* [syzbot] [cgroups?] [mm?] KASAN: wild-memory-access Read in lookup_swap_cgroup_id (2)
@ 2026-02-06 7:24 syzbot
2026-02-06 7:31 ` Dmitry Vyukov
0 siblings, 1 reply; 4+ messages in thread
From: syzbot @ 2026-02-06 7:24 UTC (permalink / raw)
To: akpm, cgroups, hannes, linux-kernel, linux-mm, mhocko,
muchun.song, roman.gushchin, shakeel.butt, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: 18f7fcd5e69a Linux 6.19-rc8
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1428fc5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f1fac0919970b671
dashboard link: https://syzkaller.appspot.com/bug?extid=e12bd9ca48157add237a
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2c19d9acc149/disk-18f7fcd5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/02cf07c94e58/vmlinux-18f7fcd5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/84011cec9819/bzImage-18f7fcd5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e12bd9ca48157add237a@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: wild-memory-access in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: wild-memory-access in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: wild-memory-access in __swap_cgroup_id_lookup mm/swap_cgroup.c:28 [inline]
BUG: KASAN: wild-memory-access in lookup_swap_cgroup_id+0xf9/0x1a0 mm/swap_cgroup.c:127
Read of size 4 at addr 0007fffffffffffc by task syz.5.3598/20029
CPU: 1 UID: 0 PID: 20029 Comm: syz.5.3598 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:186 [inline]
kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200
instrument_atomic_read include/linux/instrumented.h:68 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
__swap_cgroup_id_lookup mm/swap_cgroup.c:28 [inline]
lookup_swap_cgroup_id+0xf9/0x1a0 mm/swap_cgroup.c:127
swap_pte_batch+0x3c3/0x720 mm/internal.h:390
zap_nonpresent_ptes mm/memory.c:1749 [inline]
do_zap_pte_range mm/memory.c:1818 [inline]
zap_pte_range mm/memory.c:1858 [inline]
zap_pmd_range mm/memory.c:1950 [inline]
zap_pud_range mm/memory.c:1978 [inline]
zap_p4d_range mm/memory.c:1999 [inline]
unmap_page_range+0x1f6f/0x43e0 mm/memory.c:2020
unmap_single_vma+0x153/0x240 mm/memory.c:2062
unmap_vmas+0x218/0x470 mm/memory.c:2104
exit_mmap+0x181/0xae0 mm/mmap.c:1277
__mmput+0x12a/0x410 kernel/fork.c:1173
mmput+0x67/0x80 kernel/fork.c:1196
exit_mm kernel/exit.c:581 [inline]
do_exit+0x78a/0x2a30 kernel/exit.c:959
do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
exit_to_user_mode_loop+0x86/0x4b0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x4fe/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2f8f19aeb9
Code: Unable to access opcode bytes at 0x7f2f8f19ae8f.
