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[70.44.39.90]) by smtp.gmail.com with ESMTPSA id o7sm13242112qki.63.2021.03.15.16.41.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Mar 2021 16:41:00 -0700 (PDT) From: Johannes Weiner To: Andrew Morton Cc: Michal Hocko , Roman Gushchin , Shakeel Butt , Tejun Heo , =?UTF-8?q?Michal=20Koutn=C3=BD?= , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH] mm: memcontrol: switch to rstat fix Date: Mon, 15 Mar 2021 19:41:00 -0400 Message-Id: <20210315234100.64307-1-hannes@cmpxchg.org> X-Mailer: git-send-email 2.30.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fix a sleep in atomic section problem: wb_writeback() takes a spinlock and calls wb_over_bg_thresh() -> mem_cgroup_wb_stats, but the regular rstat flushing function called from in there does lockbreaking and may sleep. Switch to the atomic variant, cgroup_rstat_irqsafe(). To be consistent with other memcg flush calls, but without adding another memcg wrapper, inline and drop memcg_flush_vmstats() instead. Signed-off-by: Johannes Weiner --- mm/memcontrol.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f7fb12d3c2fc..9091913ec877 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -757,11 +757,6 @@ mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz) return mz; } -static void memcg_flush_vmstats(struct mem_cgroup *memcg) -{ - cgroup_rstat_flush(memcg->css.cgroup); -} - /** * __mod_memcg_state - update cgroup memory statistics * @memcg: the memory cgroup @@ -1572,7 +1567,7 @@ static char *memory_stat_format(struct mem_cgroup *memcg) * * Current memory state: */ - memcg_flush_vmstats(memcg); + cgroup_rstat_flush(memcg->css.cgroup); for (i = 0; i < ARRAY_SIZE(memory_stats); i++) { u64 size; @@ -3523,7 +3518,7 @@ static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) unsigned long val; if (mem_cgroup_is_root(memcg)) { - memcg_flush_vmstats(memcg); + cgroup_rstat_flush(memcg->css.cgroup); val = memcg_page_state(memcg, NR_FILE_PAGES) + memcg_page_state(memcg, NR_ANON_MAPPED); if (swap) @@ -3925,7 +3920,7 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v) int nid; struct mem_cgroup *memcg = mem_cgroup_from_seq(m); - memcg_flush_vmstats(memcg); + cgroup_rstat_flush(memcg->css.cgroup); for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) { seq_printf(m, "%s=%lu", stat->name, @@ -3997,7 +3992,7 @@ static int memcg_stat_show(struct seq_file *m, void *v) BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats)); - memcg_flush_vmstats(memcg); + cgroup_rstat_flush(memcg->css.cgroup); for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) { unsigned long nr; @@ -4500,7 +4495,7 @@ void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages, struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); struct mem_cgroup *parent; - memcg_flush_vmstats(memcg); + cgroup_rstat_flush_irqsafe(memcg->css.cgroup); *pdirty = memcg_page_state(memcg, NR_FILE_DIRTY); *pwriteback = memcg_page_state(memcg, NR_WRITEBACK); -- 2.30.1