====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.287/8049 is trying to acquire lock: ffff0000d9d75510 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x28/0x8c include/linux/mmap_lock.h:377 but task is already holding lock: ffff0000c1844988 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x214/0x79c fs/kernfs/dir.c:1893 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x50/0xc0 kernel/locking/rwsem.c:1590 kernfs_add_one+0x48/0x60c fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xd4/0x12c fs/kernfs/dir.c:1093 sysfs_create_dir_ns+0x114/0x24c fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x5a8/0xb20 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x118/0x17c lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x110/0x268 fs/btrfs/sysfs.c:2645 btrfs_quota_enable+0x210/0x2438 fs/btrfs/qgroup.c:1022 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3667 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5333 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #5 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:598 __mutex_lock kernel/locking/mutex.c:760 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:812 btrfs_quota_enable+0x24c/0x2438 fs/btrfs/qgroup.c:1051 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3667 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5333 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #4 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x190/0xb5c fs/btrfs/transaction.c:321 start_transaction+0x778/0x155c fs/btrfs/transaction.c:705 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:816 btrfs_rebuild_free_space_tree+0xac/0x6c0 fs/btrfs/free-space-tree.c:1340 btrfs_start_pre_rw_mount+0xed8/0x1728 fs/btrfs/disk-io.c:3062 open_ctree+0x24cc/0x358c fs/btrfs/disk-io.c:3619 btrfs_fill_super fs/btrfs/super.c:987 [inline] btrfs_get_tree_super fs/btrfs/super.c:1951 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2094 [inline] btrfs_get_tree+0xd94/0x15dc fs/btrfs/super.c:2128 vfs_get_tree+0x90/0x28c fs/super.c:1758 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3642 [inline] do_new_mount+0x284/0x944 fs/namespace.c:3718 path_mount+0x5b4/0xdfc fs/namespace.c:4028 do_mount fs/namespace.c:4041 [inline] __do_sys_mount fs/namespace.c:4229 [inline] __se_sys_mount fs/namespace.c:4206 [inline] __arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4206 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #3 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x198/0x39c kernel/locking/lockdep.c:5889 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs.h:1911 [inline] sb_end_intwrite+0x3c/0x348 include/linux/fs.h:2028 __btrfs_end_transaction+0x1f4/0x5f4 fs/btrfs/transaction.c:1076 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1110 btrfs_dirty_inode+0x140/0x190 fs/btrfs/inode.c:6286 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6306 inode_update_time fs/inode.c:2129 [inline] __file_update_time fs/inode.c:2357 [inline] file_update_time+0x2a4/0x3c0 fs/inode.c:2387 btrfs_page_mkwrite+0x580/0x1714 fs/btrfs/file.c:1915 do_page_mkwrite+0x138/0x2b8 mm/memory.c:3489 wp_page_shared mm/memory.c:3890 [inline] do_wp_page+0x1d30/0x4158 mm/memory.c:4109 handle_pte_fault mm/memory.c:6250 [inline] __handle_mm_fault+0xd78/0x4798 mm/memory.c:6366 handle_mm_fault+0x274/0x7fc mm/memory.c:6535 do_page_fault+0x410/0x13cc arch/arm64/mm/fault.c:657 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:933 el0_da+0x64/0x230 arch/arm64/kernel/entry-common.c:540 el0t_64_sync_handler+0x90/0x12c arch/arm64/kernel/entry-common.c:746 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #2 (sb_pagefaults#4){.+.+}-{0:0}: 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:1916 [inline] sb_start_pagefault include/linux/fs.h:2081 [inline] btrfs_page_mkwrite+0x284/0x1714 fs/btrfs/file.c:1874 do_page_mkwrite+0x138/0x2b8 mm/memory.c:3489 wp_page_shared mm/memory.c:3890 [inline] do_wp_page+0x1d30/0x4158 mm/memory.c:4109 handle_pte_fault mm/memory.c:6250 [inline] __handle_mm_fault+0xd78/0x4798 mm/memory.c:6366 handle_mm_fault+0x274/0x7fc mm/memory.c:6535 do_page_fault+0x410/0x13cc arch/arm64/mm/fault.c:657 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:933 el0_da+0x64/0x230 arch/arm64/kernel/entry-common.c:540 el0t_64_sync_handler+0x90/0x12c arch/arm64/kernel/entry-common.c:746 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #1 (vm_lock){++++}-{0:0}: __vma_enter_locked+0x184/0x354 mm/mmap_lock.c:63 __vma_start_write+0x34/0x158 mm/mmap_lock.c:87 vma_start_write include/linux/mmap_lock.h:212 [inline] vma_expand+0x1c0/0x8f8 mm/vma.c:1131 relocate_vma_down+0x224/0x3ec mm/vma_exec.c:58 setup_arg_pages+0x4ac/0x914 fs/exec.c:690 load_elf_binary+0x8f4/0x1de4 fs/binfmt_elf.c:1028 search_binary_handler fs/exec.c:1670 [inline] exec_binprm fs/exec.c:1702 [inline] bprm_execve+0x788/0x1104 fs/exec.c:1754 kernel_execve+0x70c/0x7f4 fs/exec.c:1920 run_init_process+0x1bc/0x1ec init/main.c:1404 try_to_run_init_process+0x20/0x7c init/main.c:1411 kernel_init+0xa8/0x1dc init/main.c:1539 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:844 -> #0 (&mm->mmap_lock){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 down_read_killable+0x60/0x32c kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x28/0x8c include/linux/mmap_lock.h:377 get_mmap_lock_carefully mm/mmap_lock.c:377 [inline] lock_mm_and_find_vma+0x2a4/0x2d8 mm/mmap_lock.c:428 do_page_fault+0x50c/0x13cc arch/arm64/mm/fault.c:678 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:793 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:933 el1_abort+0x40/0x64 arch/arm64/kernel/entry-common.c:303 el1h_64_sync_handler+0x50/0xfc arch/arm64/kernel/entry-common.c:437 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:591 __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:169 [inline] filldir64+0x2ec/0x6bc fs/readdir.c:379 dir_emit include/linux/fs.h:3988 [inline] kernfs_fop_readdir+0x498/0x79c fs/kernfs/dir.c:1910 iterate_dir+0x2dc/0x478 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64 fs/readdir.c:396 [inline] __arm64_sys_getdents64+0x110/0x2fc fs/readdir.c:396 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 other info that might help us debug this: Chain exists of: &mm->mmap_lock --> &fs_info->qgroup_ioctl_lock --> &root->kernfs_rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&root->kernfs_rwsem); lock(&fs_info->qgroup_ioctl_lock); lock(&root->kernfs_rwsem); rlock(&mm->mmap_lock); *** DEADLOCK *** 3 locks held by syz.0.287/8049: #0: ffff0000d75d4638 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x1fc/0x2a0 fs/file.c:1232 #1: ffff0000f6608148 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x224/0x478 fs/readdir.c:101 #2: ffff0000c1844988 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x214/0x79c fs/kernfs/dir.c:1893 stack backtrace: CPU: 0 UID: 0 PID: 8049 Comm: syz.0.287 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5868 down_read_killable+0x60/0x32c kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x28/0x8c include/linux/mmap_lock.h:377 get_mmap_lock_carefully mm/mmap_lock.c:377 [inline] lock_mm_and_find_vma+0x2a4/0x2d8 mm/mmap_lock.c:428 do_page_fault+0x50c/0x13cc arch/arm64/mm/fault.c:678 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:793 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:933 el1_abort+0x40/0x64 arch/arm64/kernel/entry-common.c:303 el1h_64_sync_handler+0x50/0xfc arch/arm64/kernel/entry-common.c:437 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:591 __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:169 [inline] (P) filldir64+0x2ec/0x6bc fs/readdir.c:379 (P) dir_emit include/linux/fs.h:3988 [inline] kernfs_fop_readdir+0x498/0x79c fs/kernfs/dir.c:1910 iterate_dir+0x2dc/0x478 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64 fs/readdir.c:396 [inline] __arm64_sys_getdents64+0x110/0x2fc fs/readdir.c:396 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596