The patch titled
Subject: mm/memcontrol: fix a data race in scan count
has been added to the -mm tree. Its filename is
mm-memcontrol-fix-a-data-race-in-scan-count.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcontrol-fix-a-data-race-in-scan-count.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcontrol-fix-a-data-race-in-scan-count.patch
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------------------------------------------------------
From: Qian Cai <cai@xxxxxx>
Subject: mm/memcontrol: fix a data race in scan count
struct mem_cgroup_per_node mz.lru_zone_size[zone_idx][lru] could be
accessed concurrently as noticed by KCSAN,
BUG: KCSAN: data-race in lruvec_lru_size / mem_cgroup_update_lru_size
write to 0xffff9c804ca285f8 of 8 bytes by task 50951 on cpu 12:
mem_cgroup_update_lru_size+0x11c/0x1d0
mem_cgroup_update_lru_size at mm/memcontrol.c:1266
isolate_lru_pages+0x6a9/0xf30
shrink_active_list+0x123/0xcc0
shrink_lruvec+0x8fd/0x1380
shrink_node+0x317/0xd80
do_try_to_free_pages+0x1f7/0xa10
try_to_free_pages+0x26c/0x5e0
__alloc_pages_slowpath+0x458/0x1290
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x170/0x700
__handle_mm_fault+0xc9f/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
read to 0xffff9c804ca285f8 of 8 bytes by task 50964 on cpu 95:
lruvec_lru_size+0xbb/0x270
mem_cgroup_get_zone_lru_size at include/linux/memcontrol.h:536
(inlined by) lruvec_lru_size at mm/vmscan.c:326
shrink_lruvec+0x1d0/0x1380
shrink_node+0x317/0xd80
do_try_to_free_pages+0x1f7/0xa10
try_to_free_pages+0x26c/0x5e0
__alloc_pages_slowpath+0x458/0x1290
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_current+0xa6/0x120
alloc_slab_page+0x3b1/0x540
allocate_slab+0x70/0x660
new_slab+0x46/0x70
___slab_alloc+0x4ad/0x7d0
__slab_alloc+0x43/0x70
kmem_cache_alloc+0x2c3/0x420
getname_flags+0x4c/0x230
getname+0x22/0x30
do_sys_openat2+0x205/0x3b0
do_sys_open+0x9a/0xf0
__x64_sys_openat+0x62/0x80
do_syscall_64+0x91/0xb47
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Reported by Kernel Concurrency Sanitizer on:
CPU: 95 PID: 50964 Comm: cc1 Tainted: G W O L 5.5.0-next-20200204+ #6
Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
The write is under lru_lock, but the read is done as lockless. The scan
count is used to determine how aggressively the anon and file LRU lists
should be scanned. Load tearing could generate an inefficient heuristic,
so fix it by adding READ_ONCE() for the read.
Link: http://lkml.kernel.org/r/20200206034945.2481-1-cai@xxxxxx
Signed-off-by: Qian Cai <cai@xxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/memcontrol.h~mm-memcontrol-fix-a-data-race-in-scan-count
+++ a/include/linux/memcontrol.h
@@ -533,7 +533,7 @@ unsigned long mem_cgroup_get_zone_lru_si
struct mem_cgroup_per_node *mz;
mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
- return mz->lru_zone_size[zone_idx][lru];
+ return READ_ONCE(mz->lru_zone_size[zone_idx][lru]);
}
void mem_cgroup_handle_over_high(void);
_
Patches currently in -mm which might be from cai@xxxxxx are
mm-swapfile-fix-and-annotate-various-data-races.patch
mm-memcontrol-fix-a-data-race-in-scan-count.patch
mm-list_lru-fix-a-data-race-in-list_lru_count_one.patch
mm-frontswap-mark-various-intentional-data-races.patch
mm-page_io-mark-various-intentional-data-races.patch
mm-swap_state-mark-various-intentional-data-races.patch
