Re: [syzbot] [btrfs?] WARNING in create_pending_snapshot

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: sleeping function called from invalid context in btrfs_get_free_objectid

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 5526, name: syz-executor.0
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
10 locks held by syz-executor.0/5526:
 #0: ffff8880751f4418 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write_file+0x61/0x200 fs/namespace.c:448
 #1: ffff888073da1818 (&type->i_mutex_dir_key#8/1){+.+.}-{3:3}, at: btrfs_mksubvol+0x1c9/0x750 fs/btrfs/ioctl.c:967
 #2: ffff888020974be8 (&fs_info->subvol_sem){++++}-{3:3}, at: btrfs_mksubvol+0x52a/0x750 fs/btrfs/ioctl.c:989
 #3: ffff8880751f4608 (sb_internal#2){.+.+}-{0:0}, at: create_snapshot+0x437/0x7e0 fs/btrfs/ioctl.c:837
 #4: ffff888020976458 (btrfs_trans_completed){.+.+}-{0:0}, at: btrfs_commit_transaction+0x17b/0x3730 fs/btrfs/transaction.c:2214
 #5: ffff888020976430 (btrfs_trans_super_committed){.+.+}-{0:0}, at: btrfs_commit_transaction+0x17b/0x3730 fs/btrfs/transaction.c:2214
 #6: ffff888020976408 (btrfs_trans_unblocked){++++}-{0:0}, at: btrfs_commit_transaction+0x17b/0x3730 fs/btrfs/transaction.c:2214
 #7: ffff888020974cb8 (&fs_info->reloc_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xf14/0x3730 fs/btrfs/transaction.c:2433
 #8: ffff888020975818 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_create_qgroup+0xa2/0x280 fs/btrfs/qgroup.c:1707
 #9: ffff888020975780 (&fs_info->qgroup_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #9: ffff888020975780 (&fs_info->qgroup_lock){+.+.}-{2:2}, at: btrfs_create_qgroup+0x226/0x280 fs/btrfs/qgroup.c:1729
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 PID: 5526 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15365-g305230142ae0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 __might_resched+0x5cf/0x780 kernel/sched/core.c:10151
 __mutex_lock_common kernel/locking/mutex.c:580 [inline]
 __mutex_lock+0xc1/0xd60 kernel/locking/mutex.c:747
 btrfs_get_free_objectid+0x34/0x180 fs/btrfs/disk-io.c:4924
 add_qgroup_rb+0x3a0/0x440 fs/btrfs/qgroup.c:236
 btrfs_create_qgroup+0x234/0x280 fs/btrfs/qgroup.c:1730
 create_pending_snapshot+0x8cc/0x2b70 fs/btrfs/transaction.c:1776
 create_pending_snapshots+0x195/0x1d0 fs/btrfs/transaction.c:1967
 btrfs_commit_transaction+0xf1c/0x3730 fs/btrfs/transaction.c:2440
 create_snapshot+0x4a5/0x7e0 fs/btrfs/ioctl.c:845
 btrfs_mksubvol+0x5d0/0x750 fs/btrfs/ioctl.c:995
 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1041
 __btrfs_ioctl_snap_create+0x344/0x460 fs/btrfs/ioctl.c:1294
 btrfs_ioctl_snap_create+0x13c/0x190 fs/btrfs/ioctl.c:1321
 btrfs_ioctl+0xbbf/0xd40
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f6d5147cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6d5220d0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6d5159c050 RCX: 00007f6d5147cae9
RDX: 0000000020000a80 RSI: 0000000050009401 RDI: 0000000000000004
RBP: 00007f6d514c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f6d5159c050 R15: 00007ffcea145098
 </TASK>

=============================
[ BUG: Invalid wait context ]
6.6.0-syzkaller-15365-g305230142ae0-dirty #0 Tainted: G        W         
-----------------------------
syz-executor.0/5526 is trying to lock:
ffff8880277522d8 (&root->objectid_mutex){+.+.}-{3:3}, at: btrfs_get_free_objectid+0x34/0x180 fs/btrfs/disk-io.c:4924
other info that might help us debug this:
context-{4:4}
10 locks held by syz-executor.0/5526:
 #0: ffff8880751f4418 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write_file+0x61/0x200 fs/namespace.c:448
 #1: ffff888073da1818 (&type->i_mutex_dir_key#8/1){+.+.}-{3:3}, at: btrfs_mksubvol+0x1c9/0x750 fs/btrfs/ioctl.c:967
 #2: ffff888020974be8 (&fs_info->subvol_sem){++++}-{3:3}, at: btrfs_mksubvol+0x52a/0x750 fs/btrfs/ioctl.c:989
 #3: ffff8880751f4608 (sb_internal#2){.+.+}-{0:0}, at: create_snapshot+0x437/0x7e0 fs/btrfs/ioctl.c:837
 #4: ffff888020976458 (btrfs_trans_completed){.+.+}-{0:0}, at: btrfs_commit_transaction+0x17b/0x3730 fs/btrfs/transaction.c:2214
 #5: ffff888020976430 (btrfs_trans_super_committed){.+.+}-{0:0}, at: btrfs_commit_transaction+0x17b/0x3730 fs/btrfs/transaction.c:2214
 #6: ffff888020976408 (btrfs_trans_unblocked){++++}-{0:0}, at: btrfs_commit_transaction+0x17b/0x3730 fs/btrfs/transaction.c:2214
 #7: ffff888020974cb8 (&fs_info->reloc_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xf14/0x3730 fs/btrfs/transaction.c:2433
 #8: ffff888020975818 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}, at: btrfs_create_qgroup+0xa2/0x280 fs/btrfs/qgroup.c:1707
 #9: ffff888020975780 (&fs_info->qgroup_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #9: ffff888020975780 (&fs_info->qgroup_lock){+.+.}-{2:2}, at: btrfs_create_qgroup+0x226/0x280 fs/btrfs/qgroup.c:1729
stack backtrace:
CPU: 1 PID: 5526 Comm: syz-executor.0 Tainted: G        W          6.6.0-syzkaller-15365-g305230142ae0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_lock_invalid_wait_context kernel/locking/lockdep.c:4750 [inline]
 check_wait_context kernel/locking/lockdep.c:4820 [inline]
 __lock_acquire+0x1825/0x7f70 kernel/locking/lockdep.c:5086
 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5753
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x136/0xd60 kernel/locking/mutex.c:747
 btrfs_get_free_objectid+0x34/0x180 fs/btrfs/disk-io.c:4924
 add_qgroup_rb+0x3a0/0x440 fs/btrfs/qgroup.c:236
 btrfs_create_qgroup+0x234/0x280 fs/btrfs/qgroup.c:1730
 create_pending_snapshot+0x8cc/0x2b70 fs/btrfs/transaction.c:1776
 create_pending_snapshots+0x195/0x1d0 fs/btrfs/transaction.c:1967
 btrfs_commit_transaction+0xf1c/0x3730 fs/btrfs/transaction.c:2440
 create_snapshot+0x4a5/0x7e0 fs/btrfs/ioctl.c:845
 btrfs_mksubvol+0x5d0/0x750 fs/btrfs/ioctl.c:995
 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1041
 __btrfs_ioctl_snap_create+0x344/0x460 fs/btrfs/ioctl.c:1294
 btrfs_ioctl_snap_create+0x13c/0x190 fs/btrfs/ioctl.c:1321
 btrfs_ioctl+0xbbf/0xd40
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f6d5147cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6d5220d0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6d5159c050 RCX: 00007f6d5147cae9
RDX: 0000000020000a80 RSI: 0000000050009401 RDI: 0000000000000004
RBP: 00007f6d514c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f6d5159c050 R15: 00007ffcea145098
 </TASK>


Tested on:

commit:         30523014 Merge tag 'pm-6.7-rc1-2' of git://git.kernel...
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=12c3dc70e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=4d81015bc10889fd12ea
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=122f123f680000