====================================================== WARNING: possible circular locking dependency detected 6.1.27-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.3/13961 is trying to acquire lock: ffff88807549c460 (sb_writers#4){.+.+}-{0:0}, at: ext4_multi_mount_protect+0x54a/0x990 fs/ext4/mmp.c:349 but task is already holding lock: ffff88807549c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: vfs_fsconfig_locked fs/fsopen.c:253 [inline] ffff88807549c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: __do_sys_fsconfig fs/fsopen.c:439 [inline] ffff88807549c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: __se_sys_fsconfig+0x981/0xec0 fs/fsopen.c:314 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&type->s_umount_key#31){++++}-{3:3}: lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669 down_read+0x39/0x50 kernel/locking/rwsem.c:1520 __do_sys_quotactl_fd fs/quota/quota.c:999 [inline] __se_sys_quotactl_fd+0x24a/0x3b0 fs/quota/quota.c:972 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/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+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1832 [inline] sb_start_write include/linux/fs.h:1907 [inline] write_mmp_block+0xe1/0x930 fs/ext4/mmp.c:50 ext4_multi_mount_protect+0x54a/0x990 fs/ext4/mmp.c:349 __ext4_remount fs/ext4/super.c:6530 [inline] ext4_reconfigure+0x2d30/0x3610 fs/ext4/super.c:6629 reconfigure_super+0x3c5/0x7c0 fs/super.c:957 vfs_fsconfig_locked fs/fsopen.c:254 [inline] __do_sys_fsconfig fs/fsopen.c:439 [inline] __se_sys_fsconfig+0x98b/0xec0 fs/fsopen.c:314 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/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.3/13961: #0: ffff88805274c070 (&fc->uapi_mutex){+.+.}-{3:3}, at: __do_sys_fsconfig fs/fsopen.c:437 [inline] #0: ffff88805274c070 (&fc->uapi_mutex){+.+.}-{3:3}, at: __se_sys_fsconfig+0x7c1/0xec0 fs/fsopen.c:314 #1: ffff88807549c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: vfs_fsconfig_locked fs/fsopen.c:253 [inline] #1: ffff88807549c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: __do_sys_fsconfig fs/fsopen.c:439 [inline] #1: ffff88807549c0e0 (&type->s_umount_key#31){++++}-{3:3}, at: __se_sys_fsconfig+0x981/0xec0 fs/fsopen.c:314 stack backtrace: CPU: 0 PID: 13961 Comm: syz-executor.3 Not tainted 6.1.27-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 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+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1832 [inline] sb_start_write include/linux/fs.h:1907 [inline] write_mmp_block+0xe1/0x930 fs/ext4/mmp.c:50 ext4_multi_mount_protect+0x54a/0x990 fs/ext4/mmp.c:349 __ext4_remount fs/ext4/super.c:6530 [inline] ext4_reconfigure+0x2d30/0x3610 fs/ext4/super.c:6629 reconfigure_super+0x3c5/0x7c0 fs/super.c:957 vfs_fsconfig_locked fs/fsopen.c:254 [inline] __do_sys_fsconfig fs/fsopen.c:439 [inline] __se_sys_fsconfig+0x98b/0xec0 fs/fsopen.c:314 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fac9d48c169 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:00007fac9e182168 EFLAGS: 00000246 ORIG_RAX: 00000000000001af RAX: ffffffffffffffda RBX: 00007fac9d5ac050 RCX: 00007fac9d48c169 RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000004 RBP: 00007fac9d4e7ca1 R08: 0004000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe20dbf96f R14: 00007fac9e182300 R15: 0000000000022000 EXT4-fs warning (device loop3): ext4_multi_mount_protect:386: Unable to create kmmpd thread for loop3.