Subject: Re: [PATCH v2] mm/cma: always check which page cause allocation
 failure
To: Joonsoo Kim <js1304@gmail.com>, Andrew Morton <akpm@linux-foundation.org>
References: <20151125023913.GA9563@js1304-P5Q-DELUXE>
 <1448429565-29748-1-git-send-email-iamjoonsoo.kim@lge.com>
Cc: Michal Nazarewicz <mina86@mina86.com>, Minchan Kim <minchan@kernel.org>,
        David Rientjes <rientjes@google.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>
From: Vlastimil Babka <vbabka@suse.cz>
Message-ID: <56559165.5080304@suse.cz>
Date: Wed, 25 Nov 2015 11:45:57 +0100
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On 11/25/2015 06:32 AM, Joonsoo Kim wrote:
> Now, we have tracepoint in test_pages_isolated() to notify
> pfn which cannot be isolated. But, in alloc_contig_range(),
> some error path doesn't call test_pages_isolated() so it's still
> hard to know exact pfn that causes allocation failure.
> 
> This patch change this situation by calling test_pages_isolated()
> in almost error path. In allocation failure case, some overhead
> is added by this change, but, allocation failure is really rare
> event so it would not matter.
> 
> In fatal signal pending case, we don't call test_pages_isolated()
> because this failure is intentional one.
> 
> There was a bogus outer_start problem due to unchecked buddy order
> and this patch also fix it. Before this patch, it didn't matter,
> because end result is same thing. But, after this patch,
> tracepoint will report failed pfn so it should be accurate.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

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

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