From e0a3c6cf7328cc67e56494da841aa815e8d77c29 Mon Sep 17 00:00:00 2001 From: Chris Down Date: Wed, 1 Apr 2020 21:07:17 -0700 Subject: [PATCH 2155/2944] mm, memcg: prevent memory.high load/store tearing task #31315199 commit f6f989c5cebcc38b2d28c5b5f045d9a0a2082a9b upstream A mem_cgroup's high attribute can be concurrently set at the same time as we are trying to read it -- for example, if we are in memory_high_write at the same time as we are trying to do high reclaim. Signed-off-by: Chris Down Signed-off-by: Andrew Morton Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Roman Gushchin Cc: Tejun Heo Link: http://lkml.kernel.org/r/2f66f7038ed1d4688e59de72b627ae0ea52efa83.1584034301.git.chris@chrisdown.name Signed-off-by: Linus Torvalds Signed-off-by: zhongjiang-ali Reviewed-by: Xunlei Pang --- mm/memcontrol.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 0730a0d..1bcc97db 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2382,7 +2382,7 @@ static void reclaim_high(struct mem_cgroup *memcg, gfp_t gfp_mask) { do { - if (page_counter_read(&memcg->memory) <= memcg->high) + if (page_counter_read(&memcg->memory) <= READ_ONCE(memcg->high)) continue; memcg_memory_event(memcg, MEMCG_HIGH); try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true); @@ -2745,7 +2745,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, break; } - if (page_counter_read(&memcg->memory) > memcg->high) { + if (page_counter_read(&memcg->memory) > READ_ONCE(memcg->high)) { /* Don't bother a random interrupted task */ if (in_interrupt()) { schedule_work(&memcg->high_work); @@ -5143,7 +5143,8 @@ 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, memcg->high); + unsigned long ceiling = min(memcg->memory.max, + READ_ONCE(memcg->high)); unsigned long used = page_counter_read(&memcg->memory); *pheadroom = min(*pheadroom, ceiling - min(ceiling, used)); @@ -5477,7 +5478,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, if (err) return err; - memcg->high = high; + WRITE_ONCE(memcg->high, high); nr_pages = page_counter_read(&memcg->memory); if (nr_pages > high) @@ -5991,7 +5992,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) if (!memcg) return ERR_PTR(error); - memcg->high = PAGE_COUNTER_MAX; + WRITE_ONCE(memcg->high, PAGE_COUNTER_MAX); memcg->soft_limit = PAGE_COUNTER_MAX; if (parent) { memcg->swappiness = max(mem_cgroup_swappiness(parent), 0); @@ -6154,7 +6155,7 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css) page_counter_set_low(&memcg->memory, 0); page_counter_set_wmark_low(&memcg->memory, PAGE_COUNTER_MAX); page_counter_set_wmark_high(&memcg->memory, PAGE_COUNTER_MAX); - memcg->high = PAGE_COUNTER_MAX; + WRITE_ONCE(memcg->high, PAGE_COUNTER_MAX); memcg->soft_limit = PAGE_COUNTER_MAX; memcg_wb_domain_size_changed(memcg); } -- 1.8.3.1