BTRFS info (device loop2): enabling ssd optimizations
======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc6-syzkaller-00176-g08ad43d554ba #0 Not tainted
------------------------------------------------------
syz-executor.2/19133 is trying to acquire lock:
ffff88807c86b418 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0x8f/0x110 mm/memory.c:5645
but task is already holding lock:
ffff888074ff62e8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline]
ffff888074ff62e8 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline]
ffff888074ff62e8 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (btrfs-root-00){++++}-{3:3}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
down_read_nested+0x3c/0x50 kernel/locking/rwsem.c:1634
__btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline]
btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline]
btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279
btrfs_search_forward+0x10f/0xe70 fs/btrfs/ctree.c:4488
btrfs_uuid_scan_kthread+0x25e/0xbc0 fs/btrfs/volumes.c:4654
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
join_transaction+0x19f/0xe60 fs/btrfs/transaction.c:299
start_transaction+0x6fb/0x1180 fs/btrfs/transaction.c:658
btrfs_uuid_scan_kthread+0x6c1/0xbc0 fs/btrfs/volumes.c:4690
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
reacquire_held_locks+0x386/0x650 kernel/locking/lockdep.c:5193
__lock_release kernel/locking/lockdep.c:5382 [inline]
lock_release+0x2e2/0x820 kernel/locking/lockdep.c:5688
percpu_up_read include/linux/percpu-rwsem.h:99 [inline]
__sb_end_write include/linux/fs.h:1821 [inline]
sb_end_intwrite+0x1e/0x1a0 include/linux/fs.h:1877
__btrfs_end_transaction+0x388/0x790 fs/btrfs/transaction.c:995
btrfs_dirty_inode+0x177/0x1c0 fs/btrfs/inode.c:6099
inode_update_time fs/inode.c:1871 [inline]
touch_atime+0x315/0x630 fs/inode.c:1944
file_accessed include/linux/fs.h:2521 [inline]
btrfs_file_mmap+0xbb/0x120 fs/btrfs/file.c:2333
call_mmap include/linux/fs.h:2196 [inline]
mmap_region+0xfe6/0x1e20 mm/mmap.c:2625
do_mmap+0x8d9/0xf30 mm/mmap.c:1412
vm_mmap_pgoff+0x19e/0x2b0 mm/util.c:520
ksys_mmap_pgoff+0x48c/0x6d0 mm/mmap.c:1458
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
-> #0 (&mm->mmap_lock#2){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__might_fault+0xb2/0x110 mm/memory.c:5646
_copy_to_user+0x26/0x130 lib/usercopy.c:29
copy_to_user include/linux/uaccess.h:169 [inline]
btrfs_ioctl_get_subvol_rootref+0x8cf/0xa90 fs/btrfs/ioctl.c:3203
btrfs_ioctl+0xb7c/0xc10 fs/btrfs/ioctl.c:5556
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
other info that might help us debug this:
Chain exists of:
&mm->mmap_lock#2 --> btrfs_trans_num_extwriters --> btrfs-root-00
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(btrfs-root-00);
lock(btrfs_trans_num_extwriters);
lock(btrfs-root-00);
lock(&mm->mmap_lock#2);
*** DEADLOCK ***
1 lock held by syz-executor.2/19133:
#0: ffff888074ff62e8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline]
#0: ffff888074ff62e8 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline]
#0: ffff888074ff62e8 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279
stack backtrace:
CPU: 0 PID: 19133 Comm: syz-executor.2 Not tainted 6.1.0-rc6-syzkaller-00176-g08ad43d554ba #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__might_fault+0xb2/0x110 mm/memory.c:5646
_copy_to_user+0x26/0x130 lib/usercopy.c:29
copy_to_user include/linux/uaccess.h:169 [inline]
btrfs_ioctl_get_subvol_rootref+0x8cf/0xa90 fs/btrfs/ioctl.c:3203
btrfs_ioctl+0xb7c/0xc10 fs/btrfs/ioctl.c:5556
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff74f68c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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:00007ff7504cd168 EFLAGS: 00000246
ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff74f7abf80 RCX: 00007ff74f68c0d9
RDX: 0000000020000100 RSI: 00000000d000943d RDI: 0000000000000004
RBP: 00007ff74f6e7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdba8e9b0f R14: 00007ff7504cd300 R15: 0000000000022000
</TASK>