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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 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Score: -4.30 X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[16]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:mid,huawei.com:email] X-Spam-Flag: NO X-Spam-Level: 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.