linux-kernel - Re: [PATCH v2 07/12] mm/hugetlb: do not modify user provided gfp

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Date:   Wed, 10 Jun 2020 14:12:56 +0900
From:   Joonsoo Kim <js1304@...il.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel-team@....com,
        Vlastimil Babka <vbabka@...e.cz>,
        Christoph Hellwig <hch@...radead.org>,
        Roman Gushchin <guro@...com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 07/12] mm/hugetlb: do not modify user provided gfp_mask

2020년 6월 9일 (화) 오후 10:54, Michal Hocko <mhocko@...nel.org>님이 작성:
>
> On Wed 27-05-20 15:44:58, Joonsoo Kim wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@....com>
> >
> > It's not good practice to modify user input. Instead of using it to
> > build correct gfp_mask for APIs, this patch introduces another gfp_mask
> > field, __gfp_mask, for internal usage.
>
> Ugh, this is really ugly. It is just hugetlb to add __GFP_THISNODE as a
> special case. This is an ugly hack but I do not think we want to work
> around it by yet another hack. Moreover it seems that the __GFP_THISNODE
> might be not needed anymore as pointed out in a reply to earlier patch.

If you mean __GFP_THISNODE handling is ugly, as you pointed out,
__GFP_THISNODE handling would be removed in the next version.

If you mean introducing __gfp_mask is ugly, I will try to use a local variable
to keep modified gfp_mask rather than introducing a field in alloc_control.

Thanks.