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| author | Andrey Vagin <avagin@openvz.org> | 2013-08-28 16:35:20 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-08-28 19:26:38 -0700 |
| commit | 6f6b8951897e487ea6f77b90ea01f70a9c363770 (patch) | |
| tree | d0ae26e13a2324ef65603d4c970319e52cc26b82 | |
| parent | 21ea9f5ace3a7317cc3ba1fbc749758021a83136 (diff) | |
| download | linux-6f6b8951897e487ea6f77b90ea01f70a9c363770.tar.gz linux-6f6b8951897e487ea6f77b90ea01f70a9c363770.tar.xz | |
memcg: check that kmem_cache has memcg_params before accessing it
If the system had a few memory groups and all of them were destroyed,
memcg_limited_groups_array_size has non-zero value, but all new caches
are created without memcg_params, because memcg_kmem_enabled() returns
false.
We try to enumirate child caches in a few places and all of them are
potentially dangerous.
For example my kernel is compiled with CONFIG_SLAB and it crashed when I
tryed to mount a NFS share after a few experiments with kmemcg.
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: [<ffffffff8118166a>] do_tune_cpucache+0x8a/0xd0
PGD b942a067 PUD b999f067 PMD 0
Oops: 0000 [#1] SMP
Modules linked in: fscache(+) ip6table_filter ip6_tables iptable_filter ip_tables i2c_piix4 pcspkr virtio_net virtio_balloon i2c_core floppy
CPU: 0 PID: 357 Comm: modprobe Not tainted 3.11.0-rc7+ #59
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
task: ffff8800b9f98240 ti: ffff8800ba32e000 task.ti: ffff8800ba32e000
RIP: 0010:[<ffffffff8118166a>] [<ffffffff8118166a>] do_tune_cpucache+0x8a/0xd0
RSP: 0018:ffff8800ba32fb70 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffff8800b9f98910 RDI: 0000000000000246
RBP: ffff8800ba32fba0 R08: 0000000000000002 R09: 0000000000000004
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000010
R13: 0000000000000008 R14: 00000000000000d0 R15: ffff8800375d0200
FS: 00007f55f1378740(0000) GS:ffff8800bfa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007f24feba57a0 CR3: 0000000037b51000 CR4: 00000000000006f0
Call Trace:
enable_cpucache+0x49/0x100
setup_cpu_cache+0x215/0x280
__kmem_cache_create+0x2fa/0x450
kmem_cache_create_memcg+0x214/0x350
kmem_cache_create+0x2b/0x30
fscache_init+0x19b/0x230 [fscache]
do_one_initcall+0xfa/0x1b0
load_module+0x1c41/0x26d0
SyS_finit_module+0x86/0xb0
system_call_fastpath+0x16/0x1b
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Glauber Costa <glommer@openvz.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/slab.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/slab.h b/mm/slab.h index 620ceeddbe1a..a535033f7e9a 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -162,6 +162,8 @@ static inline const char *cache_name(struct kmem_cache *s) static inline struct kmem_cache *cache_from_memcg(struct kmem_cache *s, int idx) { + if (!s->memcg_params) + return NULL; return s->memcg_params->memcg_caches[idx]; } |