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Subject: Re: [patch v2] mm, thp: fix defrag setting if newline is not used
To:     David Rientjes <rientjes@google.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Mel Gorman <mgorman@techsingularity.net>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
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From:   Vlastimil Babka <vbabka@suse.cz>
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Message-ID: <dc911eac-f843-31a3-f74c-53b0bbcc8817@suse.cz>
Date:   Sat, 18 Jan 2020 11:54:15 +0100
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Sender: linux-kernel-owner@vger.kernel.org
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On 1/17/20 11:11 PM, David Rientjes wrote:
> If thp defrag setting "defer" is used and a newline is *not* used when
> writing to the sysfs file, this is interpreted as the "defer+madvise"
> option.
> 
> This is because we do prefix matching and if five characters are written
> without a newline, the current code ends up comparing to the first five
> bytes of the "defer+madvise" option and using that instead.
> 
> Use the more appropriate sysfs_streq() that handles the trailing newline
> for us.  Since this doubles as a nice cleanup, do it in enabled_store()
> as well.
> 
> Fixes: 21440d7eb904 ("mm, thp: add new defer+madvise defrag option")
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: David Rientjes <rientjes@google.com>

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