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bh=m3SFScDyttEY9US8ubeRIrvuSvpvEfTK2KFVStD/P3k=; b=r43ox+5yxWxW0pcpayTd7dSW8e3o5/EoCe1cI+2FFKxf2EqW5JQUdaS2pVVxSRuzK4ZhcV K+cL2ltSWsgKHeJ9P6KVEGFnN+Uwrjs/ykxbL3ahjhoKddsJlZSeELQByMK2zIlGEE0M7a 0LPDcqVp94/opumCJL+RySyWgpvK2zoNXRyEm3+jizdyp/XvmWLhzPKASoN1QDKQ8SUmPL Qv9kTeqvYyGVX0qkSgzYy1J4PgpAjqafZPyysWYVvLB5xv8YjKedU+tp3lDNI/GO5oqczL C+CrMJhdtyckSczRJhmbSzTB0V0+q0VAqdMljJyKID7A25Xi3caf9zyAq7U32g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1741952647; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=m3SFScDyttEY9US8ubeRIrvuSvpvEfTK2KFVStD/P3k=; b=+GRAJ06pNMGb19/QXxJwxJTeaTS8JcSgCno6lJCaFovNgikauelmaFZoVxGaZ1VhO7dawM iM3nbJTtA8vrQ/AA== From: Sebastian Andrzej Siewior To: Vlastimil Babka Cc: Shakeel Butt , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [RFC PATCH 07/10] memcg: use __mod_memcg_state in drain_obj_stock Message-ID: <20250314114405.4x6EuYYW@linutronix.de> References: <20250314061511.1308152-1-shakeel.butt@linux.dev> <20250314061511.1308152-8-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: rsf4zo4a4a44z7egs4sunjj91imtu6s3 X-Rspamd-Queue-Id: AE9CF4000B X-HE-Tag: 1741952648-29971 X-HE-Meta: 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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: On 2025-03-14 11:27:40 [+0100], Vlastimil Babka wrote: > On 3/14/25 07:15, 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 > > Maybe it'll make sense later but as of this patch itself it begs a question > why put memcg_stats_lock()/unlock() in __mod_memcg_state itself and not just > around the call in drain_obj_stock()? The memcg_stats_lock() were introduce to protect the per-CPU counters (vmstats_percpu) on PREEMPT_RT which are protected on !PREEMPT_RT by disabling interrupts. Other modifier have this already except for __mod_memcg_state() because mod_memcg_state() was the only user and already disables interrupt for the operation. Sebastian