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Author SHA1 Message Date
Kirill A. Shutemov
d281ee6145 rmap: add argument to charge compound page 
We're going to allow mapping of individual 4k pages of THP compound
page.  It means we cannot rely on PageTransHuge() check to decide if
map/unmap small page or THP.

The patch adds new argument to rmap functions to indicate whether we
want to operate on whole compound page or only the small page.

[n-horiguchi@ah.jp.nec.com: fix mapcount mismatch in hugepage migration]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov
48c935ad88 page-flags: define PG_locked behavior on compound pages 
lock_page() must operate on the whole compound page.  It doesn't make
much sense to lock part of compound page.  Change code to use head
page's PG_locked, if tail page is passed.

This patch also gets rid of custom helper functions --
__set_page_locked() and __clear_page_locked().  They are replaced with
helpers generated by __SETPAGEFLAG/__CLEARPAGEFLAG.  Tail pages to these
helper would trigger VM_BUG_ON().

SLUB uses PG_locked as a bit spin locked.  IIUC, tail pages should never
appear there.  VM_BUG_ON() is added to make sure that this assumption is
correct.

[akpm@linux-foundation.org: fix fs/cifs/file.c]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Mel Gorman
71baba4b92 mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 
__GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep.  Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep.  The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake.  As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags.  This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-06 17:50:42 -08:00
Mel Gorman
d0164adc89 mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-06 17:50:42 -08:00
Hugh Dickins
42cb14b110 mm: migrate dirty page without clear_page_dirty_for_io etc 
clear_page_dirty_for_io() has accumulated writeback and memcg subtleties
since v2.6.16 first introduced page migration; and the set_page_dirty()
which completed its migration of PageDirty, later had to be moderated to
__set_page_dirty_nobuffers(); then PageSwapBacked had to skip that too.

No actual problems seen with this procedure recently, but if you look into
what the clear_page_dirty_for_io(page)+set_page_dirty(newpage) is actually
achieving, it turns out to be nothing more than moving the PageDirty flag,
and its NR_FILE_DIRTY stat from one zone to another.

It would be good to avoid a pile of irrelevant decrementations and
incrementations, and improper event counting, and unnecessary descent of
the radix_tree under tree_lock (to set the PAGECACHE_TAG_DIRTY which
radix_tree_replace_slot() left in place anyway).

Do the NR_FILE_DIRTY movement, like the other stats movements, while
interrupts still disabled in migrate_page_move_mapping(); and don't even
bother if the zone is the same.  Do the PageDirty movement there under
tree_lock too, where old page is frozen and newpage not yet visible:
bearing in mind that as soon as newpage becomes visible in radix_tree, an
un-page-locked set_page_dirty() might interfere (or perhaps that's just
not possible: anything doing so should already hold an additional
reference to the old page, preventing its migration; but play safe).

But we do still need to transfer PageDirty in migrate_page_copy(), for
those who don't go the mapping route through migrate_page_move_mapping().

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
cf4b769abb mm: page migration avoid touching newpage until no going back 
We have had trouble in the past from the way in which page migration's
newpage is initialized in dribs and drabs - see commit 8bdd638091 ("mm:
fix direct reclaim writeback regression") which proposed a cleanup.

We have no actual problem now, but I think the procedure would be clearer
(and alternative get_new_page pools safer to implement) if we assert that
newpage is not touched until we are sure that it's going to be used -
except for taking the trylock on it in __unmap_and_move().

So shift the early initializations from move_to_new_page() into
migrate_page_move_mapping(), mapping and NULL-mapping paths.  Similarly
migrate_huge_page_move_mapping(), but its NULL-mapping path can just be
deleted: you cannot reach hugetlbfs_migrate_page() with a NULL mapping.

Adjust stages 3 to 8 in the Documentation file accordingly.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
03f15c86c8 mm: simplify page migration's anon_vma comment and flow 
__unmap_and_move() contains a long stale comment on page_get_anon_vma()
and PageSwapCache(), with an odd control flow that's hard to follow.
Mostly this reflects our confusion about the lifetime of an anon_vma, in
the early days of page migration, before we could take a reference to one.
 Nowadays this seems quite straightforward: cut it all down to essentials.

I cannot see the relevance of swapcache here at all, so don't treat it any
differently: I believe the old comment reflects in part our anon_vma
confusions, and in part the original v2.6.16 page migration technique,
which used actual swap to migrate anon instead of swap-like migration
entries.  Why should a swapcache page not be migrated with the aid of
migration entry ptes like everything else?  So lose that comment now, and
enable migration entries for swapcache in the next patch.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
5c3f9a6737 mm: page migration remove_migration_ptes at lock+unlock level 
Clean up page migration a little more by calling remove_migration_ptes()
from the same level, on success or on failure, from __unmap_and_move() or
from unmap_and_move_huge_page().

Don't reset page->mapping of a PageAnon old page in move_to_new_page(),
leave that to when the page is freed.  Except for here in page migration,
it has been an invariant that a PageAnon (bit set in page->mapping) page
stays PageAnon until it is freed, and I think we're safer to keep to that.

And with the above rearrangement, it's necessary because zap_pte_range()
wants to identify whether a migration entry represents a file or an anon
page, to update the appropriate rss stats without waiting on it.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
7db7671f83 mm: page migration trylock newpage at same level as oldpage 
Clean up page migration a little by moving the trylock of newpage from
move_to_new_page() into __unmap_and_move(), where the old page has been
locked.  Adjust unmap_and_move_huge_page() and balloon_page_migrate()
accordingly.

But make one kind-of-functional change on the way: whereas trylock of
newpage used to BUG() if it failed, now simply return -EAGAIN if so.
Cutting out BUG()s is good, right?  But, to be honest, this is really to
extend the usefulness of the custom put_new_page feature, allowing a pool
of new pages to be shared perhaps with racing uses.

Use an "else" instead of that "skip_unmap" label.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
2def7424c9 mm: page migration use the put_new_page whenever necessary 
I don't know of any problem from the way it's used in our current tree,
but there is one defect in page migration's custom put_new_page feature.

An unused newpage is expected to be released with the put_new_page(), but
there was one MIGRATEPAGE_SUCCESS (0) path which released it with
putback_lru_page(): which can be very wrong for a custom pool.

Fixed more easily by resetting put_new_page once it won't be needed, than
by adding a further flag to modify the rc test.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
14e0f9bcc9 mm: correct a couple of page migration comments 
It's migrate.c not migration,c, and nowadays putback_movable_pages() not
putback_lru_pages().

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
45637bab30 mm: rename mem_cgroup_migrate to mem_cgroup_replace_page 
After v4.3's commit 0610c25daa ("memcg: fix dirty page migration")
mem_cgroup_migrate() doesn't have much to offer in page migration: convert
migrate_misplaced_transhuge_page() to set_page_memcg() instead.

Then rename mem_cgroup_migrate() to mem_cgroup_replace_page(), since its
remaining callers are replace_page_cache_page() and shmem_replace_page():
both of whom passed lrucare true, so just eliminate that argument.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Hugh Dickins
51afb12ba8 mm: page migration fix PageMlocked on migrated pages 
Commit e6c509f854 ("mm: use clear_page_mlock() in page_remove_rmap()")
in v3.7 inadvertently made mlock_migrate_page() impotent: page migration
unmaps the page from userspace before migrating, and that commit clears
PageMlocked on the final unmap, leaving mlock_migrate_page() with
nothing to do.  Not a serious bug, the next attempt at reclaiming the
page would fix it up; but a betrayal of page migration's intent - the
new page ought to emerge as PageMlocked.

