[Xen-devel] Re: [PATCH] fix pgd_lock deadlock

To:	Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject:	[Xen-devel] Re: [PATCH] fix pgd_lock deadlock
From:	Rik van Riel <riel@xxxxxxxxxx>
Date:	Wed, 16 Feb 2011 11:26:31 -0500
Cc:	Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "Xen-devel@xxxxxxxxxxxxxxxxxxx" <Xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Hugh Dickins <hughd@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>, Larry Woodman <lwoodman@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Johannes Weiner <jweiner@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Andi Kleen <ak@xxxxxxx>
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On 02/16/2011 09:49 AM, Andrea Arcangeli wrote:

Subject: fix pgd_lock deadlock

From: Andrea Arcangeli<aarcange@xxxxxxxxxx>

It's forbidden to take the page_table_lock with the irq disabled or if there's
contention the IPIs (for tlb flushes) sent with the page_table_lock held will
never run leading to a deadlock.

Apparently nobody takes the pgd_lock from irq so the _irqsave can be removed.

Signed-off-by: Andrea Arcangeli<aarcange@xxxxxxxxxx>



Acked-by: Rik van Riel <riel@xxxxxxxxxx>

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[Xen-devel] Re: [PATCH] fix pgd_lock deadlock