====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 Not tainted ------------------------------------------------------ syz.2.668/11880 is trying to acquire lock: ffff888058ef2618 (sb_internal#2){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6225 but task is already holding lock: ffff888058ef2520 (sb_pagefaults#7){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310 mm/memory.c:3378 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (sb_pagefaults#7){.+.+}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1795 [inline] sb_start_pagefault include/linux/fs.h:1960 [inline] btrfs_page_mkwrite+0x308/0x18b0 fs/btrfs/file.c:1852 do_page_mkwrite+0x14d/0x310 mm/memory.c:3378 do_shared_fault mm/memory.c:5666 [inline] do_fault mm/memory.c:5728 [inline] do_pte_missing mm/memory.c:4251 [inline] handle_pte_fault mm/memory.c:6069 [inline] __handle_mm_fault+0x1a60/0x5620 mm/memory.c:6212 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #5 (&mm->mmap_lock){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 down_read_killable+0x50/0x350 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:421 get_mmap_lock_carefully mm/mmap_lock.c:197 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/mmap_lock.c:248 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir64+0x2d4/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3921 [inline] kernfs_fop_readdir+0x534/0x870 fs/kernfs/dir.c:1910 iterate_dir+0x5af/0x770 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&root->kernfs_rwsem){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577 kernfs_add_one+0x41/0x520 fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1093 sysfs_create_dir_ns+0x123/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x59f/0xb40 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x125/0x190 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x111/0x2b0 fs/btrfs/sysfs.c:2635 btrfs_quota_enable+0x278/0x1d50 fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747 btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 join_transaction+0x1a4/0xd70 fs/btrfs/transaction.c:321 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_rebuild_free_space_tree+0xad/0x550 fs/btrfs/free-space-tree.c:1352 btrfs_start_pre_rw_mount+0xd76/0x1180 fs/btrfs/disk-io.c:3078 open_ctree+0x2078/0x2800 fs/btrfs/disk-io.c:3618 btrfs_fill_super+0x19d/0x2e0 fs/btrfs/super.c:968 btrfs_get_tree_super fs/btrfs/super.c:1893 [inline] btrfs_get_tree+0x107c/0x1630 fs/btrfs/super.c:2088 vfs_get_tree+0x92/0x2b0 fs/super.c:1804 fc_mount+0x1c/0xb0 fs/namespace.c:1290 btrfs_get_tree_subvol fs/btrfs/super.c:2046 [inline] btrfs_get_tree+0x67d/0x1630 fs/btrfs/super.c:2089 vfs_get_tree+0x92/0x2b0 fs/super.c:1804 do_new_mount+0x24a/0xa40 fs/namespace.c:3902 do_mount fs/namespace.c:4239 [inline] __do_sys_mount fs/namespace.c:4450 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4427 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 join_transaction+0x182/0xd70 fs/btrfs/transaction.c:320 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_rebuild_free_space_tree+0xad/0x550 fs/btrfs/free-space-tree.c:1352 btrfs_start_pre_rw_mount+0xd76/0x1180 fs/btrfs/disk-io.c:3078 open_ctree+0x2078/0x2800 fs/btrfs/disk-io.c:3618 btrfs_fill_super+0x19d/0x2e0 fs/btrfs/super.c:968 btrfs_get_tree_super fs/btrfs/super.c:1893 [inline] btrfs_get_tree+0x107c/0x1630 fs/btrfs/super.c:2088 vfs_get_tree+0x92/0x2b0 fs/super.c:1804 fc_mount+0x1c/0xb0 fs/namespace.c:1290 btrfs_get_tree_subvol fs/btrfs/super.c:2046 [inline] btrfs_get_tree+0x67d/0x1630 fs/btrfs/super.c:2089 vfs_get_tree+0x92/0x2b0 fs/super.c:1804 do_new_mount+0x24a/0xa40 fs/namespace.c:3902 do_mount fs/namespace.c:4239 [inline] __do_sys_mount fs/namespace.c:4450 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4427 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (sb_internal#2){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1795 [inline] sb_start_intwrite include/linux/fs.h:1978 [inline] start_transaction+0x56e/0x1620 fs/btrfs/transaction.c:699 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6225 inode_update_time fs/inode.c:2076 [inline] __file_update_time fs/inode.c:2305 [inline] file_update_time+0x347/0x490 fs/inode.c:2335 btrfs_page_mkwrite+0x572/0x18b0 fs/btrfs/file.c:1870 do_page_mkwrite+0x14d/0x310 mm/memory.c:3378 do_shared_fault mm/memory.c:5666 [inline] do_fault mm/memory.c:5728 [inline] do_pte_missing mm/memory.c:4251 [inline] handle_pte_fault mm/memory.c:6069 [inline] __handle_mm_fault+0x1a60/0x5620 mm/memory.c:6212 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 other info that might help us debug this: Chain exists of: sb_internal#2 --> &mm->mmap_lock --> sb_pagefaults#7 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(sb_pagefaults#7); lock(&mm->mmap_lock); lock(sb_pagefaults#7); rlock(sb_internal#2); *** DEADLOCK *** 2 locks held by syz.2.668/11880: #0: ffff88802ec801e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:431 [inline] #0: ffff88802ec801e0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:188 [inline] #0: ffff88802ec801e0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x32/0x300 mm/mmap_lock.c:248 #1: ffff888058ef2520 (sb_pagefaults#7){.+.+}-{0:0}, at: do_page_mkwrite+0x14d/0x310 mm/memory.c:3378 stack backtrace: CPU: 1 UID: 0 PID: 11880 Comm: syz.2.668 Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2046 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1795 [inline] sb_start_intwrite include/linux/fs.h:1978 [inline] start_transaction+0x56e/0x1620 fs/btrfs/transaction.c:699 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6225 inode_update_time fs/inode.c:2076 [inline] __file_update_time fs/inode.c:2305 [inline] file_update_time+0x347/0x490 fs/inode.c:2335 btrfs_page_mkwrite+0x572/0x18b0 fs/btrfs/file.c:1870 do_page_mkwrite+0x14d/0x310 mm/memory.c:3378 do_shared_fault mm/memory.c:5666 [inline] do_fault mm/memory.c:5728 [inline] do_pte_missing mm/memory.c:4251 [inline] handle_pte_fault mm/memory.c:6069 [inline] __handle_mm_fault+0x1a60/0x5620 mm/memory.c:6212 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0033:0x7f3d2eb5666b Code: fa 10 73 2d 83 fa 08 73 46 83 fa 04 73 16 83 fa 01 7c 10 8a 0e 74 0a 0f b7 74 16 fe 66 89 74 17 fe 88 0f c3 8b 4c 16 fc 8b 36 <89> 4c 17 fc 89 37 c3 c5 fa 6f 06 c5 fa 6f 4c 16 f0 c5 fa 7f 07 c5 RSP: 002b:00007ffeef97c6a8 EFLAGS: 00010202 RAX: 00002000000005c0 RBX: 0000000000000004 RCX: 0000000000737562 RDX: 0000000000000006 RSI: 0000000075622f2e RDI: 00002000000005c0 RBP: 00007f3d2edb7ba0 R08: 00007f3d2ea00000 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000009 R12: 00007f3d2edb5fac R13: 00007f3d2edb5fa0 R14: fffffffffffffffe R15: 00007ffeef97c7c0