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| author | Chris Down <chris@chrisdown.name> | 2020-04-01 21:07:20 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-02 09:35:28 -0700 |
| commit | 15b42562d46debadaebd77ac1a647abae139a231 (patch) | |
| tree | 870fb610282ff7f4506932768df358439298fc32 /mm | |
| parent | f6f989c5cebcc38b2d28c5b5f045d9a0a2082a9b (diff) | |
| download | linux-15b42562d46debadaebd77ac1a647abae139a231.tar.bz2 | |
mm, memcg: prevent memory.max load tearing
This one is a bit more nuanced because we have memcg_max_mutex, which is
mostly just used for enforcing invariants, but we still need to READ_ONCE
since (despite its name) it doesn't really protect memory.max access.
On write (page_counter_set_max() and memory_max_write()) we use xchg(),
which uses smp_mb(), so that's already fine.
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/50a31e5f39f8ae6c8fb73966ba1455f0924e8f44.1584034301.git.chris@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memcontrol.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b1bb62485622..f7af5aea0054 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1521,7 +1521,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg) pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n", K((u64)page_counter_read(&memcg->memory)), - K((u64)memcg->memory.max), memcg->memory.failcnt); + K((u64)READ_ONCE(memcg->memory.max)), memcg->memory.failcnt); 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)), @@ -1552,7 +1552,7 @@ unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg) { unsigned long max; - max = memcg->memory.max; + max = READ_ONCE(memcg->memory.max); if (mem_cgroup_swappiness(memcg)) { unsigned long memsw_max; unsigned long swap_max; @@ -3068,7 +3068,7 @@ static int mem_cgroup_resize_max(struct mem_cgroup *memcg, * Make sure that the new limit (memsw or memory limit) doesn't * break our basic invariant rule memory.max <= memsw.max. */ - limits_invariant = memsw ? max >= memcg->memory.max : + limits_invariant = memsw ? max >= READ_ONCE(memcg->memory.max) : max <= memcg->memsw.max; if (!limits_invariant) { mutex_unlock(&memcg_max_mutex); @@ -3815,8 +3815,8 @@ static int memcg_stat_show(struct seq_file *m, void *v) /* Hierarchical information */ memory = memsw = PAGE_COUNTER_MAX; for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) { - memory = min(memory, mi->memory.max); - memsw = min(memsw, mi->memsw.max); + memory = min(memory, READ_ONCE(mi->memory.max)); + memsw = min(memsw, READ_ONCE(mi->memsw.max)); } seq_printf(m, "hierarchical_memory_limit %llu\n", (u64)memory * PAGE_SIZE); @@ -4325,7 +4325,7 @@ void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages, *pheadroom = PAGE_COUNTER_MAX; while ((parent = parent_mem_cgroup(memcg))) { - unsigned long ceiling = min(memcg->memory.max, + unsigned long ceiling = min(READ_ONCE(memcg->memory.max), READ_ONCE(memcg->high)); unsigned long used = page_counter_read(&memcg->memory); |