From: Michal Hocko <mhocko@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>,
Rong Chen <rong.a.chen@intel.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
linux-kernel@vger.kernel.org,
Linux Memory Management List <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>, LKP <lkp@01.org>,
Oscar Salvador <osalvador@suse.de>
Subject: Re: [LKP] efad4e475c [ 40.308255] Oops: 0000 [#1] PREEMPT SMP PTI
Date: Mon, 18 Feb 2019 19:11:55 +0100 [thread overview]
Message-ID: <20190218181155.GC4525@dhcp22.suse.cz> (raw)
In-Reply-To: <20190218175726.GU12668@bombadil.infradead.org>
On Mon 18-02-19 09:57:26, Matthew Wilcox wrote:
> On Mon, Feb 18, 2019 at 06:05:58PM +0100, Michal Hocko wrote:
> > + end_pfn = min(start_pfn + nr_pages,
> > + zone_end_pfn(page_zone(pfn_to_page(start_pfn))));
> >
> > /* Check the starting page of each pageblock within the range */
> > - for (; page < end_page; page = next_active_pageblock(page)) {
> > - if (!is_pageblock_removable_nolock(page))
> > + for (; start_pfn < end_pfn; start_pfn = next_active_pageblock(start_pfn)) {
> > + if (!is_pageblock_removable_nolock(start_pfn))
>
> If you have a zone which contains pfns that run from ULONG_MAX-n to ULONG_MAX,
> end_pfn is going to wrap around to 0 and this loop won't execute.
Is this a realistic situation to bother?
> I think
> you should use:
>
> max_pfn = min(start_pfn + nr_pages,
> zone_end_pfn(page_zone(pfn_to_page(start_pfn)))) - 1;
>
> for (; start_pfn <= max_pfn; ...)
I do not really care strongly, but we have more places were we do
start_pfn + nr_pages and then use it as pfn < end_pfn construct. I
suspect we would need to make a larger audit and make the code
consistent so unless there are major concerns I would stick with what
I have for now and leave the rest for the cleanup. Does that sound
reasonable?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-02-18 18:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 5:28 [LKP] efad4e475c [ 40.308255] Oops: 0000 [#1] PREEMPT SMP PTI kernel test robot
2019-02-18 7:08 ` Michal Hocko
2019-02-18 8:47 ` Rong Chen
2019-02-18 9:03 ` Michal Hocko
2019-02-18 9:11 ` Rong Chen
2019-02-18 9:29 ` Michal Hocko
2019-02-18 8:55 ` Michal Hocko
2019-02-18 10:01 ` Rong Chen
2019-02-18 10:30 ` Michal Hocko
2019-02-18 14:05 ` Mike Rapoport
2019-02-18 15:20 ` Michal Hocko
2019-02-18 15:22 ` Michal Hocko
2019-02-18 16:48 ` Mike Rapoport
2019-02-18 17:05 ` Michal Hocko
2019-02-18 17:48 ` Mike Rapoport
2019-02-18 17:57 ` Matthew Wilcox
2019-02-18 18:11 ` Michal Hocko [this message]
2019-02-18 19:05 ` Matthew Wilcox
2019-02-18 18:15 ` [RFC PATCH] mm, memory_hotplug: fix off-by-one in is_pageblock_removable Michal Hocko
2019-02-18 18:31 ` Mike Rapoport
2019-02-20 8:33 ` Oscar Salvador
2019-02-20 12:57 ` Michal Hocko
2019-02-21 3:18 ` [LKP] " Rong Chen
2019-02-21 7:25 ` Michal Hocko
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