diff options
| author | Roman Gushchin <guro@fb.com> | 2018-11-02 15:47:49 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-11-03 10:09:37 -0700 |
| commit | e68599a3c3ad0f3171a7cb4e48aa6f9a69381902 (patch) | |
| tree | 8875f414c9f0acbf22857484d1cb32a0804ca92f | |
| parent | 5f21585384a4a69b8bfdd2cae7e3648ae805f57d (diff) | |
| download | linux-e68599a3c3ad0f3171a7cb4e48aa6f9a69381902.tar.bz2 | |
mm: handle no memcg case in memcg_kmem_charge() properly
Mike Galbraith reported a regression caused by the commit 9b6f7e163cd0
("mm: rework memcg kernel stack accounting") on a system with
"cgroup_disable=memory" boot option: the system panics with the following
stack trace:
BUG: unable to handle kernel NULL pointer dereference at 00000000000000f8
PGD 0 P4D 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 0 PID: 1 Comm: systemd Not tainted 4.19.0-preempt+ #410
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20180531_142017-buildhw-08.phx2.fed4
RIP: 0010:page_counter_try_charge+0x22/0xc0
Code: 41 5d c3 c3 0f 1f 40 00 0f 1f 44 00 00 48 85 ff 0f 84 a7 00 00 00 41 56 48 89 f8 49 89 fe 49
Call Trace:
try_charge+0xcb/0x780
memcg_kmem_charge_memcg+0x28/0x80
memcg_kmem_charge+0x8b/0x1d0
copy_process.part.41+0x1ca/0x2070
_do_fork+0xd7/0x3d0
do_syscall_64+0x5a/0x180
entry_SYSCALL_64_after_hwframe+0x49/0xbe
The problem occurs because get_mem_cgroup_from_current() returns the NULL
pointer if memory controller is disabled. Let's check if this is a case
at the beginning of memcg_kmem_charge() and just return 0 if
mem_cgroup_disabled() returns true. This is how we handle this case in
many other places in the memory controller code.
Link: http://lkml.kernel.org/r/20181029215123.17830-1-guro@fb.com
Fixes: 9b6f7e163cd0 ("mm: rework memcg kernel stack accounting")
Signed-off-by: Roman Gushchin <guro@fb.com>
Reported-by: Mike Galbraith <efault@gmx.de>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/memcontrol.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 54920cbc46bf..6e1469b80cb7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2593,7 +2593,7 @@ int memcg_kmem_charge(struct page *page, gfp_t gfp, int order) struct mem_cgroup *memcg; int ret = 0; - if (memcg_kmem_bypass()) + if (mem_cgroup_disabled() || memcg_kmem_bypass()) return 0; memcg = get_mem_cgroup_from_current(); |