------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 9210 at lib/refcount.c:190 refcount_sub_and_test_checked lib/refcount.c:190 [inline]
WARNING: CPU: 0 PID: 9210 at lib/refcount.c:190 refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 9210 Comm: syz-executor.3 Not tainted 5.2.0-rc5+ #38
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+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x2cb/0x744 kernel/panic.c:219
 __warn.cold+0x20/0x4d kernel/panic.c:576
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:986
RIP: 0010:refcount_sub_and_test_checked lib/refcount.c:190 [inline]
RIP: 0010:refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
Code: 1d 7e 69 48 06 31 ff 89 de e8 dc 62 3c fe 84 db 75 94 e8 93 61 3c fe 48 c7 c7 60 9c a4 87 c6 05 5e 69 48 06 01 e8 9e 9a 0e fe <0f> 0b e9 75 ff ff ff e8 74 61 3c fe e9 6e ff ff ff 48 89 df e8 d7
RSP: 0018:ffff888059587880 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000006cca RSI: ffffffff815ad926 RDI: ffffed100b2b0f02
RBP: ffff888059587918 R08: ffff888090c50400 R09: ffffed1015d060a1
R10: ffffed1015d060a0 R11: ffff8880ae830507 R12: 00000000ffffffff
R13: 0000000000000001 R14: ffff8880595878f0 R15: 0000000000000000
 refcount_dec_and_test_checked+0x1b/0x20 lib/refcount.c:220
 kref_put include/linux/kref.h:64 [inline]
 p9_req_put+0x20/0x60 net/9p/client.c:386
 p9_conn_destroy net/9p/trans_fd.c:865 [inline]
 p9_fd_close+0x2ee/0x570 net/9p/trans_fd.c:898
 p9_client_create+0x98c/0x1400 net/9p/client.c:1068
 v9fs_session_init+0x1e7/0x18c0 fs/9p/v9fs.c:406
 v9fs_mount+0x7d/0x920 fs/9p/vfs_super.c:120
 legacy_get_tree+0x108/0x220 fs/fs_context.c:661
 vfs_get_tree+0x8e/0x390 fs/super.c:1476
 do_new_mount fs/namespace.c:2791 [inline]
 do_mount+0x138c/0x1c00 fs/namespace.c:3111
 ksys_mount+0xdb/0x150 fs/namespace.c:3320
 __do_sys_mount fs/namespace.c:3334 [inline]
 __se_sys_mount fs/namespace.c:3331 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3331
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4592c9
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fa094ed9c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00000000004592c9
RDX: 0000000020000100 RSI: 0000000020000040 RDI: 0000000000000000
RBP: 000000000075bf20 R08: 0000000020000280 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa094eda6d4
R13: 00000000004c5683 R14: 00000000004d9ab8 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..