====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/6491 is trying to acquire lock: ffff888064afa650 (sb_internal#4){.+.+}-{0:0}, at: btrfs_dirty_inode+0xcc/0x1c0 fs/btrfs/inode.c:6085 but task is already holding lock: ffff888064afa558 (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: -> #6 (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 -> #5 (&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 -> #4 (btrfs-root-00){++++}-{3:3}: 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 up_write+0x75/0x580 kernel/locking/rwsem.c:1614 btrfs_tree_unlock fs/btrfs/locking.c:213 [inline] btrfs_tree_unlock_rw fs/btrfs/locking.h:113 [inline] btrfs_unlock_up_safe+0x229/0x490 fs/btrfs/locking.c:237 search_leaf fs/btrfs/ctree.c:1819 [inline] btrfs_search_slot+0x25dd/0x2fe0 fs/btrfs/ctree.c:2061 btrfs_insert_empty_items+0x96/0x180 fs/btrfs/ctree.c:4119 btrfs_insert_empty_item fs/btrfs/ctree.h:3127 [inline] btrfs_add_root_ref+0x2f7/0x940 fs/btrfs/root-tree.c:422 create_pending_snapshot+0xdd5/0x2560 fs/btrfs/transaction.c:1770 create_pending_snapshots+0x1a8/0x1e0 fs/btrfs/transaction.c:1868 btrfs_commit_transaction+0x13f0/0x3760 fs/btrfs/transaction.c:2323 create_snapshot+0x4aa/0x7e0 fs/btrfs/ioctl.c:833 btrfs_mksubvol+0x62e/0x760 fs/btrfs/ioctl.c:983 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1029 __btrfs_ioctl_snap_create+0x339/0x450 fs/btrfs/ioctl.c:2184 btrfs_ioctl_snap_create+0x134/0x190 fs/btrfs/ioctl.c:2211 btrfs_ioctl+0x15c/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 -> #3 (&fs_info->reloc_mutex){+.+.}-{3:3}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 __mutex_lock_common+0x1bd/0x26e0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799 btrfs_record_root_in_trans+0x153/0x180 fs/btrfs/transaction.c:484 start_transaction+0x3af/0x1180 fs/btrfs/transaction.c:721 create_snapshot+0x43a/0x7e0 fs/btrfs/ioctl.c:825 btrfs_mksubvol+0x62e/0x760 fs/btrfs/ioctl.c:983 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1029 __btrfs_ioctl_snap_create+0x339/0x450 fs/btrfs/ioctl.c:2184 btrfs_ioctl_snap_create+0x134/0x190 fs/btrfs/ioctl.c:2211 btrfs_ioctl+0x15c/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 create_snapshot+0x43a/0x7e0 fs/btrfs/ioctl.c:825 btrfs_mksubvol+0x62e/0x760 fs/btrfs/ioctl.c:983 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1029 __btrfs_ioctl_snap_create+0x339/0x450 fs/btrfs/ioctl.c:2184 btrfs_ioctl_snap_create+0x134/0x190 fs/btrfs/ioctl.c:2211 btrfs_ioctl+0x15c/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 -> #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 create_snapshot+0x43a/0x7e0 fs/btrfs/ioctl.c:825 btrfs_mksubvol+0x62e/0x760 fs/btrfs/ioctl.c:983 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1029 __btrfs_ioctl_snap_create+0x339/0x450 fs/btrfs/ioctl.c:2184 btrfs_ioctl_snap_create+0x134/0x190 fs/btrfs/ioctl.c:2211 btrfs_ioctl+0x15c/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 -> #0 (sb_internal#4){.+.+}-{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#4 --> &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#4); *** DEADLOCK *** 2 locks held by syz-executor.4/6491: #0: ffff888072ead858 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_read_lock+0x17/0x50 include/linux/mmap_lock.h:117 #1: ffff888064afa558 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2978 stack backtrace: CPU: 1 PID: 6491 Comm: syz-executor.4 Not tainted 6.1.0-rc6-syzkaller #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: 0033:0x7fa5dfc2bdb9 Code: 48 8b 04 24 48 85 c0 74 17 48 8b 54 24 18 48 0f ca 48 89 54 24 18 48 83 f8 01 0f 85 9b 02 00 00 48 8b 44 24 10 48 8b 54 24 18 <48> 89 10 e9 c2 fd ff ff 48 8b 44 24 10 0f b7 10 48 8b 04 24 48 85 RSP: 002b:00007ffd258fecf0 EFLAGS: 00010246 RAX: 0000000020000100 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000020000000 RSI: 0000000000000000 RDI: 00005555574922e8 RBP: 00007ffd258fede8 R08: 0000000000000000 R09: 0000000000000000 R10: 00007fa5df8058f8 R11: 0000000000000246 R12: 000000000004ee56 R13: 00007ffd258fee10 R14: 00007fa5dfdabf80 R15: 0000000000000032