linux-stable.git/mm, branch linux-2.6.37.y

fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away

2011-03-27T19:00:31+00:00

commit 95f28604a65b1c40b6c6cd95e58439cd7ded3add upstream.

We don't have proper reference counting for this yet, so we run into
cases where the device is pulled and we OOPS on flushing the fs data.
This happens even though the dirty inodes have already been
migrated to the default_backing_dev_info.

Reported-by: Torsten Hilbrich 
Tested-by: Torsten Hilbrich 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

oom: avoid deferring oom killer if exiting task is being traced

2011-03-27T19:00:12+00:00

commit edd45544c6f09550df0a5491aa8a07af24767e73 upstream.

The oom killer naturally defers killing anything if it finds an eligible
task that is already exiting and has yet to detach its ->mm.  This avoids
unnecessarily killing tasks when one is already in the exit path and may
free enough memory that the oom killer is no longer needed.  This is
detected by PF_EXITING since threads that have already detached its ->mm
are no longer considered at all.

The problem with always deferring when a thread is PF_EXITING, however, is
that it may never actually exit when being traced, specifically if another
task is tracing it with PTRACE_O_TRACEEXIT.  The oom killer does not want
to defer in this case since there is no guarantee that thread will ever
exit without intervention.

This patch will now only defer the oom killer when a thread is PF_EXITING
and no ptracer has stopped its progress in the exit path.  It also ensures
that a child is sacrificed for the chosen parent only if it has a
different ->mm as the comment implies: this ensures that the thread group
leader is always targeted appropriately.

Signed-off-by: David Rientjes 
Reported-by: Oleg Nesterov 
Cc: KOSAKI Motohiro 
Cc: KAMEZAWA Hiroyuki 
Cc: Hugh Dickins 
Cc: Andrey Vagin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

oom: skip zombies when iterating tasklist

2011-03-27T19:00:12+00:00

commit 30e2b41f20b6238f51e7cffb879c7a0f0073f5fe upstream.

We shouldn't defer oom killing if a thread has already detached its ->mm
and still has TIF_MEMDIE set.  Memory needs to be freed, so find kill
other threads that pin the same ->mm or find another task to kill.

Signed-off-by: Andrey Vagin 
Signed-off-by: David Rientjes 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

oom: prevent unnecessary oom kills or kernel panics

2011-03-27T19:00:11+00:00

commit 3a5dda7a17cf3706f79b86293f29db02d61e0d48 upstream.

This patch prevents unnecessary oom kills or kernel panics by reverting
two commits:

	495789a5 (oom: make oom_score to per-process value)
	cef1d352 (oom: multi threaded process coredump don't make deadlock)

First, 495789a5 (oom: make oom_score to per-process value) ignores the
fact that all threads in a thread group do not necessarily exit at the
same time.

It is imperative that select_bad_process() detect threads that are in the
exit path, specifically those with PF_EXITING set, to prevent needlessly
killing additional tasks.  If a process is oom killed and the thread group
leader exits, select_bad_process() cannot detect the other threads that
are PF_EXITING by iterating over only processes.  Thus, it currently
chooses another task unnecessarily for oom kill or panics the machine when
nothing else is eligible.

By iterating over threads instead, it is possible to detect threads that
are exiting and nominate them for oom kill so they get access to memory
reserves.

Second, cef1d352 (oom: multi threaded process coredump don't make
deadlock) erroneously avoids making the oom killer a no-op when an
eligible thread other than current isfound to be exiting.  We want to
detect this situation so that we may allow that exiting thread time to
exit and free its memory; if it is able to exit on its own, that should
free memory so current is no loner oom.  If it is not able to exit on its
own, the oom killer will nominate it for oom kill which, in this case,
only means it will get access to memory reserves.

Without this change, it is easy for the oom killer to unnecessarily target
tasks when all threads of a victim don't exit before the thread group
leader or, in the worst case, panic the machine.

Signed-off-by: David Rientjes 
Cc: KOSAKI Motohiro 
Cc: KAMEZAWA Hiroyuki 
Cc: Oleg Nesterov 
Cc: Hugh Dickins 
Cc: Andrey Vagin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: swap: unlock swapfile inode mutex before closing file on bad swapfiles

2011-03-27T19:00:11+00:00

commit 52c50567d8ab0a0a87f12cceaa4194967854f0bd upstream.

