BTRFS info (device loop4): enabling ssd optimizations ====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc5-syzkaller-32269-g9500fc6e9e60 #0 Not tainted ------------------------------------------------------ syz-executor.4/29193 is trying to acquire lock: ffff0000edef0148 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0x54/0xb4 mm/memory.c:5645 but task is already holding lock: ffff000121370b18 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] ffff000121370b18 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] ffff000121370b18 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x13c/0x1c0 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}: down_read_nested+0x64/0x84 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+0x13c/0x1c0 fs/btrfs/locking.c:279 btrfs_search_slot_get_root+0x8c/0x374 fs/btrfs/ctree.c:1665 btrfs_search_slot+0x1dc/0x107c fs/btrfs/ctree.c:1985 btrfs_update_root+0x6c/0x5a4 fs/btrfs/root-tree.c:132 _btrfs_ioctl_set_received_subvol+0x3c8/0x640 fs/btrfs/ioctl.c:4867 btrfs_ioctl_set_received_subvol+0x58/0x154 fs/btrfs/ioctl.c:4951 btrfs_ioctl+0x850/0xa64 fs/btrfs/ioctl.c:5518 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0xd0/0x140 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584 -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x10c/0x65c fs/btrfs/transaction.c:299 start_transaction+0x460/0x944 fs/btrfs/transaction.c:658 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:750 create_snapshot+0x1b0/0x330 fs/btrfs/ioctl.c:825 btrfs_mksubvol+0x3ac/0x40c fs/btrfs/ioctl.c:983 btrfs_mksnapshot+0xbc/0x14c fs/btrfs/ioctl.c:1029 __btrfs_ioctl_snap_create+0x208/0x26c fs/btrfs/ioctl.c:2184 btrfs_ioctl_snap_create_v2+0xf8/0x230 fs/btrfs/ioctl.c:2271 btrfs_ioctl+0x93c/0xa64 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0xd0/0x140 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584 -> #1 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5382 [inline] lock_release+0x148/0x2b4 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+0x50/0x22c include/linux/fs.h:1877 __btrfs_end_transaction+0x15c/0x3e4 fs/btrfs/transaction.c:995 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1029 btrfs_dirty_inode+0x11c/0x13c fs/btrfs/inode.c:6099 btrfs_update_time+0x120/0x138 fs/btrfs/inode.c:6127 inode_update_time fs/inode.c:1871 [inline] touch_atime+0x1f0/0x4a8 fs/inode.c:1944 file_accessed include/linux/fs.h:2521 [inline] btrfs_file_mmap+0x50/0x88 fs/btrfs/file.c:2333 call_mmap include/linux/fs.h:2196 [inline] mmap_region+0x8a0/0x1064 mm/mmap.c:2625 do_mmap+0x6e8/0xa30 mm/mmap.c:1412 vm_mmap_pgoff+0xe8/0x1d0 mm/util.c:520 ksys_mmap_pgoff+0x1cc/0x278 mm/mmap.c:1458 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0x58/0x6c arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584 -> #0 (&mm->mmap_lock){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668 __might_fault+0x7c/0xb4 mm/memory.c:5646 _copy_to_user include/linux/uaccess.h:143 [inline] copy_to_user include/linux/uaccess.h:169 [inline] btrfs_ioctl_get_subvol_rootref+0x3a8/0x4bc fs/btrfs/ioctl.c:3203 btrfs_ioctl+0xa08/0xa64 fs/btrfs/ioctl.c:5556 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0xd0/0x140 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Chain exists of: &mm->mmap_lock --> 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); *** DEADLOCK *** 1 lock held by syz-executor.4/29193: #0: ffff000121370b18 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] #0: ffff000121370b18 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] #0: ffff000121370b18 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x13c/0x1c0 fs/btrfs/locking.c:279 stack backtrace: CPU: 0 PID: 29193 Comm: syz-executor.4 Not tainted 6.1.0-rc5-syzkaller-32269-g9500fc6e9e60 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156 show_stack+0x2c/0x54 arch/arm64/kernel/stacktrace.c:163 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2055 check_noncircular+0x14c/0x154 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 kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x1530/0x3084 kernel/locking/lockdep.c:5055 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668 __might_fault+0x7c/0xb4 mm/memory.c:5646 _copy_to_user include/linux/uaccess.h:143 [inline] copy_to_user include/linux/uaccess.h:169 [inline] btrfs_ioctl_get_subvol_rootref+0x3a8/0x4bc fs/btrfs/ioctl.c:3203 btrfs_ioctl+0xa08/0xa64 fs/btrfs/ioctl.c:5556 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0xd0/0x140 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584