[v5.15] BUG: sleeping function called from invalid context in __lookup_slow

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9eec9a14ee10 Linux 5.15.198
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10105a94580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=5fb3bdc9a852ff2f43e7
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7146a7b4242e/disk-9eec9a14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a11468b96c22/vmlinux-9eec9a14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e7cb8f058e1c/bzImage-9eec9a14.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5fb3bd...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 16
erofs: (device loop0): mounted with root inode @ nid 36.
erofs: (device loop0): z_erofs_readpage: failed to read, err [-95]
BUG: sleeping function called from invalid context at fs/dcache.c:877
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4905, name: syz.0.189
1 lock held by syz.0.189/4905:
#0: ffff88805ea206c0 (&type->i_mutex_dir_key#9){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
#0: ffff88805ea206c0 (&type->i_mutex_dir_key#9){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1687
Preemption disabled at:
[<ffffffff83990d27>] kmap_atomic include/linux/highmem-internal.h:196 [inline]
[<ffffffff83990d27>] z_erofs_reload_indexes+0x347/0x590 fs/erofs/zmap.c:146
CPU: 0 PID: 4905 Comm: syz.0.189 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
___might_sleep+0x493/0x610 kernel/sched/core.c:9658
dput+0x26/0x1a0 fs/dcache.c:877
__lookup_slow+0x398/0x410 fs/namei.c:1674
lookup_slow+0x53/0x70 fs/namei.c:1688
walk_component+0x319/0x460 fs/namei.c:1984
link_path_walk+0x665/0xd70 fs/namei.c:-1
path_parentat fs/namei.c:2510 [inline]
__filename_parentat+0x252/0x690 fs/namei.c:2534
filename_parentat fs/namei.c:2552 [inline]
filename_create+0xd5/0x470 fs/namei.c:3824
do_mkdirat+0xa5/0x5b0 fs/namei.c:4088
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fcca4900eb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcca2b5c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fcca4b7bfa0 RCX: 00007fcca4900eb9
RDX: 00000000000001ff RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007fcca496ec1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcca4b7c038 R14: 00007fcca4b7bfa0 R15: 00007ffebed584c8
</TASK>
BUG: scheduling while atomic: syz.0.189/4905/0x00000002
no locks held by syz.0.189/4905.
Modules linked in:
Preemption disabled at:
[<ffffffff83990d27>] kmap_atomic include/linux/highmem-internal.h:196 [inline]
[<ffffffff83990d27>] z_erofs_reload_indexes+0x347/0x590 fs/erofs/zmap.c:146


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 9eec9a14ee10 Linux 5.15.198
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=176cebfa580000

kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=5fb3bdc9a852ff2f43e7
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15a8f05a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1102e322580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7146a7b4242e/disk-9eec9a14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a11468b96c22/vmlinux-9eec9a14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e7cb8f058e1c/bzImage-9eec9a14.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/01bc24264484/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=1468fa44580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5fb3bd...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 16
erofs: (device loop0): mounted with root inode @ nid 36.
erofs: (device loop0): z_erofs_readpage: failed to read, err [-95]
BUG: sleeping function called from invalid context at fs/dcache.c:877

in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4314, name: syz.0.17
1 lock held by syz.0.17/4314:
#0: ffff88805cd80180 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
#0: ffff88805cd80180 (&type->i_mutex_dir_key#8){.+.+}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1687

Preemption disabled at:
[<ffffffff83990d27>] kmap_atomic include/linux/highmem-internal.h:196 [inline]
[<ffffffff83990d27>] z_erofs_reload_indexes+0x347/0x590 fs/erofs/zmap.c:146

CPU: 1 PID: 4314 Comm: syz.0.17 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
___might_sleep+0x493/0x610 kernel/sched/core.c:9658
dput+0x26/0x1a0 fs/dcache.c:877
__lookup_slow+0x398/0x410 fs/namei.c:1674
lookup_slow+0x53/0x70 fs/namei.c:1688
walk_component+0x319/0x460 fs/namei.c:1984
link_path_walk+0x665/0xd70 fs/namei.c:-1
path_parentat fs/namei.c:2510 [inline]
__filename_parentat+0x252/0x690 fs/namei.c:2534
filename_parentat fs/namei.c:2552 [inline]
filename_create+0xd5/0x470 fs/namei.c:3824
do_mkdirat+0xa5/0x5b0 fs/namei.c:4088
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

RIP: 0033:0x7fd6277ebeb9

Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007ffe9dd21d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fd627a66fa0 RCX: 00007fd6277ebeb9

RDX: 00000000000001ff RSI: 0000200000000000 RDI: ffffffffffffff9c

RBP: 00007fd627859c1f R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007fd627a66fac R14: 00007fd627a66fa0 R15: 00007fd627a66fa0
</TASK>
BUG: scheduling while atomic: syz.0.17/4314/0x00000002
no locks held by syz.0.17/4314.

Modules linked in:
Preemption disabled at:
[<ffffffff83990d27>] kmap_atomic include/linux/highmem-internal.h:196 [inline]
[<ffffffff83990d27>] z_erofs_reload_indexes+0x347/0x590 fs/erofs/zmap.c:146


---

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