acquiring duplicate lock of same type: "ftlk"

[Ulrich Spörlein]

Hi, I'm on RELENG_8/amd64 now and while using flash inside FF3 I
observed the following

acquiring duplicate lock of same type: "ftlk"
 1st ftlk @ /data/freebsd-head/sys/modules/linux/../../compat/linux/linux_futex.c:177
 2nd ftlk @ /data/freebsd-head/sys/modules/linux/../../compat/linux/linux_futex.c:203
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
_witness_debugger() at _witness_debugger+0x2e
witness_checkorder() at witness_checkorder+0x8ef
_sx_xlock() at _sx_xlock+0x55
futex_get0() at futex_get0+0xfe
linux_sys_futex() at linux_sys_futex+0x96
ia32_syscall() at ia32_syscall+0x19c
Xint0x80_syscall() at Xint0x80_syscall+0x95
--- syscall (240, Linux ELF32, linux_sys_futex), rip = 0x287d89b3, rsp = 0xffffaa8c, rbp = 0x4000001 ---

I'm running with linux-f8 (f10 gave me trouble last time I tried on CURRENT) and flash10.

Is this a known problem? Is someone working on this or shall I file a PR?

Regards,
Uli

PS: please keep me CC'ed. thx.