====================================================== WARNING: possible circular locking dependency detected 6.4.0-rc1-syzkaller-00011-g1dc3731daf1f #0 Not tainted ------------------------------------------------------ syz-executor.0/10995 is trying to acquire lock: ffff8880488c60e0 (&type->s_umount_key#32){++++}-{3:3}, at: __do_sys_quotactl_fd+0x27e/0x3f0 fs/quota/quota.c:999 but task is already holding lock: ffff8880488c6460 (sb_writers#4){.+.+}-{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#4){.+.+}-{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_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 -> #0 (&type->s_umount_key#32){++++}-{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_read+0x3d/0x50 kernel/locking/rwsem.c:1520 __do_sys_quotactl_fd+0x27e/0x3f0 fs/quota/quota.c:999 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(sb_writers#4); lock(&type->s_umount_key#32); lock(sb_writers#4); rlock(&type->s_umount_key#32 ); *** DEADLOCK *** 1 lock held by syz-executor.0/10995: #0: ffff8880488c6460 (sb_writers#4){.+.+}-{0:0}, at: __do_sys_quotactl_fd+0xd3/0x3f0 fs/quota/quota.c:990 stack backtrace: CPU: 3 PID: 10995 Comm: syz-executor.0 Not tainted 6.4.0-rc1-syzkaller-00011-g1dc3731daf1f #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_read+0x3d/0x50 kernel/locking/rwsem.c:1520 __do_sys_quotactl_fd+0x27e/0x3f0 fs/quota/quota.c:999 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 RIP: 0023:0xf7fe8579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f7fe35cc EFLAGS: 00000296 ORIG_RAX: 00000000000001bb RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000 RDX: 000000000000ee01 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 retq 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi