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Thu, 28 Aug 2025 02:51:38 -0700 (PDT) Received: from devbig569.cln6.facebook.com ([2a03:2880:31ff:5a::]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45b797dd66dsm24817265e9.20.2025.08.28.02.51.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Aug 2025 02:51:37 -0700 (PDT) Date: Thu, 28 Aug 2025 02:51:35 -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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2182c715-aaf1-46d1-809e-e4142bc083af@suse.cz> X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: DB6B6C000F X-Stat-Signature: 5j5yq9sioir6fjz44coqckmcq5ja557e X-HE-Tag: 1756374699-876433 X-HE-Meta: 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 t0GY5wy0 InTBYAS5WkhFj1zeqAxwe38ZedgUGKsiS49K2nVQ7WotIVn4KgNa5EF1t/CyGbbkbqkSs/8DnzdOXq6xFDzXAwbo/Z1X0A6Ewl4paFjlactpJ5dbYyPcCCdytibRPgJkLIcQP7dqNNxWitxBwFnKjlM7VD2WsioltiNQQrBY7+Fwz0m6CKM6dij5KM5dCHIpKXKtZ66GabyMGPR/L8tSHVRG3PRxCmIkAaRlsqWyNs0hfwtX1v6sb2u6nm2SsyPLq9x/dcHY8H7AwR/2ado55VprlzpSUoOa0PpE07Xk4O9KlsLpvxgbYGEOgvlogKyEPZZU3g1wTroZ8UtO64dvxqAt6znaHdSUIiQs3z7uMuGlgXPa+FBTwyyiJjGVCfzcSf+ZARyY9M43nAVYxPEiPbbEtHLPyR0w4xxbDono0aVli9KLFI8xUiRaehSFA/mD1uu/EnFT+CGY/CvmJzze6MrbGROfubaO2QInQxHZeAJvD/hIILtAVZNz3DwSsOOAoGqmk 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 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. Thanks Pan