From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [RFC PATCH v9 02/13] x86: always set IF before oopsing from page
	fault
Date: Wed, 3 Apr 2019 17:12:56 -0700
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To: Khalid Aziz <khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Cc: Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>, steven.sistare-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>, Tycho Andersen <tycho-E0fblnxP3wo@public.gmane.org>, Andi Kleen <ak-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, aneesh.kumar-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org, James Morris <jmorris-gx6/JNMH7DfYtjvyW6yDsg@public.gmane.org>, David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, anthony.yznaga-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, Rik van Riel <riel-ebMLmSuQjDVBDgjK7y7TUQ@public.gmane.org>, Nicholas Piggin <npiggin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Mike Rapoport <rppt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Andrew Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Greg KH <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>, Randy Dunlap <rdunlap-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Souptick Joarder <jrdr.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Jiri Kosina <jkosina-AlSwsSmVLrQ@public.gmane.org>, Joe Perches <joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org>, arunks-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, "Woodhouse, David" <dwmw-vV1OtcyAfmbQXOPxS62xeg@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, open
List-Id: iommu@lists.linux-foundation.org

On Wed, Apr 3, 2019 at 10:36 AM Khalid Aziz <khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
>
> From: Tycho Andersen <tycho-E0fblnxP3wo@public.gmane.org>
>
> Oopsing might kill the task, via rewind_stack_do_exit() at the bottom, and
> that might sleep:
>


> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 9d5c75f02295..7891add0913f 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -858,6 +858,12 @@ no_context(struct pt_regs *regs, unsigned long error_code,
>         /* Executive summary in case the body of the oops scrolled away */
>         printk(KERN_DEFAULT "CR2: %016lx\n", address);
>
> +       /*
> +        * We're about to oops, which might kill the task. Make sure we're
> +        * allowed to sleep.
> +        */
> +       flags |= X86_EFLAGS_IF;
> +
>         oops_end(flags, regs, sig);
>  }
>


NAK.  If there's a bug in rewind_stack_do_exit(), please fix it in
rewind_stack_do_exit().