* [syzbot] [mm?] WARNING in lock_list_lru_of_memcg (2)
@ 2025-11-05 18:38 syzbot
2025-11-06 1:01 ` Shakeel Butt
0 siblings, 1 reply; 3+ messages in thread
From: syzbot @ 2025-11-05 18:38 UTC (permalink / raw)
To: akpm, david, linux-kernel, linux-mm, muchun.song, roman.gushchin,
syzkaller-bugs, zhengqi.arch
Hello,
syzbot found the following issue on:
HEAD commit: ba36dd5ee6fd Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16515704580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e46b8a1c645465a9
dashboard link: https://syzkaller.appspot.com/bug?extid=c5b060ce82921a2fd500
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: i386
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/62471ef815ed/disk-ba36dd5e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e7a72af6e621/vmlinux-ba36dd5e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/352eec7dbce0/bzImage-ba36dd5e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c5b060ce82921a2fd500@syzkaller.appspotmail.com
------------[ cut here ]------------
WARNING: CPU: 0 PID: 13908 at mm/list_lru.c:100 lock_list_lru_of_memcg+0x30c/0x4c0 mm/list_lru.c:100
Modules linked in:
CPU: 0 UID: 0 PID: 13908 Comm: syz.0.1878 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:lock_list_lru_of_memcg+0x30c/0x4c0 mm/list_lru.c:100
Code: 42 80 3c 30 00 74 0b 48 89 fb e8 2f 40 1d 00 48 89 df 48 8b 3f 48 8b 54 24 10 48 8b 74 24 28 e9 0a fe ff ff e8 e5 8a b7 ff 90 <0f> 0b 90 eb be 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 1e fe ff ff 48
RSP: 0018:ffffc9000fb165c0 EFLAGS: 00010083
RAX: ffffffff82087bab RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000f013000 RSI: 00000000000127d4 RDI: 00000000000127d5
RBP: 0000000000000001 R08: ffff88801e3b8000 R09: 0000000000000002
R10: 0000000000000406 R11: 0000000000000002 R12: ffffffff997ec9a0
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88812613e000(0063) knlGS:00000000f541bb40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f74089b4 CR3: 000000002ef4a000 CR4: 00000000003526f0
Call Trace:
<TASK>
list_lru_add+0x58/0x270 mm/list_lru.c:167
list_lru_add_obj+0x191/0x270 mm/list_lru.c:190
workingset_update_node+0x1d5/0x260 mm/workingset.c:629
xas_update lib/xarray.c:357 [inline]
update_node lib/xarray.c:765 [inline]
xas_store+0xac4/0x1880 lib/xarray.c:852
page_cache_delete mm/filemap.c:141 [inline]
__filemap_remove_folio+0x3c7/0x500 mm/filemap.c:227
__remove_mapping+0xb06/0xe40 mm/vmscan.c:811
shrink_folio_list+0x2896/0x4c70 mm/vmscan.c:1553
reclaim_folio_list+0xeb/0x500 mm/vmscan.c:2233
reclaim_pages+0x454/0x520 mm/vmscan.c:2270
madvise_cold_or_pageout_pte_range+0x1974/0x1d00 mm/madvise.c:565
walk_pmd_range mm/pagewalk.c:130 [inline]
walk_pud_range mm/pagewalk.c:224 [inline]
walk_p4d_range mm/pagewalk.c:262 [inline]
walk_pgd_range+0xfe9/0x1d40 mm/pagewalk.c:303
__walk_page_range+0x14c/0x710 mm/pagewalk.c:410
walk_page_range_vma+0x393/0x440 mm/pagewalk.c:717
madvise_pageout_page_range mm/madvise.c:624 [inline]
madvise_pageout mm/madvise.c:649 [inline]
madvise_vma_behavior+0x311f/0x3a10 mm/madvise.c:1352
madvise_walk_vmas+0x51c/0xa30 mm/madvise.c:1669
madvise_do_behavior+0x38e/0x550 mm/madvise.c:1885
