From: Michal Hocko <mhocko@kernel.org>
To: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
qiuxishi@huawei.com, arbab@linux.vnet.ibm.com,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH] mm/memory_hotplug: fix wrong casting for __remove_section()
Date: Wed, 13 Sep 2017 07:59:14 +0200 [thread overview]
Message-ID: <20170913055914.3npcxevhdwghcmdd@dhcp22.suse.cz> (raw)
In-Reply-To: <587bdecd-2584-21be-94b8-61b427f1b0e8@gmail.com>
On Tue 12-09-17 13:05:39, YASUAKI ISHIMATSU wrote:
> Hi Michal,
>
> Thanks you for reviewing my patch.
>
> On 09/12/2017 08:49 AM, Michal Hocko wrote:
> > On Fri 08-09-17 16:43:04, YASUAKI ISHIMATSU wrote:
> >> __remove_section() calls __remove_zone() to shrink zone and pgdat.
> >> But due to wrong castings, __remvoe_zone() cannot shrink zone
> >> and pgdat correctly if pfn is over 0xffffffff.
> >>
> >> So the patch fixes the following 3 wrong castings.
> >>
> >> 1. find_smallest_section_pfn() returns 0 or start_pfn which defined
> >> as unsigned long. But the function always returns 32bit value
> >> since the function is defined as int.
> >>
> >> 2. find_biggest_section_pfn() returns 0 or pfn which defined as
> >> unsigned long. the function always returns 32bit value
> >> since the function is defined as int.
> >
> > this is indeed wrong. Pfns over would be really broken 15TB. Not that
> > unrealistic these days
>
> Why 15TB?
0xffffffff>>28
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-09-13 5:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-08 20:43 YASUAKI ISHIMATSU
2017-09-12 12:49 ` Michal Hocko
2017-09-12 17:05 ` YASUAKI ISHIMATSU
2017-09-13 5:59 ` Michal Hocko [this message]
2017-09-14 15:43 ` YASUAKI ISHIMATSU
2017-09-15 9:36 ` Michal Hocko
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