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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , David Rientjes , Shakeel Butt , Andrew Morton , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Nhat Pham , Johannes Weiner , Zi Yan , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Kairui Song , Balbir Singh , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Kiryl Shutsemau , Yu-cheng Yu , Dave Hansen , Dennis Zhou , Tejun Heo , Christoph Lameter , Peng Fan , Josef Bacik , Chris Mason , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Borislav Petkov (AMD)" , Mark Brown , "Dennis Zhou (Facebook)" , Rick Edgecombe , stable@vger.kernel.org Subject: Re: [PATCH 01/13] mm/mmap: free gathered pages before MMF_OOM_SKIP Message-ID: References: <20261111-mason-migrate-et-al-fixes-v1-0-3d2454362e8d@kernel.org> <20261111-mason-migrate-et-al-fixes-v1-1-3d2454362e8d@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: E142CC0006 X-Stat-Signature: a8xe3mskfgkomeks5owg4mi3uuzkazzi X-Rspam-User: X-HE-Tag: 1794485912-349697 X-HE-Meta: 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 5+NID5LV h+8vscD4rk/h0Gfkrsq+mnciLeg9EUJy6Eevg51foBHcuo+/7PvnmMbi92ymMJOF/T84toeZkI9sk1DKCc25Hh5ZKywsLpGSDlGuxoUEyv/A1GNrtIvO/u5GMt8/MUee9pBzWQCV+FVFX49aunyZtpUTOiP7jJrLuIl5RxuCBnZJHEGhVFiYagx2Seicsq/xMJefnqHXSJqYY5Oq5q5mSVFYkA+PS97b8e7LHyZJGkkfQhmubAypHebYrP8FqdH22XSSbJV8s1588HSy61dhny6GFbODxBRbHF0CeCZdvbHZr7/MtdwIRbda3Nkuo/tXyEZ1Rh7pFJEBWxsA2NDQV8FDXO6DtQc4EX63jVVwQ0auzsezvVl3tXqGM9ACv8xRYQe+Ejw9k/4HlGbyl9RUpKQLlot/gd2X4J8Z1C/N6ypJsnVwSs/6imbcfQgf1/2M+JIA7bhHW3ElfM+Y= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Wed, Nov 11, 2026 at 10:49:34PM +0000, Usama Arif wrote: > > > On 11/11/2026 18:13, Lorenzo Stoakes (ARM) wrote: > > The OOM killer can quickly trigger again after having selected a > > victim. That victim might not have freed its memory yet, but its mm will > > be marked MMF_OOM_SKIP by this point, so the OOM killer will ignore it. > > > > This can cause the OOM killer to kill an innocent process when the first > > might have freed enough memory to relieve the memory pressure. > > > > Fix the issue by freeing the memory before marking the mm MMF_OOM_SKIP. > > > > Note that the task which calls mmput() might not be the victim - if it > > took a reference on the mm (e.g. ptrace), it may hold the last reference > > and release it when it calls mmput(). > > > > Therefore we cannot rely on current to tell whether the mm belongs to an > > OOM victim. Instead, partially revert commit b3541d912a84 ("mm: delete > > unused MMF_OOM_VICTIM flag") to reinstate MMF_OOM_VICTIM, which > > mark_oom_victim() sets on the victim's mm, and check that. > > > > Reported-by: Chris Mason > > Fixes: bf3980c85212 ("mm: drop oom code from exit_mmap") > > Cc: > > Signed-off-by: Lorenzo Stoakes (ARM) > > --- > > Makes sense, it will free an OOM victim’s pages before setting MMF_OOM_SKIP, > avoiding unnecessary additional kills. Thanks, yeah I tried to find the smallest way of doing this, it is subtle though! > > Acked-by: Usama Arif Thanks! :) -- Cheers, Lorenzo