diff options
| author | Laura Abbott <lauraa@codeaurora.org> | 2016-01-30 06:07:30 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-08 01:34:58 (GMT) |
| commit | 18e77054de741ef3ed2a2489bc9bf82a318b2d5e (patch) | |
| tree | f8f332e555f49153b73dcd97f0597a6125bc106e /drivers/staging/android | |
| parent | 092c78f24a89c0ef837cc905fb40f67db39ba257 (diff) | |
| download | linux-18e77054de741ef3ed2a2489bc9bf82a318b2d5e.tar.xz | |
staging: ashmem: Avoid deadlock with mmap/shrink
Both ashmem_mmap and ashmem_shrink take the ashmem_lock. It may
be possible for ashmem_mmap to invoke ashmem_shrink:
-000|mutex_lock(lock = 0x0)
-001|ashmem_shrink(?, sc = 0x0) <--- try to take ashmem_mutex again
-002|shrink_slab(shrink = 0xDA5F1CC0, nr_pages_scanned = 0, lru_pages
-002|=
-002|124)
-003|try_to_free_pages(zonelist = 0x0, ?, ?, ?)
-004|__alloc_pages_nodemask(gfp_mask = 21200, order = 1, zonelist =
-004|0xC11D0940,
-005|new_slab(s = 0xE4841E80, ?, node = -1)
-006|__slab_alloc.isra.43.constprop.50(s = 0xE4841E80, gfpflags =
-006|2148925462, ad
-007|kmem_cache_alloc(s = 0xE4841E80, gfpflags = 208)
-008|shmem_alloc_inode(?)
-009|alloc_inode(sb = 0xE480E800)
-010|new_inode_pseudo(?)
-011|new_inode(?)
-012|shmem_get_inode(sb = 0xE480E800, dir = 0x0, ?, dev = 0, flags =
-012|187)
-013|shmem_file_setup(?, ?, flags = 187)
-014|ashmem_mmap(?, vma = 0xC5D64210) <---- Acquire ashmem_mutex
-015|mmap_region(file = 0xDF8E2C00, addr = 1772974080, len = 233472,
-015|flags = 57,
-016|sys_mmap_pgoff(addr = 0, len = 230400, prot = 3, flags = 1, fd =
-016|157, pgoff
-017|ret_fast_syscall(asm)
-->|exception
-018|NUR:0x40097508(asm)
---|end of frame
Avoid this deadlock by using mutex_trylock in ashmem_shrink; if the mutex
is already held, do not attempt to shrink.
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Android Kernel Team <kernel-team@android.com>
Reported-by: Matt Wagantall <mattw@codeaurora.org>
Reported-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
Reported-by: Osvaldo Banuelos <osvaldob@codeaurora.org>
Reported-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
[jstultz: Minor commit message tweaks]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/android')
| -rw-r--r-- | drivers/staging/android/ashmem.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c index 5bb1283..8ae1308 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -441,7 +441,9 @@ ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) if (!(sc->gfp_mask & __GFP_FS)) return SHRINK_STOP; - mutex_lock(&ashmem_mutex); + if (!mutex_trylock(&ashmem_mutex)) + return -1; + list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) { loff_t start = range->pgstart * PAGE_SIZE; loff_t end = (range->pgend + 1) * PAGE_SIZE; |