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Wed, 12 Feb 2025 09:34:06 +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 thPMJg5rrGcNRgAAD6G6ig (envelope-from ); Wed, 12 Feb 2025 09:34:06 +0000 Message-ID: Date: Wed, 12 Feb 2025 10:34:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/oom_kill: revert watchdog reset in global OOM process To: Chen Ridong , Michal Hocko Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, yosryahmed@google.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, davidf@vimeo.com, mkoutny@suse.com, paulmck@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, chenridong@huawei.com, wangweiyang2@huawei.com References: <20250212025707.67009-1-chenridong@huaweicloud.com> Content-Language: en-US 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+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 7995618000D X-Stat-Signature: qm8f1rf9sc8t818fkawoc16toa8kycri X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1739352848-725068 X-HE-Meta: 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 iaCENVmD RRvSjuF0kXC85aoX4z4Z7/EusCm+tw3UqKZMOBTH7msmmVbyi6MsYuBbX2b/yjvCIROEkzNGUJksWHu6b3FtE5+hdRRBIco2/Tm4CR+Z1Rrn/oytO7WfKhaVfJMzI94c30CFM2aMriBYumQV/5lfpoDM+lmKHYk/BpAr1MEpuzA8uoFUoj0IRWJ5hVLk8483y+RHNl8z8udsSpQlqsAx299d/EvwkewT/E4tIFEuGz4C6LOSwhjDXZcXK7AsUHdPLcgDX0UzGck9vA3705W8wm+GHOrNJbpJS/094ywzuPkJtA6DN2nxoZUcfHJJVtQxPb3QXjgJsuDdezde7+Rgxwyst1+Lls5XJ8Wa1HKldm+Rz4vsCIDZ6RDLbOoyW/7wTSFUxYFYJRsL/9CTaO9TAAYjefw== 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 2/12/25 10:19, Chen Ridong wrote: > > > On 2025/2/12 16:57, Michal Hocko wrote: >> On Wed 12-02-25 02:57:07, Chen Ridong wrote: >>> From: Chen Ridong >>> >>> Unlike memcg OOM, which is relatively common, global OOM events are rare >>> and typically indicate that the entire system is under severe memory >>> pressure. The commit ade81479c7dd ("memcg: fix soft lockup in the OOM >>> process") added the touch_softlockup_watchdog in the global OOM handler to >>> suppess the soft lockup issues. However, while this change can suppress >>> soft lockup warnings, it does not address RCU stalls, which can still be >>> detected and may cause unnecessary disturbances. Simply remove the >>> modification from the global OOM handler. >>> >>> Fixes: ade81479c7dd ("memcg: fix soft lockup in the OOM process") >> >> But this is not really fixing anything, is it? While this doesn't >> address a potential RCU stall it doesn't address any actual problem. >> So why do we want to do this? >> > > > [1] > https://lore.kernel.org/cgroups/0d9ea655-5c1a-4ba9-9eeb-b45d74cc68d0@huaweicloud.com/ > > As previously discussed, the work I have done on the global OOM is 'half > of the job'. Based on our discussions, I thought that it would be best > to abandon this approach for global OOM. Therefore, I am sending this > patch to revert the changes. > > Or just leave it? I suggested that part doesn't need to be in the patch, but if it was merged with it, we can just leave it there. Thanks.