linux-kernel - Re: [PATCH v2 1/3] mm: Trigger bug on if a section is not found in __section

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Message-ID: <d4af66721ea53ce7df2d45a567d17a30575672b2.camel@d-silva.org>
Date:   Wed, 26 Jun 2019 16:27:30 +1000
From:   "Alastair D'Silva" <alastair@...ilva.org>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        Oscar Salvador <osalvador@...e.de>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Baoquan He <bhe@...hat.com>,
        Wei Yang <richard.weiyang@...il.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v2 1/3] mm: Trigger bug on if a section is not found in
 __section_nr

On Wed, 2019-06-26 at 08:21 +0200, Michal Hocko wrote:
> On Wed 26-06-19 16:11:21, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@...ilva.org>
> > 
> > If a memory section comes in where the physical address is greater
> > than
> > that which is managed by the kernel, this function would not
> > trigger the
> > bug and instead return a bogus section number.
> > 
> > This patch tracks whether the section was actually found, and
> > triggers the
> > bug if not.
> 
> Why do we want/need that? In other words the changelog should contina
> WHY and WHAT. This one contains only the later one.
>  

Thanks, I'll update the comment.

During driver development, I tried adding peristent memory at a memory
address that exceeded the maximum permissable address for the platform.

This caused __section_nr to silently return bogus section numbers,
rather than complaining.

-- 
Alastair D'Silva           mob: 0423 762 819
skype: alastair_dsilva    
Twitter: @EvilDeece
blog: http://alastair.d-silva.org