From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E605160A5BDA for ; Thu, 12 Nov 2026 11:21:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=f8PKmcO3; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=Qc8cqb2R; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=f8PKmcO3; dkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=Qc8cqb2R Received: by kanga.kvack.org (Postfix) id 1B3196B05B0; Thu, 12 Nov 2026 06:21:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 18BC16B05B4; Thu, 12 Nov 2026 06:21:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0A18A6B05C4; Thu, 12 Nov 2026 06:21:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id DAA866B05B0 for ; Thu, 12 Nov 2026 06:21:46 -0500 (EST) Received: from smtpin19.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 5C59780524 for ; Thu, 12 Nov 2026 11:21:46 +0000 (UTC) X-FDA: 85426227012.19.40191FB Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) by imf31.hostedemail.com (Postfix) with ESMTP id 2E0D220006 for ; Thu, 12 Nov 2026 11:21:44 +0000 (UTC) Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=f8PKmcO3; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=Qc8cqb2R; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=f8PKmcO3; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=Qc8cqb2R; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf31.hostedemail.com: domain of pfalcato@suse.de designates 195.135.223.131 as permitted sender) smtp.mailfrom=pfalcato@suse.de ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794482504; b=UNfa+ZNW364Ho6+U3HX00fdI7nxmJc3v8clyUceQ0Jrr48um5HJLBAVP+ILXB0f3GXBoWt W9kn85g62kIBxRvtmybMd6NrXUv3akh4PDDGPhTLFhu3WbFllWmq5yj6wiQJBdj67n707E WWSYr62JGzXeg0QB8i7MtX9tWxkPg+M= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1794482504; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=b68hR85FMy64ZLKPI+SkETJKcoWTtrleDFFCwxd3C7E=; b=hMXe+onxYWWOsVV3uqrVhmSBGEp27u0FPugKb7sXgvtktAEBlRnfOLMFdR4FiwAtTguESZ wvON/P0Hf7YGUgBzgUAdhKHeFknqy8CpZaam9wBKkyph+nPRhOXn8yInrLALxjg8SGzsGa qLGIn70TwDnrzC5z7dnjYU84/8T/ryU= ARC-Authentication-Results: i=1; imf31.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=f8PKmcO3; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=Qc8cqb2R; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=f8PKmcO3; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=Qc8cqb2R; dmarc=pass (policy=none) header.from=suse.de; spf=pass (imf31.hostedemail.com: domain of pfalcato@suse.de designates 195.135.223.131 as permitted sender) smtp.mailfrom=pfalcato@suse.de Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 83E481F74D; Thu, 12 Nov 2026 11:21:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1794482502; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=b68hR85FMy64ZLKPI+SkETJKcoWTtrleDFFCwxd3C7E=; b=f8PKmcO3THEm97E0clNHriq4Z64U95UVpQJKVzAHSFQsf2uA8U5cIRr+Kz2zuNFySoOqlP 3/9gmJ7WZkgL7nmxglnkqVcbIcqwyepaDSFJL9+m2XXYD4mn0Yp/i1+4uEaZ+yUYK3bBAO Z/Zk+ThUwR6EC8Xo9kGfRh86noaXH6Y= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1794482502; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=b68hR85FMy64ZLKPI+SkETJKcoWTtrleDFFCwxd3C7E=; b=Qc8cqb2RCIXsDmnVlLXr1Rg/oe9HO72E9kGX41HXI6G+yK09O6MWVLkmK8wuduiymKcucb szOlGWoh9SGsTfDw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1794482502; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=b68hR85FMy64ZLKPI+SkETJKcoWTtrleDFFCwxd3C7E=; b=f8PKmcO3THEm97E0clNHriq4Z64U95UVpQJKVzAHSFQsf2uA8U5cIRr+Kz2zuNFySoOqlP 3/9gmJ7WZkgL7nmxglnkqVcbIcqwyepaDSFJL9+m2XXYD4mn0Yp/i1+4uEaZ+yUYK3bBAO