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Message-ID: <edac179f0626a6e0bd91922d876934abf1b9bb19.camel@d-silva.org>
Subject: Re: [PATCH v2 2/3] mm: don't hide potentially null memmap pointer
 in sparse_remove_one_section
From:   "Alastair D'Silva" <alastair@d-silva.org>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Pavel Tatashin <pasha.tatashin@oracle.com>,
        Oscar Salvador <osalvador@suse.de>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Baoquan He <bhe@redhat.com>, Qian Cai <cai@lca.pw>,
        Logan Gunthorpe <logang@deltatee.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Date:   Wed, 26 Jun 2019 16:30:55 +1000
In-Reply-To: <20190626062344.GG17798@dhcp22.suse.cz>
References: <20190626061124.16013-1-alastair@au1.ibm.com>
         <20190626061124.16013-3-alastair@au1.ibm.com>
         <20190626062344.GG17798@dhcp22.suse.cz>
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On Wed, 2019-06-26 at 08:23 +0200, Michal Hocko wrote:
> On Wed 26-06-19 16:11:22, Alastair D'Silva wrote:
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > By adding offset to memmap before passing it in to
> > clear_hwpoisoned_pages,
> > we hide a potentially null memmap from the null check inside
> > clear_hwpoisoned_pages.
> > 
> > This patch passes the offset to clear_hwpoisoned_pages instead,
> > allowing
> > memmap to successfully peform it's null check.
> 
> Same issue with the changelog as the previous patch (missing WHY).
> 

The first paragraph explains what the problem is with the existing code
(same applies to 1/3 too).

-- 
Alastair D'Silva           mob: 0423 762 819
skype: alastair_dsilva    
Twitter: @EvilDeece
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