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Received: from 30.74.144.118(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X8r1lbl_1786523383 cluster:ay36) by smtp.aliyun-inc.com; Wed, 12 Aug 2026 16:29:44 +0800 Message-ID: <88ed8a93-ae55-4281-b99d-ec4a6b6a2deb@linux.alibaba.com> Date: Wed, 12 Aug 2026 16:29:42 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] WARNING in set_mm_walk To: Shakeel Butt , 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 Xie References: <6a7a6929.b50370da.49fe0.005e.GAE@google.com> <20260810174852.aca0f73ab7ad71c70dcdefda@linux-foundation.org> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 2994E40003 X-Stat-Signature: tosph7isfnmwxzyizorkni3enh941emp X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1786523390-479328 X-HE-Meta: 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 itwqdKI/ 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 4htNuJ/l tJ/N/7WWA4njQB9unsA9nEGib4nvI6Z96LXj3fExf4B24un2bztteQex4mCidZBOCqIFAoaQTx2loWjkXEiEY6wJOqiIq5Rg1s5vtOKGMf3xSP7FH7iS2stiDdcghSfsLpBpNbU67m1ZB1PkBkcfWVKsBXrAjNSjN14Pg3j79YVbKD2w3jxyVg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/11/26 12:39 PM, Shakeel Butt wrote: > 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. MGLRU doesn't actually support memcg-v1's soft limit: unsigned long memcg1_soft_limit_reclaim(pg_data_t *pgdat, int order, gfp_t gfp_mask, unsigned long *total_scanned) { ...... if (lru_gen_enabled()) return 0; ...... } The call trace below likely showed up because the test repeatedly toggled MGLRU on and off, which isn't a normal operation and should be avoided in practice. I also agree that removing the deprecated memcg-v1 soft limit is the better way forward. >>> 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