD(&h->hugepage_activelist);
h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
huge_page_size(h)/1024);
/*
* Add cgroup control files only if the huge page consists
* of more than two normal pages. This is because we use
* page[2].lru.next for storing cgoup details.
*/
if (order >= HUGETLB_CGROUP_MIN_ORDER)
hugetlb_cgroup_file_init(hugetlb_max_hstate - 1);
parsed_hstate = h;
}
static int __init hugetlb_nrpages_setup(char *s)
{
unsigned long *mhp;
static unsigned long *last_mhp;
/*
* !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
* so this hugepages= parameter goes to the "default hstate".
*/
if (!hugetlb_max_hstate)
mhp = &default_hstate_max_huge_pages;
else
mhp = &parsed_hstate->max_huge_pages;
if (mhp == last_mhp) {
printk(KERN_WARNING "hugepages= specified twice without "
"interleaving hugepagesz=, ignoring\n");
return 1;
}
if (sscanf(s, "%lu", mhp) <= 0)
*mhp = 0;
/*
* Global state is always initialized later in hugetlb_init.
* But we need to allocate >= MAX_ORDER hstates here early to still
* use the bootmem allocator.
*/
if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER)
hugetlb_hstate_alloc_pages(parsed_hstate);
last_mhp = mhp;
return 1;
}
__setup("hugepages=", hugetlb_nrpages_setup);
static int __init hugetlb_default_setup(char *s)
{
default_hstate_size = memparse(s, &s);
return 1;
}
__setup("default_hugepagesz=", hugetlb_default_setup);
static unsigned int cpuset_mems_nr(unsigned int *array)
{
int node;
unsigned int nr = 0;
for_each_node_mask(node, cpuset_current_mems_allowed)
nr += array[node];
return nr;
}
#ifdef CONFIG_SYSCTL
static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
struct ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
struct hstate *h = &default_hstate;
unsigned long tmp;
int ret;
tmp = h->max_huge_pages;
if (write && h->order >= MAX_ORDER)
return -EINVAL;
table->data = &tmp;
table->maxlen = sizeof(unsigned long);
ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
if (ret)
goto out;
if (write) {
NODEMASK_ALLOC(nodemask_t, nodes_allowed,
GFP_KERNEL | __GFP_NORETRY);
if (!(obey_mempolicy &&
init_nodemask_of_mempolicy(nodes_allowed))) {
NODEMASK_FREE(nodes_allowed);
nodes_allowed = &node_states[N_HIGH_MEMORY];
}
h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
if (nodes_allowed != &node_states[N_HIGH_MEMORY])
NODEMASK_FREE(nodes_allowed);
}
out:
return ret;
}
int hugetlb_sysctl_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
return hugetlb_sysctl_handler_common(false, table, write,
buffer, length, ppos);
}
#ifdef CONFIG_NUMA
int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
return hugetlb_sysctl_handler_common(true, table, write,
buffer, length, ppos);
}
#endif /* CONFIG_NUMA */
int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
void __user *buffer,
size_t *length, loff_t *ppos)
{
proc_dointvec(table, write, buffer, length, ppos);
if (hugepages_treat_as_movable)
htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
else
htlb_alloc_mask = GFP_HIGHUSER;
return 0;
}
int hugetlb_overcommit_handler(struct ctl_table *table, int write,
void __user *buffer,
size_t *length, loff_t *ppos)
{
struct hstate *h = &default_hstate;
unsigned long tmp;
int ret;
tmp = h->nr_overcommit_huge_pages;
if (write && h->order >= MAX_ORDER)
return -EINVAL;
table->data = &tmp;
table->maxlen = sizeof(unsigned long);
ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
if (ret)
goto out;
if (write) {
spin_lock(&hugetlb_lock);
h->nr_overcommit_huge_pages = tmp;
spin_unlock(&hugetlb_lock);
}
out:
return ret;
}
#endif /* CONFIG_SYSCTL */
void hugetlb_report_meminfo(struct seq_file *m)
{
