linux-toradex.git/mm, branch v3.16-rc5

Merge branch 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2014-07-10T18:38:23+00:00

Pull cgroup fixes from Tejun Heo:
 "Mostly fixes for the fallouts from the recent cgroup core changes.

  The decoupled nature of cgroup dynamic hierarchy management
  (hierarchies are created dynamically on mount but may or may not be
  reused once unmounted depending on remaining usages) led to more
  ugliness being added to kernfs.

  Hopefully, this is the last of it"

* 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset: break kernfs active protection in cpuset_write_resmask()
  cgroup: fix a race between cgroup_mount() and cgroup_kill_sb()
  kernfs: introduce kernfs_pin_sb()
  cgroup: fix mount failure in a corner case
  cpuset,mempolicy: fix sleeping function called from invalid context
  cgroup: fix broken css_has_online_children()

shmem: fix init_page_accessed use to stop !PageLRU bug

2014-07-03T16:21:54+00:00

Under shmem swapping load, I sometimes hit the VM_BUG_ON_PAGE(!PageLRU)
in isolate_lru_pages() at mm/vmscan.c:1281!

Commit 2457aec63745 ("mm: non-atomically mark page accessed during page
cache allocation where possible") looks like interrupted work-in-progress.

mm/filemap.c's call to init_page_accessed() is fine, but not mm/shmem.c's
- shmem_write_begin() is clearly wrong to use it after shmem_getpage(),
when the page is always visible in radix_tree, and often already on LRU.

Revert change to shmem_write_begin(), and use init_page_accessed() or
mark_page_accessed() appropriately for SGP_WRITE in shmem_getpage_gfp().

SGP_WRITE also covers shmem_symlink(), which did not mark_page_accessed()
before; but since many other filesystems use [__]page_symlink(), which did
and does mark the page accessed, consider this as rectifying an oversight.

Signed-off-by: Hugh Dickins 
Acked-by: Mel Gorman 
Cc: Johannes Weiner 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Dave Hansen 
Cc: Prabhakar Lad 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

hwpoison: fix the handling path of the victimized page frame that belong to non-LRU

2014-07-03T16:21:54+00:00

Until now, the kernel has the same policy to handle victimized page
frames that belong to kernel-space(reserved/slab-subsystem) or
non-LRU(unknown page state).  In other word, the result of handling
either of these victimized page frames is (IGNORED | FAILED), and the
return value of memory_failure() is -EBUSY.

This patch is to avoid that memory_failure() returns very soon due to
the "true" value of (!PageLRU(p)), and it also ensures that
action_result() can report more precise information("reserved kernel",
"kernel slab", and "unknown page state") instead of "non LRU",
especially for memory errors which are detected by memory-scrubbing.

Andi said:

: While running the mcelog test suite on 3.14 I hit the following VM_BUG_ON:
:
: soft_offline: 0x56d4: unknown non LRU page type 3ffff800008000
: page:ffffea000015b400 count:3 mapcount:2097169 mapping:          (null) index:0xffff8800056d7000
: page flags: 0x3ffff800004081(locked|slab|head)
: ------------[ cut here ]------------
: kernel BUG at mm/rmap.c:1495!
:
: I think what happened is that a LRU page turned into a slab page in
: parallel with offlining.  memory_failure initially tests for this case,
: but doesn't retest later after the page has been locked.
:
: ...
:
: I ran this patch in a loop over night with some stress plus
: the mcelog test suite running in a loop. I cannot guarantee it hit it,
: but it should have given it a good beating.
:
: The kernel survived with no messages, although the mcelog test suite
: got killed at some point because it couldn't fork anymore. Probably
: some unrelated problem.
:
: So the patch is ok for me for .16.

Signed-off-by: Chen Yucong 
Acked-by: Naoya Horiguchi 
Reported-by: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

msync: fix incorrect fstart calculation

2014-07-03T16:21:53+00:00

Fix a regression caused by 7fc34a62ca44 ("mm/msync.c: sync only the
requested range in msync()").

xfstests generic/075 fail occured on ext4 data=journal mode because the
intended range was not syncing due to wrong fstart calculation.