I don't see how to fix it for mlock_migrate_page() itself; but easily
fixed in remove_migration_pte(), by calling mlock_vma_page() when the vma
is VM_LOCKED - under pte lock as in try_to_unmap_one().

Delete mlock_migrate_page()?  Not quite, it does still serve a purpose for
migrate_misplaced_transhuge_page(): where we could replace it by a test,
clear_page_mlock(), mlock_vma_page() sequence; but would that be an
improvement?  mlock_migrate_page() is fairly lean, and let's make it
leaner by skipping the irq save/restore now clearly not needed.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Vlastimil Babka
f2f81fb2b7 mm, migrate: count pages failing all retries in vmstat and tracepoint 
Migration tries up to 10 times to migrate pages that return -EAGAIN until
it gives up.  If some pages fail all retries, they are counted towards the
number of failed pages that migrate_pages() returns.  They should also be
counted in the /proc/vmstat pgmigrate_fail and in the mm_migrate_pages
tracepoint.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Greg Thelen
0610c25daa memcg: fix dirty page migration 
The problem starts with a file backed dirty page which is charged to a
memcg.  Then page migration is used to move oldpage to newpage.

Migration:
 - copies the oldpage's data to newpage
 - clears oldpage.PG_dirty
 - sets newpage.PG_dirty
 - uncharges oldpage from memcg
 - charges newpage to memcg

Clearing oldpage.PG_dirty decrements the charged memcg's dirty page
count.

However, because newpage is not yet charged, setting newpage.PG_dirty
does not increment the memcg's dirty page count.  After migration
completes newpage.PG_dirty is eventually cleared, often in
account_page_cleaned().  At this time newpage is charged to a memcg so
the memcg's dirty page count is decremented which causes underflow
because the count was not previously incremented by migration.  This
underflow causes balance_dirty_pages() to see a very large unsigned
number of dirty memcg pages which leads to aggressive throttling of
buffered writes by processes in non root memcg.

This issue:
 - can harm performance of non root memcg buffered writes.
 - can report too small (even negative) values in
   memory.stat[(total_)dirty] counters of all memcg, including the root.

To avoid polluting migrate.c with #ifdef CONFIG_MEMCG checks, introduce
page_memcg() and set_page_memcg() helpers.

Test:
    0) setup and enter limited memcg
    mkdir /sys/fs/cgroup/test
    echo 1G > /sys/fs/cgroup/test/memory.limit_in_bytes
    echo $$ > /sys/fs/cgroup/test/cgroup.procs

    1) buffered writes baseline
    dd if=/dev/zero of=/data/tmp/foo bs=1M count=1k
    sync
    grep ^dirty /sys/fs/cgroup/test/memory.stat

    2) buffered writes with compaction antagonist to induce migration
    yes 1 > /proc/sys/vm/compact_memory &
    rm -rf /data/tmp/foo
    dd if=/dev/zero of=/data/tmp/foo bs=1M count=1k
    kill %
    sync
    grep ^dirty /sys/fs/cgroup/test/memory.stat

    3) buffered writes without antagonist, should match baseline
    rm -rf /data/tmp/foo
    dd if=/dev/zero of=/data/tmp/foo bs=1M count=1k
    sync
    grep ^dirty /sys/fs/cgroup/test/memory.stat

                       (speed, dirty residue)
             unpatched                       patched
    1) 841 MB/s 0 dirty pages          886 MB/s 0 dirty pages
    2) 611 MB/s -33427456 dirty pages  793 MB/s 0 dirty pages
    3) 114 MB/s -33427456 dirty pages  891 MB/s 0 dirty pages

    Notice that unpatched baseline performance (1) fell after
    migration (3): 841 -> 114 MB/s.  In the patched kernel, post
    migration performance matches baseline.

Fixes: c4843a7593 ("memcg: add per cgroup dirty page accounting")
Signed-off-by: Greg Thelen <gthelen@google.com>
Reported-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-10-01 21:42:35 -04:00
Naoya Horiguchi
3aaa76e125 mm: migrate: hugetlb: putback destination hugepage to active list 
Since commit bcc5422230 ("mm: hugetlb: introduce page_huge_active")
each hugetlb page maintains its active flag to avoid a race condition
betwe= en multiple calls of isolate_huge_page(), but current kernel
doesn't set the f= lag on a hugepage allocated by migration because the
proper putback routine isn= 't called.  This means that users could
still encounter the race referred to by bcc5422230 in this special
case, so this patch fixes it.

Fixes: bcc5422230 ("mm: hugetlb: introduce page_huge_active")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>  [4.1.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-22 15:09:53 -07:00
Vladimir Davydov
33c3fc71c8 mm: introduce idle page tracking 
Knowing the portion of memory that is not used by a certain application or
memory cgroup (idle memory) can be useful for partitioning the system
efficiently, e.g.  by setting memory cgroup limits appropriately.
Currently, the only means to estimate the amount of idle memory provided
by the kernel is /proc/PID/{clear_refs,smaps}: the user can clear the
access bit for all pages mapped to a particular process by writing 1 to
clear_refs, wait for some time, and then count smaps:Referenced.  However,
this method has two serious shortcomings:

 - it does not count unmapped file pages
 - it affects the reclaimer logic

To overcome these drawbacks, this patch introduces two new page flags,
Idle and Young, and a new sysfs file, /sys/kernel/mm/page_idle/bitmap.
A page's Idle flag can only be set from userspace by setting bit in
/sys/kernel/mm/page_idle/bitmap at the offset corresponding to the page,
and it is cleared whenever the page is accessed either through page tables
(it is cleared in page_referenced() in this case) or using the read(2)
system call (mark_page_accessed()). Thus by setting the Idle flag for
pages of a particular workload, which can be found e.g.  by reading
/proc/PID/pagemap, waiting for some time to let the workload access its
working set, and then reading the bitmap file, one can estimate the amount
of pages that are not used by the workload.

The Young page flag is used to avoid interference with the memory
reclaimer.  A page's Young flag is set whenever the Access bit of a page
table entry pointing to the page is cleared by writing to the bitmap file.
If page_referenced() is called on a Young page, it will add 1 to its
return value, therefore concealing the fact that the Access bit was
cleared.

Note, since there is no room for extra page flags on 32 bit, this feature
uses extended page flags when compiled on 32 bit.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: kpageidle requires an MMU]
[akpm@linux-foundation.org: decouple from page-flags rework]
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-10 13:29:01 -07:00
Vlastimil Babka
96db800f5d mm: rename alloc_pages_exact_node() to __alloc_pages_node() 
alloc_pages_exact_node() was introduced in commit 6484eb3e2a ("page
allocator: do not check NUMA node ID when the caller knows the node is
valid") as an optimized variant of alloc_pages_node(), that doesn't
fallback to current node for nid == NUMA_NO_NODE.  Unfortunately the
name of the function can easily suggest that the allocation is
restricted to the given node and fails otherwise.  In truth, the node is
only preferred, unless __GFP_THISNODE is passed among the gfp flags.

The misleading name has lead to mistakes in the past, see for example
commits 5265047ac3 ("mm, thp: really limit transparent hugepage
allocation to local node") and b360edb43f ("mm, mempolicy:
migrate_to_node should only migrate to node").

Another issue with the name is that there's a family of
alloc_pages_exact*() functions where 'exact' means exact size (instead
of page order), which leads to more confusion.