Z/Zk+ThUwR6EC8Xo9kGfRh86noaXH6Y= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1794482502; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=b68hR85FMy64ZLKPI+SkETJKcoWTtrleDFFCwxd3C7E=; b=Qc8cqb2RCIXsDmnVlLXr1Rg/oe9HO72E9kGX41HXI6G+yK09O6MWVLkmK8wuduiymKcucb szOlGWoh9SGsTfDw== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id D635A134A0; Thu, 12 Nov 2026 11:21:39 +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 fxoaJEOh9WodfQAAD6G6ig (envelope-from ); Thu, 12 Nov 2026 11:21:39 +0000 Date: Thu, 12 Nov 2026 11:21:38 +0000 From: Pedro Falcato To: "Lorenzo Stoakes (ARM)" Cc: David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , David Rientjes , Shakeel Butt , Andrew Morton , Jann Horn , "Matthew Wilcox (Oracle)" , Jan Kara , Nhat Pham , Johannes Weiner , Zi Yan , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Usama Arif , 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=us-ascii Content-Disposition: inline In-Reply-To: <20261111-mason-migrate-et-al-fixes-v1-1-3d2454362e8d@kernel.org> X-Rspamd-Action: no action X-Spam-Score: -12.01 X-Spam-Level: X-Rspamd-Queue-Id: 2E0D220006 X-Rspamd-Server: rspam12 X-Stat-Signature: kk8cx4zkyc9t41xkfik4kyrmq4ah6po5 X-Rspam-User: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794482504-544038 X-HE-Meta: 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 lmKIDn1i 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 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 06:13:15PM +0000, 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) Looks good, thank you! Reviewed-by: Pedro Falcato > --- > include/linux/mm_types.h | 2 ++ > include/linux/oom.h | 9 +++++++++ > mm/mmap.c | 9 ++++++++- > mm/oom_kill.c | 4 +++- > 4 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 1ed35d258d2e..09e63ff12b04 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -2030,6 +2030,8 @@ enum { > #define MMF_TOPDOWN 31 /* mm searches top down by default */ > #define MMF_TOPDOWN_MASK BIT(MMF_TOPDOWN) > > +#define MMF_OOM_VICTIM 32 /* mm is the oom victim */ > + > #define MMF_INIT_LEGACY_MASK (MMF_DUMP_FILTER_MASK |\ > MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK |\ > MMF_VM_MERGE_ANY_MASK | MMF_TOPDOWN_MASK) > diff --git a/include/linux/oom.h b/include/linux/oom.h > index 00da05d227e6..a9390cb70541 100644 > --- a/include/linux/oom.h > +++ b/include/linux/oom.h > @@ -76,6 +76,15 @@ static inline bool tsk_is_oom_victim(struct task_struct * tsk) > return tsk->signal->oom_mm; > } > > +/* > + * Use this helper if tsk->mm != mm and the victim mm needs a special > + * handling. This is guaranteed to stay true after once set. > + */ > +static inline bool mm_is_oom_victim(struct mm_struct *mm) > +{ > + return mm_flags_test(MMF_OOM_VICTIM, mm); > +} > + > /* > * Checks whether a page fault on the given mm is still reliable. > * This is no longer true if the oom reaper started to reap the > diff --git a/mm/mmap.c b/mm/mmap.c > index 7618e72766a5..4cb18b217048 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1313,11 +1313,18 @@ void exit_mmap(struct mm_struct *mm) > /* update_hiwater_rss(mm) here? but nobody should be looking */ > /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */ > unmap_vmas(&tlb, &unmap); > + > + /* > + * Free the memory before marking MMF_OOM_SKIP so a re-triggered OOM > + * killer will only skip this mm if it's already freed all it can. > + */ > + if (mm_is_oom_victim(mm)) > + tlb_flush_mmu(&tlb); I see there's a different tlb_flush_mmu() call below (in the actual function). Is tlb_flush_mmu() idempotent? -- Pedro