------------[ cut here ]------------
WARNING: CPU: 0 PID: 7085 at lib/debugobjects.c:263 debug_print_object+0x181/0x210 lib/debugobjects.c:260
ODEBUG: free active (active state 0) object type: work_struct hint: p9_read_work+0x0/0xac0 include/linux/workqueue.h:535
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7085 Comm: syz-executor2 Not tainted 4.9.119-g9dc978d #23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff88019e2a7520 ffffffff81eb4be9 ffffffff83c48980 00000000ffffffff
 0000000000000000 0000000000000000 0000000000000107 ffff88019e2a75e0
 ffffffff81421c95 0000000041b58ab3 ffffffff843bc020 ffffffff81421ad6
Call Trace:
 [<ffffffff81eb4be9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4be9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81421c95>] panic+0x1bf/0x3bc kernel/panic.c:179
 [<ffffffff81421f81>] __warn.cold.9+0xc1/0x17f kernel/panic.c:542
 [<ffffffff811366d2>] warn_slowpath_fmt+0xc2/0x100 kernel/panic.c:565
 [<ffffffff81f1d0c1>] debug_print_object+0x181/0x210 lib/debugobjects.c:260
 [<ffffffff81f1fa2b>] __debug_check_no_obj_freed lib/debugobjects.c:720 [inline]
 [<ffffffff81f1fa2b>] debug_check_no_obj_freed+0x4fb/0x930 lib/debugobjects.c:749
 [<ffffffff81538d3d>] slab_free_hook mm/slub.c:1348 [inline]
 [<ffffffff81538d3d>] slab_free_freelist_hook mm/slub.c:1377 [inline]
 [<ffffffff81538d3d>] slab_free mm/slub.c:2958 [inline]
 [<ffffffff81538d3d>] kfree+0x18d/0x310 mm/slub.c:3878
 [<ffffffff839c5ee8>] p9_fd_close+0x298/0x330 net/9p/trans_fd.c:890
 [<ffffffff839b7325>] p9_client_create+0x825/0x10a0 net/9p/client.c:1050
 [<ffffffff8195b613>] v9fs_session_init+0x333/0x13a0 fs/9p/v9fs.c:343
 [<ffffffff8194cf0d>] v9fs_mount+0x7d/0x810 fs/9p/vfs_super.c:130
 [<ffffffff8157e65c>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815dde81>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e57a9>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e57a9>] do_new_mount fs/namespace.c:2513 [inline]
 [<ffffffff815e57a9>] do_mount+0x3c9/0x2740 fs/namespace.c:2835
 [<ffffffff815e84fe>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e84fe>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Shutting down cpus with NMI
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..