RSP: 002b:00007f2f900350e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f2f8f416098 RCX: 00007f2f8f19aeb9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f2f8f416098
RBP: 00007f2f8f416090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2f8f416128 R14: 00007ffc0c8cc050 R15: 00007ffc0c8cc138
</TASK>
==================================================================
---
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] 4+ messages in thread
* Re: [syzbot] [cgroups?] [mm?] KASAN: wild-memory-access Read in lookup_swap_cgroup_id (2)
2026-02-06 7:24 [syzbot] [cgroups?] [mm?] KASAN: wild-memory-access Read in lookup_swap_cgroup_id (2) syzbot
@ 2026-02-06 7:31 ` Dmitry Vyukov
2026-02-06 17:30 ` Shakeel Butt
0 siblings, 1 reply; 4+ messages in thread
From: Dmitry Vyukov @ 2026-02-06 7:31 UTC (permalink / raw)
To: syzbot
Cc: akpm, cgroups, hannes, linux-kernel, linux-mm, mhocko,
muchun.song, roman.gushchin, shakeel.butt, syzkaller-bugs
On Fri, 6 Feb 2026 at 08:24, syzbot
<syzbot+e12bd9ca48157add237a@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 18f7fcd5e69a Linux 6.19-rc8
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1428fc5a580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f1fac0919970b671
> dashboard link: https://syzkaller.appspot.com/bug?extid=e12bd9ca48157add237a
> compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/2c19d9acc149/disk-18f7fcd5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/02cf07c94e58/vmlinux-18f7fcd5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/84011cec9819/bzImage-18f7fcd5.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+e12bd9ca48157add237a@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: wild-memory-access in instrument_atomic_read include/linux/instrumented.h:68 [inline]
> BUG: KASAN: wild-memory-access in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
> BUG: KASAN: wild-memory-access in __swap_cgroup_id_lookup mm/swap_cgroup.c:28 [inline]
> BUG: KASAN: wild-memory-access in lookup_swap_cgroup_id+0xf9/0x1a0 mm/swap_cgroup.c:127
> Read of size 4 at addr 0007fffffffffffc by task syz.5.3598/20029
>
> CPU: 1 UID: 0 PID: 20029 Comm: syz.5.3598 Tainted: G L syzkaller #0 PREEMPT(full)
> Tainted: [L]=SOFTLOCKUP
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
> kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
> check_region_inline mm/kasan/generic.c:186 [inline]
> kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200
> instrument_atomic_read include/linux/instrumented.h:68 [inline]
> atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
> __swap_cgroup_id_lookup mm/swap_cgroup.c:28 [inline]
> lookup_swap_cgroup_id+0xf9/0x1a0 mm/swap_cgroup.c:127
> swap_pte_batch+0x3c3/0x720 mm/internal.h:390
> zap_nonpresent_ptes mm/memory.c:1749 [inline]
> do_zap_pte_range mm/memory.c:1818 [inline]
> zap_pte_range mm/memory.c:1858 [inline]
> zap_pmd_range mm/memory.c:1950 [inline]
> zap_pud_range mm/memory.c:1978 [inline]
> zap_p4d_range mm/memory.c:1999 [inline]
> unmap_page_range+0x1f6f/0x43e0 mm/memory.c:2020
> unmap_single_vma+0x153/0x240 mm/memory.c:2062
> unmap_vmas+0x218/0x470 mm/memory.c:2104
> exit_mmap+0x181/0xae0 mm/mmap.c:1277
> __mmput+0x12a/0x410 kernel/fork.c:1173
> mmput+0x67/0x80 kernel/fork.c:1196
> exit_mm kernel/exit.c:581 [inline]
> do_exit+0x78a/0x2a30 kernel/exit.c:959
> do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
> get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
> arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
> __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
> exit_to_user_mode_loop+0x86/0x4b0 kernel/entry/common.c:75
> __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
> syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
> syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
> syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
> do_syscall_64+0x4fe/0xf80 arch/x86/entry/syscall_64.c:100
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f2f8f19aeb9
> Code: Unable to access opcode bytes at 0x7f2f8f19ae8f.
> RSP: 002b:00007f2f900350e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> RAX: fffffffffffffe00 RBX: 00007f2f8f416098 RCX: 00007f2f8f19aeb9
> RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f2f8f416098
> RBP: 00007f2f8f416090 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f2f8f416128 R14: 00007ffc0c8cc050 R15: 00007ffc0c8cc138
> </TASK>
> ==================================================================
This happened before:
https://lore.kernel.org/all/67d04360.050a0220.1939a6.000e.GAE@google.com/T/
and now 2 more times.
All reports look similar: exit_mm -> zap_p4d_range
And all access addresses look the same: top 13 bits are zeros, then
some garbage (0007fffffffffffc).
