From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C5AA717B506; Sun, 18 Jan 2026 00:57:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768697843; cv=none; b=nmUYmdDmJ/empvgvNwAMbDzZY/FsHsldX0orh8sSpgYossgpni+VloCRMi1/11psu+kiv3E5XiwsfjDocnw+PI3e/Zph3IZ3dowS6q6i6234ENs5OTX2Iq8VY1pvs7jA12RNh+A8xU+qf0XLBQWfm4EgSkWismEgPdyJLIznThM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768697843; c=relaxed/simple; bh=+qlEcociOsXhFIAAdcAIVtM1BeAAOHRNXsXknKhk1Ls=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=UUYHKLfrvxcgO8Fi8l3Kuq0/eGvngTDwbPcZFFsomFjlMdEf9apEx70K8Mgk8IFD1vSRByHojna8E8sulweYW7dfr4cZt0j0a1feqNnYrBiL//uS41V4MykniggsQ5Nr6zBsnMr675EHEnqiUVqp6mJADR8+KLkHeMry5v3JO68= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=n8OmmJFe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="n8OmmJFe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17332C4CEF7; Sun, 18 Jan 2026 00:57:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1768697843; bh=+qlEcociOsXhFIAAdcAIVtM1BeAAOHRNXsXknKhk1Ls=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=n8OmmJFeegpmjTXfCuPr2nsg2Ue6kyfKGMGToVw4/bRZTybt/tEyM8TIi4ilXkN/o qTY7n2OxXZpNLddYJZCg32+yFIOXNJXnUtSjF6bL8Bpn/PQ9MNGJoAcI45Wt01Sbrp EGUMyYxytM7ELn4tlZqNLM9//8orztSXrFJ9YIGQ= Date: Sat, 17 Jan 2026 16:57:22 -0800 From: Andrew Morton To: syzbot Cc: cgroups@vger.kernel.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, muchun.song@linux.dev, roman.gushchin@linux.dev, shakeel.butt@linux.dev, syzkaller-bugs@googlegroups.com, Johannes Weiner , Muchun Song , Deepanshu Kartikey , Minchan Kim Subject: Re: [syzbot] [cgroups?] [mm?] WARNING in memcg1_swapout Message-Id: <20260117165722.6dc25d72fd58254cb89e711b@linux-foundation.org> In-Reply-To: <696b56b1.050a0220.3390f1.0007.GAE@google.com> References: <696b56b1.050a0220.3390f1.0007.GAE@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Sat, 17 Jan 2026 01:30:25 -0800 syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 0f853ca2a798 Add linux-next specific files for 20260113 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=14f7259a580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=8d6e5303d96e21b5 > dashboard link: https://syzkaller.appspot.com/bug?extid=079a3b213add54dd18a7 > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167ef922580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16d295fa580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/480cd223f3f6/disk-0f853ca2.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/1ca2f0dbb7cc/vmlinux-0f853ca2.xz > kernel image: https://storage.googleapis.com/syzbot-assets/60a0fef5805b/bzImage-0f853ca2.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+079a3b213add54dd18a7@syzkaller.appspotmail.com Thanks. > ------------[ cut here ]------------ > WARNING: mm/memcontrol-v1.c:642 at memcg1_swapout+0x6c2/0x8d0 mm/memcontrol-v1.c:642, CPU#0: syz.4.233/6746 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.