struct hstate *h = &default_hstate;
seq_printf(m,
"HugePages_Total: %5lu\n"
"HugePages_Free: %5lu\n"
"HugePages_Rsvd: %5lu\n"
"HugePages_Surp: %5lu\n"
"Hugepagesize: %8lu kB\n",
h->nr_huge_pages,
h->free_huge_pages,
h->resv_huge_pages,
h->surplus_huge_pages,
1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
}
int hugetlb_report_node_meminfo(int nid, char *buf)
{
struct hstate *h = &default_hstate;
return sprintf(buf,
"Node %d HugePages_Total: %5u\n"
"Node %d HugePages_Free: %5u\n"
"Node %d HugePages_Surp: %5u\n",
nid, h->nr_huge_pages_node[nid],
nid, h->free_huge_pages_node[nid],
nid, h->surplus_huge_pages_node[nid]);
}
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
unsigned long hugetlb_total_pages(void)
{
struct hstate *h = &default_hstate;
return h->nr_huge_pages * pages_per_huge_page(h);
}
static int hugetlb_acct_memory(struct hstate *h, long delta)
{
int ret = -ENOMEM;
spin_lock(&hugetlb_lock);
/*
* When cpuset is configured, it breaks the strict hugetlb page
* reservation as the accounting is done on a global variable. Such
* reservation is completely rubbish in the presence of cpuset because
* the reservation is not checked against page availability for the
* current cpuset. Application can still potentially OOM'ed by kernel
* with lack of free htlb page in cpuset that the task is in.
* Attempt to enforce strict accounting with cpuset is almost
* impossible (or too ugly) because cpuset is too fluid that
* task or memory node can be dynamically moved between cpusets.
*
* The change of semantics for shared hugetlb mapping with cpuset is
* undesirable. However, in order to preserve some of the semantics,
* we fall back to check against current free page availability as
* a best attempt and hopefully to minimize the impact of changing
* semantics that cpuset has.
*/
if (delta > 0) {
if (gather_surplus_pages(h, delta) < 0)
goto out;
if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
return_unused_surplus_pages(h, delta);
goto out;
}
}
ret = 0;
if (delta < 0)
return_unused_surplus_pages(h, (unsigned long) -delta);
out:
spin_unlock(&hugetlb_lock);
return ret;
}
static void hugetlb_vm_op_open(struct vm_area_struct *vma)
{
struct resv_map *reservations = vma_resv_map(vma);
/*
* This new VMA should share its siblings reservation map if present.
* The VMA will only ever have a valid reservation map pointer where
* it is being copied for another still existing VMA. As that VMA
* has a reference to the reservation map it cannot disappear until
* after this open call completes. It is therefore safe to take a
* new reference here without additional locking.
*/
if (reservations)
kref_get(&reservations->refs);
}
static void resv_map_put(struct vm_area_struct *vma)
{
struct resv_map *reservations = vma_resv_map(vma);
if (!reservations)
return;
kref_put(&reservations->refs, resv_map_release);
}
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
struct hstate *h = hstate_vma(vma);
struct resv_map *reservations = vma_resv_map(vma);
struct hugepage_subpool *spool = subpool_vma(vma);
unsigned long reserve;
unsigned long start;
unsigned long end;
if (reservations) {
start = vma_hugecache_offset(h, vma, vma->vm_start);
end = vma_hugecache_offset(h, vma, vma->vm_end);
reserve = (end - start) -
region_count(&reservations->regions, start, end);
resv_map_put(vma);
if (reserve) {
hugetlb_acct_memory(h, -reserve);
hugepage_subpool_put_pages(spool, reserve);
}
}
}
/*
* We cannot handle pagefaults against hugetlb pages at all. They cause
* handle_mm_fault() to try to instantiate regular-sized pages in the
* hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
* this far.
