mm: preemptibility [LWN.net]

From:		Peter Zijlstra <a.p.zijlstra@chello.nl>
To:		Andrea Arcangeli <aarcange@redhat.com>, Avi Kivity <avi@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Rik van Riel <riel@redhat.com>, Ingo Molnar <mingo@elte.hu>, akpm@linux-foundation.org
Subject:		[PATCH 0/7] mm: preemptibility
Date:		Fri, 02 Apr 2010 16:16:01 +0200
Message-ID:		<20100402141601.435955404@chello.nl>
Cc:		linux-kernel@vger.kernel.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Hugh Dickins <hugh.dickins@tiscali.co.uk>, Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@suse.de>, Peter Zijlstra <a.p.zijlstra@chello.nl>
Archive-link:		Article, Thread

Hi,

This (incomplete) patch-set makes part of the mm a lot more preemptible.
It converts i_mmap_lock and anon_vma->lock to mutexes.
On the way there it also makes mmu_gather preemptible.

The main motivation was making mm_take_all_locks() preemptible, since
it appears people are nesting hundreds of spinlocks there.

The side-effects are that we can finally make mmu_gather preemptible,
something which lots of people have wanted to do for a long time.

It also gets us anon_vma refcounting which seems to be wanted by
KSM as well as Mel's compaction work.

This patch set seems to build and boot on my x86_64 machine and even
builds a kernel. I'll work on getting PPC working again and audit other
architectures their mmu_gather implementation.

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