To prevent further mistakes, this patch effectively renames
alloc_pages_exact_node() to __alloc_pages_node() to better convey that
it's an optimized variant of alloc_pages_node() not intended for general
usage.  Both functions get described in comments.

It has been also considered to really provide a convenience function for
allocations restricted to a node, but the major opinion seems to be that
__GFP_THISNODE already provides that functionality and we shouldn't
duplicate the API needlessly.  The number of users would be small
anyway.

Existing callers of alloc_pages_exact_node() are simply converted to
call __alloc_pages_node(), with the exception of sba_alloc_coherent()
which open-codes the check for NUMA_NO_NODE, so it is converted to use
alloc_pages_node() instead.  This means it no longer performs some
VM_BUG_ON checks, and since the current check for nid in
alloc_pages_node() uses a 'nid < 0' comparison (which includes
NUMA_NO_NODE), it may hide wrong values which would be previously
exposed.

Both differences will be rectified by the next patch.

To sum up, this patch makes no functional changes, except temporarily
hiding potentially buggy callers.  Restricting the checks in
alloc_pages_node() is left for the next patch which can in turn expose
more existing buggy callers.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Robin Holt <robinmholt@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Cliff Whickman <cpw@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Wanpeng Li
da1b13ccfb mm/hwpoison: fix race between soft_offline_page and unpoison_memory 
Wanpeng Li reported a race between soft_offline_page() and
unpoison_memory(), which causes the following kernel panic:

   BUG: Bad page state in process bash  pfn:97000
   page:ffffea00025c0000 count:0 mapcount:1 mapping:          (null) index:0x7f4fdbe00
   flags: 0x1fffff80080048(uptodate|active|swapbacked)
   page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
   bad because of flags:
   flags: 0x40(active)
   Modules linked in: snd_hda_codec_hdmi i915 rpcsec_gss_krb5 nfsv4 dns_resolver bnep rfcomm nfsd bluetooth auth_rpcgss nfs_acl nfs rfkill lockd grace sunrpc i2c_algo_bit drm_kms_helper snd_hda_codec_realtek snd_hda_codec_generic drm snd_hda_intel fscache snd_hda_codec x86_pkg_temp_thermal coretemp kvm_intel snd_hda_core snd_hwdep kvm snd_pcm snd_seq_dummy snd_seq_oss crct10dif_pclmul snd_seq_midi crc32_pclmul snd_seq_midi_event ghash_clmulni_intel snd_rawmidi aesni_intel lrw gf128mul snd_seq glue_helper ablk_helper snd_seq_device cryptd fuse snd_timer dcdbas serio_raw mei_me parport_pc snd mei ppdev i2c_core video lp soundcore parport lpc_ich shpchp mfd_core ext4 mbcache jbd2 sd_mod e1000e ahci ptp libahci crc32c_intel libata pps_core
   CPU: 3 PID: 2211 Comm: bash Not tainted 4.2.0-rc5-mm1+ #45
   Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015
   Call Trace:
     dump_stack+0x48/0x5c
     bad_page+0xe6/0x140
     free_pages_prepare+0x2f9/0x320
     ? uncharge_list+0xdd/0x100
     free_hot_cold_page+0x40/0x170
     __put_single_page+0x20/0x30
     put_page+0x25/0x40
     unmap_and_move+0x1a6/0x1f0
     migrate_pages+0x100/0x1d0
     ? kill_procs+0x100/0x100
     ? unlock_page+0x6f/0x90
     __soft_offline_page+0x127/0x2a0
     soft_offline_page+0xa6/0x200

This race is explained like below:

  CPU0                    CPU1

  soft_offline_page
  __soft_offline_page
  TestSetPageHWPoison
                        unpoison_memory
                        PageHWPoison check (true)
                        TestClearPageHWPoison
                        put_page    -> release refcount held by get_hwpoison_page in unpoison_memory
                        put_page    -> release refcount held by isolate_lru_page in __soft_offline_page
  migrate_pages

The second put_page() releases refcount held by isolate_lru_page() which
will lead to unmap_and_move() releases the last refcount of page and w/
mapcount still 1 since try_to_unmap() is not called if there is only one
user map the page.  Anyway, the page refcount and mapcount will still
mess if the page is mapped by multiple users.

This race was introduced by commit 4491f71260 ("mm/memory-failure: set
PageHWPoison before migrate_pages()"), which focuses on preventing the
reuse of successfully migrated page.  Before this commit we prevent the
reuse by changing the migratetype to MIGRATE_ISOLATE during soft
offlining, which has the following problems, so simply reverting the
commit is not a best option:

  1) it doesn't eliminate the reuse completely, because
     set_migratetype_isolate() can fail to set MIGRATE_ISOLATE to the
     target page if the pageblock of the page contains one or more
     unmovable pages (i.e.  has_unmovable_pages() returns true).

  2) the original code changes migratetype to MIGRATE_ISOLATE
     forcibly, and sets it to MIGRATE_MOVABLE forcibly after soft offline,
     regardless of the original migratetype state, which could impact
     other subsystems like memory hotplug or compaction.

This patch moves PageSetHWPoison just after put_page() in
unmap_and_move(), which closes up the reported race window and minimizes
another race window b/w SetPageHWPoison and reallocation (which causes
the reuse of soft-offlined page.) The latter race window still exists
but it's acceptable, because it's rare and effectively the same as
ordinary "containment failure" case even if it happens, so keep the
window open is acceptable.

Fixes: 4491f71260 ("mm/memory-failure: set PageHWPoison before migrate_pages()")
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Wanpeng Li <wanpeng.li@hotmail.com>
Tested-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Kirill A. Shutemov
d899844e9c mm: fix status code which move_pages() returns for zero page 
The manpage for move_pages(2) specifies that status code for zero page is
supposed to be -EFAULT.  Currently kernel return -ENOENT in this case.

follow_page() can do it for us, if we would ask for FOLL_DUMP.  The use of
FOLL_DUMP also means that the upper layer page tables pages are no longer
allocated.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-04 16:54:41 -07:00
Naoya Horiguchi
4491f71260 mm/memory-failure: set PageHWPoison before migrate_pages() 
Now page freeing code doesn't consider PageHWPoison as a bad page, so by
setting it before completing the page containment, we can prevent the
error page from being reused just after successful page migration.

I added TTU_IGNORE_HWPOISON for try_to_unmap() to make sure that the
page table entry is transformed into migration entry, not to hwpoison
entry.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Dean Nelson <dnelson@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-08-07 04:39:42 +03:00
Naoya Horiguchi
f4c18e6f7b mm: check __PG_HWPOISON separately from PAGE_FLAGS_CHECK_AT_* 
The race condition addressed in commit add05cecef ("mm: soft-offline:
don't free target page in successful page migration") was not closed
completely, because that can happen not only for soft-offline, but also
for hard-offline.  Consider that a slab page is about to be freed into
buddy pool, and then an uncorrected memory error hits the page just
after entering __free_one_page(), then VM_BUG_ON_PAGE(page->flags &
PAGE_FLAGS_CHECK_AT_PREP) is triggered, despite the fact that it's not
necessary because the data on the affected page is not consumed.

To solve it, this patch drops __PG_HWPOISON from page flag checks at
allocation/free time.  I think it's justified because __PG_HWPOISON
flags is defined to prevent the page from being reused, and setting it
outside the page's alloc-free cycle is a designed behavior (not a bug.)