*/
static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
BUG();
return 0;
}
const struct vm_operations_struct hugetlb_vm_ops = {
.fault = hugetlb_vm_op_fault,
.open = hugetlb_vm_op_open,
.close = hugetlb_vm_op_close,
};
static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
int writable)
{
pte_t entry;
if (writable) {
entry =
pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
} else {
entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
}
entry = pte_mkyoung(entry);
entry = pte_mkhuge(entry);
entry = arch_make_huge_pte(entry, vma, page, writable);
return entry;
}
static void set_huge_ptep_writable(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep)
{
pte_t entry;
entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1))
update_mmu_cache(vma, address, ptep);
}
int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
struct vm_area_struct *vma)
{
pte_t *src_pte, *dst_pte, entry;
struct page *ptepage;
unsigned long addr;
int cow;
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
src_pte = huge_pte_offset(src, addr);
if (!src_pte)
continue;
dst_pte = huge_pte_alloc(dst, addr, sz);
if (!dst_pte)
goto nomem;
/* If the pagetables are shared don't copy or take references */
if (dst_pte == src_pte)
continue;
spin_lock(&dst->page_table_lock);
spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
if (!huge_pte_none(huge_ptep_get(src_pte))) {
if (cow)
huge_ptep_set_wrprotect(src, addr, src_pte);
entry = huge_ptep_get(src_pte);
ptepage = pte_page(entry);
get_page(ptepage);
page_dup_rmap(ptepage);
set_huge_pte_at(dst, addr, dst_pte, entry);
}
spin_unlock(&src->page_table_lock);
spin_unlock(&dst->page_table_lock);
}
return 0;
nomem:
return -ENOMEM;
}
static int is_hugetlb_entry_migration(pte_t pte)
{
swp_entry_t swp;
if (huge_pte_none(pte) || pte_present(pte))
return 0;
swp = pte_to_swp_entry(pte);
if (non_swap_entry(swp) && is_migration_entry(swp))
return 1;
else
return 0;
}
static int is_hugetlb_entry_hwpoisoned(pte_t pte)
{
swp_entry_t swp;
if (huge_pte_none(pte) || pte_present(pte))
return 0;
swp = pte_to_swp_entry(pte);
if (non_swap_entry(swp) && is_hwpoison_entry(swp))
return 1;
else
return 0;
}
void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct page *ref_page)
{
int force_flush = 0;
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
pte_t *ptep;
pte_t pte;
struct page *page;
struct hstate *h = hstate_vma(vma);
unsigned long sz = huge_page_size(h);
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~huge_page_mask(h));
BUG_ON(end & ~huge_page_mask(h));
tlb_start_vma(tlb, vma);
mmu_notifier_invalidate_range_start(mm, start, end);
again:
spin_lock(&mm->page_table_lock);
for (address = start; address < end; address += sz) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
if (huge_pmd_unshare(mm, &address, ptep))
continue;
pte = huge_ptep_get(ptep);
if (huge_pte_none(pte))
continue;
/*
* HWPoisoned hugepage is already unmapped and dropped reference
*/
if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
continue;
page = pte_page(pte);
/*
* If a reference page is supplied, it is because a specific
* page is being unmapped, not a range. Ensure the page we
* are about to unmap is the actual page of interest.
*/
if (ref_page) {
if (page != ref_page)
continue;
/*
* Mark the VMA as having unmapped its page so that
* future faults in this VMA will fail rather than
* looking like data was lost
*/
set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
}
pte = huge_ptep_get_and_clear(mm, address, ptep);
tlb_remove_tlb_entry(tlb, ptep, address);
if (pte_dirty(pte))
set_page_dirty(page);
page_remove_rmap(page);
force_flush = !__tlb_remove_page(tlb, page);
if (force_flush)
break;
/* Bail out after unmapping reference page if supplied */
if (ref_page)
break;
}
spin_unlock(&mm->page_table_lock);
/*
* mmu_gather ran out of room to batch pages, we break out of
* the PTE lock to avoid doing the potential expensive TLB invalidate
* and page-free while holding it.
*/
if (force_flush) {
force_flush = 0;
tlb_flush_mmu(tlb);
if (address < end && !ref_page)
goto again;
}
mmu_notifier_invalidate_range_end(mm, start, end);
tlb_end_vma(tlb, vma);
}
void __unmap_hugepage_range_final(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start,
unsigned long end, struct page *ref_page)
{
__unmap_hugepage_range(tlb, vma, start, end, ref_page);
/*
* Clear this flag so that x86's huge_pmd_share page_table_shareable
* test will fail on a vma being torn down, and not grab a page table
* on its way out. We're lucky that the flag has such an appropriate
* name, and can in fact be safely cleared here. We could clear it
* before the __unmap_hugepage_range above, but all that's necessary
* is to clear it before releasing the i_mmap_mutex. This works
* because in the context this is called, the VMA is about to be
* destroyed and the i_mmap_mutex is held.
