BTRFS info (device loop2): enabling ssd optimizations ====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller-00012-g4312098baf37 #0 Not tainted ------------------------------------------------------ syz-executor.2/14953 is trying to acquire lock: ffff88807c8c5858 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0x8f/0x110 mm/memory.c:5645 but task is already holding lock: ffff888078dce6c8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] ffff888078dce6c8 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] ffff888078dce6c8 (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: -> #4 (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 -> #3 (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_commit_super+0x9a/0xd0 fs/btrfs/disk-io.c:4496 close_ctree+0x3a7/0xbde fs/btrfs/disk-io.c:4653 generic_shutdown_super+0x130/0x310 fs/super.c:492 kill_anon_super+0x36/0x60 fs/super.c:1086 btrfs_kill_super+0x3d/0x50 fs/btrfs/super.c:2441 deactivate_locked_super+0xa7/0xf0 fs/super.c:332 cleanup_mnt+0x494/0x520 fs/namespace.c:1186 task_work_run+0x243/0x300 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0x124/0x150 kernel/entry/common.c:171 exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:296 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #2 (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] __file_update_time fs/inode.c:2088 [inline] file_update_time+0x3df/0x5d0 fs/inode.c:2119 btrfs_page_mkwrite+0x3a8/0xc80 fs/btrfs/inode.c:8431 do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2978 do_shared_fault mm/memory.c:4619 [inline] do_fault mm/memory.c:4687 [inline] handle_pte_fault mm/memory.c:4955 [inline] __handle_mm_fault mm/memory.c:5097 [inline] handle_mm_fault+0x1c63/0x3630 mm/memory.c:5218 do_user_addr_fault+0x69b/0xcb0 arch/x86/mm/fault.c:1428 handle_page_fault arch/x86/mm/fault.c:1519 [inline] exc_page_fault+0x7a/0x110 arch/x86/mm/fault.c:1575 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570 -> #1 (sb_pagefaults#3){.+.+}-{0:0}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1826 [inline] sb_start_pagefault include/linux/fs.h:1930 [inline] btrfs_page_mkwrite+0x1ea/0xc80 fs/btrfs/inode.c:8415 do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2978 do_shared_fault mm/memory.c:4619 [inline] do_fault mm/memory.c:4687 [inline] handle_pte_fault mm/memory.c:4955 [inline] __handle_mm_fault mm/memory.c:5097 [inline] handle_mm_fault+0x1c63/0x3630 mm/memory.c:5218 do_user_addr_fault+0x69b/0xcb0 arch/x86/mm/fault.c:1428 handle_page_fault arch/x86/mm/fault.c:1519 [inline] exc_page_fault+0x7a/0x110 arch/x86/mm/fault.c:1575 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570 -> #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.2/14953: #0: ffff888078dce6c8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] #0: ffff888078dce6c8 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] #0: ffff888078dce6c8 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279 stack backtrace: CPU: 1 PID: 14953 Comm: syz-executor.2 Not tainted 6.1.0-rc6-syzkaller-00012-g4312098baf37 #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: 0033:0x7f59af28c0d9 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:00007f59b000d168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f59af3abf80 RCX: 00007f59af28c0d9 RDX: 0000000020000100 RSI: 00000000d000943d RDI: 0000000000000004 RBP: 00007f59af2e7ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff8536d06f R14: 00007f59b000d300 R15: 0000000000022000