Re: [syzbot] [f2fs?] BUG: sleeping function called from invalid context in f2fs_drop_inode

[Chao Yu <chao@kernel.org>]

#syz fix f2fs: don't call iput() from f2fs_drop_inode()

On 10/8/25 00:34, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    ba9dac987319 Merge tag 'libnvdimm-for-6.18' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=122ab92f980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c1486b135ff0ff9b
> dashboard link: https://syzkaller.appspot.com/bug?extid=635fba516c2c7858f799
> compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> 
> 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-ba9dac98.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d1fa0e7fa86d/vmlinux-ba9dac98.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/fbfd63ebd788/bzImage-ba9dac98.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+635fba516c2c7858f799@syzkaller.appspotmail.com
> 
> BUG: sleeping function called from invalid context at fs/inode.c:1928
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 5328, name: syz.0.0
> preempt_count: 1, expected: 0
> RCU nest depth: 0, expected: 0
> 1 lock held by syz.0.0/5328:
>  #0: ffff88801fcd9b80 (&sb->s_type->i_lock_key#35){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
>  #0: ffff88801fcd9b80 (&sb->s_type->i_lock_key#35){+.+.}-{3:3}, at: f2fs_drop_inode+0x67e/0x950 fs/f2fs/super.c:1822
> Preemption disabled at:
> [<0000000000000000>] 0x0
> CPU: 0 UID: 0 PID: 5328 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
>  __might_resched+0x495/0x610 kernel/sched/core.c:8925
>  iput+0x2b/0xc50 fs/inode.c:1928
>  f2fs_drop_inode+0x686/0x950 fs/f2fs/super.c:1823
>  iput_final fs/inode.c:1884 [inline]
>  iput+0x6d9/0xc50 fs/inode.c:1966
>  __dentry_kill+0x209/0x660 fs/dcache.c:669
>  dput+0x19f/0x2b0 fs/dcache.c:911
>  __fput+0x68e/0xa70 fs/file_table.c:476
>  task_work_run+0x1d1/0x260 kernel/task_work.c:227
>  resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
>  exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
>  exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
>  syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
>  syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
>  do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fb96098eec9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd5e7bbf08 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
> RAX: 0000000000000000 RBX: 00007fb960be7da0 RCX: 00007fb96098eec9
> RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
> RBP: 00007fb960be7da0 R08: 0000000000018f14 R09: 000000125e7bc1ff
> R10: 0000000000de6eb8 R11: 0000000000000246 R12: 0000000000015259
> R13: 00007fb960be6090 R14: ffffffffffffffff R15: 00007ffd5e7bc020
>  </TASK>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 5328 at fs/inode.c:1933 iput+0x38c/0xc50 fs/inode.c:1933
> Modules linked in:
> CPU: 0 UID: 0 PID: 5328 Comm: syz.0.0 Tainted: G        W           syzkaller #0 PREEMPT(full) 
> Tainted: [W]=WARN
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:iput+0x38c/0xc50 fs/inode.c:1933
> Code: 80 3d a0 88 49 0d 01 0f 85 b2 00 00 00 e8 4c 82 80 ff 4c 89 f7 be 10 00 00 00 e8 af 84 06 00 e9 2c fd ff ff e8 35 82 80 ff 90 <0f> 0b 90 e9 70 fd ff ff e8 27 82 80 ff 90 0f 0b 90 e9 d7 fe ff ff
> RSP: 0018:ffffc9000d47fbb0 EFLAGS: 00010293
> RAX: ffffffff823e919b RBX: 0000000000000001 RCX: ffff888000394900
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
> RBP: ffff88801fcd9bb8 R08: ffffffff9297b047 R09: 1ffffffff252f608
> R10: dffffc0000000000 R11: fffffbfff252f609 R12: ffff88801fcd9ce8
> R13: dffffc0000000000 R14: ffff88801fcd9ae8 R15: 1ffffffff1f3c766
> FS:  00005555645a1500(0000) GS:ffff88808d30c000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fb960bd75f0 CR3: 00000000127cb000 CR4: 0000000000352ef0
> Call Trace:
>  <TASK>
>  f2fs_drop_inode+0x686/0x950 fs/f2fs/super.c:1823
>  iput_final fs/inode.c:1884 [inline]
>  iput+0x6d9/0xc50 fs/inode.c:1966
>  __dentry_kill+0x209/0x660 fs/dcache.c:669
>  dput+0x19f/0x2b0 fs/dcache.c:911
>  __fput+0x68e/0xa70 fs/file_table.c:476
>  task_work_run+0x1d1/0x260 kernel/task_work.c:227
>  resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
>  exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
>  exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
>  syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
>  syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
>  do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fb96098eec9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd5e7bbf08 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
> RAX: 0000000000000000 RBX: 00007fb960be7da0 RCX: 00007fb96098eec9
> RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
> RBP: 00007fb960be7da0 R08: 0000000000018f14 R09: 000000125e7bc1ff
> R10: 0000000000de6eb8 R11: 0000000000000246 R12: 0000000000015259
> R13: 00007fb960be6090 R14: ffffffffffffffff R15: 00007ffd5e7bc020
>  </TASK>
> 
> 
> ---
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