*/
vma->vm_flags &= ~VM_MAYSHARE;
}
void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end, struct page *ref_page)
{
struct mm_struct *mm;
struct mmu_gather tlb;
mm = vma->vm_mm;
tlb_gather_mmu(&tlb, mm, 0);
__unmap_hugepage_range(&tlb, vma, start, end, ref_page);
tlb_finish_mmu(&tlb, start, end);
}
/*
* This is called when the original mapper is failing to COW a MAP_PRIVATE
* mappping it owns the reserve page for. The intention is to unmap the page
* from other VMAs and let the children be SIGKILLed if they are faulting the
* same region.
*/
static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
struct page *page, unsigned long address)
{
struct hstate *h = hstate_vma(vma);
struct vm_area_struct *iter_vma;
struct address_space *mapping;
struct prio_tree_iter iter;
pgoff_t pgoff;
/*
* vm_pgoff is in PAGE_SIZE units, hence the different calculation
* from page cache lookup which is in HPAGE_SIZE units.
*/
address = address & huge_page_mask(h);
pgoff = vma_hugecache_offset(h, vma, address);
mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
/*
* Take the mapping lock for the duration of the table walk. As
* this mapping should be shared between all the VMAs,
* __unmap_hugepage_range() is called as the lock is already held
*/
mutex_lock(&mapping->i_mmap_mutex);
vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
/* Do not unmap the current VMA */
if (iter_vma == vma)
continue;
/*
* Unmap the page from other VMAs without their own reserves.
* They get marked to be SIGKILLed if they fault in these
* areas. This is because a future no-page fault on this VMA
* could insert a zeroed page instead of the data existing
* from the time of fork. This would look like data corruption
*/
if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
unmap_hugepage_range(iter_vma, address,
address + huge_page_size(h), page);
}
mutex_unlock(&mapping->i_mmap_mutex);
return 1;
}
/*
* Hugetlb_cow() should be called with page lock of the original hugepage held.
* Called with hugetlb_instantiation_mutex held and pte_page locked so we
* cannot race with other handlers or page migration.
* Keep the pte_same checks anyway to make transition from the mutex easier.
*/
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pte_t *ptep, pte_t pte,
struct page *pagecache_page)
{
struct hstate *h = hstate_vma(vma);
struct page *old_page, *new_page;
int avoidcopy;
int outside_reserve = 0;
old_page = pte_page(pte);
retry_avoidcopy:
/* If no-one else is actually using this page, avoid the copy
* and just make the page writable */
avoidcopy = (page_mapcount(old_page) == 1);
if (avoidcopy) {
if (PageAnon(old_page))
page_move_anon_rmap(old_page, vma, address);
set_huge_ptep_writable(vma, address, ptep);
return 0;
}
/*
* If the process that created a MAP_PRIVATE mapping is about to
* perform a COW due to a shared page count, attempt to satisfy
* the allocation without using the existing reserves. The pagecache
* page is used to determine if the reserve at this address was
* consumed or not. If reserves were used, a partial faulted mapping
* at the time of fork() could consume its reserves on COW instead
* of the full address range.
*/
if (!(vma->vm_flags & VM_MAYSHARE) &&
is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
old_page != pagecache_page)
outside_reserve = 1;
page_cache_get(old_page);
/* Drop page_table_lock as buddy allocator may be called */
spin_unlock(&mm->page_table_lock);
new_page = alloc_huge_page(vma, address, outside_reserve);
if (IS_ERR(new_page)) {
long err = PTR_ERR(new_page);
page_cache_release(old_page);
/*
* If a process owning a MAP_PRIVATE mapping fails to COW,
* it is due to references held by a child and an insufficient
* huge page pool. To guarantee the original mappers
* reliability, unmap the page from child processes. The child
* may get SIGKILLed if it later faults.