I am pretty sure it's telling us something, some kind of tricky race,
rather than a previous corruption. Swp entry is somehow invalid?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [cgroups?] [mm?] KASAN: wild-memory-access Read in lookup_swap_cgroup_id (2)
2026-02-06 7:31 ` Dmitry Vyukov
@ 2026-02-06 17:30 ` Shakeel Butt
2026-02-13 16:04 ` Kairui Song
0 siblings, 1 reply; 4+ messages in thread
From: Shakeel Butt @ 2026-02-06 17:30 UTC (permalink / raw)
To: Dmitry Vyukov
Cc: syzbot, akpm, cgroups, hannes, linux-kernel, linux-mm, mhocko,
muchun.song, roman.gushchin, syzkaller-bugs, kasong
+Kairui
On Fri, Feb 06, 2026 at 08:31:19AM +0100, Dmitry Vyukov wrote:
> On Fri, 6 Feb 2026 at 08:24, syzbot
> <syzbot+e12bd9ca48157add237a@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 18f7fcd5e69a Linux 6.19-rc8
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1428fc5a580000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=f1fac0919970b671
> > dashboard link: https://syzkaller.appspot.com/bug?extid=e12bd9ca48157add237a
> > compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/2c19d9acc149/disk-18f7fcd5.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/02cf07c94e58/vmlinux-18f7fcd5.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/84011cec9819/bzImage-18f7fcd5.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+e12bd9ca48157add237a@syzkaller.appspotmail.com
> >
> > ==================================================================
> > BUG: KASAN: wild-memory-access in instrument_atomic_read include/linux/instrumented.h:68 [inline]
> > BUG: KASAN: wild-memory-access in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
> > BUG: KASAN: wild-memory-access in __swap_cgroup_id_lookup mm/swap_cgroup.c:28 [inline]
> > BUG: KASAN: wild-memory-access in lookup_swap_cgroup_id+0xf9/0x1a0 mm/swap_cgroup.c:127
> > Read of size 4 at addr 0007fffffffffffc by task syz.5.3598/20029
> >
> > CPU: 1 UID: 0 PID: 20029 Comm: syz.5.3598 Tainted: G L syzkaller #0 PREEMPT(full)
> > Tainted: [L]=SOFTLOCKUP
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
> > Call Trace:
> > <TASK>
> > __dump_stack lib/dump_stack.c:94 [inline]
> > dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
> > kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
> > check_region_inline mm/kasan/generic.c:186 [inline]
> > kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200
> > instrument_atomic_read include/linux/instrumented.h:68 [inline]
> > atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
> > __swap_cgroup_id_lookup mm/swap_cgroup.c:28 [inline]
> > lookup_swap_cgroup_id+0xf9/0x1a0 mm/swap_cgroup.c:127
> > swap_pte_batch+0x3c3/0x720 mm/internal.h:390
> > zap_nonpresent_ptes mm/memory.c:1749 [inline]
> > do_zap_pte_range mm/memory.c:1818 [inline]
> > zap_pte_range mm/memory.c:1858 [inline]
> > zap_pmd_range mm/memory.c:1950 [inline]
> > zap_pud_range mm/memory.c:1978 [inline]
> > zap_p4d_range mm/memory.c:1999 [inline]
> > unmap_page_range+0x1f6f/0x43e0 mm/memory.c:2020
> > unmap_single_vma+0x153/0x240 mm/memory.c:2062
> > unmap_vmas+0x218/0x470 mm/memory.c:2104
> > exit_mmap+0x181/0xae0 mm/mmap.c:1277
> > __mmput+0x12a/0x410 kernel/fork.c:1173
> > mmput+0x67/0x80 kernel/fork.c:1196
> > exit_mm kernel/exit.c:581 [inline]
> > do_exit+0x78a/0x2a30 kernel/exit.c:959
> > do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
> > get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
> > arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
> > __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
> > exit_to_user_mode_loop+0x86/0x4b0 kernel/entry/common.c:75
> > __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
> > syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
> > syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
> > syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
> > do_syscall_64+0x4fe/0xf80 arch/x86/entry/syscall_64.c:100
> > entry_SYSCALL_64_after_hwframe+0x77/0x7f
> > RIP: 0033:0x7f2f8f19aeb9
> > Code: Unable to access opcode bytes at 0x7f2f8f19ae8f.
