syzbot


possible deadlock in do_unlinkat

Status: upstream: reported C repro on 2023/05/29 17:13
Subsystems: reiserfs
[Documentation on labels]
Reported-by: syzbot+ada12d2d935bbc82aa7f@syzkaller.appspotmail.com
First crash: 279d, last: 51d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: fixed by (bisect log) :
commit 6f861765464f43a71462d52026fbddfc858239a5
Author: Jan Kara <jack@suse.cz>
Date: Wed Nov 1 17:43:10 2023 +0000

  fs: Block writes to mounted block devices

  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [reiserfs?] possible deadlock in do_unlinkat 0 (2) 2024/02/19 17:26
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 possible deadlock in do_unlinkat origin:upstream missing-backport C error 2 45d 277d 0/3 upstream: reported C repro on 2023/05/27 20:30
linux-6.1 possible deadlock in do_unlinkat origin:upstream C 2 4d09h 278d 0/3 upstream: reported C repro on 2023/05/26 03:11
Last patch testing requests (10)
Created Duration User Patch Repo Result
2024/02/03 05:00 28m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci OK log
2024/01/23 19:31 19m retest repro upstream OK log
2024/01/22 17:50 16m retest repro upstream OK log
2024/01/08 16:56 13m retest repro upstream report log
2023/11/23 02:04 24m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2023/11/09 00:46 10m retest repro upstream report log
2023/10/25 21:52 21m retest repro upstream report log
2023/10/25 21:52 19m retest repro upstream report log
2023/09/13 13:53 17m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2023/08/29 18:23 22m retest repro upstream report log
Fix bisection attempts (3)
Created Duration User Patch Repo Result
2024/02/19 12:23 5h01m bisect fix upstream job log (1)
2023/12/23 02:42 2h00m bisect fix upstream job log (0) log
2023/08/07 10:00 1h29m bisect fix upstream job log (0) log

Sample crash report:
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc7-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor375/5063 is trying to acquire lock:
ffff88807ce06090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff88806ff039c0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:837 [inline]
ffff88806ff039c0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x284/0x740 fs/namei.c:4369

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+0x3d/0x50 kernel/locking/rwsem.c:1695
       inode_lock_nested include/linux/fs.h:837 [inline]
       do_unlinkat+0x284/0x740 fs/namei.c:4369
       __do_sys_unlinkat fs/namei.c:4425 [inline]
       __se_sys_unlinkat fs/namei.c:4418 [inline]
       __x64_sys_unlinkat+0xc1/0x130 fs/namei.c:4418
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #1 (sb_writers#10){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1635 [inline]
       sb_start_write include/linux/fs.h:1710 [inline]
       mnt_want_write_file+0x98/0x600 fs/namespace.c:448
       reiserfs_ioctl+0x194/0x2e0 fs/reiserfs/ioctl.c:103
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #0 (&sbi->lock){+.+.}-{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:3869 [inline]
       __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:747
       reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27
       reiserfs_lookup+0x184/0x690 fs/reiserfs/namei.c:364
       lookup_one_qstr_excl+0x116/0x180 fs/namei.c:1609
       do_unlinkat+0x29c/0x740 fs/namei.c:4370
       __do_sys_unlinkat fs/namei.c:4425 [inline]
       __se_sys_unlinkat fs/namei.c:4418 [inline]
       __x64_sys_unlinkat+0xc1/0x130 fs/namei.c:4418
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

other info that might help us debug this:

Chain exists of:
  &sbi->lock --> sb_writers#10 --> &type->i_mutex_dir_key#6/1

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&type->i_mutex_dir_key#6/1);
                               lock(sb_writers#10);
                               lock(&type->i_mutex_dir_key#6/1);
  lock(&sbi->lock);

 *** DEADLOCK ***

2 locks held by syz-executor375/5063:
 #0: ffff88802059e418 (sb_writers#10){.+.+}-{0:0}, at: do_unlinkat+0x1cf/0x740 fs/namei.c:4365
 #1: ffff88806ff039c0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:837 [inline]
 #1: ffff88806ff039c0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: do_unlinkat+0x284/0x740 fs/namei.c:4369

stack backtrace:
CPU: 0 PID: 5063 Comm: syz-executor375 Not tainted 6.7.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x317/0x400 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:3869 [inline]
 __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:747
 reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27
 reiserfs_lookup+0x184/0x690 fs/reiserfs/namei.c:364
 lookup_one_qstr_excl+0x116/0x180 fs/namei.c:1609
 do_unlinkat+0x29c/0x740 fs/namei.c:4370
 __do_sys_unlinkat fs/namei.c:4425 [inline]
 __se_sys_unlinkat fs/namei.c:4418 [inline]
 __x64_sys_unlinkat+0xc1/0x130 fs/namei.c:4418
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f181d00cb99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdd54fdcb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f181d00cb99
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000005
RBP: 00007f181d0805f0 R08: 0000555556dd74c0 R09: 0000555556dd74c0
R10: 0000555556dd74c0 R11: 0000000000000246 R12: 00007ffdd54fdce0
R13: 00007ffdd54fdf08 R14: 431bde82d7b634db R15: 00007f181d05503b
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/12/25 16:27 upstream 861deac3b092 fb427a07 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-selinux-root possible deadlock in do_unlinkat
2023/10/11 14:04 upstream 1c8b86a3799f 83165b57 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-smack-root possible deadlock in do_unlinkat
2023/06/27 02:37 upstream c0a572d9d32f 4cd5bb25 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-root possible deadlock in do_unlinkat
2023/05/25 17:51 upstream 933174ae28ba 0513b3e6 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs possible deadlock in do_unlinkat
2023/05/25 17:24 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1fcbaa18b28 0513b3e6 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-gce-arm64 possible deadlock in do_unlinkat
2023/06/10 09:35 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci d8b213732169 7086cdb9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in do_unlinkat
2023/05/25 17:11 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci f1fcbaa18b28 0513b3e6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 possible deadlock in do_unlinkat
* Struck through repros no longer work on HEAD.