*/
if (outside_reserve) {
BUG_ON(huge_pte_none(pte));
if (unmap_ref_private(mm, vma, old_page, address)) {
BUG_ON(huge_pte_none(pte));
spin_lock(&mm->page_table_lock);
ptep = huge_pte_offset(mm, address & huge_page_mask(h));
if (likely(pte_same(huge_ptep_get(ptep), pte)))
goto retry_avoidcopy;
/*
* race occurs while re-acquiring page_table_lock, and
* our job is done.
*/
return 0;
}
WARN_ON_ONCE(1);
}
/* Caller expects lock to be held */
spin_lock(&mm->page_table_lock);
if (err == -ENOMEM)
return VM_FAULT_OOM;
else
return VM_FAULT_SIGBUS;
}
/*
* When the original hugepage is shared one, it does not have
* anon_vma prepared.
*/
if (unlikely(anon_vma_prepare(vma))) {
page_cache_release(new_page);
page_cache_release(old_page);
/* Caller expects lock to be held */
spin_lock(&mm->page_table_lock);
return VM_FAULT_OOM;
}
copy_user_huge_page(new_page, old_page, address, vma,
pages_per_huge_page(h));
__SetPageUptodate(new_page);
/*
* Retake the page_table_lock to check for racing updates
* before the page tables are altered
*/
spin_lock(&mm->page_table_lock);
ptep = huge_pte_offset(mm, address & huge_page_mask(h));
if (likely(pte_same(huge_ptep_get(ptep), pte))) {
/* Break COW */
mmu_notifier_invalidate_range_start(mm,
address & huge_page_mask(h),
(address & huge_page_mask(h)) + huge_page_size(h));
huge_ptep_clear_flush(vma, address, ptep);
set_huge_pte_at(mm, address, ptep,
make_huge_pte(vma, new_page, 1));
page_remove_rmap(old_page);
hugepage_add_new_anon_rmap(new_page, vma, address);
/* Make the old page be freed below */
new_page = old_page;
mmu_notifier_invalidate_range_end(mm,
address & huge_page_mask(h),
(address & huge_page_mask(h)) + huge_page_size(h));
}
page_cache_release(new_page);
page_cache_release(old_page);
return 0;
}
/* Return the pagecache page at a given address within a VMA */
static struct page *hugetlbfs_pagecache_page(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
struct address_space *mapping;
pgoff_t idx;
mapping = vma->vm_file->f_mapping;
idx = vma_hugecache_offset(h, vma, address);
return find_lock_page(mapping, idx);
}
/*
* Return whether there is a pagecache page to back given address within VMA.
* Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
*/
static bool hugetlbfs_pagecache_present(struct hstate *h,
struct vm_area_struct *vma, unsigned long address)
{
struct address_space *mapping;
pgoff_t idx;
struct page *page;
mapping = vma->vm_file->f_mapping;
idx = vma_hugecache_offset(h, vma, address);
page = find_get_page(mapping, idx);
if (page)
put_page(page);
return page != NULL;
}
static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, pte_t *ptep, unsigned int flags)
{
struct hstate *h = hstate_vma(vma);
int ret = VM_FAULT_SIGBUS;
int anon_rmap = 0;
pgoff_t idx;
unsigned long size;
struct page *page;
struct address_space *mapping;
pte_t new_pte;
/*
* Currently, we are forced to kill the process in the event the
* original mapper has unmapped pages from the child due to a failed
* COW. Warn that such a situation has occurred as it may not be obvious
*/
if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
printk(KERN_WARNING
"PID %d killed due to inadequate hugepage pool\n",
current->pid);
return ret;
}
mapping = vma->vm_file->f_mapping;
idx = vma_hugecache_offset(h, vma, address);
/*
* Use page lock to guard against racing truncation
* before we get page_table_lock.