do_madvise+0x1bc/0x270 mm/madvise.c:1978
__do_sys_madvise mm/madvise.c:1987 [inline]
__se_sys_madvise mm/madvise.c:1985 [inline]
__ia32_sys_madvise+0xa7/0xc0 mm/madvise.c:1985
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
__do_fast_syscall_32+0xb6/0x2b0 arch/x86/entry/syscall_32.c:306
do_fast_syscall_32+0x34/0x80 arch/x86/entry/syscall_32.c:331
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf706d539
Code: 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f541b55c EFLAGS: 00000206 ORIG_RAX: 00000000000000db
RAX: ffffffffffffffda RBX: 0000000080000000 RCX: 0000000000600000
RDX: 0000000000000015 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess):
0: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
4: 10 07 adc %al,(%rdi)
6: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
a: 10 08 adc %cl,(%rax)
c: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
20: 00 51 52 add %dl,0x52(%rcx)
23: 55 push %rbp
24: 89 e5 mov %esp,%ebp
26: 0f 34 sysenter
28: cd 80 int $0x80
* 2a: 5d pop %rbp <-- trapping instruction
2b: 5a pop %rdx
2c: 59 pop %rcx
2d: c3 ret
2e: 90 nop
2f: 90 nop
30: 90 nop
31: 90 nop
32: 90 nop
33: 90 nop
34: 90 nop
35: 90 nop
36: 90 nop
37: 90 nop
38: 90 nop
39: 90 nop
3a: 90 nop
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 90 nop
3f: 90 nop
---
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [syzbot] [mm?] WARNING in lock_list_lru_of_memcg (2)
2025-11-05 18:38 [syzbot] [mm?] WARNING in lock_list_lru_of_memcg (2) syzbot
@ 2025-11-06 1:01 ` Shakeel Butt
2025-11-06 5:58 ` Kairui Song
0 siblings, 1 reply; 3+ messages in thread
From: Shakeel Butt @ 2025-11-06 1:01 UTC (permalink / raw)
To: syzbot
Cc: akpm, david, linux-kernel, linux-mm, muchun.song, roman.gushchin,
syzkaller-bugs, zhengqi.arch, Kairui Song
+Kairui
On Wed, Nov 05, 2025 at 10:38:35AM -0800, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: ba36dd5ee6fd Merge tag 'bpf-fixes' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16515704580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e46b8a1c645465a9
> dashboard link: https://syzkaller.appspot.com/bug?extid=c5b060ce82921a2fd500
> compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/62471ef815ed/disk-ba36dd5e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/e7a72af6e621/vmlinux-ba36dd5e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/352eec7dbce0/bzImage-ba36dd5e.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c5b060ce82921a2fd500@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 13908 at mm/list_lru.c:100 lock_list_lru_of_memcg+0x30c/0x4c0 mm/list_lru.c:100
This is VM_WARN_ON(!css_is_dying(&memcg->css)) in
lock_list_lru_of_memcg(). It is unexpected as it can only happen if
(1) list_lru_from_memcg_idx() returns NULL or (2) lock_list_lru()
find l->nr_items is LONG_MIN which is set after CSS_DYING is set.
I don't see how (2) can happen. For (1) to happen, somehow someone has
deleted the given alive memcg's list_lru_memcg from shadow_nodes
list_lru. Not sure how that can happen without some memory corruption or
unsafe updates to shadow_nodes.
I think we need to wait for syzbot to generate a reproducer to debug
further.
