From: kernel test robot <oliver.sang@intel.com>
To: Chao Yu <chao@kernel.org>
Cc: <oe-lkp@lists.linux.dev>, <lkp@intel.com>,
Chao Yu <chao@kernel.org>, <oliver.sang@intel.com>
Subject: [chao:bugfix/common] [f2fs] cf29f79136: BUG:KASAN:null-ptr-deref_in_kthread_stop
Date: Wed, 15 Jul 2026 14:26:12 +0800 [thread overview]
Message-ID: <202607151422.5161cc44-lkp@intel.com> (raw)
Hello,
kernel test robot noticed "BUG:KASAN:null-ptr-deref_in_kthread_stop" on:
commit: cf29f791365285201d5910134a8ce6ec846265b6 ("f2fs: embed f2fs_gc_kthread in f2fs_sb_info")
https://git.kernel.org/cgit/linux/kernel/git/chao/linux.git bugfix/common
in testcase: xfstests
version: xfstests-x86_64-ffc8bad1-1_20260702
with following parameters:
disk: 4HDD
fs: f2fs
test: generic-group-00
config: x86_64-rhel-9.4-func
compiler: gcc-14
test machine: 8 threads Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz (Skylake) with 28G memory
(please refer to attached dmesg/kmsg for entire log/backtrace)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202607151422.5161cc44-lkp@intel.com
[ 79.877831][ T7985] BUG: KASAN: null-ptr-deref in kthread_stop (linux/instrumented.h:112 linux/atomic/atomic-instrumented.h:252 linux/refcount.h:283 linux/refcount.h:366 linux/refcount.h:383 linux/sched/task.h:116 kthread.c:754)
[ 79.884648][ T7985] Write of size 4 at addr 0000000000000028 by task umount/7985
[ 79.892072][ T7985]
[ 79.894267][ T7985] CPU: 2 UID: 0 PID: 7985 Comm: umount Tainted: G S 7.2.0-rc1+ #1 PREEMPT(lazy)
[ 79.894272][ T7985] Tainted: [S]=CPU_OUT_OF_SPEC
[ 79.894273][ T7985] Hardware name: Dell Inc. OptiPlex 7040/0Y7WYT, BIOS 1.2.8 01/26/2016
[ 79.894275][ T7985] Call Trace:
[ 79.894276][ T7985] <TASK>
[ 79.894277][ T7985] dump_stack_lvl (dump_stack.c:94 dump_stack.c:120)
[ 79.894281][ T7985] ? kthread_stop (linux/instrumented.h:112 linux/atomic/atomic-instrumented.h:252 linux/refcount.h:283 linux/refcount.h:366 linux/refcount.h:383 linux/sched/task.h:116 kthread.c:754)
[ 79.894284][ T7985] kasan_report (kasan/report.c:595)
[ 79.894289][ T7985] ? kthread_stop (linux/instrumented.h:112 linux/atomic/atomic-instrumented.h:252 linux/refcount.h:283 linux/refcount.h:366 linux/refcount.h:383 linux/sched/task.h:116 kthread.c:754)
[ 79.894292][ T7985] kasan_check_range (kasan/generic.c:186 kasan/generic.c:200)
[ 79.894294][ T7985] kthread_stop (linux/instrumented.h:112 linux/atomic/atomic-instrumented.h:252 linux/refcount.h:283 linux/refcount.h:366 linux/refcount.h:383 linux/sched/task.h:116 kthread.c:754)
[ 79.894298][ T7985] f2fs_stop_gc_thread (f2fs/gc.c:240) f2fs
[ 79.894364][ T7985] kill_f2fs_super (f2fs/super.c:5573) f2fs
[ 79.894423][ T7985] ? __pfx_kill_f2fs_super (linux/srcutree.h:292 (discriminator 2)) f2fs
[ 79.894526][ T7985] ? __virt_addr_valid (linux/mmzone.h:2187 (discriminator 1) linux/mmzone.h:2269 (discriminator 1) x86/mm/physaddr.c:54 (discriminator 1))
[ 79.894529][ T7985] ? rcu_segcblist_enqueue (linux/instrumented.h:112 linux/atomic/atomic-instrumented.h:3260 rcu/rcu_segcblist.c:214 rcu/rcu_segcblist.c:231 rcu/rcu_segcblist.c:332)
[ 79.894532][ T7985] ? __call_rcu_common+0x341/0x970
[ 79.894535][ T7985] ? mutex_unlock (linux/instrumented.h:55 linux/atomic/atomic-instrumented.h:4480 locking/mutex.c:172 locking/mutex.c:579)
