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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) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D726440004 X-Stat-Signature: q1ox6bjwt8q3kw8cm4rfgswj8s4za5mk X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1768697844-155069 X-HE-Meta: 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 Z/MyWg/1 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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.