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Thu, 28 Aug 2025 15:10:06 -0700 (PDT) Received: from devbig569.cln6.facebook.com ([2a03:2880:31ff:4a::]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3cf33fbb238sm765573f8f.53.2025.08.28.15.10.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Aug 2025 15:10:06 -0700 (PDT) Date: Thu, 28 Aug 2025 15:10:03 -0700 From: Yueyang Pan To: Vlastimil Babka Cc: Andrew Morton , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Usama Arif , linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 2/2] mm/show_mem: Add trylock while printing alloc info Message-ID: References: <7e2bc96faab1a338829e549246189ad96e6c866b.1756318426.git.pyyjason@gmail.com> <20250827150619.4e468e68988f224f9f9bea6f@linux-foundation.org> <2182c715-aaf1-46d1-809e-e4142bc083af@suse.cz> <92a3320e-2433-4ee8-8ed5-d5db6098b43e@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <92a3320e-2433-4ee8-8ed5-d5db6098b43e@suse.cz> X-Rspamd-Queue-Id: 2E4E4140004 X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: ujemxzq1t7a793e8zqexy3hmtccotd5y X-HE-Tag: 1756419007-805347 X-HE-Meta: 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 B/RuNV2e 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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 Thu, Aug 28, 2025 at 11:54:58AM +0200, Vlastimil Babka wrote: > On 8/28/25 11:51, Yueyang Pan wrote: > > On Thu, Aug 28, 2025 at 10:53:01AM +0200, Vlastimil Babka wrote: > >> On 8/28/25 10:47, Yueyang Pan wrote: > >> > On Thu, Aug 28, 2025 at 10:41:23AM +0200, Vlastimil Babka wrote: > >> >> On 8/28/25 10:34, Yueyang Pan wrote: > >> >> > On Wed, Aug 27, 2025 at 03:06:19PM -0700, Andrew Morton wrote: > >> >> >> On Wed, 27 Aug 2025 11:34:23 -0700 Yueyang Pan wrote: > >> >> >> > >> >> >> > In production, show_mem() can be called concurrently from two > >> >> >> > different entities, for example one from oom_kill_process() > >> >> >> > another from __alloc_pages_slowpath from another kthread. This > >> >> >> > patch adds a mutex and invokes trylock before printing out the > >> >> >> > kernel alloc info in show_mem(). This way two alloc info won't > >> >> >> > interleave with each other, which then makes parsing easier. > >> >> > >> >> What about the rest of the information printed by show_mem() being interleaved? > >> > > >> > Thanks for your feedback, Vlastimil. We cannot use trylock for the rest > >> > part as node filter can be different. > >> > >> Right. > >> > >> > Do you think we need a lock to prevent the whole show_mem() from being > >> > interleaved and to acquire it at the very beginning? Will it be too > >> > heavy? > >> > >> It might be risky so perhaps let's not. Guess we can disentangle by dmesg > >> showing the thread id prefix. > > > > I have thought about this. Since each line can interleave with another, we > > would end up adding tid to each line. Not sure if this is acceptable. > > I meant that printk/dmesg already does that so it's fine. Cool. Then I will do this for the previous part before memory allocation info. > > > Thanks > > Pan >