bisecting fixing commit since 13d2ce42de8cb98ff952f8de6307f896203854c2
building syzkaller on c2c1d1dd603b7d66d283253ffbd61b8692712bd2
testing commit 13d2ce42de8cb98ff952f8de6307f896203854c2 with gcc (GCC) 8.1.0
kernel signature: 0f0ea1e7d7fed22f85d20430c736a764b99f6860ac00e160401e2ca9c29e8768
run #0: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop2]
run #1: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop2]
run #2: crashed: kernel BUG in iput
run #3: crashed: kernel BUG in corrupted
run #4: crashed: kernel BUG in iput
run #5: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop3]
run #6: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop3]
run #7: crashed: kernel BUG in corrupted
run #8: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop2]
run #9: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop5]
testing current HEAD 2263955bf7e71ca8419b64d7a60510aad29002f6
testing commit 2263955bf7e71ca8419b64d7a60510aad29002f6 with gcc (GCC) 8.1.0
kernel signature: 0ff7985f3516a109c843e93a130eb4e7535ae2dc23fd6a0676bfd3e6119a8d49
run #0: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop2]
run #1: crashed: kernel BUG in corrupted
run #2: crashed: kernel BUG in corrupted
run #3: crashed: kernel BUG in corrupted
run #4: crashed: kernel BUG in iput
run #5: crashed: kernel BUG in iput
run #6: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop5]
run #7: crashed: kernel BUG in iput
run #8: crashed: kernel BUG in iput
run #9: crashed: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop5]
revisions tested: 2, total time: 23m11.213493355s (build: 16m32.390846831s, test: 6m9.511072473s)
the crash still happens on HEAD
commit msg: Linux 4.19.170
crash: BUG: Dentry ADDR{i=0,n=/} still in use (-128) [unmount of erofs loop5]
 erofs_mount+0x6a/0x90 drivers/staging/erofs/super.c:512
 mount_fs+0x7f/0x2b0 fs/super.c:1261
 vfs_kern_mount.part.11+0x58/0x3d0 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 do_new_mount fs/namespace.c:2469 [inline]
 do_mount+0x376/0x2710 fs/namespace.c:2799
 ksys_mount+0xba/0xe0 fs/namespace.c:3015
BUG: Dentry 000000007cbc735c{i=0,n=/}  still in use (-128) [unmount of erofs loop5]
 __do_sys_mount fs/namespace.c:3029 [inline]
 __se_sys_mount fs/namespace.c:3026 [inline]
 __x64_sys_mount+0xb9/0x150 fs/namespace.c:3026
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x460b9a
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 ad 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 8a 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f2eea563a78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f2eea563b10 RCX: 0000000000460b9a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f2eea563ad0
RBP: 00007f2eea563ad0 R08: 00007f2eea563b10 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020000040
CPU: 1 PID: 10402 Comm: syz-executor.2 Not tainted 4.19.170-syzkaller #0
------------[ cut here ]------------
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x17c/0x226 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold.2+0x5/0xa lib/fault-inject.c:149
 __should_failslab+0xba/0xf0 mm/failslab.c:32
 should_failslab+0x9/0x20 mm/slab_common.c:1588
 slab_pre_alloc_hook mm/slab.h:424 [inline]
 slab_alloc mm/slab.c:3383 [inline]
 kmem_cache_alloc+0x47/0x390 mm/slab.c:3557
WARNING: CPU: 0 PID: 10412 at fs/dcache.c:1518 umount_check.cold.19+0xe2/0x14f fs/dcache.c:1518
 mempool_alloc_slab+0x3a/0x50 mm/mempool.c:505