syzbot

kernel panic at kern/drivers/dev/mnt.c:1201, from core 0: mntchk 3: can't happen
Stack Backtrace on Core 0:
#01 [<0xffffffffc200a33c>] in backtrace at src/kdebug.c:229
#02 [<0xffffffffc2009acd>] in _panic at src/init.c:267
#03 [<0xffffffffc207f921>] in mntchk at drivers/dev/mnt.c:1201
#04 [<0xffffffffc207fb8b>] in mntopencreate at drivers/dev/mnt.c:546
#05 [<0xffffffffc207fd88>] in mntopen at drivers/dev/mnt.c:580
#06 [<0xffffffffc2033960>] in __namec_from at src/ns/chan.c:1233
#07 [<0xffffffffc203413f>] in namec at src/ns/chan.c:1517
#08 [<0xffffffffc20414b6>] in sysopenat at src/ns/sysfile.c:592
#09 [<0xffffffffc205934f>] in sys_openat at src/syscall.c:1724
#10 [<0xffffffffc2059f09>] in syscall at src/syscall.c:2465
#11 [<0xffffffffc205a0d4>] in run_local_syscall at src/syscall.c:2500
#12 [<0xffffffffc205a609>] in prep_syscalls at src/syscall.c:2520
#13 [<0xffffffffc20abc0a>] in sysenter_callwrapper at arch/x86/trap.c:854