[ 79.894538][ T7985] ? __pfx_mutex_unlock (trace/events/lock.h:140 (discriminator 15))
[ 79.894541][ T7985] ? __pfx___call_rcu_common+0x10/0x10
[ 79.894544][ T7985] deactivate_locked_super (super.c:477)
[ 79.894547][ T7985] cleanup_mnt (namespace.c:1317)
[ 79.894551][ T7985] task_work_run (task_work.c:233)
[ 79.894553][ T7985] ? path_umount (namespace.c:1411 namespace.c:2051)
[ 79.894555][ T7985] ? __pfx_task_work_run (task_work.c:190)
[ 79.894558][ T7985] ? __x64_sys_umount (namespace.c:2070 namespace.c:2075 namespace.c:2073 namespace.c:2073)
[ 79.894560][ T7985] exit_to_user_mode_loop (linux/resume_user_mode.h:50 entry/common.c:70 entry/common.c:101)
[ 79.894564][ T7985] ? __do_sys_getegid (sys.c:1048 (discriminator 2))
[ 79.894567][ T7985] do_syscall_64 (linux/irq-entry-common.h:207 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 79.894570][ T7985] ? __x64_sys_access (open.c:547 open.c:545 open.c:545)
[ 79.894573][ T7985] ? do_syscall_64 (linux/irq-entry-common.h:210 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 79.894575][ T7985] ? do_syscall_64 (linux/irq-entry-common.h:210 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 79.894578][ T7985] ? do_syscall_64 (linux/irq-entry-common.h:210 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 79.894580][ T7985] ? do_syscall_64 (linux/randomize_kstack.h:57 x86/entry/syscall_64.c:92)
[ 79.894583][ T7985] entry_SYSCALL_64_after_hwframe (x86/entry/entry_64.S:121)
[ 79.894586][ T7985] RIP: 0033:0x7fbb5f66d257
[ 79.894588][ T7985] Code: 0d 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 89 3b 0d 00 f7 d8 64 89 02 b8
All code
========
0: 0d 00 f7 d8 64 or $0x64d8f700,%eax
5: 89 02 mov %eax,(%rdx)
7: b8 ff ff ff ff mov $0xffffffff,%eax
c: c3 ret
d: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
13: 31 f6 xor %esi,%esi
15: e9 09 00 00 00 jmp 0x23
1a: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
21: 00 00
23: b8 a6 00 00 00 mov $0xa6,%eax
28: 0f 05 syscall
2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction
30: 77 01 ja 0x33
32: c3 ret
33: 48 8b 15 89 3b 0d 00 mov 0xd3b89(%rip),%rdx # 0xd3bc3
3a: f7 d8 neg %eax
3c: 64 89 02 mov %eax,%fs:(%rdx)
3f: b8 .byte 0xb8
Code starting with the faulting instruction
===========================================
0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
6: 77 01 ja 0x9
8: c3 ret
9: 48 8b 15 89 3b 0d 00 mov 0xd3b89(%rip),%rdx # 0xd3b99
10: f7 d8 neg %eax
12: 64 89 02 mov %eax,%fs:(%rdx)
15: b8 .byte 0xb8
[ 79.894591][ T7985] RSP: 002b:00007fff9e2b3248 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[ 79.894595][ T7985] RAX: 0000000000000000 RBX: 00005578ba7bfaf8 RCX: 00007fbb5f66d257
[ 79.894597][ T7985] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00005578ba7c5030
[ 79.894598][ T7985] RBP: 0000000000000000 R08: 0000000000000020 R09: 0000000000000001
[ 79.894600][ T7985] R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbb5f7cb26c
[ 79.894601][ T7985] R13: 00005578ba7c5030 R14: 00005578ba7bfe30 R15: 00005578ba7bf9f0
[ 79.894604][ T7985] </TASK>
[ 79.894605][ T7985] ==================================================================
[ 80.152391][ T7985] Disabling lock debugging due to kernel taint
