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Mon, 17 Mar 2025 20:56:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id TRyVH4eM2GddYQAAD6G6ig (envelope-from ); Mon, 17 Mar 2025 20:56:39 +0000 Message-ID: <7d50a14a-edfb-410d-840e-17876806a63b@suse.cz> Date: Mon, 17 Mar 2025 21:56:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 7/9] memcg: use __mod_memcg_state in drain_obj_stock Content-Language: en-US To: Shakeel Butt , Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Sebastian Andrzej Siewior , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team References: <20250315174930.1769599-1-shakeel.butt@linux.dev> <20250315174930.1769599-8-shakeel.butt@linux.dev> From: Vlastimil Babka In-Reply-To: <20250315174930.1769599-8-shakeel.butt@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 90AF9100007 X-Stat-Signature: 4wyducyobbrr54fpe98gggf19mnsf716 X-HE-Tag: 1742245001-448800 X-HE-Meta: U2FsdGVkX1/6+4uwIEFbsyk/sd7AGmEMv1tb/xIjHh60G7sQD9t5nUyC1GIAyfN68wOw0AHE+8FEO7Ue88rjjs+bDSyiQ72jfXz85GkI37O1/Ijqtm8OF3w6AJ7X1juq82ZJUZeQwZBE64U9bh1KYusVybQGOkE3Sz3tIvGY0SZdHq+xRC3z/ptmObkUm2pyXqxndsY5GDeJh4sE8R2OqFSTq882PRlBCqOreuncs8qAZivg0VtLWFsZ4iGp4M5fsq5alYCPGapOs3ULq9aRJGOVERCPfshJsoK+NftiOUwTpP86iKhfC0u9+OUY1uedb4CUgiqXyGCVGA+WYj7KNV00nJuERVMfc/jl9hKHntVifNvJrKSjomRANL4dlg9Z4qrVJ0x26wxgZJVxYk2nkz8Y3silNptsYx+1qxONGbkeXYOY0tqDzSxsufl06Y+BtlFDafqygO5xtpVisfsnv1fHgPA0GKPqzb6vBw7oWwKbtxcPpwoCeDRqaaMAs29GGIsa8PQ0D2swcEV2VYJy2BbuIzbJMDD1Ruf02Rdt2edZdxWoiyiYJuk/bRQ+MR/Z9qljb/aCnzIRSu0yHyZCJwB4oVtIH6IPliaLAVH6qf7hoPbP6g/UqXuWBdELdwuFleEk9tHpb6X5LwyF+4QsLSSM2NGamdt00FmP3NGkFFRkexzFGB+GSbDhRSd8SOR2s1R2whQGJ4gn1kgm9p/YhZGAq5QDd7Njt6ongPrx5o+c9GNuAfMwjrKKI9BHE9HPOg4BHqz3MuV3GvxgSTWJnrfGQvpJs+H9ft67zehlQj/Zihq1WONLMI50CpsAudcMXy+kQ1gYd1GkqvKwXsJkaCz6v53CKRinjSY/30o9DLDZ3Rn9ilMqnSJBJcaHlOdSkjm4DuuDh5ppGZ4JJR7F/TTitusnkXA+69tyaU1zZP373Uwpr3XHuV962+Mxk2yPkFqEPRQUeXCssD5ED2L OZW6GtF2 yPUhyuX7v03e3xWTfCMZu/hrvYL/ZAQVdno/9213WpxjPn4sSHPLs5gpwNlYDU2nEmRkM1x68G/dLYIl5ruganBEdb+8yesiT4ulz/dy5dElz7m1AM6gKRvxbAFHsqY5F6NvopwEsHZEll+bDduarFXxiy31DVCXxqCYZZWDzvsVBVzUQ/thunl4/XNkUna6h0qE/ny9xHNd8gisYCfeKtC/K9GhCM+vqDmq0/W7FAMOvqqUNltkmiRWcz67T1zCR0g0E0gfhc2cHzjP3F/dieaPcijg9/XioP0F5ghYu++H4Mk7iRsyMF0brWKw6ndfe+gdX0aXCElSXU9A= 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: On 3/15/25 18:49, Shakeel Butt wrote: > For non-PREEMPT_RT kernels, drain_obj_stock() is always called with irq > disabled, so we can use __mod_memcg_state() instead of > mod_memcg_state(). For PREEMPT_RT, we need to add memcg_stats_[un]lock > in __mod_memcg_state(). > > Signed-off-by: Shakeel Butt > Reviewed-by: Sebastian Andrzej Siewior I've asked in the RFC and from Sebastian's answer I think my question was misunderstod, so let me try again. After this patch we'll have from mod_memcg_state(): mod_memcg_state() local_irq_save(flags); __mod_memcg_state() memcg_stats_lock(); <- new and unnecessary? Instead of modifying __mod_memcg_state() we could be more targetted and just do in drain_obj_stock(): memcg_stats_lock(); __mod_memcg_state(); memcg_stats_unlock(); Am I missing something? > --- > mm/memcontrol.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 3c4de384b5a0..dfe9c2eb7816 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -707,10 +707,12 @@ void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, > if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) > return; > > + memcg_stats_lock(); > __this_cpu_add(memcg->vmstats_percpu->state[i], val); > val = memcg_state_val_in_pages(idx, val); > memcg_rstat_updated(memcg, val); > trace_mod_memcg_state(memcg, idx, val); > + memcg_stats_unlock(); > } > > #ifdef CONFIG_MEMCG_V1 > @@ -2845,7 +2847,7 @@ static void drain_obj_stock(struct memcg_stock_pcp *stock) > > memcg = get_mem_cgroup_from_objcg(old); > > - mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages); > + __mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages); > memcg1_account_kmem(memcg, -nr_pages); > if (!mem_cgroup_is_root(memcg)) > memcg_uncharge(memcg, nr_pages);