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040fa02077
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Pavel Emelyanov 040fa02077 clear_refs: sanitize accepted commands declaration 
This is the implementation of the soft-dirty bit concept that should
help keep track of changes in user memory, which in turn is very-very
required by the checkpoint-restore project (http://criu.org).

To create a dump of an application(s) we save all the information about
it to files, and the biggest part of such dump is the contents of tasks'
memory.  However, there are usage scenarios where it's not required to
get _all_ the task memory while creating a dump.  For example, when
doing periodical dumps, it's only required to take full memory dump only
at the first step and then take incremental changes of memory.  Another
example is live migration.  We copy all the memory to the destination
node without stopping all tasks, then stop them, check for what pages
has changed, dump it and the rest of the state, then copy it to the
destination node.  This decreases freeze time significantly.

That said, some help from kernel to watch how processes modify the
contents of their memory is required.

The proposal is to track changes with the help of new soft-dirty bit
this way:

1. First do "echo 4 > /proc/$pid/clear_refs".
   At that point kernel clears the soft dirty _and_ the writable bits from all
   ptes of process $pid. From now on every write to any page will result in #pf
   and the subsequent call to pte_mkdirty/pmd_mkdirty, which in turn will set
   the soft dirty flag.

2. Then read the /proc/$pid/pagemap2 and check the soft-dirty bit reported there
   (the 55'th one). If set, the respective pte was written to since last call
   to clear refs.

The soft-dirty bit is the _PAGE_BIT_HIDDEN one.  Although it's used by
kmemcheck, the latter one marks kernel pages with it, while the former
bit is put on user pages so they do not conflict to each other.

This patch:

A new clear-refs type will be added in the next patch, so prepare
code for that.

[akpm@linux-foundation.org: don't assume that sizeof(enum clear_refs_types) == sizeof(int)]
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-03 16:07:25 -07:00
..
9p Lots of bug fixes, cleanups and optimizations. In the bug fixes 2013-07-02 09:39:34 -07:00
adfs Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
affs Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
afs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
autofs4 [readdir] switch dcache_readdir() users to ->iterate() 2013-06-29 12:46:48 +04:00
befs [readdir] convert befs 2013-06-29 12:56:55 +04:00
bfs [readdir] convert bfs 2013-06-29 12:56:33 +04:00
btrfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
cachefiles cachefiles: remove unused macro list_to_page() 2013-06-19 14:16:47 +01:00
ceph Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
cifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
coda coda: don't bother with find_inode_number() 2013-06-29 12:57:20 +04:00
configfs configfs: use capped length for ->store_attribute() 2013-07-03 16:07:23 -07:00
cramfs [readdir] convert f2fs 2013-06-29 12:56:46 +04:00
debugfs debugfs: write_file_bool() - ensure strtobool() operates on valid data 2013-06-03 13:55:02 -07:00
devpts fs: Limit sys_mount to only request filesystem modules (Part 2). 2013-03-07 01:08:55 -08:00
dlm dlm: Avoid LVB truncation 2013-06-26 11:38:02 -05:00
ecryptfs ecryptfs: switch ecryptfs_decode_and_decrypt_filename() from dentry to sb 2013-06-29 12:57:25 +04:00
efivarfs Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
efs [readdir] convert efs 2013-06-29 12:56:31 +04:00
exofs Lots of bug fixes, cleanups and optimizations. In the bug fixes 2013-07-02 09:39:34 -07:00
exportfs [readdir] constify ->actor 2013-06-29 12:57:05 +04:00
ext2 [O_TMPFILE] it's still short a few helpers, but infrastructure should be OK now... 2013-06-29 12:57:10 +04:00
ext3 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
ext4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
f2fs This patch-set includes the following major enhancement patches. 2013-07-02 09:42:38 -07:00
fat Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
freevxfs [readdir] convert freevxfs 2013-06-29 12:56:53 +04:00
fscache FS-Cache: Don't use spin_is_locked() in assertions 2013-06-19 14:16:47 +01:00
fuse Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
gfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
hfs Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
hfsplus Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
hostfs [readdir] convert hostfs 2013-06-29 12:56:59 +04:00
hpfs Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
hppfs [readdir] convert procfs 2013-06-29 12:56:32 +04:00
hugetlbfs hugetlbfs: fix mmap failure in unaligned size request 2013-05-07 18:38:27 -07:00
isofs Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
jbd jbd: change journal_invalidatepage() to accept length 2013-05-21 23:26:36 -04:00
jbd2 jbd2: invalidate handle if jbd2_journal_restart() fails 2013-07-01 08:12:41 -04:00
jffs2 [readdir] convert jffs2 2013-06-29 12:56:47 +04:00
jfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
lockd locks: add a new "lm_owner_key" lock operation 2013-06-29 12:57:45 +04:00
logfs Lots of bug fixes, cleanups and optimizations. In the bug fixes 2013-07-02 09:39:34 -07:00
minix minix: bug widening a binary "not" operation 2013-06-29 12:57:35 +04:00
ncpfs Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
nfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
nfs_common
nfsd locks: protect most of the file_lock handling with i_lock 2013-06-29 12:57:42 +04:00
nilfs2 [readdir] convert nilfs2 2013-06-29 12:56:36 +04:00
nls
notify fanotify: quit wanking with FASYNC in ->release() 2013-06-29 12:57:23 +04:00
ntfs Lots of bug fixes, cleanups and optimizations. In the bug fixes 2013-07-02 09:39:34 -07:00
ocfs2 ocfs2: fix NULL pointer dereference when traversing o2hb_all_regions 2013-07-03 16:07:25 -07:00
omfs [readdir] convert omfs 2013-06-29 12:56:37 +04:00
openpromfs [readdir] convert openpromfs 2013-06-29 12:56:32 +04:00
proc clear_refs: sanitize accepted commands declaration 2013-07-03 16:07:25 -07:00
pstore Couple of pstore cleanups 2013-05-09 16:42:10 -07:00
qnx4 [readdir] convert qnx4 2013-06-29 12:56:38 +04:00
qnx6 [readdir] convert qnx6 2013-06-29 12:56:39 +04:00
quota quota: add missing use of dq_data_lock in __dquot_initialize 2013-03-11 22:05:56 +01:00
ramfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
reiserfs Lots of bug fixes, cleanups and optimizations. In the bug fixes 2013-07-02 09:39:34 -07:00
romfs [readdir] convert romfs 2013-06-29 12:56:29 +04:00
squashfs [readdir] convert squashfs 2013-06-29 12:56:28 +04:00
sysfs Driver core patches for 3.11-rc1 2013-07-02 11:44:19 -07:00
sysv Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
ubifs Lots of bug fixes, cleanups and optimizations. In the bug fixes 2013-07-02 09:39:34 -07:00
udf udf: provide ->tmpfile() 2013-06-29 12:57:12 +04:00
ufs [readdir] simple local unixlike: switch to ->iterate() 2013-06-29 12:46:47 +04:00
xfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
aio.c constify rw_verify_area() 2013-06-29 12:57:34 +04:00
anon_inodes.c get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero 2013-02-26 02:46:11 -05:00
attr.c
bad_inode.c [readdir] ->readdir() is gone 2013-06-29 12:57:04 +04:00
binfmt_aout.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-05-01 17:51:54 -07:00
binfmt_elf_fdpic.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2013-05-02 10:16:16 -07:00
binfmt_elf.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2013-05-02 10:16:16 -07:00
binfmt_em86.c
binfmt_flat.c new helper: read_code() 2013-04-29 15:40:23 -04:00
binfmt_misc.c binfmt_misc: reuse string_unescape_inplace() 2013-04-30 17:04:03 -07:00
binfmt_script.c
binfmt_som.c
bio-integrity.c bio-integrity: Add explicit field for owner of bip_buf 2013-03-23 14:26:34 -07:00
bio.c Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block 2013-05-08 10:13:35 -07:00
block_dev.c block_dev: switch to fixed_size_llseek() 2013-06-29 12:57:52 +04:00
buffer.c mm: change invalidatepage prototype to accept length 2013-05-21 23:17:23 -04:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c compat.c: LOOP_CLR_FD is taken care of in loop.c itself... 2013-06-29 12:46:44 +04:00
compat.c [readdir] constify ->actor 2013-06-29 12:57:05 +04:00
coredump.c do_coredump(): don't wait for thaw if coredump has already been interrupted 2013-05-04 14:45:54 -04:00
coredump.h
dcache.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
dcookies.c consolidate compat lookup_dcookie() 2013-03-03 23:00:23 -05:00
direct-io.c Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block 2013-05-08 10:13:35 -07:00
drop_caches.c
eventfd.c
eventpoll.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-05-01 07:21:43 -07:00
exec.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
fcntl.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
fhandle.c
file_table.c Replace a bunch of file->dentry->d_inode refs with file_inode() 2013-06-29 12:57:13 +04:00
file.c don't bother with deferred freeing of fdtables 2013-05-01 17:31:42 -04:00
filesystems.c fs: Limit sys_mount to only request filesystem modules. 2013-03-03 19:36:31 -08:00
fs_struct.c constify path_get/path_put and fs_struct.c stuff 2013-03-01 23:51:07 -05:00
fs-writeback.c sync: don't block the flusher thread waiting on IO 2013-07-02 09:16:42 -07:00
generic_acl.c
inode.c allow the temp files created by open() to be linked to 2013-06-29 12:57:11 +04:00
internal.h constify rw_verify_area() 2013-06-29 12:57:34 +04:00
ioctl.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
ioprio.c
Kconfig efivarfs: Move to fs/efivarfs 2013-04-17 13:25:09 +01:00
Kconfig.binfmt fs: make binfmt support for #! scripts modular and removable 2013-04-30 17:04:04 -07:00
libfs.c [readdir] switch dcache_readdir() users to ->iterate() 2013-06-29 12:46:48 +04:00
locks.c locks: give the blocked_hash its own spinlock 2013-06-29 12:57:46 +04:00
Makefile Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-05-01 17:51:54 -07:00
mbcache.c
mount.h get rid of full-hash scan on detaching vfsmounts 2013-04-09 14:12:52 -04:00
mpage.c
namei.c Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
namespace.c create_mnt_ns: unidiomatic use of list_add() 2013-05-04 15:18:53 -04:00
no-block.c
open.c [O_TMPFILE] it's still short a few helpers, but infrastructure should be OK now... 2013-06-29 12:57:10 +04:00
pipe.c aio: don't include aio.h in sched.h 2013-05-07 20:16:25 -07:00
pnode.c vfs: Fix invalid ida_remove() call 2013-05-31 15:16:33 -04:00
pnode.h Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-05-01 17:51:54 -07:00
posix_acl.c
proc_namespace.c
read_write.c vfs: export lseek_execute() to modules 2013-07-03 16:23:27 +04:00
readdir.c [readdir] constify ->actor 2013-06-29 12:57:05 +04:00
select.c
seq_file.c new helper: single_open_size() 2013-04-09 14:13:29 -04:00
signalfd.c switch signalfd{,4}() to COMPAT_SYSCALL_DEFINE 2013-03-03 22:58:46 -05:00
splice.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-07-03 09:10:19 -07:00
stack.c
stat.c switch vfs_getattr() to struct path 2013-02-26 02:46:08 -05:00
statfs.c
super.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
sync.c teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long 2013-03-03 22:46:22 -05:00
timerfd.c compat: restore timerfd settime and gettime compat syscalls 2013-03-02 09:35:13 -05:00
utimes.c
xattr_acl.c
xattr.c