[ 80.158468][ T7985] BUG: kernel NULL pointer dereference, address: 0000000000000028
[ 80.166168][ T7985] #PF: supervisor write access in kernel mode
[ 80.172112][ T7985] #PF: error_code(0x0002) - not-present page
[ 80.177966][ T7985] PGD 0 P4D 0
[ 80.181210][ T7985] Oops: Oops: 0002 [#1] SMP KASAN PTI
[ 80.186470][ T7985] CPU: 2 UID: 0 PID: 7985 Comm: umount Tainted: G S B 7.2.0-rc1+ #1 PREEMPT(lazy)
[ 80.196958][ T7985] Tainted: [S]=CPU_OUT_OF_SPEC, [B]=BAD_PAGE
[ 80.202811][ T7985] Hardware name: Dell Inc. OptiPlex 7040/0Y7WYT, BIOS 1.2.8 01/26/2016
[ 80.210932][ T7985] RIP: 0010:kthread_stop (x86/include/asm/atomic.h:93 (discriminator 4) linux/atomic/atomic-arch-fallback.h:749 (discriminator 4) linux/atomic/atomic-instrumented.h:253 (discriminator 4) linux/refcount.h:283 (discriminator 4) linux/refcount.h:366 (discriminator 4) linux/refcount.h:383 (discriminator 4) linux/sched/task.h:116 (discriminator 4) kthread.c:754 (discriminator 4))
[ 80.216005][ T7985] Code: 90 90 90 0f 1f 44 00 00 41 54 55 53 48 89 fb 0f 1f 44 00 00 4c 8d 63 28 be 04 00 00 00 4c 89 e7 e8 5e 02 9c 00 b8 01 00 00 00 <f0> 0f c1 43 28 85 c0 0f 84 ce 02 00 00 8d 50 01 09 c2 0f 88 98 02
All code
========
0: 90 nop
1: 90 nop
2: 90 nop
3: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
8: 41 54 push %r12
a: 55 push %rbp
b: 53 push %rbx
c: 48 89 fb mov %rdi,%rbx
f: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
14: 4c 8d 63 28 lea 0x28(%rbx),%r12
18: be 04 00 00 00 mov $0x4,%esi
1d: 4c 89 e7 mov %r12,%rdi
20: e8 5e 02 9c 00 call 0x9c0283
25: b8 01 00 00 00 mov $0x1,%eax
2a:* f0 0f c1 43 28 lock xadd %eax,0x28(%rbx) <-- trapping instruction
2f: 85 c0 test %eax,%eax
31: 0f 84 ce 02 00 00 je 0x305
37: 8d 50 01 lea 0x1(%rax),%edx
3a: 09 c2 or %eax,%edx
3c: 0f .byte 0xf
3d: 88 .byte 0x88
3e: 98 cwtl
3f: 02 .byte 0x2
Code starting with the faulting instruction
===========================================
0: f0 0f c1 43 28 lock xadd %eax,0x28(%rbx)
5: 85 c0 test %eax,%eax
7: 0f 84 ce 02 00 00 je 0x2db
d: 8d 50 01 lea 0x1(%rax),%edx
10: 09 c2 or %eax,%edx
12: 0f .byte 0xf
13: 88 .byte 0x88
14: 98 cwtl
15: 02 .byte 0x2
[ 80.235571][ T7985] RSP: 0018:ffffc900020dfb98 EFLAGS: 00010246
[ 80.241528][ T7985] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81534c76
[ 80.249406][ T7985] RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff87a10b40
[ 80.257270][ T7985] RBP: ffff88871df74920 R08: 0000000000000001 R09: fffffbfff0f42168
[ 80.265130][ T7985] R10: ffffffff87a10b47 R11: 0000000000000001 R12: 0000000000000028
[ 80.272991][ T7985] R13: ffff88871df74050 R14: ffff8881107a3388 R15: ffff8881a5f4d4ec
[ 80.280849][ T7985] FS: 00007fbb5f414840(0000) GS:ffff88868c1a9000(0000) knlGS:0000000000000000
[ 80.289667][ T7985] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 80.296130][ T7985] CR2: 0000000000000028 CR3: 0000000213894001 CR4: 00000000003726f0
[ 80.303987][ T7985] Call Trace:
[ 80.307137][ T7985] <TASK>
[ 80.309941][ T7985] f2fs_stop_gc_thread (f2fs/gc.c:240) f2fs
[ 80.315425][ T7985] kill_f2fs_super (f2fs/super.c:5573) f2fs
[ 80.320779][ T7985] ? __pfx_kill_f2fs_super (linux/srcutree.h:292 (discriminator 2)) f2fs
[ 80.326603][ T7985] ? __virt_addr_valid (linux/mmzone.h:2187 (discriminator 1) linux/mmzone.h:2269 (discriminator 1) x86/mm/physaddr.c:54 (discriminator 1))
[ 80.331513][ T7985] ? rcu_segcblist_enqueue (linux/instrumented.h:112 linux/atomic/atomic-instrumented.h:3260 rcu/rcu_segcblist.c:214 rcu/rcu_segcblist.c:231 rcu/rcu_segcblist.c:332)
[ 80.336672][ T7985] ? __call_rcu_common+0x341/0x970
[ 80.342702][ T7985] ? mutex_unlock (linux/instrumented.h:55 linux/atomic/atomic-instrumented.h:4480 locking/mutex.c:172 locking/mutex.c:579)
[ 80.347077][ T7985] ? __pfx_mutex_unlock (trace/events/lock.h:140 (discriminator 15))
[ 80.351979][ T7985] ? __pfx___call_rcu_common+0x10/0x10
[ 80.358360][ T7985] deactivate_locked_super (super.c:477)
[ 80.363607][ T7985] cleanup_mnt (namespace.c:1317)
[ 80.367893][ T7985] task_work_run (task_work.c:233)
[ 80.372355][ T7985] ? path_umount (namespace.c:1411 namespace.c:2051)
[ 80.376816][ T7985] ? __pfx_task_work_run (task_work.c:190)
[ 80.381803][ T7985] ? __x64_sys_umount (namespace.c:2070 namespace.c:2075 namespace.c:2073 namespace.c:2073)
[ 80.386611][ T7985] exit_to_user_mode_loop (linux/resume_user_mode.h:50 entry/common.c:70 entry/common.c:101)
[ 80.391857][ T7985] ? __do_sys_getegid (sys.c:1048 (discriminator 2))
[ 80.396579][ T7985] do_syscall_64 (linux/irq-entry-common.h:207 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 80.401040][ T7985] ? __x64_sys_access (open.c:547 open.c:545 open.c:545)
[ 80.405762][ T7985] ? do_syscall_64 (linux/irq-entry-common.h:210 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 80.410400][ T7985] ? do_syscall_64 (linux/irq-entry-common.h:210 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 80.415036][ T7985] ? do_syscall_64 (linux/irq-entry-common.h:210 linux/irq-entry-common.h:230 linux/entry-common.h:318 x86/entry/syscall_64.c:100)
[ 80.419672][ T7985] ? do_syscall_64 (linux/randomize_kstack.h:57 x86/entry/syscall_64.c:92)
[ 80.424220][ T7985] entry_SYSCALL_64_after_hwframe (x86/entry/entry_64.S:121)
[ 80.429990][ T7985] RIP: 0033:0x7fbb5f66d257
[ 80.434277][ T7985] Code: 0d 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 89 3b 0d 00 f7 d8 64 89 02 b8
All code
========
0: 0d 00 f7 d8 64 or $0x64d8f700,%eax
5: 89 02 mov %eax,(%rdx)
7: b8 ff ff ff ff mov $0xffffffff,%eax
c: c3 ret
d: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
13: 31 f6 xor %esi,%esi
15: e9 09 00 00 00 jmp 0x23
1a: 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
21: 00 00
23: b8 a6 00 00 00 mov $0xa6,%eax
28: 0f 05 syscall
2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction
30: 77 01 ja 0x33
32: c3 ret
33: 48 8b 15 89 3b 0d 00 mov 0xd3b89(%rip),%rdx # 0xd3bc3
3a: f7 d8 neg %eax
3c: 64 89 02 mov %eax,%fs:(%rdx)
3f: b8 .byte 0xb8
Code starting with the faulting instruction
===========================================
0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
6: 77 01 ja 0x9
8: c3 ret
9: 48 8b 15 89 3b 0d 00 mov 0xd3b89(%rip),%rdx # 0xd3b99
10: f7 d8 neg %eax
12: 64 89 02 mov %eax,%fs:(%rdx)
15: b8 .byte 0xb8
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260715/202607151422.5161cc44-lkp@intel.com
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
reply other threads:[~2026-07-15 6:26 UTC|newest]
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