syzbot

BTRFS info (device loop1): setting compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2)
======================================================
WARNING: possible circular locking dependency detected
5.15.173-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor212/4138 is trying to acquire lock:
ffff0000dc07c650 (sb_internal#2){.+.+}-{0:0}, at: btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:791

but task is already holding lock:
ffff0000d353a398 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
ffff0000d353a398 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x15c/0x2b4 mm/util.c:549

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc8/0x128 mm/memory.c:5355
       filldir64+0x2bc/0x9e4 fs/readdir.c:335
       dir_emit include/linux/fs.h:3717 [inline]
       call_filldir fs/ext4/dir.c:545 [inline]
       ext4_dx_readdir fs/ext4/dir.c:621 [inline]
       ext4_readdir+0x2ab4/0x32b4 fs/ext4/dir.c:142
       iterate_dir+0x1f4/0x4ec
       __do_sys_getdents64 fs/readdir.c:369 [inline]
       __se_sys_getdents64 fs/readdir.c:354 [inline]
       __arm64_sys_getdents64+0x1c4/0x4c4 fs/readdir.c:354
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #3 (&type->i_mutex_dir_key#3){++++}-{3:3}:
       down_read+0xc0/0x398 kernel/locking/rwsem.c:1498
       inode_lock_shared include/linux/fs.h:799 [inline]
       lookup_slow+0x50/0x84 fs/namei.c:1679
       walk_component+0x394/0x4cc fs/namei.c:1976
       lookup_last fs/namei.c:2431 [inline]
       path_lookupat+0x13c/0x3d0 fs/namei.c:2455
       filename_lookup+0x1c4/0x4c8 fs/namei.c:2484
       kern_path+0x4c/0x194 fs/namei.c:2582
       lookup_bdev+0xc0/0x25c block/bdev.c:979
       device_matched fs/btrfs/volumes.c:568 [inline]
       btrfs_free_stale_devices+0x658/0x9ec fs/btrfs/volumes.c:608
       btrfs_forget_devices+0x5c/0x98 fs/btrfs/volumes.c:1395
       btrfs_control_ioctl+0x12c/0x248 fs/btrfs/super.c:2451
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #2 (&fs_devs->device_list_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       btrfs_run_dev_stats+0xe4/0xe24 fs/btrfs/volumes.c:7949
       commit_cowonly_roots+0x17c/0x808 fs/btrfs/transaction.c:1290
       btrfs_commit_transaction+0xef4/0x30f0 fs/btrfs/transaction.c:2392
       btrfs_clear_free_space_tree+0x5d0/0x9bc fs/btrfs/free-space-tree.c:1264
       btrfs_start_pre_rw_mount+0x24c/0x578 fs/btrfs/disk-io.c:3079
       open_ctree+0x2290/0x28f4 fs/btrfs/disk-io.c:3634
       btrfs_fill_super+0x1b4/0x2c8 fs/btrfs/super.c:1387
       btrfs_mount_root+0x6f8/0x7f8 fs/btrfs/super.c:1752
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
       vfs_get_tree+0x90/0x274 fs/super.c:1530
       fc_mount fs/namespace.c:1000 [inline]
       vfs_kern_mount+0xdc/0x178 fs/namespace.c:1030
       btrfs_mount+0x328/0x9b8 fs/btrfs/super.c:1812
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
       vfs_get_tree+0x90/0x274 fs/super.c:1530
       do_new_mount+0x278/0x8fc fs/namespace.c:3012
       path_mount+0x594/0x101c fs/namespace.c:3342
       do_mount fs/namespace.c:3355 [inline]
       __do_sys_mount fs/namespace.c:3563 [inline]
       __se_sys_mount fs/namespace.c:3540 [inline]
       __arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3540
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&fs_info->tree_log_mutex){+.+.}-{3:3}:
       __lock_release kernel/locking/lockdep.c:5339 [inline]
       lock_release+0x340/0xa1c kernel/locking/lockdep.c:5643
       __mutex_unlock_slowpath+0xe0/0x6d4 kernel/locking/mutex.c:851
       mutex_unlock+0x8c/0xe0 kernel/locking/mutex.c:536
       btrfs_commit_transaction+0x1650/0x30f0 fs/btrfs/transaction.c:2439
       btrfs_clear_free_space_tree+0x5d0/0x9bc fs/btrfs/free-space-tree.c:1264
       btrfs_start_pre_rw_mount+0x24c/0x578 fs/btrfs/disk-io.c:3079
       open_ctree+0x2290/0x28f4 fs/btrfs/disk-io.c:3634
       btrfs_fill_super+0x1b4/0x2c8 fs/btrfs/super.c:1387
       btrfs_mount_root+0x6f8/0x7f8 fs/btrfs/super.c:1752
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
       vfs_get_tree+0x90/0x274 fs/super.c:1530
       fc_mount fs/namespace.c:1000 [inline]
       vfs_kern_mount+0xdc/0x178 fs/namespace.c:1030
       btrfs_mount+0x328/0x9b8 fs/btrfs/super.c:1812
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:611
       vfs_get_tree+0x90/0x274 fs/super.c:1530
       do_new_mount+0x278/0x8fc fs/namespace.c:3012
       path_mount+0x594/0x101c fs/namespace.c:3342
       do_mount fs/namespace.c:3355 [inline]
       __do_sys_mount fs/namespace.c:3563 [inline]
       __se_sys_mount fs/namespace.c:3540 [inline]
       __arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3540
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (sb_internal#2){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
       lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1813 [inline]
       sb_start_intwrite include/linux/fs.h:1930 [inline]
       start_transaction+0x644/0x1480 fs/btrfs/transaction.c:678
       btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:791
       btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6436
       btrfs_update_time+0x248/0x270 fs/btrfs/inode.c:6478
       inode_update_time fs/inode.c:1868 [inline]
       touch_atime+0x434/0xa4c fs/inode.c:1941
       file_accessed include/linux/fs.h:2523 [inline]
       btrfs_file_mmap+0xb0/0x11c fs/btrfs/file.c:2451
       call_mmap include/linux/fs.h:2179 [inline]
       mmap_region+0xcb4/0x12f0 mm/mmap.c:1791
       do_mmap+0x6c0/0xcec mm/mmap.c:1575
       vm_mmap_pgoff+0x1a4/0x2b4 mm/util.c:551
       ksys_mmap_pgoff+0x458/0x668 mm/mmap.c:1624
       __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
       __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
       __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
  sb_internal#2 --> &type->i_mutex_dir_key#3 --> &mm->mmap_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_lock);
                               lock(&type->i_mutex_dir_key#3);
                               lock(&mm->mmap_lock);
  lock(sb_internal#2);