Signed-off-by: Namjae Jeon 
Signed-off-by: Ashish Sangwan 
Reported-by: Eric Whitney 
Tested-by: Eric Whitney 
Acked-by: Matthew Wilcox 
Reviewed-by: Lukas Czerner 
Tested-by: Lukas Czerner 
Reviewed-by: Theodore Ts'o 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

slub: fix off by one in number of slab tests

2014-07-03T16:21:53+00:00

min_partial means minimum number of slab cached in node partial list.
So, if nr_partial is less than it, we keep newly empty slab on node
partial list rather than freeing it.  But if nr_partial is equal or
greater than it, it means that we have enough partial slabs so should
free newly empty slab.  Current implementation missed the equal case so
if we set min_partial is 0, then, at least one slab could be cached.
This is critical problem to kmemcg destroying logic because it doesn't
works properly if some slabs is cached.  This patch fixes this problem.

Fixes 91cb69620284 ("slub: make dead memcg caches discard free slabs
immediately").

Signed-off-by: Joonsoo Kim 
Acked-by: Vladimir Davydov 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Acked-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: page_alloc: fix CMA area initialisation when pageblock > MAX_ORDER

2014-07-03T16:21:53+00:00

With a kernel configured with ARM64_64K_PAGES && !TRANSPARENT_HUGEPAGE,
the following is triggered at early boot:

  SMP: Total of 8 processors activated.
  devtmpfs: initialized
  Unable to handle kernel NULL pointer dereference at virtual address 00000008
  pgd = fffffe0000050000
  [00000008] *pgd=00000043fba00003, *pmd=00000043fba00003, *pte=00e0000078010407
  Internal error: Oops: 96000006 [#1] SMP
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.15.0-rc864k+ #44
  task: fffffe03bc040000 ti: fffffe03bc080000 task.ti: fffffe03bc080000
  PC is at __list_add+0x10/0xd4
  LR is at free_one_page+0x270/0x638
  ...
  Call trace:
    __list_add+0x10/0xd4
    free_one_page+0x26c/0x638
    __free_pages_ok.part.52+0x84/0xbc
    __free_pages+0x74/0xbc
    init_cma_reserved_pageblock+0xe8/0x104
    cma_init_reserved_areas+0x190/0x1e4
    do_one_initcall+0xc4/0x154
    kernel_init_freeable+0x204/0x2a8
    kernel_init+0xc/0xd4

This happens because init_cma_reserved_pageblock() calls
__free_one_page() with pageblock_order as page order but it is bigger
than MAX_ORDER.  This in turn causes accesses past zone->free_list[].

Fix the problem by changing init_cma_reserved_pageblock() such that it
splits pageblock into individual MAX_ORDER pages if pageblock is bigger
than a MAX_ORDER page.

In cases where !CONFIG_HUGETLB_PAGE_SIZE_VARIABLE, which is all
architectures expect for ia64, powerpc and tile at the moment, the
âpageblock_order > MAX_ORDERâ condition will be optimised out since both
sides of the operator are constants.  In cases where pageblock size is
variable, the performance degradation should not be significant anyway
since init_cma_reserved_pageblock() is called only at boot time at most
MAX_CMA_AREAS times which by default is eight.

Signed-off-by: Michal Nazarewicz 
Reported-by: Mark Salter 
Tested-by: Mark Salter 
Tested-by: Christopher Covington 
Cc: Mel Gorman 
Cc: David Rientjes 
Cc: Marek Szyprowski 
Cc: Catalin Marinas 
Cc: 	[3.5+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset,mempolicy: fix sleeping function called from invalid context

2014-06-25T13:42:11+00:00

When runing with the kernel(3.15-rc7+), the follow bug occurs:
[ 9969.258987] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586
[ 9969.359906] in_atomic(): 1, irqs_disabled(): 0, pid: 160655, name: python
[ 9969.441175] INFO: lockdep is turned off.
[ 9969.488184] CPU: 26 PID: 160655 Comm: python Tainted: G       A      3.15.0-rc7+ #85
[ 9969.581032] Hardware name: FUJITSU-SV PRIMEQUEST 1800E/SB, BIOS PRIMEQUEST 1000 Series BIOS Version 1.39 11/16/2012
[ 9969.706052]  ffffffff81a20e60 ffff8803e941fbd0 ffffffff8162f523 ffff8803e941fd18
[ 9969.795323]  ffff8803e941fbe0 ffffffff8109995a ffff8803e941fc58 ffffffff81633e6c
[ 9969.884710]  ffffffff811ba5dc ffff880405c6b480 ffff88041fdd90a0 0000000000002000
[ 9969.974071] Call Trace:
[ 9970.003403]  [] dump_stack+0x4d/0x66
[ 9970.065074]  [] __might_sleep+0xfa/0x130
[ 9970.130743]  [] mutex_lock_nested+0x3c/0x4f0
[ 9970.200638]  [] ? kmem_cache_alloc+0x1bc/0x210
[ 9970.272610]  [] cpuset_mems_allowed+0x27/0x140
[ 9970.344584]  [] ? __mpol_dup+0x63/0x150
[ 9970.409282]  [] __mpol_dup+0xe5/0x150
[ 9970.471897]  [] ? __mpol_dup+0x63/0x150
[ 9970.536585]  [] ? copy_process.part.23+0x606/0x1d40
[ 9970.613763]  [] ? trace_hardirqs_on+0xd/0x10
[ 9970.683660]  [] ? monotonic_to_bootbased+0x2f/0x50
[ 9970.759795]  [] copy_process.part.23+0x670/0x1d40
[ 9970.834885]  [] do_fork+0xd8/0x380
[ 9970.894375]  [] ? __audit_syscall_entry+0x9c/0xf0
[ 9970.969470]  [] SyS_clone+0x16/0x20
[ 9971.030011]  [] stub_clone+0x69/0x90
[ 9971.091573]  [] ? system_call_fastpath+0x16/0x1b

The cause is that cpuset_mems_allowed() try to take
mutex_lock(&callback_mutex) under the rcu_read_lock(which was hold in
__mpol_dup()). And in cpuset_mems_allowed(), the access to cpuset is
under rcu_read_lock, so in __mpol_dup, we can reduce the rcu_read_lock
protection region to protect the access to cpuset only in
current_cpuset_is_being_rebound(). So that we can avoid this bug.

This patch is a temporary solution that just addresses the bug
mentioned above, can not fix the long-standing issue about cpuset.mems
rebinding on fork():

"When the forker's task_struct is duplicated (which includes
 ->mems_allowed) and it races with an update to cpuset_being_rebound
 in update_tasks_nodemask() then the task's mems_allowed doesn't get
 updated. And the child task's mems_allowed can be wrong if the
 cpuset's nodemask changes before the child has been added to the
 cgroup's tasklist."

Signed-off-by: Gu Zheng 
Acked-by: Li Zefan 
Signed-off-by: Tejun Heo 
Cc: stable

mm: fix crashes from mbind() merging vmas

2014-06-23T23:47:44+00:00

In v2.6.34 commit 9d8cebd4bcd7 ("mm: fix mbind vma merge problem")
introduced vma merging to mbind(), but it should have also changed the
convention of passing start vma from queue_pages_range() (formerly
check_range()) to new_vma_page(): vma merging may have already freed
that structure, resulting in BUG at mm/mempolicy.c:1738 and probably
worse crashes.

Fixes: 9d8cebd4bcd7 ("mm: fix mbind vma merge problem")
Reported-by: Naoya Horiguchi 
Tested-by: Naoya Horiguchi 
Signed-off-by: Hugh Dickins 
Acked-by: Christoph Lameter 
Cc: KOSAKI Motohiro 
Cc: Minchan Kim 
Cc: 	[2.6.34+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

slab: fix oops when reading /proc/slab_allocators

2014-06-23T23:47:44+00:00

Commit b1cb0982bdd6 ("change the management method of free objects of
the slab") introduced a bug on slab leak detector
('/proc/slab_allocators').  This detector works like as following
decription.

 1. traverse all objects on all the slabs.
 2. determine whether it is active or not.
 3. if active, print who allocate this object.

but that commit changed the way how to manage free objects, so the logic
determining whether it is active or not is also changed.  In before, we
regard object in cpu caches as inactive one, but, with this commit, we
mistakenly regard object in cpu caches as active one.

This intoduces kernel oops if DEBUG_PAGEALLOC is enabled.  If
DEBUG_PAGEALLOC is enabled, kernel_map_pages() is used to detect who
corrupt free memory in the slab.  It unmaps page table mapping if object
is free and map it if object is active.  When slab leak detector check
object in cpu caches, it mistakenly think this object active so try to
access object memory to retrieve caller of allocation.  At this point,
page table mapping to this object doesn't exist, so oops occurs.

Following is oops message reported from Dave.

It blew up when something tried to read /proc/slab_allocators
(Just cat it, and you should see the oops below)

  Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
  Modules linked in:
  [snip...]
  CPU: 1 PID: 9386 Comm: trinity-c33 Not tainted 3.14.0-rc5+ #131
  task: ffff8801aa46e890 ti: ffff880076924000 task.ti: ffff880076924000
  RIP: 0010:[]  [] handle_slab+0x8a/0x180
  RSP: 0018:ffff880076925de0  EFLAGS: 00010002
  RAX: 0000000000001000 RBX: 0000000000000000 RCX: 000000005ce85ce7
  RDX: ffffea00079be100 RSI: 0000000000001000 RDI: ffff880107458000
  RBP: ffff880076925e18 R08: 0000000000000001 R09: 0000000000000000
  R10: 0000000000000000 R11: 000000000000000f R12: ffff8801e6f84000
  R13: ffffea00079be100 R14: ffff880107458000 R15: ffff88022bb8d2c0
  FS:  00007fb769e45740(0000) GS:ffff88024d040000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffff8801e6f84ff8 CR3: 00000000a22db000 CR4: 00000000001407e0
  DR0: 0000000002695000 DR1: 0000000002695000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000070602
  Call Trace:
    leaks_show+0xce/0x240
    seq_read+0x28e/0x490
    proc_reg_read+0x3d/0x80
    vfs_read+0x9b/0x160
    SyS_read+0x58/0xb0
    tracesys+0xd4/0xd9
  Code: f5 00 00 00 0f 1f 44 00 00 48 63 c8 44 3b 0c 8a 0f 84 e3 00 00 00 83 c0 01 44 39 c0 72 eb 41 f6 47 1a 01 0f 84 e9 00 00 00 89 f0 <4d> 8b 4c 04 f8 4d 85 c9 0f 84 88 00 00 00 49 8b 7e 08 4d 8d 46
  RIP   handle_slab+0x8a/0x180

To fix the problem, I introduce an object status buffer on each slab.
With this, we can track object status precisely, so slab leak detector
would not access active object and no kernel oops would occur.  Memory
overhead caused by this fix is only imposed to CONFIG_DEBUG_SLAB_LEAK
which is mainly used for debugging, so memory overhead isn't big
problem.

Signed-off-by: Joonsoo Kim 
Reported-by: Dave Jones 
Reported-by: Tetsuo Handa 
Reviewed-by: Vladimir Davydov 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

shmem: fix faulting into a hole while it's punched

2014-06-23T23:47:44+00:00

Trinity finds that mmap access to a hole while it's punched from shmem
can prevent the madvise(MADV_REMOVE) or fallocate(FALLOC_FL_PUNCH_HOLE)
from completing, until the reader chooses to stop; with the puncher's
hold on i_mutex locking out all other writers until it can complete.

It appears that the tmpfs fault path is too light in comparison with its
hole-punching path, lacking an i_data_sem to obstruct it; but we don't
want to slow down the common case.

Extend shmem_fallocate()'s existing range notification mechanism, so
shmem_fault() can refrain from faulting pages into the hole while it's
punched, waiting instead on i_mutex (when safe to sleep; or repeatedly
faulting when not).

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Hugh Dickins 
Reported-by: Sasha Levin 
Tested-by: Sasha Levin 
Cc: Dave Jones 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds