linux-kernel - Re: [PATCH] mm: make __GFP_SKIP_ZERO visible to skip zero operation

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Message-ID: <CAGWkznGAJVZtn49zNHsMAjRSfTRR707QXYY0m8Q+yABTsiig2Q@mail.gmail.com>
Date:   Fri, 1 Sep 2023 18:29:07 +0800
From:   Zhaoyang Huang <huangzhaoyang@...il.com>
To:     Matthew Wilcox <willy@...radead.org>, glider@...gle.com
Cc:     "zhaoyang.huang" <zhaoyang.huang@...soc.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, ke.wang@...soc.com
Subject: Re: [PATCH] mm: make __GFP_SKIP_ZERO visible to skip zero operation

loop alex

On Thu, Aug 31, 2023 at 8:16 PM Matthew Wilcox <willy@...radead.org> wrote:
>
> On Thu, Aug 31, 2023 at 06:52:52PM +0800, zhaoyang.huang wrote:
> > From: Zhaoyang Huang <zhaoyang.huang@...soc.com>
> >
> > There is no explicit gfp flags to let the allocation skip zero
> > operation when CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y. I would like to make
> > __GFP_SKIP_ZERO be visible even if kasan is not configured.
>
> This bypasses a security feature so you're going to have to do a little
> better than "I want it".
Thanks for pointing this out. What I want to do is to give the user a
way to exempt some types of pages from being zeroed, which could help
on performance issues.  Could we have the most safety concern admin
use INIT_ON_FREE while the less concerned use INIT_ON_ALLOC &
__GFP_SKIP_ZERO as a light version method?
>
> > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
> > ---
> >  include/linux/gfp_types.h | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >  mode change 100644 => 100755 include/linux/gfp_types.h
>
> What is this garbage?  Header files should not be executable.
sorry for that, will remove