Re: [syzbot] [reiserfs?] possible deadlock in super_lock
From: syzbot
Date: Sun Oct 08 2023 - 11:15:03 EST
syzbot has found a reproducer for the following issue on:
HEAD commit: 19af4a4ed414 Merge branch 'for-next/core', remote-tracking..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1627a911680000
kernel config: https://syzkaller.appspot.com/x/.config?x=80eedef55cd21fa4
dashboard link: https://syzkaller.appspot.com/bug?extid=062317ea1d0a6d5e29e7
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13deb1c9680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1006a759680000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/702d996331e0/disk-19af4a4e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2a48ce0aeb32/vmlinux-19af4a4e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/332eb4a803d2/Image-19af4a4e.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/97d89134ed25/mount_2.gz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+062317ea1d0a6d5e29e7@xxxxxxxxxxxxxxxxxxxxxxxxx
======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc4-syzkaller-g19af4a4ed414 #0 Not tainted
------------------------------------------------------
syz-executor254/6025 is trying to acquire lock:
ffff0000db54a0e0 (&type->s_umount_key#25){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
ffff0000db54a0e0 (&type->s_umount_key#25){++++}-{3:3}, at: super_lock+0x160/0x328 fs/super.c:117
but task is already holding lock:
ffff0000c1540c88 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_flushbuf block/ioctl.c:370 [inline]
ffff0000c1540c88 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_common_ioctl+0x7fc/0x2884 block/ioctl.c:502
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&bdev->bd_holder_lock){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799
bd_finish_claiming+0x218/0x3dc block/bdev.c:566
blkdev_get_by_dev+0x3f4/0x55c block/bdev.c:799
setup_bdev_super+0x68/0x51c fs/super.c:1484
mount_bdev+0x1a0/0x2b4 fs/super.c:1626
get_super_block+0x44/0x58 fs/reiserfs/super.c:2601
legacy_get_tree+0xd4/0x16c fs/fs_context.c:638
vfs_get_tree+0x90/0x288 fs/super.c:1750
do_new_mount+0x25c/0x8c8 fs/namespace.c:3335
path_mount+0x590/0xe04 fs/namespace.c:3662
init_mount+0xe4/0x144 fs/init.c:25
do_mount_root+0x104/0x3e4 init/do_mounts.c:166
mount_root_generic+0x1f0/0x594 init/do_mounts.c:205
mount_block_root+0x6c/0x7c init/do_mounts.c:378
mount_root+0xb4/0xe4 init/do_mounts.c:405
prepare_namespace+0xdc/0x11c init/do_mounts.c:489
kernel_init_freeable+0x35c/0x474 init/main.c:1560
kernel_init+0x24/0x29c init/main.c:1437
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:857
-> #2 (bdev_lock
){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799
bd_finish_claiming+0x84/0x3dc block/bdev.c:557
blkdev_get_by_dev+0x3f4/0x55c block/bdev.c:799
setup_bdev_super+0x68/0x51c fs/super.c:1484
mount_bdev+0x1a0/0x2b4 fs/super.c:1626
get_super_block+0x44/0x58 fs/reiserfs/super.c:2601
legacy_get_tree+0xd4/0x16c fs/fs_context.c:638
vfs_get_tree+0x90/0x288 fs/super.c:1750
do_new_mount+0x25c/0x8c8 fs/namespace.c:3335
path_mount+0x590/0xe04 fs/namespace.c:3662
init_mount+0xe4/0x144 fs/init.c:25
do_mount_root+0x104/0x3e4 init/do_mounts.c:166
mount_root_generic+0x1f0/0x594 init/do_mounts.c:205
mount_block_root+0x6c/0x7c init/do_mounts.c:378
mount_root+0xb4/0xe4 init/do_mounts.c:405
prepare_namespace+0xdc/0x11c init/do_mounts.c:489
kernel_init_freeable+0x35c/0x474 init/main.c:1560
kernel_init+0x24/0x29c init/main.c:1437
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:857
-> #1 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799
blkdev_get_by_dev+0x114/0x55c block/bdev.c:786
journal_init_dev fs/reiserfs/journal.c:2626 [inline]
journal_init+0xa60/0x1e44 fs/reiserfs/journal.c:2786
reiserfs_fill_super+0xd50/0x2028 fs/reiserfs/super.c:2022
mount_bdev+0x1e8/0x2b4 fs/super.c:1629
get_super_block+0x44/0x58 fs/reiserfs/super.c:2601
legacy_get_tree+0xd4/0x16c fs/fs_context.c:638
vfs_get_tree+0x90/0x288 fs/super.c:1750
do_new_mount+0x25c/0x8c8 fs/namespace.c:3335
path_mount+0x590/0xe04 fs/namespace.c:3662
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount fs/namespace.c:3861 [inline]
__arm64_sys_mount+0x45c/0x594 fs/namespace.c:3861
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595
-> #0 (&type->s_umount_key#25){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x3370/0x75e8 kernel/locking/lockdep.c:5136
lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
down_read+0x58/0x2fc kernel/locking/rwsem.c:1520
__super_lock fs/super.c:58 [inline]
super_lock+0x160/0x328 fs/super.c:117
super_lock_shared fs/super.c:146 [inline]
super_lock_shared_active fs/super.c:1431 [inline]
fs_bdev_sync+0xa4/0x168 fs/super.c:1466
blkdev_flushbuf block/ioctl.c:372 [inline]
blkdev_common_ioctl+0x848/0x2884 block/ioctl.c:502
blkdev_ioctl+0x35c/0xae4 block/ioctl.c:624
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl fs/ioctl.c:857 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595
other info that might help us debug this:
Chain exists of:
&type->s_umount_key#25 --> bdev_lock --> &bdev->bd_holder_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&bdev->bd_holder_lock);
lock(bdev_lock);
lock(&bdev->bd_holder_lock);
rlock(&type->s_umount_key#25);
*** DEADLOCK ***
1 lock held by syz-executor254/6025:
#0: ffff0000c1540c88 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_flushbuf block/ioctl.c:370 [inline]
#0: ffff0000c1540c88 (&bdev->bd_holder_lock){+.+.}-{3:3}, at: blkdev_common_ioctl+0x7fc/0x2884 block/ioctl.c:502
stack backtrace:
CPU: 0 PID: 6025 Comm: syz-executor254 Not tainted 6.6.0-rc4-syzkaller-g19af4a4ed414 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
dump_stack+0x1c/0x28 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x3370/0x75e8 kernel/locking/lockdep.c:5136
lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
down_read+0x58/0x2fc kernel/locking/rwsem.c:1520
__super_lock fs/super.c:58 [inline]
super_lock+0x160/0x328 fs/super.c:117
super_lock_shared fs/super.c:146 [inline]
super_lock_shared_active fs/super.c:1431 [inline]
fs_bdev_sync+0xa4/0x168 fs/super.c:1466
blkdev_flushbuf block/ioctl.c:372 [inline]
blkdev_common_ioctl+0x848/0x2884 block/ioctl.c:502
blkdev_ioctl+0x35c/0xae4 block/ioctl.c:624
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl fs/ioctl.c:857 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595
---
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