From: Andrea Arcangeli <aarcange@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>, 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>,
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 13:47:21 -0500 [thread overview]
Message-ID: <X76muVFFENroWb7w@redhat.com> (raw)
In-Reply-To: <33612969-92a1-6c49-a2e0-3a95715b1e7f@redhat.com>
On Wed, Nov 25, 2020 at 12:41:55PM +0100, David Hildenbrand wrote:
> On 25.11.20 12:04, David Hildenbrand wrote:
> > On 25.11.20 11:39, Mel Gorman wrote:
> >> On Wed, Nov 25, 2020 at 07:45:30AM +0100, David Hildenbrand wrote:
> >>>> Something must have changed more recently than v5.1 that caused the
> >>>> zoneid of reserved pages to be wrong, a possible candidate for the
> >>>> real would be this change below:
> >>>>
> >>>> + __init_single_page(pfn_to_page(pfn), pfn, 0, 0);
> >>>>
> >>>
> >>> Before that change, the memmap of memory holes were only zeroed out. So the zones/nid was 0, however, pages were not reserved and had a refcount of zero - resulting in other issues.
> >>>
> >>> Most pfn walkers shouldn???t mess with reserved pages and simply skip them. That would be the right fix here.
> >>>
> >>
> >> Ordinarily yes, pfn walkers should not care about reserved pages but it's
> >> still surprising that the node/zone linkages would be wrong for memory
> >> holes. If they are in the middle of a zone, it means that a hole with
> >> valid struct pages could be mistaken for overlapping nodes (if the hole
> >> was in node 1 for example) or overlapping zones which is just broken.
> >
> > I agree within zones - but AFAIU, the issue is reserved memory between
> > zones, right?
>
> Double checking, I was confused. This applies also to memory holes
> within zones in x86.
Yes this is a memory hole within the DMA32 zone.
Still why there should be any difference?
As long as a page struct exists it's in a well defined mem_map array
which comes for one and only one zoneid/nid combination.
So what would be the benefit of treating memory holes within zones or
in between zones differently and leave one or the other with a
zoneid/nid uninitialized?
next prev parent reply other threads:[~2020-11-25 18:47 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
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 [this message]
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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