> Modules linked in:
> CPU: 0 UID: 0 PID: 13908 Comm: syz.0.1878 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
> RIP: 0010:lock_list_lru_of_memcg+0x30c/0x4c0 mm/list_lru.c:100
> Code: 42 80 3c 30 00 74 0b 48 89 fb e8 2f 40 1d 00 48 89 df 48 8b 3f 48 8b 54 24 10 48 8b 74 24 28 e9 0a fe ff ff e8 e5 8a b7 ff 90 <0f> 0b 90 eb be 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 1e fe ff ff 48
> RSP: 0018:ffffc9000fb165c0 EFLAGS: 00010083
> RAX: ffffffff82087bab RBX: 0000000000000000 RCX: 0000000000080000
> RDX: ffffc9000f013000 RSI: 00000000000127d4 RDI: 00000000000127d5
> RBP: 0000000000000001 R08: ffff88801e3b8000 R09: 0000000000000002
> R10: 0000000000000406 R11: 0000000000000002 R12: ffffffff997ec9a0
> R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000000
> FS: 0000000000000000(0000) GS:ffff88812613e000(0063) knlGS:00000000f541bb40
> CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
> CR2: 00000000f74089b4 CR3: 000000002ef4a000 CR4: 00000000003526f0
> Call Trace:
> <TASK>
> list_lru_add+0x58/0x270 mm/list_lru.c:167
> list_lru_add_obj+0x191/0x270 mm/list_lru.c:190
> workingset_update_node+0x1d5/0x260 mm/workingset.c:629
> xas_update lib/xarray.c:357 [inline]
> update_node lib/xarray.c:765 [inline]
> xas_store+0xac4/0x1880 lib/xarray.c:852
> page_cache_delete mm/filemap.c:141 [inline]
> __filemap_remove_folio+0x3c7/0x500 mm/filemap.c:227
> __remove_mapping+0xb06/0xe40 mm/vmscan.c:811
> shrink_folio_list+0x2896/0x4c70 mm/vmscan.c:1553
> reclaim_folio_list+0xeb/0x500 mm/vmscan.c:2233
> reclaim_pages+0x454/0x520 mm/vmscan.c:2270
> madvise_cold_or_pageout_pte_range+0x1974/0x1d00 mm/madvise.c:565
> walk_pmd_range mm/pagewalk.c:130 [inline]
> walk_pud_range mm/pagewalk.c:224 [inline]
> walk_p4d_range mm/pagewalk.c:262 [inline]
> walk_pgd_range+0xfe9/0x1d40 mm/pagewalk.c:303
> __walk_page_range+0x14c/0x710 mm/pagewalk.c:410
> walk_page_range_vma+0x393/0x440 mm/pagewalk.c:717
> madvise_pageout_page_range mm/madvise.c:624 [inline]
> madvise_pageout mm/madvise.c:649 [inline]
> madvise_vma_behavior+0x311f/0x3a10 mm/madvise.c:1352
> madvise_walk_vmas+0x51c/0xa30 mm/madvise.c:1669
> madvise_do_behavior+0x38e/0x550 mm/madvise.c:1885
> do_madvise+0x1bc/0x270 mm/madvise.c:1978
> __do_sys_madvise mm/madvise.c:1987 [inline]
> __se_sys_madvise mm/madvise.c:1985 [inline]
> __ia32_sys_madvise+0xa7/0xc0 mm/madvise.c:1985
> do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
> __do_fast_syscall_32+0xb6/0x2b0 arch/x86/entry/syscall_32.c:306
> do_fast_syscall_32+0x34/0x80 arch/x86/entry/syscall_32.c:331
> entry_SYSENTER_compat_after_hwframe+0x84/0x8e
> RIP: 0023:0xf706d539
> Code: 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
> RSP: 002b:00000000f541b55c EFLAGS: 00000206 ORIG_RAX: 00000000000000db
> RAX: ffffffffffffffda RBX: 0000000080000000 RCX: 0000000000600000
> RDX: 0000000000000015 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> </TASK>
> ----------------
> Code disassembly (best guess):
> 0: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
> 4: 10 07 adc %al,(%rdi)
> 6: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
> a: 10 08 adc %cl,(%rax)
> c: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
> 20: 00 51 52 add %dl,0x52(%rcx)
> 23: 55 push %rbp
> 24: 89 e5 mov %esp,%ebp
> 26: 0f 34 sysenter
> 28: cd 80 int $0x80
> * 2a: 5d pop %rbp <-- trapping instruction