For recent months, I was annoyed about BUG_ON when soft-offlined page
remains on lru cache list for a while, which is avoided by calling
put_page() instead of putback_lru_page() in page migration's success
path.  This means that this patch reverts a major change from commit
add05cecef about the new refcounting rule of soft-offlined pages, so
"reuse window" revives.  This will be closed by a subsequent patch.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Dean Nelson <dnelson@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-08-07 04:39:42 +03:00
Aneesh Kumar K.V
8809aa2d28 mm: clarify that the function operates on hugepage pte 
We have confusing functions to clear pmd, pmd_clear_* and pmd_clear.  Add
_huge_ to pmdp_clear functions so that we are clear that they operate on
hugepage pte.

We don't bother about other functions like pmdp_set_wrprotect,
pmdp_clear_flush_young, because they operate on PTE bits and hence
indicate they are operating on hugepage ptes

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-06-24 17:49:44 -07:00
Naoya Horiguchi
add05cecef mm: soft-offline: don't free target page in successful page migration 
Stress testing showed that soft offline events for a process iterating
"mmap-pagefault-munmap" loop can trigger
VM_BUG_ON(PAGE_FLAGS_CHECK_AT_PREP) in __free_one_page():

  Soft offlining page 0x70fe1 at 0x70100008d000
  Soft offlining page 0x705fb at 0x70300008d000
  page:ffffea0001c3f840 count:0 mapcount:0 mapping:          (null) index:0x2
  flags: 0x1fffff80800000(hwpoison)
  page dumped because: VM_BUG_ON_PAGE(page->flags & ((1 << 25) - 1))
  ------------[ cut here ]------------
  kernel BUG at /src/linux-dev/mm/page_alloc.c:585!
  invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
  Modules linked in: cfg80211 rfkill crc32c_intel microcode ppdev parport_pc pcspkr serio_raw virtio_balloon parport i2c_piix4 virtio_blk virtio_net ata_generic pata_acpi floppy
  CPU: 3 PID: 1779 Comm: test_base_madv_ Not tainted 4.0.0-v4.0-150511-1451-00009-g82360a3730e6 #139
  RIP: free_pcppages_bulk+0x52a/0x6f0
  Call Trace:
    drain_pages_zone+0x3d/0x50
    drain_local_pages+0x1d/0x30
    on_each_cpu_mask+0x46/0x80
    drain_all_pages+0x14b/0x1e0
    soft_offline_page+0x432/0x6e0
    SyS_madvise+0x73c/0x780
    system_call_fastpath+0x12/0x17
  Code: ff 89 45 b4 48 8b 45 c0 48 83 b8 a8 00 00 00 00 0f 85 e3 fb ff ff 0f 1f 00 0f 0b 48 8b 7d 90 48 c7 c6 e8 95 a6 81 e8 e6 32 02 00 <0f> 0b 8b 45 cc 49 89 47 30 41 8b 47 18 83 f8 ff 0f 85 10 ff ff
  RIP  [<ffffffff811a806a>] free_pcppages_bulk+0x52a/0x6f0
   RSP <ffff88007a117d28>
  ---[ end trace 53926436e76d1f35 ]---

When soft offline successfully migrates page, the source page is supposed
to be freed.  But there is a race condition where a source page looks
isolated (i.e.  the refcount is 0 and the PageHWPoison is set) but
somewhat linked to pcplist.  Then another soft offline event calls
drain_all_pages() and tries to free such hwpoisoned page, which is
forbidden.

This odd page state seems to happen due to the race between put_page() in
putback_lru_page() and __pagevec_lru_add_fn().  But I don't want to play
with tweaking drain code as done in commit 9ab3b598d2 "mm: hwpoison:
drop lru_add_drain_all() in __soft_offline_page()", or to change page
freeing code for this soft offline's purpose.

Instead, let's think about the difference between hard offline and soft
offline.  There is an interesting difference in how to isolate the in-use
page between these, that is, hard offline marks PageHWPoison of the target
page at first, and doesn't free it by keeping its refcount 1.  OTOH, soft
offline tries to free the target page then marks PageHWPoison.  This
difference might be the source of complexity and result in bugs like the
above.  So making soft offline isolate with keeping refcount can be a
solution for this problem.

We can pass to page migration code the "reason" which shows the caller, so
let's use this more to avoid calling putback_lru_page() when called from
soft offline, which effectively does the isolation for soft offline.  With
this change, target pages of soft offline never be reused without changing
migratetype, so this patch also removes the related code.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-06-24 17:49:42 -07:00
Naoya Horiguchi
b3b3a99c53 mm/migrate: check-before-clear PageSwapCache 
With the page flag sanitization patchset, an invalid usage of
ClearPageSwapCache() is detected in migration_page_copy().
migrate_page_copy() is shared by both normal and hugepage (both thp and
hugetlb) code path, so let's check PageSwapCache() and clear it if it's
set to avoid misuse of the invalid clear operation.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-15 16:35:17 -07:00
Mel Gorman
2a8e700264 mm: numa: remove migrate_ratelimited 
This code is dead since commit 9e645ab6d0 ("sched/numa: Continue PTE
scanning even if migrate rate limited") so remove it.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-14 16:49:05 -07:00
Geert Uytterhoeven
ef2a5153b4 mm/migrate: mark unmap_and_move() "noinline" to avoid ICE in gcc 4.7.3 
With gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-12ubuntu1) :

    mm/migrate.c: In function `migrate_pages':
    mm/migrate.c:1148:1: internal compiler error: in push_minipool_fix, at config/arm/arm.c:13500
    Please submit a full bug report,
    with preprocessed source if appropriate.
    See <file:///usr/share/doc/gcc-4.7/README.Bugs> for instructions.
    Preprocessed source stored into /tmp/ccPoM1tr.out file, please attach this to your bugreport.
    make[1]: *** [mm/migrate.o] Error 1
    make: *** [mm/migrate.o] Error 2

Mark unmap_and_move() (which is used in a single place only) "noinline"
to work around this compiler bug.

[akpm@linux-foundation.org: make it conditional on gcc-4.7.3 and arm]
[khilman@kernel.org: fine-tune compiler versions]
[akpm@linux-foundation.org: fix comment]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reported-by: Kevin Hilman <khilman@kernel.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-14 16:48:59 -07:00
Mel Gorman
4d94246699 mm: convert p[te|md]_mknonnuma and remaining page table manipulations 
With PROT_NONE, the traditional page table manipulation functions are
sufficient.

[andre.przywara@arm.com: fix compiler warning in pmdp_invalidate()]
[akpm@linux-foundation.org: fix build with STRICT_MM_TYPECHECKS]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Mel Gorman
5d83306213 mm: numa: do not dereference pmd outside of the lock during NUMA hinting fault 
Automatic NUMA balancing depends on being able to protect PTEs to trap a
fault and gather reference locality information.  Very broadly speaking
it would mark PTEs as not present and use another bit to distinguish
between NUMA hinting faults and other types of faults.  It was
universally loved by everybody and caused no problems whatsoever.  That
last sentence might be a lie.

This series is very heavily based on patches from Linus and Aneesh to
replace the existing PTE/PMD NUMA helper functions with normal change
protections.  I did alter and add parts of it but I consider them
relatively minor contributions.  At their suggestion, acked-bys are in
there but I've no problem converting them to Signed-off-by if requested.

