Date: Mon, 5 Sep 2016 14:54:54 -0700 From: Mark Johnston <markj@FreeBSD.org> To: Shawn Webb <shawn.webb@hardenedbsd.org> Cc: freebsd-current@freebsd.org, mmacy@nextbsd.org Subject: Re: taskqgroup_adjust kernel panic Message-ID: <20160905215454.GE70066@wkstn-mjohnston.west.isilon.com> In-Reply-To: <20160905175538.GA81799@mutt-hardenedbsd> References: <20160905175538.GA81799@mutt-hardenedbsd>
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On Mon, Sep 05, 2016 at 01:55:38PM -0400, Shawn Webb wrote: > Hey all, > > I'm at revision 3872750 of the hardened/current/drm-next-4.7 branch in > the HardenedBSD/hardenedBSD-playground repo. I've gotten this kernel > panic a couple times when booting. I'm using full-disk encryption with > ZFS and encrypted swap. The hardware is a Purism 15 2K laptop. > > The panic doesn't happen often nor is there a way I can reproduce it > 100%. > > Here's my `uname -a` output: > > FreeBSD hbsd-dev-laptop 12.0-CURRENT-HBSD FreeBSD 12.0-CURRENT-HBSD #0 3872750(hardened/current/drm-next-4.7): Tue Aug 30 17:41:53 EDT 2016 shawn@hbsd-dev-laptop:/usr/obj/usr/src/sys/LATT-SEC amd64 > > Here's a couple pictures of the panic I took: > > https://goo.gl/photos/P5kiwabPYjwQX7Kr8 > https://goo.gl/photos/BWtvBnq7QLnwgRP28 Based on the faulting instruction, the panic probably happened because qid is uninitialized in the loop that starts with while ((gtask = LIST_FIRST(>ask_head))) { I don't know this code very well, so I'm not sure how that can happen. I suspect iflib_irq_alloc_generic() is buggy: it calls taskqgroup_attach_cpu(... CPU_FFS(&cpus) ...); and CPU_FFS returns 1-indexed IDs, but taskqgroup_attach_cpu() pretty clearly expects 0-indexed CPU IDs. There's a similar bug in find_nth() in iflib.c.
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