====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller-00176-g08ad43d554ba #0 Not tainted ------------------------------------------------------ syz-executor.5/18397 is trying to acquire lock: ffff88807426ee18 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0x8f/0x110 mm/memory.c:5645 but task is already holding lock: ffff88801f1800f8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] ffff88801f1800f8 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] ffff88801f1800f8 (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_slot_get_root fs/btrfs/ctree.c:1665 [inline] btrfs_search_slot+0x495/0x2fe0 fs/btrfs/ctree.c:1985 btrfs_del_root+0x83/0x120 fs/btrfs/root-tree.c:317 btrfs_clear_free_space_tree+0x5a7/0xbd0 fs/btrfs/free-space-tree.c:1273 btrfs_start_pre_rw_mount+0x2a7/0x660 fs/btrfs/disk-io.c:3210 open_ctree+0x27e6/0x2d6d fs/btrfs/disk-io.c:3792 btrfs_fill_super+0x1c6/0x2d0 fs/btrfs/super.c:1461 btrfs_mount_root+0x885/0x9a0 fs/btrfs/super.c:1829 legacy_get_tree+0xea/0x180 fs/fs_context.c:610 vfs_get_tree+0x88/0x270 fs/super.c:1531 fc_mount fs/namespace.c:1043 [inline] vfs_kern_mount+0xc9/0x160 fs/namespace.c:1073 btrfs_mount+0x3d3/0xbb0 fs/btrfs/super.c:1889 legacy_get_tree+0xea/0x180 fs/fs_context.c:610 vfs_get_tree+0x88/0x270 fs/super.c:1531 do_new_mount+0x289/0xad0 fs/namespace.c:3040 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount+0x2d3/0x3c0 fs/namespace.c:3568 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 -> #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 __unlink_start_trans fs/btrfs/inode.c:4403 [inline] btrfs_unlink+0x7a/0x2b0 fs/btrfs/inode.c:4412 vfs_unlink+0x357/0x5f0 fs/namei.c:4251 do_unlinkat+0x484/0x940 fs/namei.c:4319 __do_sys_unlink fs/namei.c:4367 [inline] __se_sys_unlink fs/namei.c:4365 [inline] __x64_sys_unlink+0x45/0x50 fs/namei.c:4365 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 -> #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.5/18397: #0: ffff88801f1800f8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] #0: ffff88801f1800f8 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] #0: ffff88801f1800f8 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279 stack backtrace: CPU: 1 PID: 18397 Comm: syz-executor.5 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: __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: 0033:0x7f864988c0d9 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:00007f864a6b9168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f86499abf80 RCX: 00007f864988c0d9 RDX: 00000000200000c0 RSI: 00000000d000943d RDI: 0000000000000004 RBP: 00007f86498e7ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffea7f2f95f R14: 00007f864a6b9300 R15: 0000000000022000