====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller-00015-gc3eb11fbb826 #0 Not tainted ------------------------------------------------------ syz-executor.5/22073 is trying to acquire lock: ffff88802707e650 (sb_internal#2){.+.+}-{0:0} , at: btrfs_dirty_inode+0xf4/0x250 fs/btrfs/inode.c:6085 but task is already holding lock: ffff888020fe3418 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline] ffff888020fe3418 (&mm->mmap_lock#2){++++}-{3:3}, at: vm_mmap_pgoff+0x159/0x280 mm/util.c:518 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&mm->mmap_lock#2){++++}-{3:3}: __might_fault mm/memory.c:5646 [inline] __might_fault+0x10c/0x180 mm/memory.c:5639 _copy_to_user+0x29/0x150 lib/usercopy.c:29 copy_to_user include/linux/uaccess.h:169 [inline] btrfs_ioctl_get_subvol_rootref+0x74e/0xad0 fs/btrfs/ioctl.c:3203 btrfs_ioctl+0x2de6/0x5be0 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] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #3 (btrfs-root-00){++++}-{3:3}: down_read_nested+0x9e/0x450 kernel/locking/rwsem.c:1634 __btrfs_tree_read_lock+0x32/0x350 fs/btrfs/locking.c:134 btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] btrfs_read_lock_root_node+0x82/0x3a0 fs/btrfs/locking.c:279 btrfs_search_slot_get_root fs/btrfs/ctree.c:1665 [inline] btrfs_search_slot+0x3ca/0x2c70 fs/btrfs/ctree.c:1985 btrfs_insert_empty_items+0xbd/0x1c0 fs/btrfs/ctree.c:4119 btrfs_insert_empty_item fs/btrfs/ctree.h:3127 [inline] btrfs_insert_item+0xfe/0x260 fs/btrfs/ctree.c:4148 create_subvol+0xc2c/0x1400 fs/btrfs/ioctl.c:688 btrfs_mksubvol+0xf8e/0x1440 fs/btrfs/ioctl.c:985 __btrfs_ioctl_snap_create+0x2ac/0x430 fs/btrfs/ioctl.c:2162 btrfs_ioctl_snap_create+0x15f/0x200 fs/btrfs/ioctl.c:2211 btrfs_ioctl+0x4116/0x5be0 fs/btrfs/ioctl.c:5443 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x1b3/0x10f0 fs/btrfs/transaction.c:299 start_transaction+0x407/0x1470 fs/btrfs/transaction.c:658 btrfs_create_common+0x1aa/0x260 fs/btrfs/inode.c:6633 btrfs_create+0x116/0x160 fs/btrfs/inode.c:6679 lookup_open.isra.0+0xf05/0x12a0 fs/namei.c:3413 open_last_lookups fs/namei.c:3481 [inline] path_openat+0x996/0x2860 fs/namei.c:3710 do_filp_open+0x1ba/0x410 fs/namei.c:3740 do_sys_openat2+0x16d/0x4c0 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_sys_open fs/open.c:1334 [inline] __se_sys_open fs/open.c:1330 [inline] __x64_sys_open+0x11d/0x1c0 fs/open.c:1330 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #1 (btrfs_trans_num_writers){++++}-{0:0}: join_transaction+0x18e/0x10f0 fs/btrfs/transaction.c:298 start_transaction+0x407/0x1470 fs/btrfs/transaction.c:658 btrfs_create_common+0x1aa/0x260 fs/btrfs/inode.c:6633 btrfs_create+0x116/0x160 fs/btrfs/inode.c:6679 lookup_open.isra.0+0xf05/0x12a0 fs/namei.c:3413 open_last_lookups fs/namei.c:3481 [inline] path_openat+0x996/0x2860 fs/namei.c:3710 do_filp_open+0x1ba/0x410 fs/namei.c:3740 do_sys_openat2+0x16d/0x4c0 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_sys_open fs/open.c:1334 [inline] __se_sys_open fs/open.c:1330 [inline] __x64_sys_open+0x11d/0x1c0 fs/open.c:1330 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 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 kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633 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+0x878/0x1470 fs/btrfs/transaction.c:652 btrfs_dirty_inode+0xf4/0x250 fs/btrfs/inode.c:6085 btrfs_update_time+0x25a/0x2c0 fs/btrfs/inode.c:6127 inode_update_time fs/inode.c:1871 [inline] touch_atime+0x41f/0x700 fs/inode.c:1944 file_accessed include/linux/fs.h:2521 [inline] btrfs_file_mmap+0x119/0x150 fs/btrfs/file.c:2333 call_mmap include/linux/fs.h:2196 [inline] mmap_region+0x6c3/0x1dd0 mm/mmap.c:2625 do_mmap+0x831/0xf60 mm/mmap.c:1412 vm_mmap_pgoff+0x1af/0x280 mm/util.c:520 ksys_mmap_pgoff+0x41f/0x5a0 mm/mmap.c:1458 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Chain exists of: sb_internal#2 --> btrfs-root-00 --> &mm->mmap_lock#2 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_lock#2); lock(btrfs-root-00); lock(&mm->mmap_lock#2); lock(sb_internal#2); *** DEADLOCK *** 2 locks held by syz-executor.5/22073: #0: ffff888020fe3418 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline] #0: ffff888020fe3418 (&mm->mmap_lock#2){++++}-{3:3}, at: vm_mmap_pgoff+0x159/0x280 mm/util.c:518 #1: ffff88802707e460 (sb_writers#15){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2521 [inline] #1: ffff88802707e460 (sb_writers#15){.+.+}-{0:0}, at: btrfs_file_mmap+0x119/0x150 fs/btrfs/file.c:2333 stack backtrace: CPU: 0 PID: 22073 Comm: syz-executor.5 Not tainted 6.1.0-rc6-syzkaller-00015-gc3eb11fbb826 #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+0xd1/0x138 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 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+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633 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+0x878/0x1470 fs/btrfs/transaction.c:652 btrfs_dirty_inode+0xf4/0x250 fs/btrfs/inode.c:6085 btrfs_update_time+0x25a/0x2c0 fs/btrfs/inode.c:6127 inode_update_time fs/inode.c:1871 [inline] touch_atime+0x41f/0x700 fs/inode.c:1944 file_accessed include/linux/fs.h:2521 [inline] btrfs_file_mmap+0x119/0x150 fs/btrfs/file.c:2333 call_mmap include/linux/fs.h:2196 [inline] mmap_region+0x6c3/0x1dd0 mm/mmap.c:2625 do_mmap+0x831/0xf60 mm/mmap.c:1412 vm_mmap_pgoff+0x1af/0x280 mm/util.c:520 ksys_mmap_pgoff+0x41f/0x5a0 mm/mmap.c:1458 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f52ed68c0d9 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:00007f52ee4b2168 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f52ed7abf80 RCX: 00007f52ed68c0d9 RDX: 0000000000000000 RSI: 0000000000400000 RDI: 0000000020000000 RBP: 00007f52ed6e7ae9 R08: 0000000000000004 R09: 0000000000000000 R10: 0000000000010012 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff5675a3af R14: 00007f52ee4b2300 R15: 0000000000022000