From: Vlastimil Babka <vbabka@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, thp: fix defrag setting if newline is not used
Date: Fri, 17 Jan 2020 09:24:01 +0100 [thread overview]
Message-ID: <025511aa-4721-2edb-d658-78d6368a9101@suse.cz> (raw)
In-Reply-To: <20200116191609.3972fd5301cf364a27381923@linux-foundation.org>
On 1/17/20 4:16 AM, Andrew Morton wrote:
> On Tue, 14 Jan 2020 17:58:36 -0800 (PST) David Rientjes <rientjes@google.com> 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.
>>
>> Find the length of what the user is writing and use that to guide our
>> decision on which string comparison to do.
>
> Gee, why is this code so complicated? Can't we just do
>
> if (sysfs_streq(buf, "always")) {
> ...
> } else if sysfs_streq(buf, "defer+madvise")) {
> ...
> }
> ...
Yeah, if we knew this existed :)
We would lose the prefix matching but hopefully nobody will complain.
next prev parent reply other threads:[~2020-01-17 8:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 1:58 [patch] mm, thp: fix defrag setting if newline is not used David Rientjes
2020-01-15 12:45 ` Vlastimil Babka
2020-01-17 3:16 ` Andrew Morton
2020-01-17 8:24 ` Vlastimil Babka [this message]
2020-01-17 9:43 ` David Rientjes
2020-01-17 10:12 ` Vlastimil Babka
2020-01-17 22:11 ` [patch v2] " David Rientjes
2020-01-18 10:54 ` Vlastimil Babka
2020-01-19 1:04 ` Andrew Morton
2020-01-19 21:57 ` David Rientjes
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