WARNING in set_mm_walk

Status: upstream: reported C repro on 2026/08/11 00:13
Subsystems: mm
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+12ee2725d5fde63a9c96@syzkaller.appspotmail.com
Fix commit: memcg: make the v1 soft limit knob inert
Patched on: [ci-upstream-linux-next-kasan-gce-root], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 8d18h, last: 1d07h
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
fe1ec45d repro-c Reproduced: ✅ WARNING in set_mm_walk 2026/08/11 20:04 2026/08/12 01:10 2026/08/12 03:30 f8d35649
99ad911a assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in set_mm_walk 2026/08/09 09:49 2026/08/09 09:49 2026/08/09 10:52 5d63f80b
Discussions (2)
Title Replies (including bot) Last reply
[PATCH 1/9] memcg: make the v1 soft limit knob inert 4 (4) 2026/08/13 08:22
[syzbot] [mm?] WARNING in set_mm_walk 5 (7) 2026/08/12 21:41
Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/12 11:19 20m nogikh@google.com upstream report job log log

Sample crash report:
------------[ cut here ]------------
current_is_kswapd()
WARNING: mm/vmscan.c:3800 at set_mm_walk+0x210/0x270 mm/vmscan.c:3800, CPU#2: kswapd0/111
Modules linked in:
CPU: 2 UID: 0 PID: 111 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full) 
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 19 f7 2a 00 e9 b7 fe ff ff e8 7f 68 ba ff 90 0f 0b 90 e9 d2 fe ff ff e8 71 68 ba ff 90 <0f> 0b 90 e9 74 ff ff ff 4c 89 ff e8 20 f7 2a 00 e9 4e fe ff ff 48
RSP: 0018:ffffc9000272f2b8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888023f04a80 RCX: ffffffff82500a88
RDX: ffff888023f04a80 RSI: ffffffff82500b0f RDI: ffff888023f04a80
RBP: 0000000000020000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000020000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc9000272fc38 R14: 0000000000000001 R15: ffffc9000272fc40
FS:  0000000000000000(0000) GS:ffff8880d5fec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005643a2ed4168 CR3: 000000003c7ec000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 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
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/12 12:26 upstream f5bbbfec59b4 52aa2820 .config console log report C ci-qemu-upstream WARNING in set_mm_walk
2026/08/05 01:38 upstream 562bfb501c54 52aa2820 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in set_mm_walk
* Struck through repros no longer work on HEAD.