Hello, syzbot found the following issue on: HEAD commit: f2afccfefe7b Merge tag 'net-6.3-rc6-2' of git://git.kernel.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10094d79c80000 kernel config: https://syzkaller.appspot.com/x/.config?x=d3500b143c204867 dashboard link: https://syzkaller.appspot.com/bug?extid=6b7df7d5506b32467149 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/a183ba13acb3/disk-f2afccfe.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/ffdb9ee4cb62/vmlinux-f2afccfe.xz kernel image: https://storage.googleapis.com/syzbot-assets/8e8bbb25f0c1/bzImage-f2afccfe.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6b7df7d5506b32467149@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.3.0-rc5-syzkaller-00137-gf2afccfefe7b #0 Not tainted ------------------------------------------------------ syz-executor.3/27708 is trying to acquire lock: ffff888065700460 (sb_writers#4){.+.+}-{0:0}, at: ext4_multi_mount_protect+0x50d/0xac0 fs/ext4/mmp.c:343 but task is already holding lock: ffff8880657000e0 (&type->s_umount_key#31){++++}-{3:3}, at: vfs_fsconfig_locked fs/fsopen.c:253 [inline] ffff8880657000e0 (&type->s_umount_key#31){++++}-{3:3}, at: __do_sys_fsconfig+0xa30/0xc20 fs/fsopen.c:439 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&type->s_umount_key#31){++++}-{3:3}: down_read+0x3d/0x50 kernel/locking/rwsem.c:1520 __do_sys_quotactl_fd+0x27e/0x3f0 fs/quota/quota.c:999 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 (sb_writers#4){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056 lock_acquire kernel/locking/lockdep.c:5669 [inline] lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1477 [inline] sb_start_write include/linux/fs.h:1552 [inline] write_mmp_block+0xc4/0x820 fs/ext4/mmp.c:50 ext4_multi_mount_protect+0x50d/0xac0 fs/ext4/mmp.c:343 __ext4_remount fs/ext4/super.c:6543 [inline] ext4_reconfigure+0x242b/0x2b60 fs/ext4/super.c:6642 reconfigure_super+0x40c/0xa30 fs/super.c:956 vfs_fsconfig_locked fs/fsopen.c:254 [inline] __do_sys_fsconfig+0xa3a/0xc20 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 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&type->s_umount_key#31); lock(sb_writers#4); lock(&type->s_umount_key#31); lock(sb_writers#4); *** DEADLOCK *** 2 locks held by syz-executor.3/27708: #0: ffff888078129070 (&fc->uapi_mutex){+.+.}-{3:3}, at: __do_sys_fsconfig+0x521/0xc20 fs/fsopen.c:437 #1: ffff8880657000e0 (&type->s_umount_key#31){++++}-{3:3}, at: vfs_fsconfig_locked fs/fsopen.c:253 [inline] #1: ffff8880657000e0 (&type->s_umount_key#31){++++}-{3:3}, at: __do_sys_fsconfig+0xa30/0xc20 fs/fsopen.c:439 stack backtrace: CPU: 0 PID: 27708 Comm: syz-executor.3 Not tainted 6.3.0-rc5-syzkaller-00137-gf2afccfefe7b #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Call Trace: <TASK> __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:2178 check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056 lock_acquire kernel/locking/lockdep.c:5669 [inline] lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1477 [inline] sb_start_write include/linux/fs.h:1552 [inline] write_mmp_block+0xc4/0x820 fs/ext4/mmp.c:50 ext4_multi_mount_protect+0x50d/0xac0 fs/ext4/mmp.c:343 __ext4_remount fs/ext4/super.c:6543 [inline] ext4_reconfigure+0x242b/0x2b60 fs/ext4/super.c:6642 reconfigure_super+0x40c/0xa30 fs/super.c:956 vfs_fsconfig_locked fs/fsopen.c:254 [inline] __do_sys_fsconfig+0xa3a/0xc20 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 RIP: 0033:0x7f4a4d08c169 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:00007f4a4dd13168 EFLAGS: 00000246 ORIG_RAX: 00000000000001af RAX: ffffffffffffffda RBX: 00007f4a4d1ac050 RCX: 00007f4a4d08c169 RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000004 RBP: 00007f4a4d0e7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc3d17db8f R14: 00007f4a4dd13300 R15: 0000000000022000 </TASK> EXT4-fs (loop3): re-mounted 00000000-0000-0000-0000-000000000000. 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