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Thu, 28 Aug 2025 09:54:59 +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 y3liDHMnsGjMSAAAD6G6ig (envelope-from ); Thu, 28 Aug 2025 09:54:59 +0000 Message-ID: <92a3320e-2433-4ee8-8ed5-d5db6098b43e@suse.cz> Date: Thu, 28 Aug 2025 11:54:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/2] mm/show_mem: Add trylock while printing alloc info Content-Language: en-US To: Yueyang Pan 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 References: <7e2bc96faab1a338829e549246189ad96e6c866b.1756318426.git.pyyjason@gmail.com> <20250827150619.4e468e68988f224f9f9bea6f@linux-foundation.org> <2182c715-aaf1-46d1-809e-e4142bc083af@suse.cz> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 1965AA000F X-Stat-Signature: wap3mo76khe8uiagotjuzgm78mmnn185 X-HE-Tag: 1756374900-615183 X-HE-Meta: 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 5Gvf68LO g9Wc56ZLWVfdVwaNHDaZapCAENGgkiGNNPlhYqe+XSAPjQwUMAHFkQa0MDGX450FlkANn7ojatMG8HhP1lFdK+ewOhtBSL8n5UcsVXe2qQkMi2CRkCIpUmK2MGWgSHIgebUHAZVZ6FXJgR5/ahIqoiTGBGyHFX0Uon6F/NdMKJOiQZ82HOwrQyHxNCxzEhcI9DKsB4dvO9I33qlGRoprB8IXf5e0aAhwa150FENw35NbH1QEXftW5mO+3yCXxhLy1rW8k6hRto6SHUnI4RKv/aRu5dvaQK9DqVFFlEwkoGyfJaAWGmpHVTuA7tjebn/j+hCKfnLO6OWOu+065IsJu+K7LztYr9iCRdURQ 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 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. > Thanks > Pan