AFAIK, this has received no testing on ppc64 and I'm depending on Aneesh
for that.  I tested trinity under kvm-tool and passed and ran a few
other basic tests.  At the time of writing, only the short-lived tests
have completed but testing of V2 indicated that long-term testing had no
surprises.  In most cases I'm leaving out detail as it's not that
interesting.

specjbb single JVM: There was negligible performance difference in the
	benchmark itself for short runs. However, system activity is
	higher and interrupts are much higher over time -- possibly TLB
	flushes. Migrations are also higher. Overall, this is more overhead
	but considering the problems faced with the old approach I think
	we just have to suck it up and find another way of reducing the
	overhead.

specjbb multi JVM: Negligible performance difference to the actual benchmark
	but like the single JVM case, the system overhead is noticeably
	higher.  Again, interrupts are a major factor.

autonumabench: This was all over the place and about all that can be
	reasonably concluded is that it's different but not necessarily
	better or worse.

autonumabench
                                     3.18.0-rc5            3.18.0-rc5
                                 mmotm-20141119         protnone-v3r3
User    NUMA01               32380.24 (  0.00%)    21642.92 ( 33.16%)
User    NUMA01_THEADLOCAL    22481.02 (  0.00%)    22283.22 (  0.88%)
User    NUMA02                3137.00 (  0.00%)     3116.54 (  0.65%)
User    NUMA02_SMT            1614.03 (  0.00%)     1543.53 (  4.37%)
System  NUMA01                 322.97 (  0.00%)     1465.89 (-353.88%)
System  NUMA01_THEADLOCAL       91.87 (  0.00%)       49.32 ( 46.32%)
System  NUMA02                  37.83 (  0.00%)       14.61 ( 61.38%)
System  NUMA02_SMT               7.36 (  0.00%)        7.45 ( -1.22%)
Elapsed NUMA01                 716.63 (  0.00%)      599.29 ( 16.37%)
Elapsed NUMA01_THEADLOCAL      553.98 (  0.00%)      539.94 (  2.53%)
Elapsed NUMA02                  83.85 (  0.00%)       83.04 (  0.97%)
Elapsed NUMA02_SMT              86.57 (  0.00%)       79.15 (  8.57%)
CPU     NUMA01                4563.00 (  0.00%)     3855.00 ( 15.52%)
CPU     NUMA01_THEADLOCAL     4074.00 (  0.00%)     4136.00 ( -1.52%)
CPU     NUMA02                3785.00 (  0.00%)     3770.00 (  0.40%)
CPU     NUMA02_SMT            1872.00 (  0.00%)     1959.00 ( -4.65%)

System CPU usage of NUMA01 is worse but it's an adverse workload on this
machine so I'm reluctant to conclude that it's a problem that matters.  On
the other workloads that are sensible on this machine, system CPU usage is
great.  Overall time to complete the benchmark is comparable

          3.18.0-rc5  3.18.0-rc5
        mmotm-20141119protnone-v3r3
User        59612.50    48586.44
System        460.22     1537.45
Elapsed      1442.20     1304.29

NUMA alloc hit                 5075182     5743353
NUMA alloc miss                      0           0
NUMA interleave hit                  0           0
NUMA alloc local               5075174     5743339
NUMA base PTE updates        637061448   443106883
NUMA huge PMD updates          1243434      864747
NUMA page range updates     1273699656   885857347
NUMA hint faults               1658116     1214277
NUMA hint local faults          959487      754113
NUMA hint local percent             57          62
NUMA pages migrated            5467056    61676398

The NUMA pages migrated look terrible but when I looked at a graph of the
activity over time I see that the massive spike in migration activity was
during NUMA01.  This correlates with high system CPU usage and could be
simply down to bad luck but any modifications that affect that workload
would be related to scan rates and migrations, not the protection
mechanism.  For all other workloads, migration activity was comparable.

Overall, headline performance figures are comparable but the overhead is
higher, mostly in interrupts.  To some extent, higher overhead from this
approach was anticipated but not to this degree.  It's going to be
necessary to reduce this again with a separate series in the future.  It's
still worth going ahead with this series though as it's likely to avoid
constant headaches with Xen and is probably easier to maintain.

This patch (of 10):

A transhuge NUMA hinting fault may find the page is migrating and should
wait until migration completes.  The check is race-prone because the pmd
is deferenced outside of the page lock and while the race is tiny, it'll
be larger if the PMD is cleared while marking PMDs for hinting fault.
This patch closes the race.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Naoya Horiguchi
e66f17ff71 mm/hugetlb: take page table lock in follow_huge_pmd() 
We have a race condition between move_pages() and freeing hugepages, where
move_pages() calls follow_page(FOLL_GET) for hugepages internally and
tries to get its refcount without preventing concurrent freeing.  This
race crashes the kernel, so this patch fixes it by moving FOLL_GET code
for hugepages into follow_huge_pmd() with taking the page table lock.

This patch intentionally removes page==NULL check after pte_page.
This is justified because pte_page() never returns NULL for any
architectures or configurations.

This patch changes the behavior of follow_huge_pmd() for tail pages and
then tail pages can be pinned/returned.  So the caller must be changed to
properly handle the returned tail pages.

We could have a choice to add the similar locking to
follow_huge_(addr|pud) for consistency, but it's not necessary because
currently these functions don't support FOLL_GET flag, so let's leave it
for future development.

Here is the reproducer:

  $ cat movepages.c
  #include <stdio.h>
  #include <stdlib.h>
  #include <numaif.h>

  #define ADDR_INPUT      0x700000000000UL
  #define HPS             0x200000
  #define PS              0x1000

  int main(int argc, char *argv[]) {
          int i;
          int nr_hp = strtol(argv[1], NULL, 0);
          int nr_p  = nr_hp * HPS / PS;
          int ret;
          void **addrs;
          int *status;
          int *nodes;
          pid_t pid;

          pid = strtol(argv[2], NULL, 0);
          addrs  = malloc(sizeof(char *) * nr_p + 1);
          status = malloc(sizeof(char *) * nr_p + 1);
          nodes  = malloc(sizeof(char *) * nr_p + 1);

          while (1) {
                  for (i = 0; i < nr_p; i++) {
                          addrs[i] = (void *)ADDR_INPUT + i * PS;
                          nodes[i] = 1;
                          status[i] = 0;
                  }
                  ret = numa_move_pages(pid, nr_p, addrs, nodes, status,
                                        MPOL_MF_MOVE_ALL);
                  if (ret == -1)
                          err("move_pages");

                  for (i = 0; i < nr_p; i++) {
                          addrs[i] = (void *)ADDR_INPUT + i * PS;
                          nodes[i] = 0;
                          status[i] = 0;
                  }
                  ret = numa_move_pages(pid, nr_p, addrs, nodes, status,
                                        MPOL_MF_MOVE_ALL);
                  if (ret == -1)
                          err("move_pages");
          }
          return 0;
  }

  $ cat hugepage.c
  #include <stdio.h>
  #include <sys/mman.h>
  #include <string.h>

  #define ADDR_INPUT      0x700000000000UL
  #define HPS             0x200000

  int main(int argc, char *argv[]) {
          int nr_hp = strtol(argv[1], NULL, 0);
          char *p;

          while (1) {
                  p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE,
                           MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
                  if (p != (void *)ADDR_INPUT) {
                          perror("mmap");
                          break;
                  }
                  memset(p, 0, nr_hp * HPS);
                  munmap(p, nr_hp * HPS);
          }
  }

  $ sysctl vm.nr_hugepages=40
  $ ./hugepage 10 &
  $ ./movepages 10 $(pgrep -f hugepage)

Fixes: e632a938d9 ("mm: migrate: add hugepage migration code to move_pages()")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Hugh Dickins <hughd@google.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: <stable@vger.kernel.org>	[3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-11 17:06:01 -08:00
Kirill A. Shutemov
27ba0644ea rmap: drop support of non-linear mappings 
We don't create non-linear mappings anymore.  Let's drop code which
handles them in rmap.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-10 14:30:31 -08:00
Al Viro
50062175ff vm_area_operations: kill ->migrate() 
the only instance this method has ever grown was one in kernfs -
one that call ->migrate() of another vm_ops if it exists.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
 2014-12-17 08:26:51 -05:00
Linus Torvalds
988adfdffd Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 
Pull drm updates from Dave Airlie:
 "Highlights:

   - AMD KFD driver merge

     This is the AMD HSA interface for exposing a lowlevel interface for
     GPGPU use.  They have an open source userspace built on top of this
     interface, and the code looks as good as it was going to get out of
     tree.

