syzbot


possible deadlock in bch2_symlink

Status: upstream: reported C repro on 2024/09/29 07:31
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+7836a68852a10ec3d790@syzkaller.appspotmail.com
First crash: 137d, last: 6h21m
Discussions (3)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] possible deadlock in bch2_symlink 0 (2) 2025/02/08 09:14
[syzbot] Monthly bcachefs report (Jan 2025) 0 (1) 2025/01/16 10:11
[syzbot] Monthly bcachefs report (Dec 2024) 0 (1) 2024/12/16 09:45

Sample crash report:
bcachefs (loop0): reading snapshots table
bcachefs (loop0): reading snapshots done
bcachefs (loop0): done starting filesystem
============================================
WARNING: possible recursive locking detected
6.14.0-rc1-syzkaller-00181-g7ee983c850b4 #0 Not tainted
--------------------------------------------
syz-executor294/5305 is trying to acquire lock:
ffff888044775078 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
ffff888044775078 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: bch2_symlink+0x176/0x310 fs/bcachefs/fs.c:839

but task is already holding lock:
ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_copy_up_workdir fs/overlayfs/copy_up.c:782 [inline]
ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_copy_up_flags+0x19cb/0x47c0 fs/overlayfs/copy_up.c:1257

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&sb->s_type->i_mutex_key#16);
  lock(&sb->s_type->i_mutex_key#16);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

7 locks held by syz-executor294/5305:
 #0: ffff88801df94420 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:547
 #1: ffff88804470de50 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:912 [inline]
 #1: ffff88804470de50 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3217 [inline]
 #1: ffff88804470de50 (&ovl_i_mutex_dir_key[depth]/1){+.+.}-{4:4}, at: do_renameat2+0x62c/0x13f0 fs/namei.c:5161
 #2: ffff88804470e418 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
 #2: ffff88804470e418 (&ovl_i_mutex_key[depth]){+.+.}-{4:4}, at: lock_two_nondirectories+0xe1/0x170 fs/inode.c:1281
 #3: ffff88804470e9e0 (&ovl_i_mutex_key[depth]/4){+.+.}-{4:4}, at: vfs_rename+0x6a2/0xf00 fs/namei.c:5040
 #4: ffff88804470e7d0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:650 [inline]
 #4: ffff88804470e7d0 (&ovl_i_lock_key[depth]){+.+.}-{4:4}, at: ovl_copy_up_start+0x53/0x310 fs/overlayfs/util.c:727
 #5: ffff8880477b0420 (sb_writers#9){.+.+}-{0:0}, at: ovl_copy_up_workdir fs/overlayfs/copy_up.c:781 [inline]
 #5: ffff8880477b0420 (sb_writers#9){.+.+}-{0:0}, at: ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
 #5: ffff8880477b0420 (sb_writers#9){.+.+}-{0:0}, at: ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
 #5: ffff8880477b0420 (sb_writers#9){.+.+}-{0:0}, at: ovl_copy_up_flags+0x19b4/0x47c0 fs/overlayfs/copy_up.c:1257
 #6: ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
 #6: ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_copy_up_workdir fs/overlayfs/copy_up.c:782 [inline]
 #6: ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
 #6: ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
 #6: ffff888044774148 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: ovl_copy_up_flags+0x19cb/0x47c0 fs/overlayfs/copy_up.c:1257

stack backtrace:
CPU: 0 UID: 0 PID: 5305 Comm: syz-executor294 Not tainted 6.14.0-rc1-syzkaller-00181-g7ee983c850b4 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3039
 check_deadlock kernel/locking/lockdep.c:3091 [inline]
 validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3893
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 down_write+0x99/0x220 kernel/locking/rwsem.c:1577
 inode_lock include/linux/fs.h:877 [inline]
 bch2_symlink+0x176/0x310 fs/bcachefs/fs.c:839
 vfs_symlink+0x137/0x2e0 fs/namei.c:4671
 ovl_do_symlink+0x85/0xd0 fs/overlayfs/overlayfs.h:267
 ovl_create_real+0x346/0x550 fs/overlayfs/dir.c:206
 ovl_copy_up_workdir fs/overlayfs/copy_up.c:783 [inline]
 ovl_do_copy_up fs/overlayfs/copy_up.c:1001 [inline]
 ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
 ovl_copy_up_flags+0x19fe/0x47c0 fs/overlayfs/copy_up.c:1257
 ovl_rename+0x62a/0x1760 fs/overlayfs/dir.c:1150
 vfs_rename+0xbdb/0xf00 fs/namei.c:5069
 do_renameat2+0xd94/0x13f0 fs/namei.c:5226
 __do_sys_rename fs/namei.c:5273 [inline]
 __se_sys_rename fs/namei.c:5271 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5271
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0d8dddad19
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:00007ffd9dbea2d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f0d8dddad19
RDX: 00007f0d8dddad19 RSI: 0000400000000840 RDI: 0000400000000800
RBP: 0031656c69662f2e R08: 000055558454d4c0 R09: 000055558454d4c0
R10: 000055558454d4c0 R11: 0000000000000246 R12: 00007ffd9dbea300
R13: 00007ffd9dbea528 R14: 431bde82d7b634db R15: 00007f0d8de2303b
 </TASK>
syz-executor294 (5305) used greatest stack depth: 10768 bytes left

Crashes (933):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/08 09:14 upstream 7ee983c850b4 ef44b750 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/09 22:47 upstream 69b54314c975 ef44b750 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in bch2_symlink
2025/01/21 10:55 upstream 95ec54a420b8 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in bch2_symlink
2025/02/08 20:45 upstream 8f6629c004b1 ef44b750 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/08 08:00 upstream 7ee983c850b4 ef44b750 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/07 06:57 upstream bb066fe812d6 53657d1b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/04 12:29 upstream 0de63bb7d919 8f267cef .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/03 21:43 upstream 2014c95afece a21a8419 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/03 00:30 upstream 69e858e0b8b2 568559e4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/01 09:44 upstream 69e858e0b8b2 aa47157c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/02/01 03:09 upstream 69e858e0b8b2 aa47157c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/31 11:12 upstream b4b0881156fb 4c6ac32f .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/31 09:56 upstream b4b0881156fb 4c6ac32f .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/30 19:13 upstream 72deda0abee6 e961d16c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/27 17:02 upstream c2da8b3f914f d99a33ad .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/27 12:08 upstream c2da8b3f914f d99a33ad .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/26 14:59 upstream aa22f4da2a46 9fbd772e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/25 13:06 upstream b46c89c08f41 9fbd772e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/23 20:09 upstream 21266b8df522 f6a35ef3 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/22 02:28 upstream 95ec54a420b8 da72ac06 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/21 19:24 upstream 95ec54a420b8 da72ac06 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 23:00 upstream ffd294d346d1 6e87cfa2 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 20:07 upstream ffd294d346d1 6e87cfa2 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 16:40 upstream ffd294d346d1 6e87cfa2 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 12:33 upstream ffd294d346d1 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 09:58 upstream ffd294d346d1 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 06:37 upstream 9528d418de4d f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 05:10 upstream 9528d418de4d f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 03:53 upstream 9528d418de4d f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/20 01:10 upstream 9528d418de4d f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/19 17:07 upstream fda5e3f28400 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/19 12:57 upstream fda5e3f28400 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/19 06:14 upstream fda5e3f28400 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/19 04:31 upstream fda5e3f28400 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/19 00:53 upstream 595523945be0 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/18 21:25 upstream 595523945be0 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/18 20:16 upstream 595523945be0 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/18 15:45 upstream 595523945be0 f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/18 11:33 upstream ad26fc09dabf f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/18 08:04 upstream ad26fc09dabf f2cb035c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/17 22:21 upstream 9bffa1ad25b8 bb91bdd4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/17 21:04 upstream 9bffa1ad25b8 bb91bdd4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/17 16:18 upstream 9bffa1ad25b8 bb91bdd4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/17 15:53 upstream 9bffa1ad25b8 bb91bdd4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/17 10:02 upstream 9bffa1ad25b8 f9e07a6e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/17 05:59 upstream ce69b4019001 f9e07a6e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/17 04:33 upstream ce69b4019001 f9e07a6e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2025/01/16 23:56 upstream ce69b4019001 f9e07a6e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2024/09/28 18:11 upstream ad46e8f95e93 ba29ff75 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2024/09/25 07:23 upstream 68e5c7d4cefb 349a68c4 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root possible deadlock in bch2_symlink
2024/12/31 06:20 linux-next 8155b4ef3466 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in bch2_symlink
* Struck through repros no longer work on HEAD.