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| author | Yuanyuan Zhong <a6510c@motorola.com> | 2011-01-14 09:28:55 -0600 |
|---|---|---|
| committer | Ziyan <jaraidaniel@gmail.com> | 2016-01-08 10:44:50 +0100 |
| commit | 8a300ec0aa85c4520ee140dd6dfb8ef9f3c5a42f (patch) | |
| tree | 27040d87681dc254639773a36149cca7e80b8140 /mm | |
| parent | 95c015c61de96acca5bb4f3fd77f0cdab3322060 (diff) | |
| download | kernel_samsung_tuna-8a300ec0aa85c4520ee140dd6dfb8ef9f3c5a42f.tar.gz kernel_samsung_tuna-8a300ec0aa85c4520ee140dd6dfb8ef9f3c5a42f.tar.bz2 kernel_samsung_tuna-8a300ec0aa85c4520ee140dd6dfb8ef9f3c5a42f.zip | |
mm:ashmem: avoid ashmem deadlock
This is propagation of change done in (CR).
When system memory is low, allocating memory while holding the
ashmem_mutex may try to directly reclaim memory. Then ashmem_shrink()
is called in same thread. It will deadlock at acquiring ashmem_mutex.
We end up with stack like this:
Task name: app_process pid: 16442 cpu: 0
state: 0x2 exit_state: 0x0 stack base: 0xc876c000
Stack:
[<c084ce20>] __schedule+0x664
[<c084dea4>] __mutex_lock_slowpath+0x220
[<c084ea48>] mutex_lock+0x20
[<c021f104>] ashmem_shrink+0x44
[<c01fe3a0>] shrink_slab+0x228
[<c01ff38c>] try_to_free_pages+0x3c8
[<c01f483c>] __alloc_pages_nodemask+0x4a8
[<c02236fc>] new_slab+0x70
[<c0224928>] __slab_alloc.clone.1+0x248
[<c0224bb4>] kmem_cache_alloc+0xa0
[<c020174c>] shmem_alloc_inode+0x14
[<c0243670>] alloc_inode+0x1c
[<c02439e4>] new_inode_pseudo+0x8
[<c0243a24>] new_inode+0x8
[<c0200a0c>] shmem_get_inode+0x2c
[<c0200c80>] shmem_file_setup+0x10c
[<c021f030>] ashmem_mmap+0x8c
[<c0212618>] mmap_region+0x2b8
[<c0212bc4>] sys_mmap_pgoff+0x8c
[<c0106000>] ret_fast_syscall+0x0
This change lets ashmem_shrink() return failure if ashmem_mutex is not
available. Memory will be reclaimed from others.
Change-Id: I3b2193b6e4fca4eeafd558b919ba8a76894a33a1
Signed-off-by: Yuanyuan Zhong <a6510c@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/498700
Tested-by: Jira Key <JIRAKEY@motorola.com>
Reviewed-by: Check Patch <CHEKPACH@motorola.com>
Reviewed-by: Klocwork kwcheck <klocwork-kwcheck@sourceforge.mot.com>
Reviewed-by: Jeffrey Carlyle <jeff.carlyle@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/520376
Tested-by: Jira Key <jirakey@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/ashmem.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/ashmem.c b/mm/ashmem.c index c1078aa2972..62fab280cc7 100644 --- a/mm/ashmem.c +++ b/mm/ashmem.c @@ -364,7 +364,8 @@ static int ashmem_shrink(struct shrinker *s, struct shrink_control *sc) if (!sc->nr_to_scan) return lru_count; - mutex_lock(&ashmem_mutex); + if (!mutex_trylock(&ashmem_mutex)) + return -EBUSY; list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { struct inode *inode = range->asma->file->f_dentry->d_inode; loff_t start = range->pgstart * PAGE_SIZE; |