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From: Shakeel Butt To: Andrew Morton Cc: syzbot , axelrasmussen@google.com, baohua@kernel.org, david@kernel.org, hannes@cmpxchg.org, kasong@tencent.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org, mhocko@kernel.org, qi.zheng@linux.dev, syzkaller-bugs@googlegroups.com, weixugc@google.com, yuanchu@google.com. r: Yuanchu Xie Subject: Re: [syzbot] [mm?] WARNING in set_mm_walk Message-ID: References: <6a7a6929.b50370da.49fe0.005e.GAE@google.com> <20260810174852.aca0f73ab7ad71c70dcdefda@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: <20260810174852.aca0f73ab7ad71c70dcdefda@linux-foundation.org> X-Migadu-Flow: FLOW_OUT On Mon, Aug 10, 2026 at 05:48:52PM -0700, Andrew Morton wrote: > On Mon, 10 Aug 2026 17:13:29 -0700 syzbot wrote: > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 562bfb501c54 Merge tag 'integrity-v7.2-rc7' of git://git.k.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=11a8cbb9580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782 > > dashboard link: https://syzkaller.appspot.com/bug?extid=12ee2725d5fde63a9c96 > > compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 > > Thanks. One for the MGLRU develoeprs, it seems. > > https://share.gemini.google/Wg4a5ns7E0LF might save a bit of time figuring this out. > This is memcg-v1's soft limit which is deprecated. I am more inclined to simply remove this code instead of fixing it. I will take a stab at removal. > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-562bfb50.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/9cbf6ef0490e/vmlinux-562bfb50.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/7ee52864c79a/bzImage-562bfb50.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+12ee2725d5fde63a9c96@syzkaller.appspotmail.com > > > > ------------[ cut here ]------------ > > current_is_kswapd() > > WARNING: mm/vmscan.c:3800 at set_mm_walk+0x210/0x270 mm/vmscan.c:3800, CPU#1: kswapd0/110 > > > > Modules linked in: > > CPU: 1 UID: 0 PID: 110 Comm: kswapd0 Tainted: G L syzkaller #0 PREEMPT(full) > > Tainted: [L]=SOFTLOCKUP > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > > RIP: 0010:set_mm_walk+0x210/0x270 mm/vmscan.c:3800 > > Code: 13 00 00 4d 8d 7d 08 e9 f7 fe ff ff e8 79 f5 2a 00 e9 b7 fe ff ff e8 7f 6b ba ff 90 0f 0b 90 e9 d2 fe ff ff e8 71 6b ba ff 90 <0f> 0b 90 e9 74 ff ff ff 4c 89 ff e8 80 f5 2a 00 e9 4e fe ff ff 48 > > RSP: 0018:ffffc900027772b8 EFLAGS: 00010293 > > RAX: 0000000000000000 RBX: ffff888024934a80 RCX: ffffffff824ff8e8 > > RDX: ffff888024934a80 RSI: ffffffff824ff96f RDI: ffff888024934a80 > > RBP: 0000000000020000 R08: 0000000000000005 R09: 0000000000000000 > > R10: 0000000000020000 R11: 0000000000000000 R12: 0000000000000000 > > R13: ffffc90002777c38 R14: 0000000000000001 R15: ffffc90002777c40 > > FS: 0000000000000000(0000) GS:ffff8880d5ed8000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000001b31923ffc CR3: 0000000109695000 CR4: 0000000000352ef0 > > DR0: 0000000000000005 DR1: 0000000000000005 DR2: 0000000020040004 > > DR3: 0000000000000056 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > > Call Trace: > > > > try_to_inc_max_seq+0xf0/0x1090 mm/vmscan.c:4023 > > try_to_shrink_lruvec+0x4bd/0x6b0 mm/vmscan.c:4977 > > lru_gen_shrink_lruvec mm/vmscan.c:5128 [inline] > > shrink_lruvec+0x31e/0x25b0 mm/vmscan.c:5888 > > mem_cgroup_shrink_node+0x227/0x6a0 mm/vmscan.c:6753 > > mem_cgroup_soft_reclaim mm/memcontrol-v1.c:312 [inline] > > memcg1_soft_limit_reclaim+0x2d5/0x830 mm/memcontrol-v1.c:362 > > balance_pgdat+0xa11/0x1f00 mm/vmscan.c:7177 > > kswapd+0x556/0xb50 mm/vmscan.c:7462 > > kthread+0x370/0x450 kernel/kthread.c:436 > > ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 > > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > > > > > > > --- > > This report is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > If the report is already addressed, let syzbot know by replying with: > > #syz fix: exact-commit-title > > > > If you want to overwrite report's subsystems, reply with: > > #syz set subsystems: new-subsystem > > (See the list of subsystem names on the web dashboard) > > > > If the report is a duplicate of another one, reply with: > > #syz dup: exact-subject-of-another-report > > > > If you want to undo deduplication, reply with: > > #syz undup