linux-kernel - Re: [syzbot] [fs?] BUG: sleeping function called from invalid context in hook_sb

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Message-ID: <68d3cb39.a70a0220.1b52b.02c6.GAE@google.com>
Date: Wed, 24 Sep 2025 03:43:05 -0700
From: syzbot <syzbot+12479ae15958fc3f54ec@...kaller.appspotmail.com>
To: eadavis@...com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [fs?] BUG: sleeping function called from invalid context
 in hook_sb_delete

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: sleeping function called from invalid context in hook_sb_delete

BUG: sleeping function called from invalid context at fs/inode.c:1928
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6514, name: syz.0.17
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
2 locks held by syz.0.17/6514:
 #0: ffff8880306a20e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff8880306a20e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff8880306a20e0 (&type->s_umount_key#48){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:505
 #1: ffff8880306a2998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #1: ffff8880306a2998 (&s->s_inode_list_lock){+.+.}-{3:3}, at: hook_sb_delete+0xae/0xbc0 security/landlock/fs.c:1405
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 UID: 0 PID: 6514 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 __might_resched+0x495/0x610 kernel/sched/core.c:8960
 iput+0x2b/0xc50 fs/inode.c:1928
 hook_sb_delete+0x6b7/0xbc0 security/landlock/fs.c:1468
 security_sb_delete+0x80/0x150 security/security.c:1467
 generic_shutdown_super+0xaa/0x2c0 fs/super.c:634
 kill_anon_super fs/super.c:1281 [inline]
 kill_litter_super+0x76/0xb0 fs/super.c:1291
 deactivate_locked_super+0xbc/0x130 fs/super.c:473
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1327
 task_work_run+0x1d4/0x260 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: 0033:0x7fe6d878eec9
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:00007fe6d961c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fe6d89e5fa0 RCX: 00007fe6d878eec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000002c0
RBP: 00007fe6d8811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe6d89e6038 R14: 00007fe6d89e5fa0 R15: 00007ffc5011e858
 </TASK>


Tested on:

commit:         ce7f1a98 Add linux-next specific files for 20250923
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=128f94e2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
dashboard link: https://syzkaller.appspot.com/bug?extid=12479ae15958fc3f54ec
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14e2cce2580000