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Wed, 12 Feb 2025 09:47:25 -0800 (PST) From: Alexei Starovoitov To: bpf@vger.kernel.org Cc: andrii@kernel.org, memxor@gmail.com, akpm@linux-foundation.org, peterz@infradead.org, vbabka@suse.cz, bigeasy@linutronix.de, rostedt@goodmis.org, houtao1@huawei.com, hannes@cmpxchg.org, mhocko@suse.com, willy@infradead.org, tglx@linutronix.de, jannh@google.com, tj@kernel.org, linux-mm@kvack.org, kernel-team@fb.com Subject: [PATCH bpf-next v7 4/6] memcg: Use trylock to access memcg stock_lock. Date: Wed, 12 Feb 2025 09:47:03 -0800 Message-Id: <20250212174705.44492-5-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250212174705.44492-1-alexei.starovoitov@gmail.com> References: <20250212174705.44492-1-alexei.starovoitov@gmail.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: BB5F7100010 X-Stat-Signature: poegtap46cgrpgsqb6jqxarszn8np1pk X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1739382447-427425 X-HE-Meta: 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 p87LHwU2 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Alexei Starovoitov Teach memcg to operate under trylock conditions when spinning locks cannot be used. localtry_trylock might fail and this would lead to charge cache bypass if the calling context doesn't allow spinning (gfpflags_allow_spinning). In those cases charge the memcg counter directly and fail early if that is not possible. This might cause a pre-mature charge failing but it will allow an opportunistic charging that is safe from try_alloc_pages path. Acked-by: Michal Hocko Acked-by: Vlastimil Babka Acked-by: Shakeel Butt Signed-off-by: Alexei Starovoitov --- mm/memcontrol.c | 52 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 36 insertions(+), 16 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7b3503d12aaf..f3af615f727c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1722,7 +1722,7 @@ void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) } struct memcg_stock_pcp { - local_lock_t stock_lock; + localtry_lock_t stock_lock; struct mem_cgroup *cached; /* this never be root cgroup */ unsigned int nr_pages; @@ -1737,7 +1737,7 @@ struct memcg_stock_pcp { #define FLUSHING_CACHED_CHARGE 0 }; static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = { - .stock_lock = INIT_LOCAL_LOCK(stock_lock), + .stock_lock = INIT_LOCALTRY_LOCK(stock_lock), }; static DEFINE_MUTEX(percpu_charge_mutex); @@ -1756,7 +1756,8 @@ static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, * * returns true if successful, false otherwise. */ -static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) +static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages, + gfp_t gfp_mask) { struct memcg_stock_pcp *stock; unsigned int stock_pages; @@ -1766,7 +1767,11 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) if (nr_pages > MEMCG_CHARGE_BATCH) return ret; - local_lock_irqsave(&memcg_stock.stock_lock, flags); + if (!localtry_trylock_irqsave(&memcg_stock.stock_lock, flags)) { + if (!gfpflags_allow_spinning(gfp_mask)) + return ret; + localtry_lock_irqsave(&memcg_stock.stock_lock, flags); + } stock = this_cpu_ptr(&memcg_stock); stock_pages = READ_ONCE(stock->nr_pages); @@ -1775,7 +1780,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages) ret = true; } - local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); return ret; } @@ -1814,14 +1819,14 @@ static void drain_local_stock(struct work_struct *dummy) * drain_stock races is that we always operate on local CPU stock * here with IRQ disabled */ - local_lock_irqsave(&memcg_stock.stock_lock, flags); + localtry_lock_irqsave(&memcg_stock.stock_lock, flags); stock = this_cpu_ptr(&memcg_stock); old = drain_obj_stock(stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); - local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); obj_cgroup_put(old); } @@ -1851,9 +1856,20 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) { unsigned long flags; - local_lock_irqsave(&memcg_stock.stock_lock, flags); + if (!localtry_trylock_irqsave(&memcg_stock.stock_lock, flags)) { + /* + * In case of unlikely failure to lock percpu stock_lock + * uncharge memcg directly. + */ + if (mem_cgroup_is_root(memcg)) + return; + page_counter_uncharge(&memcg->memory, nr_pages); + if (do_memsw_account()) + page_counter_uncharge(&memcg->memsw, nr_pages); + return; + } __refill_stock(memcg, nr_pages); - local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); } /* @@ -2196,9 +2212,13 @@ int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned long pflags; retry: - if (consume_stock(memcg, nr_pages)) + if (consume_stock(memcg, nr_pages, gfp_mask)) return 0; + if (!gfpflags_allow_spinning(gfp_mask)) + /* Avoid the refill and flush of the older stock */ + batch = nr_pages; + if (!do_memsw_account() || page_counter_try_charge(&memcg->memsw, batch, &counter)) { if (page_counter_try_charge(&memcg->memory, batch, &counter)) @@ -2709,7 +2729,7 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, unsigned long flags; int *bytes; - local_lock_irqsave(&memcg_stock.stock_lock, flags); + localtry_lock_irqsave(&memcg_stock.stock_lock, flags); stock = this_cpu_ptr(&memcg_stock); /* @@ -2762,7 +2782,7 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, if (nr) __mod_objcg_mlstate(objcg, pgdat, idx, nr); - local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); obj_cgroup_put(old); } @@ -2772,7 +2792,7 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) unsigned long flags; bool ret = false; - local_lock_irqsave(&memcg_stock.stock_lock, flags); + localtry_lock_irqsave(&memcg_stock.stock_lock, flags); stock = this_cpu_ptr(&memcg_stock); if (objcg == READ_ONCE(stock->cached_objcg) && stock->nr_bytes >= nr_bytes) { @@ -2780,7 +2800,7 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) ret = true; } - local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); return ret; } @@ -2872,7 +2892,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, unsigned long flags; unsigned int nr_pages = 0; - local_lock_irqsave(&memcg_stock.stock_lock, flags); + localtry_lock_irqsave(&memcg_stock.stock_lock, flags); stock = this_cpu_ptr(&memcg_stock); if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */ @@ -2890,7 +2910,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, stock->nr_bytes &= (PAGE_SIZE - 1); } - local_unlock_irqrestore(&memcg_stock.stock_lock, flags); + localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); obj_cgroup_put(old); if (nr_pages)