====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.3.2151/12707 is trying to acquire lock: ffff888079c027f8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601 but task is already holding lock: ffff88801be94180 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x272/0x8d0 fs/kernfs/dir.c:1955 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x96/0x200 kernel/locking/rwsem.c:1625 kernfs_add_one+0x41/0x5c0 fs/kernfs/dir.c:809 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1111 sysfs_create_dir_ns+0x12f/0x2a0 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x62b/0xd00 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x12b/0x1a0 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x116/0x2e0 fs/btrfs/sysfs.c:2604 btrfs_quota_enable+0x282/0x2850 fs/btrfs/qgroup.c:1034 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3540 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x19e/0x1420 kernel/locking/mutex.c:794 btrfs_quota_enable+0x2c6/0x2850 fs/btrfs/qgroup.c:1063 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3540 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x1a4/0xd60 fs/btrfs/transaction.c:324 start_transaction+0xb07/0x1790 fs/btrfs/transaction.c:719 __unlink_start_trans fs/btrfs/inode.c:4525 [inline] btrfs_unlink+0x141/0x370 fs/btrfs/inode.c:4542 vfs_unlink+0x272/0x6c0 fs/namei.c:5498 filename_unlinkat+0x3cd/0x610 fs/namei.c:5568 __do_sys_unlink fs/namei.c:5603 [inline] __se_sys_unlink+0x2e/0x140 fs/namei.c:5600 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x199/0x3c0 kernel/locking/lockdep.c:5889 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs/super.h:14 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs/super.h:101 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1096 btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6451 file_update_time_flags+0x2cf/0x4a0 fs/inode.c:2420 btrfs_page_mkwrite+0x60a/0x1a60 fs/btrfs/file.c:1914 do_page_mkwrite+0x14d/0x310 mm/memory.c:3668 wp_page_shared mm/memory.c:4069 [inline] do_wp_page+0x19ba/0x4cc0 mm/memory.c:4288 handle_pte_fault mm/memory.c:6470 [inline] __handle_mm_fault mm/memory.c:6592 [inline] handle_mm_fault+0x151d/0x3170 mm/memory.c:6761 do_user_addr_fault+0x75b/0x1340 arch/x86/mm/fault.c:1385 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:68 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline] _inline_copy_to_user include/linux/uaccess.h:206 [inline] _copy_to_user+0x8a/0xb0 lib/usercopy.c:26 copy_to_user include/linux/uaccess.h:236 [inline] btrfs_ioctl_get_subvol_info+0x77d/0x1140 fs/btrfs/ioctl.c:2053 btrfs_ioctl+0xaf9/0xd00 fs/btrfs/ioctl.c:5273 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (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/super.h:19 [inline] sb_start_pagefault include/linux/fs/super.h:159 [inline] btrfs_page_mkwrite+0x351/0x1a60 fs/btrfs/file.c:1873 do_page_mkwrite+0x14d/0x310 mm/memory.c:3668 wp_page_shared mm/memory.c:4069 [inline] do_wp_page+0x19ba/0x4cc0 mm/memory.c:4288 handle_pte_fault mm/memory.c:6470 [inline] __handle_mm_fault mm/memory.c:6592 [inline] handle_mm_fault+0x151d/0x3170 mm/memory.c:6761 do_user_addr_fault+0x75b/0x1340 arch/x86/mm/fault.c:1385 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:68 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline] _inline_copy_to_user include/linux/uaccess.h:206 [inline] _copy_to_user+0x8a/0xb0 lib/usercopy.c:26 copy_to_user include/linux/uaccess.h:236 [inline] btrfs_ioctl_get_subvol_info+0x77d/0x1140 fs/btrfs/ioctl.c:2053 btrfs_ioctl+0xaf9/0xd00 fs/btrfs/ioctl.c:5273 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 down_read_killable+0x50/0x340 kernel/locking/rwsem.c:1593 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601 get_mmap_lock_carefully mm/mmap_lock.c:450 [inline] lock_mm_and_find_vma+0x2d7/0x340 mm/mmap_lock.c:501 do_user_addr_fault+0x330/0x1340 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 filldir+0x2b3/0x650 fs/readdir.c:289 dir_emit include/linux/fs.h:3572 [inline] kernfs_fop_readdir+0x57b/0x8d0 fs/kernfs/dir.c:1972 iterate_dir+0x399/0x570 fs/readdir.c:110 __do_sys_getdents fs/readdir.c:319 [inline] __se_sys_getdents+0xf1/0x270 fs/readdir.c:304 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f 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.3.2151/12707: #0: ffff88807acd90b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1261 #1: ffff88807b348ad0 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x292/0x570 fs/readdir.c:103 #2: ffff88801be94180 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x272/0x8d0 fs/kernfs/dir.c:1955 stack backtrace: CPU: 1 UID: 0 PID: 12707 Comm: syz.3.2151 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 down_read_killable+0x50/0x340 kernel/locking/rwsem.c:1593 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601 get_mmap_lock_carefully mm/mmap_lock.c:450 [inline] lock_mm_and_find_vma+0x2d7/0x340 mm/mmap_lock.c:501 do_user_addr_fault+0x330/0x1340 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0010:filldir+0x2b3/0x650 fs/readdir.c:290 Code: 00 48 39 c8 48 0f 47 c1 0f 01 cb 48 8b 4c 24 30 48 89 48 08 48 bd 00 00 00 00 00 fc ff df 48 8b 44 24 28 48 89 02 8b 44 24 04 <66> 89 42 10 41 80 e7 0f 89 c0 44 88 7c 02 ff 48 89 44 24 28 42 c6 RSP: 0018:ffffc9000df8fc38 EFLAGS: 00050287 RAX: 0000000000000028 RBX: ffffc9000df8fe38 RCX: 0000000002177340 RDX: 0000200000001ff0 RSI: 000000000000028a RDI: 000000000000028b RBP: dffffc0000000000 R08: ffff88801e781e87 R09: 1ffff11003cf03d0 R10: dffffc0000000000 R11: ffffed1003cf03d1 R12: ffff88802a267b40 R13: 000000000000000d R14: 000000000000000d R15: 0000000000000008 dir_emit include/linux/fs.h:3572 [inline] kernfs_fop_readdir+0x57b/0x8d0 fs/kernfs/dir.c:1972 iterate_dir+0x399/0x570 fs/readdir.c:110 __do_sys_getdents fs/readdir.c:319 [inline] __se_sys_getdents+0xf1/0x270 fs/readdir.c:304 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe6be79c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fe6bc9f6028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e RAX: ffffffffffffffda RBX: 00007fe6bea15fa0 RCX: 00007fe6be79c819 RDX: 00000000000000b8 RSI: 0000200000001fc0 RDI: 0000000000000003 RBP: 00007fe6be832c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe6bea16038 R14: 00007fe6bea15fa0 R15: 00007ffce25db958 ---------------- Code disassembly (best guess): 0: 00 48 39 add %cl,0x39(%rax) 3: c8 48 0f 47 enter $0xf48,$0x47 7: c1 0f 01 rorl $0x1,(%rdi) a: cb lret b: 48 8b 4c 24 30 mov 0x30(%rsp),%rcx 10: 48 89 48 08 mov %rcx,0x8(%rax) 14: 48 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%rbp 1b: fc ff df 1e: 48 8b 44 24 28 mov 0x28(%rsp),%rax 23: 48 89 02 mov %rax,(%rdx) 26: 8b 44 24 04 mov 0x4(%rsp),%eax * 2a: 66 89 42 10 mov %ax,0x10(%rdx) <-- trapping instruction 2e: 41 80 e7 0f and $0xf,%r15b 32: 89 c0 mov %eax,%eax 34: 44 88 7c 02 ff mov %r15b,-0x1(%rdx,%rax,1) 39: 48 89 44 24 28 mov %rax,0x28(%rsp) 3e: 42 rex.X 3f: c6 .byte 0xc6