*/
retry:
page = find_lock_page(mapping, idx);
if (!page) {
size = i_size_read(mapping->host) >> huge_page_shift(h);
if (idx >= size)
goto out;
page = alloc_huge_page(vma, address, 0);
if (IS_ERR(page)) {
ret = PTR_ERR(page);
if (ret == -ENOMEM)
ret = VM_FAULT_OOM;
else
ret = VM_FAULT_SIGBUS;
goto out;
}
clear_huge_page(page, address, pages_per_huge_page(h));
__SetPageUptodate(page);
if (vma->vm_flags & VM_MAYSHARE) {
int err;
struct inode *inode = mapping->host;
err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
if (err) {
put_page(page);
if (err == -EEXIST)
goto retry;
goto out;
}
spin_lock(&inode->i_lock);
inode->i_blocks += blocks_per_huge_page(h);
spin_unlock(&inode->i_lock);
} else {
lock_page(page);
if (unlikely(anon_vma_prepare(vma))) {
ret = VM_FAULT_OOM;
goto backout_unlocked;
}
anon_rmap = 1;
}
} else {
/*
* If memory error occurs between mmap() and fault, some process
* don't have hwpoisoned swap entry for errored virtual address.
* So we need to block hugepage fault by PG_hwpoison bit check.
*/
if (unlikely(PageHWPoison(page))) {
ret = VM_FAULT_HWPOISON |
VM_FAULT_SET_HINDEX(hstate_index(h));
goto backout_unlocked;
}
}
/*
* If we are going to COW a private mapping later, we examine the
* pending reservations for this page now. This will ensure that
* any allocations necessary to record that reservation occur outside
* the spinlock.
*/
if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
if (vma_needs_reservation(h, vma, address) < 0) {
ret = VM_FAULT_OOM;
goto backout_unlocked;
}
spin_lock(&mm->page_table_lock);
size = i_size_read(mapping->host) >> huge_page_shift(h);
if (idx >= size)
goto backout;
ret = 0;
if (!huge_pte_none(huge_ptep_get(ptep)))
goto backout;
if (anon_rmap)
hugepage_add_new_anon_rmap(page, vma, address);
else
page_dup_rmap(page);
new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
set_huge_pte_at(mm, address, ptep, new_pte);
if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
/* Optimization, do the COW without a second fault */
ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
}
spin_unlock(&mm->page_table_lock);
unlock_page(page);
out:
return ret;
backout:
spin_unlock(&mm->page_table_lock);
backout_unlocked:
unlock_page(page);
put_page(page);
goto out;
}
int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
{
pte_t *ptep;
pte_t entry;
int ret;
struct page *page = NULL;
struct page *pagecache_page = NULL;
static DEFINE_MUTEX(hugetlb_instantiation_mutex);
struct hstate *h = hstate_vma(vma);
address &= huge_page_mask(h);
ptep = huge_pte_offset(mm, address);
if (ptep) {
entry = huge_ptep_get(ptep);
if (unlikely(is_hugetlb_entry_migration(entry))) {
migration_entry_wait(mm, (pmd_t *)ptep, address);
return 0;
} else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
return VM_FAULT_HWPOISON_LARGE |
VM_FAULT_SET_HINDEX(hstate_index(h));
}
ptep = huge_pte_alloc(mm, address, huge_page_size(h));
if (!ptep)
return VM_FAULT_OOM;
/*
* Serialize hugepage allocation and instantiation, so that we don't
* get spurious allocation failures if two CPUs race to instantiate
* the same page in the page cache.
*/
mutex_lock(&hugetlb_instantiation_mutex);
entry = huge_ptep_get(ptep);
if (huge_pte_none(entry)) {
ret = hugetlb_no_page(mm, vma, address, ptep, flags);
goto out_mutex;
}
ret = 0;
/*
* If we are going to COW the mapping later, we examine the pending
* reservations for this page now. This will ensure that any
* allocations necessary to record that reservation occur outside the
* spinlock. For private mappings, we also lookup the pagecache
* page now as it is used to determine if a reservation has been
* consumed.
*/
if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
if (vma_needs_reservation(h, vma, address) < 0) {
ret = VM_FAULT_OOM;
goto out_mutex;
}
if (!(vma->vm_flags & VM_MAYSHARE))
pagecache_page = hugetlbfs_pagecache_page(h,
vma, address);
}
/*
* hugetlb_cow() requires page locks of pte_page(entry) and
* pagecache_page, so here we need take the former one
* when page != pagecache_page or !pagecache_page.
* Note that locking order is always pagecache_page -> page,
* so no worry about deadlock.
*/
page = pte_page(entry);
get_page(page);
if (page != pagecache_page)
lock_page(page);
spin_lock(&mm->page_table_lock);
/* Check for a racing update before calling hugetlb_cow */
if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
goto out_page_table_lock;
if (flags & FAULT_FLAG_WRITE) {
if (!pte_write(entry)) {
ret = hugetlb_cow(mm, vma, address, ptep, entry,
pagecache_page);
goto out_page_table_lock;
}
entry = pte_mkdirty(entry);
}
entry = pte_mkyoung(entry);
if (huge_ptep_set_access_flags(vma, address, ptep, entry,
flags & FAULT_FLAG_WRITE))
update_mmu_cache(vma, address, ptep);
out_page_table_lock:
spin_unlock(&mm->page_table_lock);
if (pagecache_page) {
unlock_page(pagecache_page);
put_page(pagecache_page);
}
if (page != pagecache_page)
unlock_page(page);
put_page(page);
out_mutex:
mutex_unlock(&hugetlb_instantiation_mutex);
return ret;
}
/* Can be overriden by architectures */
__attribute__((weak)) struct page *
follow_huge_pud(struct mm_struct *mm, unsigned long address,
pud_t *pud, int write)
{
BUG();
return NULL;
}
int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,
unsigned long *position, int *length, int i,
unsigned int flags)
{
unsigned long pfn_offset;
unsigned long vaddr = *position;
int remainder = *length;
struct hstate *h = hstate_vma(vma);
spin_lock(&mm->page_table_lock);
while (vaddr < vma->vm_end && remainder) {
pte_t *pte;
int absent;
struct page *page;
/*
* Some archs (sparc64, sh*) have multiple pte_ts to
* each hugepage. We have to make sure we get the
* first, for the page indexing below to work.
*/
pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
absent = !pte || huge_pte_none(huge_ptep_get(pte));
/*
* When coredumping, it suits get_dump_page if we just return
* an error where there's an empty slot with no huge pagecache
* to back it. This way, we avoid allocating a hugepage, and
* the sparse dumpfile avoids allocating disk blocks, but its
* huge holes still show up with zeroes where they need to be.
*/
if (absent && (flags & FOLL_DUMP) &&
!hugetlbfs_pagecache_present(h, vma, vaddr)) {
remainder = 0;
break;
}
if (absent ||
((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
int ret;
spin_unlock(&mm->page_table_lock);
ret = hugetlb_fault(mm, vma, vaddr,
(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
spin_lock(&mm->page_table_lock);
if (!(ret & VM_FAULT_ERROR))
continue;
remainder = 0;
break;
}
pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
page = pte_page(huge_ptep_get(pte));
same_page:
if (pages) {
pages[i] = mem_map_offset(page, pfn_offset);
get_page(pages[i]);
}
if (vmas)
vmas[i] = vma;
vaddr += PAGE_SIZE;
++pfn_offset;
--remainder;
++i;
if (vaddr < vma->vm_end && remainder &&
pfn_offset < pages_per_huge_page(h)) {
/*
* We use pfn_offset to avoid touching the pageframes
* of this compound page.
*/
goto same_page;
}
}
spin_unlock(&mm->page_table_lock);
*length = remainder;
*position = vaddr;
return i ? i : -EFAULT;
}
void hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long start = address;
pte_t *ptep;
pte_t pte;
struct hstate *h = hstate_vma(vma);
BUG_ON(address >= end);
flush_cache_range(vma, address, end);
mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
spin_lock(&mm->page_table_lock);
for (; address < end; address += huge_page_size(h)) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
if (huge_pmd_unshare(mm, &address, ptep))
continue;
if (!huge_pte_none(huge_ptep_get(ptep))) {
pte = huge_ptep_get_and_clear(mm, address, ptep);
pte = pte_mkhuge(pte_modify(pte, newprot));
set_huge_pte_at(mm, address, ptep, pte);
}
}
spin_unlock(&mm->page_table_lock);
/*
* Must flush TLB before releasing i_mmap_mutex: x86's huge_pmd_unshare
* may have cleared our pud entry and done put_page on the page table:
* once we release i_mmap_mutex, another task can do the final put_page
* and that page table be reused and filled with junk.
*/
flush_tlb_range(vma, start, end);
mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
}
int hugetlb_reserve_pages(struct inode *inode,
long from, long to,
struct vm_area_struct *vma,
vm_flags_t vm_flags)
{
long ret, chg;
struct hstate *h = hstate_inode(inode);
struct hugepage_subpool *spool = subpool_inode(inode);
/*
* Only apply hugepage reservation if asked. At fault time, an
* attempt will be made for VM_NORESERVE to allocate a page
* without using reserves
*/
if (vm_flags & VM_NORESERVE)
return 0;
/*
* Shared mappings base their reservation on the number of pages that
* are already allocated on behalf of the file. Private mappings need
* to reserve the full area even if read-only as mprotect() may be
* called to make the mapping read-write. Assume !vma is a shm mapping
*/
if (!vma || vma->vm_flags & VM_MAYSHARE)
chg = region_chg(&inode->i_mapping->private_list, from, to);
else {
struct resv_map *resv_map = resv_map_alloc();
if (!resv_map)
return -ENOMEM;
chg = to - from;
set_vma_resv_map(vma, resv_map);
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
}
if (chg < 0) {
ret = chg;
goto out_err;
}
/* There must be enough pages in the subpool for the mapping */
if (hugepage_subpool_get_pages(spool, chg)) {
ret = -ENOSPC;
goto out_err;
}
/*
* Check enough hugepages are available for the reservation.
* Hand the pages back to the subpool if there are not
*/
ret = hugetlb_acct_memory(h, chg);
if (ret < 0) {
hugepage_subpool_put_pages(spool, chg);
goto out_err;
}
/*
* Account for the reservations made. Shared mappings record regions
* that have reservations as they are shared by multiple VMAs.
* When the last VMA disappears, the region map says how much
* the reservation was and the page cache tells how much of
* the reservation was consumed. Private mappings are per-VMA and
* only the consumed reservations are tracked. When the VMA
* disappears, the original reservation is the VMA size and the
* consumed reservations are stored in the map. Hence, nothing
* else has to be done for private mappings here
*/
if (!vma || vma->vm_flags & VM_MAYSHARE)
region_add(&inode->i_mapping->private_list, from, to);
return 0;
out_err:
if (vma)
resv_map_put(vma);
return ret;
}
void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
{
struct hstate *h = hstate_inode(inode);
long chg = region_truncate(&inode->i_mapping->private_list, offset);
struct hugepage_subpool *spool = subpool_inode(inode);
spin_lock(&inode->i_lock);
inode->i_blocks -= (blocks_per_huge_page(h) * freed);
spin_unlock(&inode->i_lock);
hugepage_subpool_put_pages(spool, (chg - freed));
hugetlb_acct_memory(h, -(chg - freed));
}
#ifdef CONFIG_MEMORY_FAILURE
/* Should be called in hugetlb_lock */
static int is_hugepage_on_freelist(struct page *hpage)
{
struct page *page;
struct page *tmp;
struct hstate *h = page_hstate(hpage);
int nid = page_to_nid(hpage);
list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru)
if (page == hpage)
return 1;
return 0;
}
/*
* This function is called from memory failure code.
* Assume the caller holds page lock of the head page.
*/
int dequeue_hwpoisoned_huge_page(struct page *hpage)
{
struct hstate *h = page_hstate(hpage);
int nid = page_to_nid(hpage);
int ret = -EBUSY;
spin_lock(&hugetlb_lock);
if (is_hugepage_on_freelist(hpage)) {
list_del(&hpage->lru);
set_page_refcounted(hpage);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
ret = 0;
}
spin_unlock(&hugetlb_lock);
return ret;
}
#endif