From: Mel Gorman <mgorman@suse.de>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Qian Cai <cai@lca.pw>,
Michal Hocko <mhocko@kernel.org>,
David Hildenbrand <david@redhat.com>,
linux-kernel@vger.kernel.org, Mike Rapoport <rppt@linux.ibm.com>,
Baoquan He <bhe@redhat.com>
Subject: Re: [PATCH 1/1] mm: compaction: avoid fast_isolate_around() to set pageblock_skip on reserved pages
Date: Wed, 25 Nov 2020 10:30:53 +0000 [thread overview]
Message-ID: <20201125103053.GL3306@suse.de> (raw)
In-Reply-To: <X71zdnZd61r429aO@redhat.com>
On Tue, Nov 24, 2020 at 03:56:22PM -0500, Andrea Arcangeli wrote:
> Hello,
>
> On Tue, Nov 24, 2020 at 01:32:05PM +0000, Mel Gorman wrote:
> > I would hope that is not the case because they are not meant to overlap.
> > However, if the beginning of the pageblock was not the start of a zone
> > then the pages would be valid but the pfn would still be outside the
> > zone boundary. If it was reserved, the struct page is valid but not
> > suitable for set_pfnblock_flags_mask. However, it is a concern in
> > general because the potential is there that pages are isolated from the
> > wrong zone.
>
> I guess we have more than one issue to correct in that function
> because the same BUG_ON reproduced again even with the tentative patch
> I posted earlier.
>
> So my guess is that the problematic reserved page isn't pointed by the
> min_pfn, but it must have been pointed by the "highest" variable
> calculated below?
>
> if (pfn >= highest)
> highest = pageblock_start_pfn(pfn);
>
> When I looked at where "highest" comes from, it lacks
> pageblock_pfn_to_page check (which was added around v5.7 to min_pfn).
>
> Is that the real bug, which may be fixed by something like this? (untested)
>
It's plausible as it is a potential source of leaking but as you note
in another mail, it's surprising to me that valid struct pages, even if
within memory holes and reserved would have broken node/zone information
in the page flags.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2020-11-25 10:30 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-23 21:25 compaction: VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn)) Qian Cai
2020-04-24 3:43 ` Baoquan He
2020-04-24 13:45 ` Qian Cai
2020-05-05 12:43 ` Baoquan He
2020-05-05 13:20 ` Qian Cai
2020-05-11 1:21 ` Baoquan He
2020-04-26 14:41 ` Mike Rapoport
2020-04-27 13:45 ` Qian Cai
2020-11-21 19:45 ` [PATCH 0/1] VM_BUG_ON_PAGE(!zone_spans_pfn) in set_pfnblock_flags_mask Andrea Arcangeli
2020-11-21 19:45 ` [PATCH 1/1] mm: compaction: avoid fast_isolate_around() to set pageblock_skip on reserved pages Andrea Arcangeli
2020-11-21 19:53 ` Andrea Arcangeli
2020-11-23 11:26 ` David Hildenbrand
2020-11-23 13:01 ` Vlastimil Babka
2020-11-24 13:32 ` Mel Gorman
2020-11-24 20:56 ` Andrea Arcangeli
2020-11-25 10:30 ` Mel Gorman [this message]
2020-11-25 17:59 ` Andrea Arcangeli
2020-11-26 10:47 ` Mel Gorman
2020-12-06 2:26 ` Andrea Arcangeli
2020-12-06 23:47 ` Mel Gorman
2020-11-25 5:34 ` Andrea Arcangeli
2020-11-25 6:45 ` David Hildenbrand
2020-11-25 8:51 ` Mike Rapoport
2020-11-25 10:39 ` Mel Gorman
2020-11-25 11:04 ` David Hildenbrand
2020-11-25 11:41 ` David Hildenbrand
2020-11-25 18:47 ` Andrea Arcangeli
2020-11-25 13:33 ` Mel Gorman
2020-11-25 13:41 ` David Hildenbrand
2020-11-25 18:28 ` Andrea Arcangeli
2020-11-25 19:27 ` David Hildenbrand
2020-11-25 20:41 ` Andrea Arcangeli
2020-11-25 21:13 ` David Hildenbrand
2020-11-25 21:04 ` Mike Rapoport
2020-11-25 21:38 ` Andrea Arcangeli
2020-11-26 9:36 ` Mike Rapoport
2020-11-26 10:05 ` David Hildenbrand
2020-11-26 17:46 ` Mike Rapoport
2020-11-29 12:32 ` Mike Rapoport
2020-12-02 0:44 ` Andrea Arcangeli
2020-12-02 17:39 ` Mike Rapoport
2020-12-03 6:23 ` Andrea Arcangeli
2020-12-03 10:51 ` Mike Rapoport
2020-12-03 17:31 ` Andrea Arcangeli
2020-12-06 8:09 ` Mike Rapoport
2020-11-26 18:15 ` Andrea Arcangeli
2020-11-26 18:29 ` Andrea Arcangeli
2020-11-26 19:44 ` Mike Rapoport
2020-11-26 20:30 ` Andrea Arcangeli
2020-11-26 21:03 ` Mike Rapoport
2020-11-26 19:21 ` Andrea Arcangeli
2020-11-25 12:08 ` Vlastimil Babka
2020-11-25 13:32 ` David Hildenbrand
2020-11-25 14:13 ` Mike Rapoport
2020-11-25 14:42 ` David Hildenbrand
2020-11-26 10:51 ` Mel Gorman
2020-11-25 19:14 ` Andrea Arcangeli
2020-11-25 19:01 ` Andrea Arcangeli
2020-11-25 19:33 ` David Hildenbrand
2020-11-26 3:40 ` Andrea Arcangeli
2020-11-26 10:43 ` Mike Rapoport
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