diff options
| author | Laura Abbott <lauraa@codeaurora.org> | 2014-01-24 15:19:49 -0800 |
|---|---|---|
| committer | Socrates Guerrero <sguerrero@google.com> | 2014-09-02 15:55:53 +0000 |
| commit | 3da67f8e9ae5272cd611a1753b466981021f887d (patch) | |
| tree | 1f90dd479f2a25bc35f2a2c8d6613f1407c39d12 | |
| parent | 3ed2f0b21e2b91cf9b77d7bb2830b175ae55aead (diff) | |
| download | omap-omapzoom-glass-omap-xrw66.tar.gz | |
staging: android: ashmem: Avoid deadlock with mmap/shrinkglass-omap-xrw66
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.
Change-Id: I222bbf55856d5849da813b730de0636c80966c8e
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>
(cherry picked from commit e2473a2c8cbfe3c476113860d9c90599819060f1)
| -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 c49480ebf85f..4de7bdacda0b 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -361,7 +361,9 @@ 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 -1; + 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; |