 *** DEADLOCK ***

2 locks held by syz-executor212/4138:
 #0: ffff0000d353a398 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #0: ffff0000d353a398 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x15c/0x2b4 mm/util.c:549
 #1: ffff0000dc07c460 (sb_writers#8){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2523 [inline]
 #1: ffff0000dc07c460 (sb_writers#8){.+.+}-{0:0}, at: btrfs_file_mmap+0xb0/0x11c fs/btrfs/file.c:2451

stack backtrace:
CPU: 1 PID: 4138 Comm: syz-executor212 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1813 [inline]
 sb_start_intwrite include/linux/fs.h:1930 [inline]
 start_transaction+0x644/0x1480 fs/btrfs/transaction.c:678
 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:791
 btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6436
 btrfs_update_time+0x248/0x270 fs/btrfs/inode.c:6478
 inode_update_time fs/inode.c:1868 [inline]
 touch_atime+0x434/0xa4c fs/inode.c:1941
 file_accessed include/linux/fs.h:2523 [inline]
 btrfs_file_mmap+0xb0/0x11c fs/btrfs/file.c:2451
 call_mmap include/linux/fs.h:2179 [inline]
 mmap_region+0xcb4/0x12f0 mm/mmap.c:1791
 do_mmap+0x6c0/0xcec mm/mmap.c:1575
 vm_mmap_pgoff+0x1a4/0x2b4 mm/util.c:551
 ksys_mmap_pgoff+0x458/0x668 mm/mmap.c:1624
 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
 __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
 __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584