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authorChris Down <chris@chrisdown.name>2020-04-01 21:07:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-02 09:35:29 -0700
commit32d087cdd9a1ff179177513a8b5d34bec2f54e62 (patch)
tree8bb5fac2aebae5d7fed207b45407e0476d9bed46
parentc3d532008661da197997fc6d8098190eef9344ad (diff)
downloadlinux-stericsson-32d087cdd9a1ff179177513a8b5d34bec2f54e62.tar.gz
mm, memcg: prevent memory.swap.max load tearing
The write side of this is xchg()/smp_mb(), so that's all good. Just a few sites missing a READ_ONCE. Signed-off-by: Chris Down <chris@chrisdown.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <guro@fb.com> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/bbec2c3d822217334855c8877a9d28b2a6d395fb.1584034301.git.chris@chrisdown.name Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memcontrol.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index dc28afa149ef..1cd944c2a734 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1525,7 +1525,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->swap)),
- K((u64)memcg->swap.max), memcg->swap.failcnt);
+ K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt);
else {
pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->memsw)),
@@ -1558,7 +1558,7 @@ unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
unsigned long swap_max;
memsw_max = memcg->memsw.max;
- swap_max = memcg->swap.max;
+ swap_max = READ_ONCE(memcg->swap.max);
swap_max = min(swap_max, (unsigned long)total_swap_pages);
max = min(max + swap_max, memsw_max);
}
@@ -7117,7 +7117,8 @@ bool mem_cgroup_swap_full(struct page *page)
return false;
for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
- if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.max)
+ if (page_counter_read(&memcg->swap) * 2 >=
+ READ_ONCE(memcg->swap.max))
return true;
return false;