From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f49.google.com (mail-qv1-f49.google.com [209.85.219.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 27E9B4DC558 for ; Wed, 21 Jan 2026 14:58:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769007527; cv=none; b=kBt7+8FZ5BJUbGJSVka6MHhVOetMElY5TFXkLcrRZM5o6Z1z5750QaNkynkjTnzvqebzv314Q1oUkZFU85Hc1aKAdk4rWPsZoVwZcrVWTLKvDB+sDS5olsFy4eg4PyDbvX8jYSmQK06/Nopw2WPlHqwbfkdJbIcACJ4NKD2tcR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769007527; c=relaxed/simple; bh=TSpaqslXVbGZxXGpTfz+xXfUztuJXIMpy7+cNgi5/Mw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AqF96K596FZgI9u+21TgewiQL/Hyls79J/bjULLeyAjjKWXMhaN6Umn/2X0uX2lnffj6R/TP+Lg18554Ts2SPz1XPiOi2mJb91NLymgKnve+sPKIXXMlv/ktRjID1/lvYJM4utH1PWGwG/2C5AJ4DtZwJ1lqmlZvlaczYlLpUxw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cmpxchg.org; spf=pass smtp.mailfrom=cmpxchg.org; dkim=pass (2048-bit key) header.d=cmpxchg.org header.i=@cmpxchg.org header.b=MXYU2Nvb; arc=none smtp.client-ip=209.85.219.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=cmpxchg.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cmpxchg.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg.org header.i=@cmpxchg.org header.b="MXYU2Nvb" Received: by mail-qv1-f49.google.com with SMTP id 6a1803df08f44-88a288811a4so66933916d6.3 for ; Wed, 21 Jan 2026 06:58:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg.org; s=google; t=1769007524; x=1769612324; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=11H3Sl0B2LnnaUo00s74ciXm10QbO4phXHCmMu1QEis=; b=MXYU2Nvb232qVeGQias07zTPbmhVWmf6xAgDWwOrQ5tv66iPqo7nt51kFov0pXfGXv +ntwUAa5R+T4+WPvyr68VVwOoxZ5lgKd/z/+7VXqg7Eds23I6bEEKwBkJvZiiqvC+i9Q QYz48cIm1weuEHRnJaTtczah2r7q/3HB38Mg+XetvnMCH+iMs3x70ldBwWHll9ktEH27 30LVHUzGLOZ8TVSTndBWVn3PEc+Bw0BGEszlmy7ozMdFmLGWGyFW/0q7NzmA1w5v9xKP T/fnPlyHyCZhmU2UYUpgBnTAj9xMawXStdJxcdcPZK+zXDOqk1dKzbdxuL+bGG/lKlok v59A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769007524; x=1769612324; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=11H3Sl0B2LnnaUo00s74ciXm10QbO4phXHCmMu1QEis=; b=tKUMZ+clWdxuRepuD1rpw5ns9Tp5nO8QKthyOTH6loVRjy6sxz99Vmu5o830ZLzaWf Ed+96ir0C947CQvz5tJDjGBDIK54zrCXHjW2cBSu5ahgmkCLzdXSpIwS2gD+8zqBXOnP nOLQadCTWyIa69+7PitoyTtNnSmFNH4T+JxDyze+su8HSwmLcZehm6gqHRD5aovjnU+X kPqDwNYlg/LJO+9UnVXuL/siwgKFt9BlD8hWUzwV+RgPInNN4yqaL3t4Qgnr7iZcVlJF xnKtq1Ljgx07NpWbkgL08Ym6gUodzP7kOYGhGjpg0Tt/Q1ovA2igGlEr3OElBKXarNPC 9quQ== X-Forwarded-Encrypted: i=1; AJvYcCXTcF/RAntsHQkqjCiydN7bBJoSaBbV24kTIXPz4+r4eFudUBl9cRBgUMMZTkUJg37yO/CVwVh7FEy7FQk=@vger.kernel.org X-Gm-Message-State: AOJu0Ywq5CZv3OatvQu0yFS5OXhmXM8pRw/46o/KM+5Kld5Be/TvO++Q Ecyr4crzYqOsOaYAhniaO/e61KoxHij0lVNc6rhMyGUqMAizGyCGNDx69JQhBFFtFa8= X-Gm-Gg: AZuq6aKKDVWG6IkDoTGaDKM2H00Bvy2jPzYNB+rmdlsKehgj496VaPXQ6rtO4M+Ca6R WGxpz8iZtwYeyqeZzdda+ann5rU15PQb1z02RnQKuT//KYWtUAv3JiOema0MpH+5Wjo13qmerJu fHXsITrcKpv7jPdA40qzDYLWJrUuMZBV3JkcDHBnZejqOKNnB9jslIFFSAMQmoA0WRBrlkSMnx6 CEoMgTEsHwTuqcOaQEk+sMbvTcJ+t6XZlEo5yYWAoLZqcXqCoYhBSAuqhQgw45IN6Nhov0dGMIK XakHoEgZi0Ba8UgU/O+sJ+Q4lmuUcWjZcVP95wTMx5xELoJHXA5kYaa16OcifxQiilaCpdg7pE4 Vp37kW4wW8NR7seaSF/zD/PU/7AxSp/+ph9LL5FJzLr6GoUx8KOCvip0G13+LZbHEWb8EhecNer ei3cLyh59z7Q== X-Received: by 2002:a05:6214:400c:b0:888:498e:5a3a with SMTP id 6a1803df08f44-89463d16ca5mr80297446d6.68.1769007523747; Wed, 21 Jan 2026 06:58:43 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:365a:60ff:fe62:ff29]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8942e6c9a9dsm132520486d6.43.2026.01.21.06.58.