====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller-00012-g4312098baf37 #0 Not tainted ------------------------------------------------------ syz-executor.2/17863 is trying to acquire lock: ffff888030022650 (sb_internal#2){.+.+}-{0:0}, at: btrfs_dirty_inode+0xcc/0x1c0 fs/btrfs/inode.c:6085 but task is already holding lock: ffff888030022558 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2978 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (sb_pagefaults#2){.+.+}-{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 -> #4 (&mm->mmap_lock#2){++++}-{3:3}: 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 -> #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_insert_empty_items fs/btrfs/ctree.c:4119 [inline] btrfs_insert_empty_item fs/btrfs/ctree.h:3127 [inline] btrfs_insert_item+0x199/0x3b0 fs/btrfs/ctree.c:4148 create_subvol+0xc9c/0x1800 fs/btrfs/ioctl.c:688 btrfs_mksubvol+0x64f/0x760 fs/btrfs/ioctl.c:985 __btrfs_ioctl_snap_create+0x198/0x450 fs/btrfs/ioctl.c:2162 btrfs_ioctl_snap_create+0x134/0x190 fs/btrfs/ioctl.c:2211 btrfs_ioctl+0xa6b/0xc10 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 -> #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_create_common+0x2c6/0x420 fs/btrfs/inode.c:6633 lookup_open fs/namei.c:3413 [inline] open_last_lookups fs/namei.c:3481 [inline] path_openat+0x12d0/0x2df0 fs/namei.c:3710 do_filp_open+0x264/0x4f0 fs/namei.c:3740 do_sys_openat2+0x124/0x4e0 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_sys_openat fs/open.c:1342 [inline] __se_sys_openat fs/open.c:1337 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1337 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}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 join_transaction+0x17a/0xe60 fs/btrfs/transaction.c:298 start_transaction+0x6fb/0x1180 fs/btrfs/transaction.c:658 btrfs_create_common+0x2c6/0x420 fs/btrfs/inode.c:6633 lookup_open fs/namei.c:3413 [inline] open_last_lookups fs/namei.c:3481 [inline] path_openat+0x12d0/0x2df0 fs/namei.c:3710 do_filp_open+0x264/0x4f0 fs/namei.c:3740 do_sys_openat2+0x124/0x4e0 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_sys_openat fs/open.c:1342 [inline] __se_sys_openat fs/open.c:1337 [inline] __x64_sys_openat+0x243/0x290 fs/open.c:1337 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 (sb_internal#2){.+.+}-{0:0}: 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 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1826 [inline] sb_start_intwrite include/linux/fs.h:1948 [inline] start_transaction+0x5cb/0x1180 fs/btrfs/transaction.c:652 btrfs_dirty_inode+0xcc/0x1c0 fs/btrfs/inode.c:6085 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 other info that might help us debug this: Chain exists of: sb_internal#2 --> &mm->mmap_lock#2 --> sb_pagefaults#2 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_pagefaults#2); lock(&mm->mmap_lock#2); lock(sb_pagefaults#2); lock(sb_internal#2); *** DEADLOCK *** 2 locks held by syz-executor.2/17863: #0: ffff888078720fd8 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_read_lock+0x17/0x50 include/linux/mmap_lock.h:117 #1: ffff888030022558 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2978 stack backtrace: CPU: 0 PID: 17863 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 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1826 [inline] sb_start_intwrite include/linux/fs.h:1948 [inline] start_transaction+0x5cb/0x1180 fs/btrfs/transaction.c:652 btrfs_dirty_inode+0xcc/0x1c0 fs/btrfs/inode.c:6085 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 RIP: 0033:0x7f3016c86d36 Code: 4c 29 c7 4c 01 c2 48 3b 15 87 41 c5 00 0f 87 cc 00 00 00 0f 10 06 0f 10 4e 10 0f 10 56 20 0f 10 5e 30 48 83 c6 40 48 83 ea 40 <0f> 29 07 0f 29 4f 10 0f 29 57 20 0f 29 5f 30 48 83 c7 40 48 83 fa RSP: 002b:00007ffc3b5cef58 EFLAGS: 00010206 RAX: 0000000020000200 RBX: 0000000000000000 RCX: 0000000020000275 RDX: 0000000000000035 RSI: 00007f3016805b18 RDI: 0000000020000210 RBP: 00007ffc3b5cf018 R08: fffffffffffffff0 R09: 00007f3016800000 R10: 00007f3016805ab0 R11: 0000000020000200 R12: 00000000000acbd6 R13: 00007ffc3b5cf040 R14: 00007ffc3b5cf060 R15: 0000000000000032