> 2b: 5a pop %rdx
> 2c: 59 pop %rcx
> 2d: c3 ret
> 2e: 90 nop
> 2f: 90 nop
> 30: 90 nop
> 31: 90 nop
> 32: 90 nop
> 33: 90 nop
> 34: 90 nop
> 35: 90 nop
> 36: 90 nop
> 37: 90 nop
> 38: 90 nop
> 39: 90 nop
> 3a: 90 nop
> 3b: 90 nop
> 3c: 90 nop
> 3d: 90 nop
> 3e: 90 nop
> 3f: 90 nop
>
>
> ---
> 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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [syzbot] [mm?] WARNING in lock_list_lru_of_memcg (2)
2025-11-06 1:01 ` Shakeel Butt
@ 2025-11-06 5:58 ` Kairui Song
0 siblings, 0 replies; 3+ messages in thread
From: Kairui Song @ 2025-11-06 5:58 UTC (permalink / raw)
To: Shakeel Butt
Cc: syzbot, akpm, david, linux-kernel, linux-mm, muchun.song,
roman.gushchin, syzkaller-bugs, zhengqi.arch
On Thu, Nov 6, 2025 at 10:58 AM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> +Kairui
Thanks for the Cc.
>
> On Wed, Nov 05, 2025 at 10:38:35AM -0800, syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: ba36dd5ee6fd Merge tag 'bpf-fixes' of git://git.kernel.org..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=16515704580000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=e46b8a1c645465a9
> > dashboard link: https://syzkaller.appspot.com/bug?extid=c5b060ce82921a2fd500
> > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> > userspace arch: i386
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/62471ef815ed/disk-ba36dd5e.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/e7a72af6e621/vmlinux-ba36dd5e.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/352eec7dbce0/bzImage-ba36dd5e.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+c5b060ce82921a2fd500@syzkaller.appspotmail.com
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 13908 at mm/list_lru.c:100 lock_list_lru_of_memcg+0x30c/0x4c0 mm/list_lru.c:100
>
> This is VM_WARN_ON(!css_is_dying(&memcg->css)) in
> lock_list_lru_of_memcg(). It is unexpected as it can only happen if
> (1) list_lru_from_memcg_idx() returns NULL or (2) lock_list_lru()
> find l->nr_items is LONG_MIN which is set after CSS_DYING is set.
>
> I don't see how (2) can happen. For (1) to happen, somehow someone has
> deleted the given alive memcg's list_lru_memcg from shadow_nodes
> list_lru. Not sure how that can happen without some memory corruption or
> unsafe updates to shadow_nodes.
Last time I saw this was due to memory corruption from other components:
https://lore.kernel.org/linux-mm/CAMgjq7Dxv4JwebBtR18_9TpNX_7ej5HXEN1s1sitB+H+4rCE-Q@mail.gmail.com/
Another time was due to an allocation of shadow node missing mapping_set_update:
https://lore.kernel.org/linux-mm/20241222122936.67501-1-ryncsn@gmail.com/
>
> I think we need to wait for syzbot to generate a reproducer to debug
> further.
Agree, this part has been very stable for a year, hard to tell if there is
any other allocation missing the xas_set_lru callback or something
else is wrong, worst thing could happen now is some minor memory
accounting leak.
I'll have a look from the code side when I have time.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2025-11-06 5:58 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2025-11-05 18:38 [syzbot] [mm?] WARNING in lock_list_lru_of_memcg (2) syzbot
2025-11-06 1:01 ` Shakeel Butt
2025-11-06 5:58 ` Kairui Song
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