linux-kernel - Re: [PATCH V2] mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand -fix

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Date:	Tue, 13 Oct 2015 09:23:05 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	yalin wang <yalin.wang2010@...il.com>, akpm@...ux-foundation.org,
	mgorman@...hsingularity.net, 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: [PATCH V2] mm, page_alloc: reserve pageblocks for high-order
 atomic allocations on demand -fix

On 10/13/2015 03:42 AM, yalin wang wrote:
> 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>

Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>   mm/page_alloc.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0d6f540..043b691 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2241,13 +2241,13 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
>   		spin_lock_irqsave(&zone->lock, flags);
>
>   		page = NULL;
> -		if (unlikely(order) && (alloc_flags & ALLOC_HARDER)) {
> +		if (alloc_flags & ALLOC_HARDER) {
>   			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
>   			if (page)
>   				trace_mm_page_alloc_zone_locked(page, order, migratetype);
>   		}
> -
> -		page = __rmqueue(zone, order, migratetype, gfp_flags);
> +		if (!page)
> +			page = __rmqueue(zone, order, migratetype, gfp_flags);
>   		spin_unlock(&zone->lock);
>   		if (!page)
>   			goto failed;
>

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