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Date: Fri, 7 Dec 2012 22:40:10 +0900
Message-ID: <CAAmzW4PDmL-1U6SVFohS_du-7uJngbR-4EBa4UUSWa-xs66Lmw@mail.gmail.com>
Subject: Re: [RFC PATCH 1/8] mm, vmalloc: change iterating a vmlist to find_vm_area()
From: JoonSoo Kim <js1304@gmail.com>
To: Pekka Enberg <penberg@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Russell King <rmk+kernel@arm.linux.org.uk>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        kexec@lists.infradead.org, Chris Metcalf <cmetcalf@tilera.com>,
        Guan Xuetao <gxt@mprc.pku.edu.cn>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>
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Hello, Pekka.

2012/12/7 Pekka Enberg <penberg@kernel.org>:
> On Thu, Dec 6, 2012 at 6:09 PM, Joonsoo Kim <js1304@gmail.com> wrote:
>> The purpose of iterating a vmlist is finding vm area with specific
>> virtual address. find_vm_area() is provided for this purpose
>> and more efficient, because it uses a rbtree.
>> So change it.
>
> You no longer take the 'vmlist_lock'. This is safe, because...?

As Bob mentioned, find_vm_area() hold a 'vmap_area_lock' during
searching a area.
When we hold a 'vmap_area_lock', area can't be removed.
So this change is safe.

Thanks.