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author | Jiri Slaby <jslaby@suse.cz> | 2019-06-01 08:30:26 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-09 10:18:17 +0300 |
commit | 1bd33537171499e1ed0528442d31fc1d5698b4c8 (patch) | |
tree | 788f476d8bde477daa829e17766ff75c17d58b4b /mm/list_lru.c | |
parent | 3d3494aa6609d2acc5e37f09a95a13bc41868af8 (diff) | |
download | linux-1bd33537171499e1ed0528442d31fc1d5698b4c8.tar.xz |
memcg: make it work on sparse non-0-node systems
commit 3e8589963773a5c23e2f1fe4bcad0e9a90b7f471 upstream.
We have a single node system with node 0 disabled:
Scanning NUMA topology in Northbridge 24
Number of physical nodes 2
Skipping disabled node 0
Node 1 MemBase 0000000000000000 Limit 00000000fbff0000
NODE_DATA(1) allocated [mem 0xfbfda000-0xfbfeffff]
This causes crashes in memcg when system boots:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
#PF error: [normal kernel read fault]
...
RIP: 0010:list_lru_add+0x94/0x170
...
Call Trace:
d_lru_add+0x44/0x50
dput.part.34+0xfc/0x110
__fput+0x108/0x230
task_work_run+0x9f/0xc0
exit_to_usermode_loop+0xf5/0x100
It is reproducible as far as 4.12. I did not try older kernels. You have
to have a new enough systemd, e.g. 241 (the reason is unknown -- was not
investigated). Cannot be reproduced with systemd 234.
The system crashes because the size of lru array is never updated in
memcg_update_all_list_lrus and the reads are past the zero-sized array,
causing dereferences of random memory.
The root cause are list_lru_memcg_aware checks in the list_lru code. The
test in list_lru_memcg_aware is broken: it assumes node 0 is always
present, but it is not true on some systems as can be seen above.
So fix this by avoiding checks on node 0. Remember the memcg-awareness by
a bool flag in struct list_lru.
Link: http://lkml.kernel.org/r/20190522091940.3615-1-jslaby@suse.cz
Fixes: 60d3fd32a7a9 ("list_lru: introduce per-memcg lists")
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/list_lru.c')
-rw-r--r-- | mm/list_lru.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/mm/list_lru.c b/mm/list_lru.c index f141f0c80ff3..dc19694d0e92 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -42,11 +42,7 @@ static void list_lru_unregister(struct list_lru *lru) #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) static inline bool list_lru_memcg_aware(struct list_lru *lru) { - /* - * This needs node 0 to be always present, even - * in the systems supporting sparse numa ids. - */ - return !!lru->node[0].memcg_lrus; + return lru->memcg_aware; } static inline struct list_lru_one * @@ -389,6 +385,8 @@ static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware) { int i; + lru->memcg_aware = memcg_aware; + if (!memcg_aware) return 0; |