linux.git, branch v3.10.87

Linux 3.10.87

2015-08-17T03:52:24+00:00

mm, vmscan: Do not wait for page writeback for GFP_NOFS allocations

2015-08-17T03:51:43+00:00

commit ecf5fc6e9654cd7a268c782a523f072b2f1959f9 upstream.

Nikolay has reported a hang when a memcg reclaim got stuck with the
following backtrace:

PID: 18308  TASK: ffff883d7c9b0a30  CPU: 1   COMMAND: "rsync"
  #0 __schedule at ffffffff815ab152
  #1 schedule at ffffffff815ab76e
  #2 schedule_timeout at ffffffff815ae5e5
  #3 io_schedule_timeout at ffffffff815aad6a
  #4 bit_wait_io at ffffffff815abfc6
  #5 __wait_on_bit at ffffffff815abda5
  #6 wait_on_page_bit at ffffffff8111fd4f
  #7 shrink_page_list at ffffffff81135445
  #8 shrink_inactive_list at ffffffff81135845
  #9 shrink_lruvec at ffffffff81135ead
 #10 shrink_zone at ffffffff811360c3
 #11 shrink_zones at ffffffff81136eff
 #12 do_try_to_free_pages at ffffffff8113712f
 #13 try_to_free_mem_cgroup_pages at ffffffff811372be
 #14 try_charge at ffffffff81189423
 #15 mem_cgroup_try_charge at ffffffff8118c6f5
 #16 __add_to_page_cache_locked at ffffffff8112137d
 #17 add_to_page_cache_lru at ffffffff81121618
 #18 pagecache_get_page at ffffffff8112170b
 #19 grow_dev_page at ffffffff811c8297
 #20 __getblk_slow at ffffffff811c91d6
 #21 __getblk_gfp at ffffffff811c92c1
 #22 ext4_ext_grow_indepth at ffffffff8124565c
 #23 ext4_ext_create_new_leaf at ffffffff81246ca8
 #24 ext4_ext_insert_extent at ffffffff81246f09
 #25 ext4_ext_map_blocks at ffffffff8124a848
 #26 ext4_map_blocks at ffffffff8121a5b7
 #27 mpage_map_one_extent at ffffffff8121b1fa
 #28 mpage_map_and_submit_extent at ffffffff8121f07b
 #29 ext4_writepages at ffffffff8121f6d5
 #30 do_writepages at ffffffff8112c490
 #31 __filemap_fdatawrite_range at ffffffff81120199
 #32 filemap_flush at ffffffff8112041c
 #33 ext4_alloc_da_blocks at ffffffff81219da1
 #34 ext4_rename at ffffffff81229b91
 #35 ext4_rename2 at ffffffff81229e32
 #36 vfs_rename at ffffffff811a08a5
 #37 SYSC_renameat2 at ffffffff811a3ffc
 #38 sys_renameat2 at ffffffff811a408e
 #39 sys_rename at ffffffff8119e51e
 #40 system_call_fastpath at ffffffff815afa89

Dave Chinner has properly pointed out that this is a deadlock in the
reclaim code because ext4 doesn't submit pages which are marked by
PG_writeback right away.

The heuristic was introduced by commit e62e384e9da8 ("memcg: prevent OOM
with too many dirty pages") and it was applied only when may_enter_fs
was specified.  The code has been changed by c3b94f44fcb0 ("memcg:
further prevent OOM with too many dirty pages") which has removed the
__GFP_FS restriction with a reasoning that we do not get into the fs
code.  But this is not sufficient apparently because the fs doesn't
necessarily submit pages marked PG_writeback for IO right away.

ext4_bio_write_page calls io_submit_add_bh but that doesn't necessarily
submit the bio.  Instead it tries to map more pages into the bio and
mpage_map_one_extent might trigger memcg charge which might end up
waiting on a page which is marked PG_writeback but hasn't been submitted
yet so we would end up waiting for something that never finishes.

Fix this issue by replacing __GFP_IO by may_enter_fs check (for case 2)
before we go to wait on the writeback.  The page fault path, which is
the only path that triggers memcg oom killer since 3.12, shouldn't
require GFP_NOFS and so we shouldn't reintroduce the premature OOM
killer issue which was originally addressed by the heuristic.

As per David Chinner the xfs is doing similar thing since 2.6.15 already
so ext4 is not the only affected filesystem.  Moreover he notes:

: For example: IO completion might require unwritten extent conversion
: which executes filesystem transactions and GFP_NOFS allocations. The
: writeback flag on the pages can not be cleared until unwritten
: extent conversion completes. Hence memory reclaim cannot wait on
: page writeback to complete in GFP_NOFS context because it is not
: safe to do so, memcg reclaim or otherwise.

[tytso@mit.edu: corrected the control flow]
Fixes: c3b94f44fcb0 ("memcg: further prevent OOM with too many dirty pages")
Reported-by: Nikolay Borisov 
Signed-off-by: Michal Hocko 
Signed-off-by: Hugh Dickins 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

md/bitmap: return an error when bitmap superblock is corrupt.

2015-08-17T03:51:43+00:00

commit b97e92574c0bf335db1cd2ec491d8ff5cd5d0b49 upstream
    Use separate bitmaps for each nodes in the cluster

bitmap_read_sb() validates the bitmap superblock that it reads in.
If it finds an inconsistency like a bad magic number or out-of-range
version number, it prints an error and returns, but it incorrectly
returns zero, so the array is still assembled with the (invalid) bitmap.

This means it could try to use a bitmap with a new version number which
it therefore does not understand.

This bug was introduced in 3.5 and fix as part of a larger patch in 4.1.
So the patch is suitable for any -stable kernel in that range.

Fixes: 27581e5ae01f ("md/bitmap: centralise allocation of bitmap file pages.")
Signed-off-by: NeilBrown 
Reported-by: GuoQing Jiang

kvm: x86: fix kvm_apic_has_events to check for NULL pointer

2015-08-17T03:51:43+00:00

commit ce40cd3fc7fa40a6119e5fe6c0f2bc0eb4541009 upstream.

Malicious (or egregiously buggy) userspace can trigger it, but it
should never happen in normal operation.

Signed-off-by: Paolo Bonzini 
Signed-off-by: Wang Kai 
Signed-off-by: Greg Kroah-Hartman

signal: fix information leak in copy_siginfo_from_user32

2015-08-17T03:51:42+00:00

commit 3c00cb5e68dc719f2fc73a33b1b230aadfcb1309 upstream.

This function can leak kernel stack data when the user siginfo_t has a
positive si_code value.  The top 16 bits of si_code descibe which fields
in the siginfo_t union are active, but they are treated inconsistently
between copy_siginfo_from_user32, copy_siginfo_to_user32 and
copy_siginfo_to_user.

copy_siginfo_from_user32 is called from rt_sigqueueinfo and
rt_tgsigqueueinfo in which the user has full control overthe top 16 bits
of si_code.

This fixes the following information leaks:
x86:   8 bytes leaked when sending a signal from a 32-bit process to
       itself. This leak grows to 16 bytes if the process uses x32.
       (si_code = __SI_CHLD)
x86:   100 bytes leaked when sending a signal from a 32-bit process to
       a 64-bit process. (si_code = -1)
sparc: 4 bytes leaked when sending a signal from a 32-bit process to a
       64-bit process. (si_code = any)

parsic and s390 have similar bugs, but they are not vulnerable because
rt_[tg]sigqueueinfo have checks that prevent sending a positive si_code
to a different process.  These bugs are also fixed for consistency.

Signed-off-by: Amanieu d'Antras 
Cc: Oleg Nesterov 
Cc: Ingo Molnar 
Cc: Russell King 
Cc: Ralf Baechle 
Cc: Benjamin Herrenschmidt 
Cc: Chris Metcalf 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

signal: fix information leak in copy_siginfo_to_user

2015-08-17T03:51:42+00:00

commit 26135022f85105ad725cda103fa069e29e83bd16 upstream.

This function may copy the si_addr_lsb, si_lower and si_upper fields to
user mode when they haven't been initialized, which can leak kernel
stack data to user mode.

Just checking the value of si_code is insufficient because the same
si_code value is shared between multiple signals.  This is solved by
checking the value of si_signo in addition to si_code.

Signed-off-by: Amanieu d'Antras 
Cc: Oleg Nesterov 
Cc: Ingo Molnar 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

signalfd: fix information leak in signalfd_copyinfo

2015-08-17T03:51:42+00:00

commit 3ead7c52bdb0ab44f4bb1feed505a8323cc12ba7 upstream.

This function may copy the si_addr_lsb field to user mode when it hasn't
been initialized, which can leak kernel stack data to user mode.

Just checking the value of si_code is insufficient because the same
si_code value is shared between multiple signals.  This is solved by
checking the value of si_signo in addition to si_code.

Signed-off-by: Amanieu d'Antras 
Cc: Oleg Nesterov 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

ARM: 7819/1: fiq: Cast the first argument of flush_icache_range()

2015-08-17T03:51:42+00:00

commit 7cb3be0a27805c625ff7cce20c53c926d9483243 upstream.

Commit 2ba85e7af4 (ARM: Fix FIQ code on VIVT CPUs) causes the following build warning:

arch/arm/kernel/fiq.c:92:3: warning: passing argument 1 of 'cpu_cache.coherent_kern_range' makes integer from pointer without a cast [enabled by default]

Cast it as '(unsigned long)base' to avoid the warning.

Signed-off-by: Fabio Estevam 
Signed-off-by: Russell King 
Cc: Martin Kaiser 
Signed-off-by: Greg Kroah-Hartman

ARM: Fix FIQ code on VIVT CPUs

2015-08-17T03:51:41+00:00

commit 2ba85e7af4c639d933c9a87a6d7363f2983d5ada upstream.

Aaro Koskinen reports the following oops:
Installing fiq handler from c001b110, length 0x164
Unable to handle kernel paging request at virtual address ffff1224
pgd = c0004000
[ffff1224] *pgd=00000000, *pte=11fff0cb, *ppte=11fff00a
...
[] (set_fiq_handler+0x0/0x6c) from [] (ams_delta_init_fiq+0xa8/0x160)
 r6:00000164 r5:c001b110 r4:00000000 r3:fefecb4c
[] (ams_delta_init_fiq+0x0/0x160) from [] (ams_delta_init+0xd4/0x114)
 r6:00000000 r5:fffece10 r4:c037a9e0
[] (ams_delta_init+0x0/0x114) from [] (customize_machine+0x24/0x30)

This is because the vectors page is now write-protected, and to change
code in there we must write to its original alias.  Make that change,
and adjust the cache flushing such that the code will become visible
to the instruction stream on VIVT CPUs.

Reported-by: Aaro Koskinen 
Tested-by: Aaro Koskinen 
Signed-off-by: Russell King 
Cc: Martin Kaiser 
Signed-off-by: Greg Kroah-Hartman

ARM: Fix !kuser helpers case

2015-08-17T03:51:41+00:00

commit 1b16c4bcf80e319b2226a886b72b8466179c8e3a upstream.

Fix yet another build failure caused by a weird set of configuration
settings:

  LD      init/built-in.o
arch/arm/kernel/built-in.o: In function `__dabt_usr':
/home/tom3q/kernel/arch/arm/kernel/entry-armv.S:377: undefined reference to `kuser_cmpxchg64_fixup'
arch/arm/kernel/built-in.o: In function `__irq_usr':
/home/tom3q/kernel/arch/arm/kernel/entry-armv.S:387: undefined reference to `kuser_cmpxchg64_fixup'

caused by:
CONFIG_KUSER_HELPERS=n
CONFIG_CPU_32v6K=n
CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG=n

Reported-by: Tomasz Figa 
Signed-off-by: Russell King 
Cc: Martin Kaiser 
Signed-off-by: Greg Kroah-Hartman