> > RSP: 002b:00007f2f900350e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> > RAX: fffffffffffffe00 RBX: 00007f2f8f416098 RCX: 00007f2f8f19aeb9
> > RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f2f8f416098
> > RBP: 00007f2f8f416090 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> > R13: 00007f2f8f416128 R14: 00007ffc0c8cc050 R15: 00007ffc0c8cc138
> > </TASK>
> > ==================================================================
>
> This happened before:
> https://lore.kernel.org/all/67d04360.050a0220.1939a6.000e.GAE@google.com/T/
> and now 2 more times.
> All reports look similar: exit_mm -> zap_p4d_range
> And all access addresses look the same: top 13 bits are zeros, then
> some garbage (0007fffffffffffc).
> I am pretty sure it's telling us something, some kind of tricky race,
> rather than a previous corruption. Swp entry is somehow invalid?
Thanks for the report. It would be good to have a reproducer. I will dig
deeper later but good to have eyes from Kairui who has recent changes
in the area.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [cgroups?] [mm?] KASAN: wild-memory-access Read in lookup_swap_cgroup_id (2)
2026-02-06 17:30 ` Shakeel Butt
@ 2026-02-13 16:04 ` Kairui Song
0 siblings, 0 replies; 4+ messages in thread
From: Kairui Song @ 2026-02-13 16:04 UTC (permalink / raw)
To: Shakeel Butt
Cc: Dmitry Vyukov, syzbot, akpm, cgroups, hannes, linux-kernel,
linux-mm, mhocko, muchun.song, roman.gushchin, syzkaller-bugs
On Sat, Feb 7, 2026 at 1:30 AM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> +Kairui
Thanks for Cc. I just noticed it while cleaning my mailbox.
> On Fri, Feb 06, 2026 at 08:31:19AM +0100, Dmitry Vyukov wrote:
> > On Fri, 6 Feb 2026 at 08:24, syzbot
> > <syzbot+e12bd9ca48157add237a@syzkaller.appspotmail.com> wrote:
> > >
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit: 18f7fcd5e69a Linux 6.19-rc8
> > > git tree: upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=1428fc5a580000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=f1fac0919970b671
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=e12bd9ca48157add237a
> > > compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> > >
> > > Unfortunately, I don't have any reproducer for this issue yet.
> > >
> > This happened before:
> > https://lore.kernel.org/all/67d04360.050a0220.1939a6.000e.GAE@google.com/T/
> > and now 2 more times.
> > All reports look similar: exit_mm -> zap_p4d_range
> > And all access addresses look the same: top 13 bits are zeros, then
> > some garbage (0007fffffffffffc).
> > I am pretty sure it's telling us something, some kind of tricky race,
> > rather than a previous corruption. Swp entry is somehow invalid?
>
> Thanks for the report. It would be good to have a reproducer. I will dig
> deeper later but good to have eyes from Kairui who has recent changes
> in the area.
I've just checked the syzbot's console log for the two times it
catched the error:
https://syzkaller.appspot.com/text?tag=CrashLog&x=1428fc5a580000
https://syzkaller.appspot.com/text?tag=CrashLog&x=16c2c694580000
(from https://syzkaller.appspot.com/bug?extid=e12bd9ca48157add237a)
In the first log, before the panic, console is full with:
get_swap_device: Bad swap file entry 4003ffffffffffff
Which indicates there is at least one, maybe a lot of invalid swap
entries of the same value in the page table. Unfortunately that's all
it can tell, maybe something corrupted the page table?
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-02-13 16:05 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-02-06 7:24 [syzbot] [cgroups?] [mm?] KASAN: wild-memory-access Read in lookup_swap_cgroup_id (2) syzbot
2026-02-06 7:31 ` Dmitry Vyukov
2026-02-06 17:30 ` Shakeel Butt
2026-02-13 16:04 ` Kairui Song
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox