====================================================== WARNING: possible circular locking dependency detected 6.4.0-rc1-syzkaller-00026-g80e62bc8487b #0 Not tainted ------------------------------------------------------ syz-executor.3/26888 is trying to acquire lock: ffff8880287a60e0 (&type->s_umount_key#50){++++}-{3:3}, at: __do_sys_quotactl_fd+0x174/0x3f0 fs/quota/quota.c:997 but task is already holding lock: ffff8880287a6460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_quotactl_fd+0xd3/0x3f0 fs/quota/quota.c:990 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sb_writers#5){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1494 [inline] sb_start_write include/linux/fs.h:1569 [inline] write_mmp_block+0xc4/0x820 fs/ext4/mmp.c:50 ext4_multi_mount_protect+0x50d/0xac0 fs/ext4/mmp.c:347 __ext4_remount fs/ext4/super.c:6578 [inline] ext4_reconfigure+0x242b/0x2b60 fs/ext4/super.c:6677 reconfigure_super+0x40c/0xa30 fs/super.c:956 vfs_fsconfig_locked fs/fsopen.c:254 [inline] __do_sys_fsconfig+0xa5e/0xc50 fs/fsopen.c:439 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (&type->s_umount_key#50){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3108 [inline] check_prevs_add kernel/locking/lockdep.c:3227 [inline] validate_chain kernel/locking/lockdep.c:3842 [inline] __lock_acquire+0x2f21/0x5df0 kernel/locking/lockdep.c:5074 lock_acquire kernel/locking/lockdep.c:5691 [inline] lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5656 down_write+0x92/0x200 kernel/locking/rwsem.c:1573 __do_sys_quotactl_fd+0x174/0x3f0 fs/quota/quota.c:997 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(sb_writers#5); lock(&type->s_umount_key#50); lock(sb_writers#5); lock(&type->s_umount_key#50); *** DEADLOCK *** 1 lock held by syz-executor.3/26888: #0: ffff8880287a6460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_quotactl_fd+0xd3/0x3f0 fs/quota/quota.c:990 stack backtrace: CPU: 3 PID: 26888 Comm: syz-executor.3 Not tainted 6.4.0-rc1-syzkaller-00026-g80e62bc8487b #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2188 check_prev_add kernel/locking/lockdep.c:3108 [inline] check_prevs_add kernel/locking/lockdep.c:3227 [inline] validate_chain kernel/locking/lockdep.c:3842 [inline] __lock_acquire+0x2f21/0x5df0 kernel/locking/lockdep.c:5074 lock_acquire kernel/locking/lockdep.c:5691 [inline] lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5656 down_write+0x92/0x200 kernel/locking/rwsem.c:1573 __do_sys_quotactl_fd+0x174/0x3f0 fs/quota/quota.c:997 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7ff5c7a8c169 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff5c88c0168 EFLAGS: 00000246 ORIG_RAX: 00000000000001bb RAX: ffffffffffffffda RBX: 00007ff5c7babf80 RCX: 00007ff5c7a8c169 RDX: 0000000000000000 RSI: ffffffff80000302 RDI: 0000000000000004 RBP: 00007ff5c7ae7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc2f5d96df R14: 00007ff5c88c0300 R15: 0000000000022000