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Wed, 12 Feb 2025 19:36:12 -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, shakeel.butt@linux.dev, 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 v8 4/6] memcg: Use trylock to access memcg stock_lock. Date: Wed, 12 Feb 2025 19:35:54 -0800 Message-Id: <20250213033556.9534-5-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250213033556.9534-1-alexei.starovoitov@gmail.com> References: <20250213033556.9534-1-alexei.starovoitov@gmail.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: EC107140002 X-Stat-Signature: gab775d8he17fkgsnk8pdbceqhq3nuo4 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1739417773-218284 X-HE-Meta: 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 HY/vnaVt 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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 46f8b372d212..7587511b92cc 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1739,7 +1739,7 @@ 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; @@ -1754,7 +1754,7 @@ 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); @@ -1773,7 +1773,8 @@ 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; @@ -1783,7 +1784,11 @@ 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); @@ -1792,7 +1797,7 @@ 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; } @@ -1831,14 +1836,14 @@ 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); } @@ -1868,9 +1873,20 @@ 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); } /* @@ -2213,9 +2229,13 @@ 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)) @@ -2699,7 +2719,7 @@ 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); /* @@ -2752,7 +2772,7 @@ 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); } @@ -2762,7 +2782,7 @@ 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) { @@ -2770,7 +2790,7 @@ 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; } @@ -2862,7 +2882,7 @@ 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 */ @@ -2880,7 +2900,7 @@ 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)