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jan 2026 06:58:42 -0800 (PST) Date: Wed, 21 Jan 2026 09:58:42 -0500 From: Johannes Weiner To: Andrew Morton Cc: Deepanshu Kartikey , syzbot , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, syzkaller-bugs@googlegroups.com, Muchun Song , Minchan Kim , Kairui Song Subject: Re: [syzbot] [cgroups?] [mm?] WARNING in memcg1_swapout Message-ID: References: <696b56b1.050a0220.3390f1.0007.GAE@google.com> <20260117165722.6dc25d72fd58254cb89e711b@linux-foundation.org> <20260118125311.e1894f598e2a8ef626f47f25@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260118125311.e1894f598e2a8ef626f47f25@linux-foundation.org> On Sun, Jan 18, 2026 at 12:53:11PM -0800, Andrew Morton wrote: > On Sun, 18 Jan 2026 12:31:43 +0530 Deepanshu Kartikey wrote: > > > > > > > > > That's > > > > > > > > VM_WARN_ON_ONCE(oldid != 0); > > > > > > > > which was added by Deepanshu's "mm/swap_cgroup: fix kernel BUG in > > > > swap_cgroup_record". > > > > > > > > This patch has Fixes: 1a4e58cce84e ("mm: introduce MADV_PAGEOUT"), > > > > which is six years old. For some reason it has no cc:stable. > > > > > > > > Deepanshu's patch has no reviews. > > > > > > > > So can I please do the memcg maintainer summoning dance here? We have a > > > > repeatable BUG happening in mainline Linux. > > > > > > > > > > Hi Andrew, > > > > > > I checked the git blame output for commit 0f853ca2a798: > > > > > > Line 763: memcg1_swapout(folio, swap); > > > Line 764: __swap_cache_del_folio(ci, folio, swap, shadow); > > > (d7a7b2f91f36b - Kairui Song, 2026-01-13 02:33:36 +0800) > > > > > > Kairui's reordering patch appears to have been merged on Jan 13. > > Eek, there are many patches, it helps to identify them carefully. > > I think you're referring to > https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-use-swap-cache-as-the-swap-in-synchronize-layer-fix.patch This was supposed to be the replacement for Deepanshu's patch below. > > > The syzbot report is also from Jan 13, likely from earlier in the > > > day before the reordering patch was merged. > > > > > > So this report is from before the fix. The warning should not appear > > > in linux-next builds after Jan 13. > > > > > > Thanks, > > > > > > Deepanshu > > > > Hi Andrew, > > > > I tested with the latest linux-next in sysbot. It is working fine > > Great, thanks. But we still don't have review for this one. IOW, this is not necessary anymore. Kairui's (cc'd) fix which you picked up fixed the syzbot reported problem. > For some reason I don't have cc:stable on this - could people > make a recommendation? So this: > From: Deepanshu Kartikey > Subject: mm/swap_cgroup: fix kernel BUG in swap_cgroup_record can be dropped. Please correct if I'm wrong.