[v6.1] possible deadlock in do_unlinkat

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a343b0dd87b4 Linux 6.1.30
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1197586d280000
kernel config: https://syzkaller.appspot.com/x/.config?x=8ec86bd749598dca
dashboard link: https://syzkaller.appspot.com/bug?extid=05875840a94b3f7a627f
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1522f24d280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=144d39b1280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/aebc00d6f042/disk-a343b0dd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7ff0321ebb5a/vmlinux-a343b0dd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c928974a56d6/Image-a343b0dd.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/2e3897d8f6bd/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+058758...@syzkaller.appspotmail.com

reiserfs: enabling write barrier flush mode
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.30-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor248/4215 is trying to acquire lock:
ffff0000d0db7090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff0000e1c682e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
ffff0000e1c682e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x2cc/0x82c fs/namei.c:4303

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}:
down_write_nested+0x64/0x94 kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:791 [inline]
do_unlinkat+0x2cc/0x82c fs/namei.c:4303
__do_sys_unlinkat fs/namei.c:4363 [inline]
__se_sys_unlinkat fs/namei.c:4356 [inline]
__arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4356
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #1 (sb_writers#8){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1832 [inline]
sb_start_write+0x7c/0x308 include/linux/fs.h:1907
mnt_want_write_file+0x64/0x1e8 fs/namespace.c:437
reiserfs_ioctl+0x184/0x454 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #0 (&sbi->lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364
__lookup_hash+0x108/0x230 fs/namei.c:1601
do_unlinkat+0x2ec/0x82c fs/namei.c:4304
__do_sys_unlinkat fs/namei.c:4363 [inline]
__se_sys_unlinkat fs/namei.c:4356 [inline]
__arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4356
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

other info that might help us debug this:

Chain exists of:
&sbi->lock --> sb_writers#8 --> &type->i_mutex_dir_key#6/1

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&type->i_mutex_dir_key#6/1);
lock(sb_writers#8);
lock(&type->i_mutex_dir_key#6/1);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor248/4215:
#0: ffff0000d6e52460 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393
#1: ffff0000e1c682e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#1: ffff0000e1c682e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x2cc/0x82c fs/namei.c:4303

stack backtrace:
CPU: 1 PID: 4215 Comm: syz-executor248 Not tainted 6.1.30-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2056
check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3098 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain kernel/locking/lockdep.c:3832 [inline]
__lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364
__lookup_hash+0x108/0x230 fs/namei.c:1601
do_unlinkat+0x2ec/0x82c fs/namei.c:4304
__do_sys_unlinkat fs/namei.c:4363 [inline]
__se_sys_unlinkat fs/namei.c:4356 [inline]
__arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4356
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581


---
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If you want to undo deduplication, reply with:
#syz undup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1fe619a7d252 Linux 5.15.113
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=104b91b9280000
kernel config: https://syzkaller.appspot.com/x/.config?x=8f10ee30ae29b021
dashboard link: https://syzkaller.appspot.com/bug?extid=6b0854d47388370d942f

compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12ba52b9280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173f1a25280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1b707a1e1816/disk-1fe619a7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/19cc598a8bbe/vmlinux-1fe619a7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a6cf7269bae5/Image-1fe619a7.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/bbcc48a8af05/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+6b0854...@syzkaller.appspotmail.com

reiserfs: enabling write barrier flush mode
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected

5.15.113-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor262/3968 is trying to acquire lock:
ffff0000d9bf3090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27

but task is already holding lock:

ffff0000dbff82e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
ffff0000dbff82e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x2cc/0x82c fs/namei.c:4260

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}:

down_write_nested+0x118/0x26c kernel/locking/rwsem.c:1657
inode_lock_nested include/linux/fs.h:822 [inline]
do_unlinkat+0x2cc/0x82c fs/namei.c:4260
__do_sys_unlinkat fs/namei.c:4320 [inline]
__se_sys_unlinkat fs/namei.c:4313 [inline]
__arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4313
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (sb_writers#8){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]

__sb_start_write include/linux/fs.h:1742 [inline]
sb_start_write+0xf0/0x3ac include/linux/fs.h:1812
mnt_want_write_file+0x64/0x1e8 fs/namespace.c:421
reiserfs_ioctl+0x188/0x4b8 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&sbi->lock){+.+.}-{3:3}:

check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3787 [inline]
__lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743

reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364

__lookup_hash+0x108/0x230 fs/namei.c:1560
do_unlinkat+0x2ec/0x82c fs/namei.c:4261
__do_sys_unlinkat fs/namei.c:4320 [inline]
__se_sys_unlinkat fs/namei.c:4313 [inline]
__arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4313
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
&sbi->lock --> sb_writers#8 --> &type->i_mutex_dir_key#6/1

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&type->i_mutex_dir_key#6/1);
lock(sb_writers#8);
lock(&type->i_mutex_dir_key#6/1);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor262/3968:
#0: ffff0000c8232460 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:377
#1: ffff0000dbff82e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
#1: ffff0000dbff82e0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x2cc/0x82c fs/namei.c:4260

stack backtrace:
CPU: 1 PID: 3968 Comm: syz-executor262 Not tainted 5.15.113-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
Call trace:

dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216

__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113

print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3787 [inline]
__lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743

reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_lookup+0x130/0x3c4 fs/reiserfs/namei.c:364

__lookup_hash+0x108/0x230 fs/namei.c:1560
do_unlinkat+0x2ec/0x82c fs/namei.c:4261
__do_sys_unlinkat fs/namei.c:4320 [inline]
__se_sys_unlinkat fs/namei.c:4313 [inline]
__arm64_sys_unlinkat+0xcc/0xfc fs/namei.c:4313
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584