If an administrator tries to swapon a file backed by NFS, the inode mutex is
taken (as it is for any swapfile) but later identified to be a bad swapfile
due to the lack of bmap and tries to cleanup. During cleanup, an attempt is
made to close the file but with inode->i_mutex still held. Closing an NFS
file syncs it which tries to acquire the inode mutex leading to deadlock. If
lockdep is enabled the following appears on the console;

    =============================================
    [ INFO: possible recursive locking detected ]
    2.6.38-rc8-autobuild #1
    ---------------------------------------------
    swapon/2192 is trying to acquire lock:
     (&sb->s_type->i_mutex_key#13){+.+.+.}, at: vfs_fsync_range+0x47/0x7c

    but task is already holding lock:
     (&sb->s_type->i_mutex_key#13){+.+.+.}, at: sys_swapon+0x28d/0xae7

    other info that might help us debug this:
    1 lock held by swapon/2192:
     #0:  (&sb->s_type->i_mutex_key#13){+.+.+.}, at: sys_swapon+0x28d/0xae7

    stack backtrace:
    Pid: 2192, comm: swapon Not tainted 2.6.38-rc8-autobuild #1
    Call Trace:
        __lock_acquire+0x2eb/0x1623
        find_get_pages_tag+0x14a/0x174
        pagevec_lookup_tag+0x25/0x2e
        vfs_fsync_range+0x47/0x7c
        lock_acquire+0xd3/0x100
        vfs_fsync_range+0x47/0x7c
        nfs_flush_one+0x0/0xdf [nfs]
        mutex_lock_nested+0x40/0x2b1
        vfs_fsync_range+0x47/0x7c
        vfs_fsync_range+0x47/0x7c
        vfs_fsync+0x1c/0x1e
        nfs_file_flush+0x64/0x69 [nfs]
        filp_close+0x43/0x72
        sys_swapon+0xa39/0xae7
        sysret_check+0x2e/0x69
        system_call_fastpath+0x16/0x1b

This patch releases the mutex if its held before calling filep_close()
so swapon fails as expected without deadlock when the swapfile is backed
by NFS.  If accepted for 2.6.39, it should also be considered a -stable
candidate for 2.6.38 and 2.6.37.

Signed-off-by: Mel Gorman 
Acked-by: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

shmem: let shared anonymous be nonlinear again

2011-03-27T19:00:10+00:00

commit bee4c36a5cf5c9f63ce1d7372aa62045fbd16d47 upstream.

Up to 2.6.22, you could use remap_file_pages(2) on a tmpfs file or a
shared mapping of /dev/zero or a shared anonymous mapping.  In 2.6.23 we
disabled it by default, but set VM_CAN_NONLINEAR to enable it on safe
mappings.  We made sure to set it in shmem_mmap() for tmpfs files, but
missed it in shmem_zero_setup() for the others.  Fix that at last.

Reported-by: Kenny Simpson 
Signed-off-by: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Revert "slab: Fix missing DEBUG_SLAB last user"

2011-03-27T19:00:09+00:00

commit 3ff84a7f36554b257cd57325b1a7c1fa4b49fbe3 upstream.

This reverts commit 5c5e3b33b7cb959a401f823707bee006caadd76e.

The commit breaks ARM thusly:

| Mount-cache hash table entries: 512
| slab error in verify_redzone_free(): cache `idr_layer_cache': memory outside object was overwritten
| Backtrace:
| [] (dump_backtrace+0x0/0x110) from [] (dump_stack+0x18/0x1c)
| [] (dump_stack+0x0/0x1c) from [] (__slab_error+0x28/0x30)
| [] (__slab_error+0x0/0x30) from [] (cache_free_debugcheck+0x1c0/0x2b8)
| [] (cache_free_debugcheck+0x0/0x2b8) from [] (kmem_cache_free+0x3c/0xc0)
| [] (kmem_cache_free+0x0/0xc0) from [] (ida_get_new_above+0x19c/0x1c0)
| [] (ida_get_new_above+0x0/0x1c0) from [] (alloc_vfsmnt+0x54/0x144)
| [] (alloc_vfsmnt+0x0/0x144) from [] (vfs_kern_mount+0x30/0xec)
| [] (vfs_kern_mount+0x0/0xec) from [] (kern_mount_data+0x1c/0x20)
| [] (kern_mount_data+0x0/0x20) from [] (sysfs_init+0x68/0xc8)
| [] (sysfs_init+0x0/0xc8) from [] (mnt_init+0x90/0x1b0)
| [] (mnt_init+0x0/0x1b0) from [] (vfs_caches_init+0x100/0x140)
| [] (vfs_caches_init+0x0/0x140) from [] (start_kernel+0x2e8/0x368)
| [] (start_kernel+0x0/0x368) from [] (__enable_mmu+0x0/0x2c)
| c0113268: redzone 1:0xd84156c5c032b3ac, redzone 2:0xd84156c5635688c0.
| slab error in cache_alloc_debugcheck_after(): cache `idr_layer_cache': double free, or memory outside object was overwritten
| ...
| c011307c: redzone 1:0x9f91102ffffffff, redzone 2:0x9f911029d74e35b
| slab: Internal list corruption detected in cache 'idr_layer_cache'(24), slabp c0113000(16). Hexdump:
|
| 000: 20 4f 10 c0 20 4f 10 c0 7c 00 00 00 7c 30 11 c0
| 010: 10 00 00 00 10 00 00 00 00 00 c9 17 fe ff ff ff
| 020: fe ff ff ff fe ff ff ff fe ff ff ff fe ff ff ff
| 030: fe ff ff ff fe ff ff ff fe ff ff ff fe ff ff ff
| 040: fe ff ff ff fe ff ff ff fe ff ff ff fe ff ff ff
| 050: fe ff ff ff fe ff ff ff fe ff ff ff 11 00 00 00
| 060: 12 00 00 00 13 00 00 00 14 00 00 00 15 00 00 00
| 070: 16 00 00 00 17 00 00 00 c0 88 56 63
| kernel BUG at /home/rmk/git/linux-2.6-rmk/mm/slab.c:2928!

Reference: https://lkml.org/lkml/2011/2/7/238
Reported-and-analyzed-by: Russell King 
Signed-off-by: Pekka Enberg 
Signed-off-by: Greg Kroah-Hartman

mm: fix possible cause of a page_mapped BUG

2011-03-14T21:17:34+00:00

commit a3e8cc643d22d2c8ed36b9be7d9c9ca21efcf7f7 upstream.

Robert Swiecki reported a BUG_ON(page_mapped) from a fuzzer, punching
a hole with madvise(,, MADV_REMOVE).  That path is under mutex, and
cannot be explained by lack of serialization in unmap_mapping_range().

Reviewing the code, I found one place where vm_truncate_count handling
should have been updated, when I switched at the last minute from one
way of managing the restart_addr to another: mremap move changes the
virtual addresses, so it ought to adjust the restart_addr.

But rather than exporting the notion of restart_addr from memory.c, or
converting to restart_pgoff throughout, simply reset vm_truncate_count
to 0 to force a rescan if mremap move races with preempted truncation.

We have no confirmation that this fixes Robert's BUG,
but it is a fix that's worth making anyway.

Signed-off-by: Hugh Dickins 
Signed-off-by: Linus Torvalds 
Cc: Kerin Millar 
Signed-off-by: Greg Kroah-Hartman

mm: vmstat: use a single setter function and callback for adjusting percpu thresholds

2011-03-07T23:05:21+00:00

commit b44129b30652c8771db2265939bb8b463724043d upstream.

reduce_pgdat_percpu_threshold() and restore_pgdat_percpu_threshold() exist
to adjust the per-cpu vmstat thresholds while kswapd is awake to avoid
errors due to counter drift.  The functions duplicate some code so this
patch replaces them with a single set_pgdat_percpu_threshold() that takes
a callback function to calculate the desired threshold as a parameter.

[akpm@linux-foundation.org: readability tweak]
[kosaki.motohiro@jp.fujitsu.com: set_pgdat_percpu_threshold(): don't use for_each_online_cpu]
Signed-off-by: Mel Gorman 
Reviewed-by: Christoph Lameter 
Reviewed-by: KAMEZAWA Hiroyuki 
Signed-off-by: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: fix dubious code in __count_immobile_pages()

2011-03-07T23:05:11+00:00

commit 29723fccc837d20039078f7a571e8d457eb0d6c6 upstream.

When pfn_valid_within() failed 'iter' was incremented twice.

Signed-off-by: Namhyung Kim 
Reviewed-by: KAMEZAWA Hiroyuki 
Reviewed-by: Minchan Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman