====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc5-syzkaller-00353-gcd802e7e5f1e #0 Not tainted ------------------------------------------------------ syz.1.444/10426 is trying to acquire lock: ffff8880292ec7e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:193 but task is already holding lock: ffff88801aef5148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x264/0x870 fs/kernfs/dir.c:1890 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&root->kernfs_rwsem){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 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:1091 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:2616 btrfs_quota_enable+0x278/0x1d50 fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3676 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746 btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3676 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 join_transaction+0x1a4/0xd70 fs/btrfs/transaction.c:321 start_transaction+0x6ae/0x1620 fs/btrfs/transaction.c:705 btrfs_rebuild_free_space_tree+0xb1/0x4e0 fs/btrfs/free-space-tree.c:1317 btrfs_start_pre_rw_mount+0xd76/0x1180 fs/btrfs/disk-io.c:3074 open_ctree+0x2075/0x2800 fs/btrfs/disk-io.c:3614 btrfs_fill_super+0x19d/0x2e0 fs/btrfs/super.c:972 btrfs_get_tree_super fs/btrfs/super.c:1897 [inline] btrfs_get_tree+0x107c/0x1620 fs/btrfs/super.c:2092 vfs_get_tree+0x8f/0x2b0 fs/super.c:1759 fc_mount+0x1c/0xb0 fs/namespace.c:1289 btrfs_get_tree_subvol fs/btrfs/super.c:2050 [inline] btrfs_get_tree+0x67d/0x1620 fs/btrfs/super.c:2093 vfs_get_tree+0x8f/0x2b0 fs/super.c:1759 do_new_mount+0x24a/0xa40 fs/namespace.c:3881 do_mount fs/namespace.c:4221 [inline] __do_sys_mount fs/namespace.c:4432 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4409 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_writers){++++}-{0:0}: reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5383 __lock_release kernel/locking/lockdep.c:5572 [inline] lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5887 percpu_up_read include/linux/percpu-rwsem.h:100 [inline] __sb_end_write include/linux/fs.h:1778 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs.h:1895 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1075 btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6143 inode_update_time fs/inode.c:2076 [inline] __file_update_time fs/inode.c:2305 [inline] file_update_time+0x344/0x490 fs/inode.c:2335 btrfs_page_mkwrite+0x634/0x16a0 fs/btrfs/file.c:1814 do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 wp_page_shared mm/memory.c:3688 [inline] do_wp_page+0x2626/0x5760 mm/memory.c:3907 handle_pte_fault mm/memory.c:6013 [inline] __handle_mm_fault+0x1028/0x5380 mm/memory.c:6140 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1337 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #1 (sb_pagefaults#4){.+.+}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 percpu_down_read include/linux/percpu-rwsem.h:52 [inline] __sb_start_write include/linux/fs.h:1783 [inline] sb_start_pagefault include/linux/fs.h:1948 [inline] btrfs_page_mkwrite+0x3b2/0x16a0 fs/btrfs/file.c:1798 do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 do_shared_fault mm/memory.c:5594 [inline] do_fault mm/memory.c:5656 [inline] do_pte_missing mm/memory.c:4160 [inline] handle_pte_fault mm/memory.c:5997 [inline] __handle_mm_fault+0x18d2/0x5380 mm/memory.c:6140 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1388 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #0 (&mm->mmap_lock){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 down_read_killable+0x50/0x350 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:193 get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/memory.c:6406 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1360 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir64+0x2b3/0x690 fs/readdir.c:371 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x534/0x870 fs/kernfs/dir.c:1907 iterate_dir+0x5ac/0x770 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:403 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:389 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 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.1.444/10426: #0: ffff8880290bb438 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x320 fs/file.c:1213 #1: ffff88805d7b9f78 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x49f/0x770 fs/readdir.c:101 #2: ffff88801aef5148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x264/0x870 fs/kernfs/dir.c:1890 stack backtrace: CPU: 1 UID: 0 PID: 10426 Comm: syz.1.444 Not tainted 6.15.0-rc5-syzkaller-00353-gcd802e7e5f1e #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:2079 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 down_read_killable+0x50/0x350 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:193 get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/memory.c:6406 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1360 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0010:filldir64+0x2b3/0x690 fs/readdir.c:372 Code: 87 4c 02 00 00 0f 01 cb 0f ae e8 48 8b 44 24 60 49 89 46 08 48 8b 4c 24 38 48 8b 44 24 58 48 89 01 48 8b 44 24 10 8b 54 24 24 <66> 89 41 10 88 51 12 4c 63 f5 42 c6 44 31 13 00 4c 8d 61 13 bf 07 RSP: 0018:ffffc90003befc68 EFLAGS: 00050287 RAX: 0000000000000020 RBX: ffffc90003befe50 RCX: 0000200000000ff8 RDX: 0000000000000008 RSI: 0000200000000fd8 RDI: 0000200000001018 RBP: 000000000000000c R08: ffff88802a79da07 R09: 1ffff110054f3b40 R10: dffffc0000000000 R11: ffffed10054f3b41 R12: 0000200000001018 R13: ffff88802748a540 R14: 0000200000000fd8 R15: 00007ffffffff000 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x534/0x870 fs/kernfs/dir.c:1907 iterate_dir+0x5ac/0x770 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:403 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:389 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3aa9f8e969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3aaae70038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007f3aaa1b6160 RCX: 00007f3aa9f8e969 RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000004 RBP: 00007f3aaa010ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f3aaa1b6160 R15: 00007ffdef0c3098 ---------------- Code disassembly (best guess): 0: 87 4c 02 00 xchg %ecx,0x0(%rdx,%rax,1) 4: 00 0f add %cl,(%rdi) 6: 01 cb add %ecx,%ebx 8: 0f ae e8 lfence b: 48 8b 44 24 60 mov 0x60(%rsp),%rax 10: 49 89 46 08 mov %rax,0x8(%r14) 14: 48 8b 4c 24 38 mov 0x38(%rsp),%rcx 19: 48 8b 44 24 58 mov 0x58(%rsp),%rax 1e: 48 89 01 mov %rax,(%rcx) 21: 48 8b 44 24 10 mov 0x10(%rsp),%rax 26: 8b 54 24 24 mov 0x24(%rsp),%edx * 2a: 66 89 41 10 mov %ax,0x10(%rcx) <-- trapping instruction 2e: 88 51 12 mov %dl,0x12(%rcx) 31: 4c 63 f5 movslq %ebp,%r14 34: 42 c6 44 31 13 00 movb $0x0,0x13(%rcx,%r14,1) 3a: 4c 8d 61 13 lea 0x13(%rcx),%r12 3e: bf .byte 0xbf 3f: 07 (bad)