panic: biodone2 already

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

Hello

I have a Xen domU that now frequently panics with "biodone2 already". I
suspect it started after upgrading to NetBSD 8.0.

The offending code is in src/sys/kern/vfs_bio.c (see below). I wonder if
we could not just release the mutex and exit in that case. Can it make
some harm?

static void
biodone2(buf_t *bp)
{
        void (*callout)(buf_t *);

        SDT_PROBE1(io, kernel, ,done, bp);

        BIOHIST_FUNC(__func__);
        BIOHIST_CALLARGS(biohist, "bp=%#jx", (uintptr_t)bp, 0, 0, 0);

        mutex_enter(bp->b_objlock);
        /* Note that the transfer is done. */
        if (ISSET(bp->b_oflags, BO_DONE))
                panic("biodone2 already");

Cou

-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost