linux-kernel - Re: [PATCH v2] mm/hwpoison: reset hwpoison filter parameters in pfn_inject

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Message-ID: <ZpdiOAjdSJfkpbr7@tiehlicka>
Date: Wed, 17 Jul 2024 08:18:32 +0200
From: Michal Hocko <mhocko@...e.com>
To: Miaohe Lin <linmiaohe@...wei.com>
Cc: akpm@...ux-foundation.org, nao.horiguchi@...il.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/hwpoison: reset hwpoison filter parameters in
 pfn_inject_exit()

On Wed 17-07-24 10:23:06, Miaohe Lin wrote:
> On 2024/7/16 16:38, Michal Hocko wrote:
> > On Tue 16-07-24 11:35:16, Miaohe Lin wrote:
> >> When hwpoison_inject module is removed, hwpoison_filter_* parameters
> >> should be reset. Otherwise these parameters will have non-default values
> >> at next insmod time.
> > 
> > There is a clear layering broken here. We have mm/memory-failure.c using
> > values and mm/hwpoison-inject.c defining the values. Both with a
> > potentially different life time. Shouldn't that be fix instead?
> 
> In fact, we have mm/memory-failure.c defining and using these values while they can
> only be modified through mm/hwpoison-inject.c from userspace.

Yes, this is exactly what I mean by broken layering that should be
fixed.

> The common usecase should be:
> 
> 1. User set hwpoison filter parameters first through mm/hwpoison-inject.c.
> 2. Then doing memory hwpoison test through mm/hwpoison-inject.c.

Why does this need to be done through different modules? Why it cannot
be part of the memory-filure.c?
-- 
Michal Hocko
SUSE Labs