Commit 32d087cd authored by Chris Down's avatar Chris Down Committed by Linus Torvalds
Browse files

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: default avatarChris Down <>
Signed-off-by: default avatarAndrew Morton <>
Acked-by: default avatarMichal Hocko <>
Cc: Johannes Weiner <>
Cc: Roman Gushchin <>
Cc: Tejun Heo <>

Signed-off-by: default avatarLinus Torvalds <>
parent c3d53200
......@@ -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)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",
......@@ -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 >=
return true;
return false;
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