linux-kernel - Re: [PATCH 1/2] selftests/mm: compaction_test: Fix incorrect write of zero to nr

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Message-ID: <93c1392e-47c3-41e2-b6cf-c41166bdab78@arm.com>
Date: Mon, 20 May 2024 10:58:05 +0530
From: Dev Jain <dev.jain@....com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: shuah@...nel.org, linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org, Anshuman.Khandual@....com,
 sjayaram@...mai.com, stable@...r.kernel.org
Subject: Re: [PATCH 1/2] selftests/mm: compaction_test: Fix incorrect write of
 zero to nr_hugepages


On 5/20/24 05:30, Andrew Morton wrote:
> On Wed, 15 May 2024 15:06:32 +0530 Dev Jain <dev.jain@....com> wrote:
>
>> nr_hugepages is not set to zero because the file offset has not been reset
>> after read(). Fix that using lseek().
>>
> Please fully describe the runtime effects of this bug.


This is not a "bug", but a discrepancy; the following comment

by the author says "Start with the initial condition of 0 huge

pages", I am just ensuring that that is actually done. Although,

I am not sure about the utility of doing this in the first place,

since we are anyways trying to increase hugepages after that.

In the second patch, I have moved away this entire logic of

setting nr_hugepages to zero, to the place before we start

filling up memory; if you feel that this patch is unnecessary,

we may squash it.