panic: pagein mfind under 4.2bsd

[Terry Laskodi]

     Our VAX 11/780 has been getting a lot of these types of panic
crashes lately, usually about 4 or 5 a week. Note this is not the
infamous panic memall mfind due to a bug in the C compiler. We've
already installed that fix and haven't seen it happen since. Below is
the appropriate piece of code from vm_page.c:

	/*
	 * Check for text detached but in free list.
	 * This can happen only if the page is filling
	 * from a inode or from the swap device, (e.g. not when reading
	 * in 407/410 execs to a zero fill page.)
	 */
	if (type == CTEXT && fileno != PG_FZERO && !nohash) {
		si = splimp();
		while ((c = mfind(dev, bncache)) != 0) {
			pf = cmtopg(c - cmap);
			if (c->c_lock == 0)
				break;
			mlock(pf);
			munlock(pf);
		}
		if (c) {
			if (c->c_type != CTEXT || c->c_gone == 0 ||
			    c->c_free == 0)
				panic("pagein mfind");


     Has anybody experienced similar problems?? I really can't remember
if we had the same problem under 4.1 since we converted to 4.2 many moons
ago. Any fixes out there???



				Terry Laskodi
				     of
				Tektronix