   - Initial atomic modesetting work

     The need for an atomic modesetting interface to allow userspace to
     try and send a complete set of modesetting state to the driver has
     arisen, and been suffering from neglect this past year.  No more,
     the start of the common code and changes for msm driver to use it
     are in this tree.  Ongoing work to get the userspace ioctl finished
     and the code clean will probably wait until next kernel.

   - DisplayID 1.3 and tiled monitor exposed to userspace.

     Tiled monitor property is now exposed for userspace to make use of.

   - Rockchip drm driver merged.

   - imx gpu driver moved out of staging

  Other stuff:

   - core:
        panel - MIPI DSI + new panels.
        expose suggested x/y properties for virtual GPUs

   - i915:
        Initial Skylake (SKL) support
        gen3/4 reset work
        start of dri1/ums removal
        infoframe tracking
        fixes for lots of things.

   - nouveau:
        tegra k1 voltage support
        GM204 modesetting support
        GT21x memory reclocking work

   - radeon:
        CI dpm fixes
        GPUVM improvements
        Initial DPM fan control

   - rcar-du:
        HDMI support added
        removed some support for old boards
        slave encoder driver for Analog Devices adv7511

   - exynos:
        Exynos4415 SoC support

   - msm:
        a4xx gpu support
        atomic helper conversion

   - tegra:
        iommu support
        universal plane support
        ganged-mode DSI support

   - sti:
        HDMI i2c improvements

   - vmwgfx:
        some late fixes.

   - qxl:
        use suggested x/y properties"

* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (969 commits)
  drm: sti: fix module compilation issue
  drm/i915: save/restore GMBUS freq across suspend/resume on gen4
  drm: sti: correctly cleanup CRTC and planes
  drm: sti: add HQVDP plane
  drm: sti: add cursor plane
  drm: sti: enable auxiliary CRTC
  drm: sti: fix delay in VTG programming
  drm: sti: prepare sti_tvout to support auxiliary crtc
  drm: sti: use drm_crtc_vblank_{on/off} instead of drm_vblank_{on/off}
  drm: sti: fix hdmi avi infoframe
  drm: sti: remove event lock while disabling vblank
  drm: sti: simplify gdp code
  drm: sti: clear all mixer control
  drm: sti: remove gpio for HDMI hot plug detection
  drm: sti: allow to change hdmi ddc i2c adapter
  drm/doc: Document drm_add_modes_noedid() usage
  drm/i915: Remove '& 0xffff' from the mask given to WA_REG()
  drm/i915: Invert the mask and val arguments in wa_add() and WA_REG()
  drm: Zero out DRM object memory upon cleanup
  drm/i915/bdw: Fix the write setting up the WIZ hashing mode
  ...
 2014-12-15 15:52:01 -08:00
Hugh Dickins
2ebba6b7e1 mm: unmapped page migration avoid unmap+remap overhead 
Page migration's __unmap_and_move(), and rmap's try_to_unmap(), were
created for use on pages almost certainly mapped into userspace.  But
nowadays compaction often applies them to unmapped page cache pages: which
may exacerbate contention on i_mmap_rwsem quite unnecessarily, since
try_to_unmap_file() makes no preliminary page_mapped() check.

Now check page_mapped() in __unmap_and_move(); and avoid repeating the
same overhead in rmap_walk_file() - don't remove_migration_ptes() when we
never inserted any.

(The PageAnon(page) comment blocks now look even sillier than before, but
clean that up on some other occasion.  And note in passing that
try_to_unmap_one() does not use a migration entry when PageSwapCache, so
remove_migration_ptes() will then not update that swap entry to newpage
pte: not a big deal, but something else to clean up later.)

Davidlohr remarked in "mm,fs: introduce helpers around the i_mmap_mutex"
conversion to i_mmap_rwsem, that "The biggest winner of these changes is
migration": a part of the reason might be all of that unnecessary taking
of i_mmap_mutex in page migration; and it's rather a shame that I didn't
get around to sending this patch in before his - this one is much less
useful after Davidlohr's conversion to rwsem, but still good.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-12-13 12:42:49 -08:00
Konstantin Khlebnikov
d6d86c0a7f mm/balloon_compaction: redesign ballooned pages management 
Sasha Levin reported KASAN splash inside isolate_migratepages_range().
Problem is in the function __is_movable_balloon_page() which tests
AS_BALLOON_MAP in page->mapping->flags.  This function has no protection
against anonymous pages.  As result it tried to check address space flags
inside struct anon_vma.

Further investigation shows more problems in current implementation:

* Special branch in __unmap_and_move() never works:
  balloon_page_movable() checks page flags and page_count.  In
  __unmap_and_move() page is locked, reference counter is elevated, thus
  balloon_page_movable() always fails.  As a result execution goes to the
  normal migration path.  virtballoon_migratepage() returns
  MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS,
  move_to_new_page() thinks this is an error code and assigns
  newpage->mapping to NULL.  Newly migrated page lose connectivity with
  balloon an all ability for further migration.

* lru_lock erroneously required in isolate_migratepages_range() for
  isolation ballooned page.  This function releases lru_lock periodically,
  this makes migration mostly impossible for some pages.

* balloon_page_dequeue have a tight race with balloon_page_isolate:
  balloon_page_isolate could be executed in parallel with dequeue between
  picking page from list and locking page_lock.  Race is rare because they
  use trylock_page() for locking.

This patch fixes all of them.

Instead of fake mapping with special flag this patch uses special state of
page->_mapcount: PAGE_BALLOON_MAPCOUNT_VALUE = -256.  Buddy allocator uses
PAGE_BUDDY_MAPCOUNT_VALUE = -128 for similar purpose.  Storing mark
directly in struct page makes everything safer and easier.

PagePrivate is used to mark pages present in page list (i.e.  not
isolated, like PageLRU for normal pages).  It replaces special rules for
reference counter and makes balloon migration similar to migration of
normal pages.  This flag is protected by page_lock together with link to
the balloon device.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Link: http://lkml.kernel.org/p/53E6CEAA.9020105@oracle.com
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: <stable@vger.kernel.org>	[3.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-09 22:26:01 -04:00
Mel Gorman
d3cb8bf608 mm: migrate: Close race between migration completion and mprotect 
A migration entry is marked as write if pte_write was true at the time the
entry was created. The VMA protections are not double checked when migration
entries are being removed as mprotect marks write-migration-entries as
read. It means that potentially we take a spurious fault to mark PTEs write
again but it's straight-forward. However, there is a race between write
migrations being marked read and migrations finishing. This potentially
allows a PTE to be write that should have been read. Close this race by
double checking the VMA permissions using maybe_mkwrite when migration
completes.

[torvalds@linux-foundation.org: use maybe_mkwrite]
Cc: stable@vger.kernel.org
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-02 11:57:18 -07:00
Johannes Weiner
0a31bc97c8 mm: memcontrol: rewrite uncharge API 
The memcg uncharging code that is involved towards the end of a page's
lifetime - truncation, reclaim, swapout, migration - is impressively
complicated and fragile.

Because anonymous and file pages were always charged before they had their
page->mapping established, uncharges had to happen when the page type
could still be known from the context; as in unmap for anonymous, page
cache removal for file and shmem pages, and swap cache truncation for swap
pages.  However, these operations happen well before the page is actually
freed, and so a lot of synchronization is necessary:

- Charging, uncharging, page migration, and charge migration all need
  to take a per-page bit spinlock as they could race with uncharging.

- Swap cache truncation happens during both swap-in and swap-out, and
  possibly repeatedly before the page is actually freed.  This means
  that the memcg swapout code is called from many contexts that make
  no sense and it has to figure out the direction from page state to
  make sure memory and memory+swap are always correctly charged.

- On page migration, the old page might be unmapped but then reused,
  so memcg code has to prevent untimely uncharging in that case.
  Because this code - which should be a simple charge transfer - is so
  special-cased, it is not reusable for replace_page_cache().

But now that charged pages always have a page->mapping, introduce
mem_cgroup_uncharge(), which is called after the final put_page(), when we
know for sure that nobody is looking at the page anymore.

For page migration, introduce mem_cgroup_migrate(), which is called after
the migration is successful and the new page is fully rmapped.  Because
the old page is no longer uncharged after migration, prevent double
charges by decoupling the page's memcg association (PCG_USED and
pc->mem_cgroup) from the page holding an actual charge.  The new bits
PCG_MEM and PCG_MEMSW represent the respective charges and are transferred
to the new page during migration.

mem_cgroup_migrate() is suitable for replace_page_cache() as well,
which gets rid of mem_cgroup_replace_page_cache().  However, care
needs to be taken because both the source and the target page can
already be charged and on the LRU when fuse is splicing: grab the page
lock on the charge moving side to prevent changing pc->mem_cgroup of a
page under migration.  Also, the lruvecs of both pages change as we
uncharge the old and charge the new during migration, and putback may
race with us, so grab the lru lock and isolate the pages iff on LRU to
prevent races and ensure the pages are on the right lruvec afterward.

Swap accounting is massively simplified: because the page is no longer
uncharged as early as swap cache deletion, a new mem_cgroup_swapout() can
transfer the page's memory+swap charge (PCG_MEMSW) to the swap entry
before the final put_page() in page reclaim.

Finally, page_cgroup changes are now protected by whatever protection the
page itself offers: anonymous pages are charged under the page table lock,
whereas page cache insertions, swapin, and migration hold the page lock.
Uncharging happens under full exclusion with no outstanding references.
Charging and uncharging also ensure that the page is off-LRU, which
serializes against charge migration.  Remove the very costly page_cgroup
lock and set pc->flags non-atomically.

[mhocko@suse.cz: mem_cgroup_charge_statistics needs preempt_disable]
[vdavydov@parallels.com: fix flags definition]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Tested-by: Jet Chen <jet.chen@intel.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Tested-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-08-08 15:57:17 -07:00
Hugh Dickins
8bdd638091 mm: fix direct reclaim writeback regression 
Shortly before 3.16-rc1, Dave Jones reported:

  WARNING: CPU: 3 PID: 19721 at fs/xfs/xfs_aops.c:971
           xfs_vm_writepage+0x5ce/0x630 [xfs]()
  CPU: 3 PID: 19721 Comm: trinity-c61 Not tainted 3.15.0+ #3
  Call Trace:
    xfs_vm_writepage+0x5ce/0x630 [xfs]
    shrink_page_list+0x8f9/0xb90
    shrink_inactive_list+0x253/0x510
    shrink_lruvec+0x563/0x6c0
    shrink_zone+0x3b/0x100
    shrink_zones+0x1f1/0x3c0
    try_to_free_pages+0x164/0x380
    __alloc_pages_nodemask+0x822/0xc90
    alloc_pages_vma+0xaf/0x1c0
    handle_mm_fault+0xa31/0xc50
  etc.

 970   if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
 971                   PF_MEMALLOC))

I did not respond at the time, because a glance at the PageDirty block
in shrink_page_list() quickly shows that this is impossible: we don't do
writeback on file pages (other than tmpfs) from direct reclaim nowadays.
Dave was hallucinating, but it would have been disrespectful to say so.

However, my own /var/log/messages now shows similar complaints

  WARNING: CPU: 1 PID: 28814 at fs/ext4/inode.c:1881 ext4_writepage+0xa7/0x38b()
  WARNING: CPU: 0 PID: 27347 at fs/ext4/inode.c:1764 ext4_writepage+0xa7/0x38b()

from stressing some mmotm trees during July.

Could a dirty xfs or ext4 file page somehow get marked PageSwapBacked,
so fail shrink_page_list()'s page_is_file_cache() test, and so proceed
to mapping->a_ops->writepage()?

Yes, 3.16-rc1's commit 68711a7463 ("mm, migration: add destination
page freeing callback") has provided such a way to compaction: if
migrating a SwapBacked page fails, its newpage may be put back on the
list for later use with PageSwapBacked still set, and nothing will clear
it.

Whether that can do anything worse than issue WARN_ON_ONCEs, and get
some statistics wrong, is unclear: easier to fix than to think through
the consequences.

Fixing it here, before the put_new_page(), addresses the bug directly,
but is probably the worst place to fix it.  Page migration is doing too
many parts of the job on too many levels: fixing it in
move_to_new_page() to complement its SetPageSwapBacked would be
preferable, except why is it (and newpage->mapping and newpage->index)
done there, rather than down in migrate_page_move_mapping(), once we are
sure of success? Not a cleanup to get into right now, especially not
with memcg cleanups coming in 3.17.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-07-26 14:38:50 -07:00
Hugh Dickins
f72e7dcdd2 mm: let mm_find_pmd fix buggy race with THP fault 
Trinity has reported:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
    IP: __lock_acquire (kernel/locking/lockdep.c:3070 (discriminator 1))
    CPU: 6 PID: 16173 Comm: trinity-c364 Tainted: G        W
                            3.15.0-rc1-next-20140415-sasha-00020-gaa90d09 #398
    lock_acquire (arch/x86/include/asm/current.h:14
                  kernel/locking/lockdep.c:3602)
    _raw_spin_lock (include/linux/spinlock_api_smp.h:143
                    kernel/locking/spinlock.c:151)
    remove_migration_pte (mm/migrate.c:137)
    rmap_walk (mm/rmap.c:1628 mm/rmap.c:1699)
    remove_migration_ptes (mm/migrate.c:224)
    migrate_pages (mm/migrate.c:922 mm/migrate.c:960 mm/migrate.c:1126)
    migrate_misplaced_page (mm/migrate.c:1733)
    __handle_mm_fault (mm/memory.c:3762 mm/memory.c:3812 mm/memory.c:3925)
    handle_mm_fault (mm/memory.c:3948)
    __get_user_pages (mm/memory.c:1851)
    __mlock_vma_pages_range (mm/mlock.c:255)
    __mm_populate (mm/mlock.c:711)
    SyS_mlockall (include/linux/mm.h:1799 mm/mlock.c:817 mm/mlock.c:791)

I believe this comes about because, whereas collapsing and splitting THP
functions take anon_vma lock in write mode (which excludes concurrent
rmap walks), faulting THP functions (write protection and misplaced
NUMA) do not - and mostly they do not need to.

But they do use a pmdp_clear_flush(), set_pmd_at() sequence which, for
an instant (indeed, for a long instant, given the inter-CPU TLB flush in
there), leaves *pmd neither present not trans_huge.

Which can confuse a concurrent rmap walk, as when removing migration
ptes, seen in the dumped trace.  Although that rmap walk has a 4k page
to insert, anon_vmas containing THPs are in no way segregated from
4k-page anon_vmas, so the 4k-intent mm_find_pmd() does need to cope with
that instant when a trans_huge pmd is temporarily absent.

I don't think we need strengthen the locking at the THP end: it's easily
handled with an ACCESS_ONCE() before testing both conditions.

And since mm_find_pmd() had only one caller who wanted a THP rather than
a pmd, let's slightly repurpose it to fail when it hits a THP or
non-present pmd, and open code split_huge_page_address() again.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Christoph Lameter <cl@gentwo.org>
Cc: Dave Jones <davej@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-23 16:47:44 -07:00
Naoya Horiguchi
100873d7a7 hugetlb: rename hugepage_migration_support() to ..._supported() 
We already have a function named hugepages_supported(), and the similar
name hugepage_migration_support() is a bit unconfortable, so let's rename
it hugepage_migration_supported().

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-04 16:54:12 -07:00
David Rientjes
68711a7463 mm, migration: add destination page freeing callback 
Memory migration uses a callback defined by the caller to determine how to
allocate destination pages.  When migration fails for a source page,
however, it frees the destination page back to the system.

This patch adds a memory migration callback defined by the caller to
determine how to free destination pages.  If a caller, such as memory
compaction, builds its own freelist for migration targets, this can reuse
already freed memory instead of scanning additional memory.

If the caller provides a function to handle freeing of destination pages,
it is called when page migration fails.  If the caller passes NULL then
freeing back to the system will be handled as usual.  This patch
introduces no functional change.

Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-04 16:54:06 -07:00
Mel Gorman
11de9927f9 mm: numa: add migrated transhuge pages to LRU the same way as base pages 
Migration of misplaced transhuge pages uses page_add_new_anon_rmap() when
putting the page back as it avoided an atomic operations and added the new
page to the correct LRU.  A side-effect is that the page gets marked
activated as part of the migration meaning that transhuge and base pages
are treated differently from an aging perspective than base page
migration.

This patch uses page_add_anon_rmap() and putback_lru_page() on completion
of a transhuge migration similar to base page migration.  It would require
fewer atomic operations to use lru_cache_add without taking an additional
reference to the page.  The downside would be that it's still different to
base page migration and unevictable pages may be added to the wrong LRU
for cleaning up later.  Testing of the usual workloads did not show any
adverse impact to the change.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-04 16:54:01 -07:00
Hugh Dickins
7e09e738af mm: fix swapops.h:131 bug if remap_file_pages raced migration 
Add remove_linear_migration_ptes_from_nonlinear(), to fix an interesting
little include/linux/swapops.h:131 BUG_ON(!PageLocked) found by trinity:
indicating that remove_migration_ptes() failed to find one of the
migration entries that was temporarily inserted.

The problem comes from remap_file_pages()'s switch from vma_interval_tree
(good for inserting the migration entry) to i_mmap_nonlinear list (no good
for locating it again); but can only be a problem if the remap_file_pages()
range does not cover the whole of the vma (zap_pte() clears the range).

remove_migration_ptes() needs a file_nonlinear method to go down the
i_mmap_nonlinear list, applying linear location to look for migration
entries in those vmas too, just in case there was this race.

The file_nonlinear method does need rmap_walk_control.arg to do this;
but it never needed vma passed in - vma comes from its own iteration.

Reported-and-tested-by: Dave Jones <davej@redhat.com>
Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-03-20 22:09:09 -07:00
Johannes Weiner
e97ca8e5b8 mm: fix GFP_THISNODE callers and clarify 
GFP_THISNODE is for callers that implement their own clever fallback to
remote nodes.  It restricts the allocation to the specified node and
does not invoke reclaim, assuming that the caller will take care of it
when the fallback fails, e.g.  through a subsequent allocation request
without GFP_THISNODE set.

However, many current GFP_THISNODE users only want the node exclusive
aspect of the flag, without actually implementing their own fallback or
triggering reclaim if necessary.  This results in things like page
migration failing prematurely even when there is easily reclaimable
memory available, unless kswapd happens to be running already or a
concurrent allocation attempt triggers the necessary reclaim.

Convert all callsites that don't implement their own fallback strategy
to __GFP_THISNODE.  This restricts the allocation a single node too, but
at the same time allows the allocator to enter the slowpath, wake
kswapd, and invoke direct reclaim if necessary, to make the allocation
happen when memory is full.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-03-10 17:26:19 -07:00
Wanpeng Li
a3978a5194 mm/migrate.c: fix setting of cpupid on page migration twice against normal page 
Commit 7851a45cd3 ("mm: numa: Copy cpupid on page migration") copies
over the cpupid at page migration time.  It is unnecessary to set it
again in alloc_misplaced_dst_page().

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-01-27 21:02:40 -08:00
Wanpeng Li
baae911b27 sched/numa: fix setting of cpupid on page migration twice 
Commit 7851a45cd3 ("mm: numa: Copy cpupid on page migration") copiess
over the cpupid at page migration time.  It is unnecessary to set it
again in migrate_misplaced_transhuge_page().

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-01-23 16:36:52 -08:00
Sasha Levin
309381feae mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 
Most of the VM_BUG_ON assertions are performed on a page.  Usually, when
one of these assertions fails we'll get a BUG_ON with a call stack and
the registers.

I've recently noticed based on the requests to add a small piece of code
that dumps the page to various VM_BUG_ON sites that the page dump is
quite useful to people debugging issues in mm.

This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what
VM_BUG_ON() does, also dumps the page before executing the actual
BUG_ON.

[akpm@linux-foundation.org: fix up includes]
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-01-23 16:36:50 -08:00
Joonsoo Kim
78d5506e82 mm/migrate: remove unused function, fail_migrate_page() 
fail_migrate_page() isn't used anywhere, so remove it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-01-21 16:19:49 -08:00
Joonsoo Kim
59c82b70dc mm/migrate: remove putback_lru_pages, fix comment on putback_movable_pages 
Some part of putback_lru_pages() and putback_movable_pages() is
duplicated, so it could confuse us what we should use.  We can remove
putback_lru_pages() since it is not really needed now.  This makes us
undestand and maintain the code more easily.

And comment on putback_movable_pages() is stale now, so fix it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-01-21 16:19:49 -08:00
Joonsoo Kim
32665f2bbf mm/migrate: correct failure handling if !hugepage_migration_support() 
We should remove the page from the list if we fail with ENOSYS, since
migrate_pages() consider error cases except -ENOMEM and -EAGAIN as
permanent failure and it assumes that the page would be removed from the
list.  Without this patch, we could overcount number of failure.

In addition, we should put back the new hugepage if
!hugepage_migration_support().  If not, we would leak hugepage memory.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-01-21 16:19:49 -08:00