linux-kernel - Re: [RFC] mm: fix a BUG, the page is allocated 2 times

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Message-ID: <20151012135250.GA3625@techsingularity.net>
Date:	Mon, 12 Oct 2015 14:52:50 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	yalin wang <yalin.wang2010@...il.com>
Cc:	akpm@...ux-foundation.org, vbabka@...e.cz, mhocko@...e.com,
	rientjes@...gle.com, js1304@...il.com,
	kirill.shutemov@...ux.intel.com, hannes@...xchg.org,
	alexander.h.duyck@...hat.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC] mm: fix a BUG, the page is allocated 2 times

On Mon, Oct 12, 2015 at 10:40:06AM +0800, yalin wang wrote:
> Remove unlikely(order), because we are sure order is not zero if
> code reach here, also add if (page == NULL), only allocate page again if
> __rmqueue_smallest() failed or alloc_flags & ALLOC_HARDER == 0
> 
> Signed-off-by: yalin wang <yalin.wang2010@...il.com>

Thanks very much for catching this!

Acked-by: Mel Gorman <mgorman@...hsingularity.net>

With your current subject and changelog, there is a small risk that Andrew
will miss this or not see it for some time. Would you mind resending the
patch with a changelog similar to this please? It spells out that it is
a fix to an mmotm patch so it'll be obvious where it should be inserted
before merging to mainline.

From: yalin wang <yalin.wang2010@...il.com>
Subject: [PATCH] mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand -fix

There is a redundant check and a memory leak introduced by a patch in
mmotm. This patch removes an unlikely(order) check as we are sure order
is not zero at the time. It also checks if a page is already allocated
to avoid a memory leak.

This is a fix to the mmotm patch
mm-page_alloc-reserve-pageblocks-for-high-order-atomic-allocations-on-demand.patch

Signed-off-by: yalin wang <yalin.wang2010@...il.com>
Acked-by: Mel Gorman <mgorman@...hsingularity.net>
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