From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: "Andrea Arcangeli" <aarcange@redhat.com>,
"Baoquan He" <bhe@redhat.com>, "Borislav Petkov" <bp@alien8.de>,
"Chris Wilson" <chris@chris-wilson.co.uk>,
"H. Peter Anvin" <hpa@zytor.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Łukasz Majczak" <lma@semihalf.com>,
"Mel Gorman" <mgorman@suse.de>,
"Michal Hocko" <mhocko@kernel.org>,
"Mike Rapoport" <rppt@linux.ibm.com>, "Qian Cai" <cai@lca.pw>,
"Sarvela, Tomi P" <tomi.p.sarvela@intel.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Vlastimil Babka" <vbabka@suse.cz>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
stable@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v6 1/1] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout
Date: Tue, 23 Feb 2021 09:04:19 +0100 [thread overview]
Message-ID: <a7f70da1-6733-967f-4d1d-92d23b95a753@redhat.com> (raw)
In-Reply-To: <20210222105728.28636-1-rppt@kernel.org>
On 22.02.21 11:57, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
>
> There could be struct pages that are not backed by actual physical memory.
> This can happen when the actual memory bank is not a multiple of
> SECTION_SIZE or when an architecture does not register memory holes
> reserved by the firmware as memblock.memory.
>
> Such pages are currently initialized using init_unavailable_mem() function
> that iterates through PFNs in holes in memblock.memory and if there is a
> struct page corresponding to a PFN, the fields of this page are set to
> default values and it is marked as Reserved.
>
> init_unavailable_mem() does not take into account zone and node the page
> belongs to and sets both zone and node links in struct page to zero.
>
> Before commit 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions
> rather that check each PFN") the holes inside a zone were re-initialized
> during memmap_init() and got their zone/node links right. However, after
> that commit nothing updates the struct pages representing such holes.
>
> On a system that has firmware reserved holes in a zone above ZONE_DMA, for
> instance in a configuration below:
>
> # grep -A1 E820 /proc/iomem
> 7a17b000-7a216fff : Unknown E820 type
> 7a217000-7bffffff : System RAM
>
> unset zone link in struct page will trigger
>
> VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
>
> because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link
> in struct page) in the same pageblock.
>
> Interleave initialization of the unavailable pages with the normal
> initialization of memory map, so that zone and node information will be
> properly set on struct pages that are not backed by the actual memory.
>
> With this change the pages for holes inside a zone will get proper
> zone/node links and the pages that are not spanned by any node will get
> links to the adjacent zone/node.
Does this include pages in the last section has handled by ...
...
> - /*
> - * Early sections always have a fully populated memmap for the whole
> - * section - see pfn_valid(). If the last section has holes at the
> - * end and that section is marked "online", the memmap will be
> - * considered initialized. Make sure that memmap has a well defined
> - * state.
> - */
> - pgcnt += init_unavailable_range(PFN_DOWN(next),
> - round_up(max_pfn, PAGES_PER_SECTION));
> -
^ this code?
Or how is that case handled now?
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-02-23 8:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 10:57 [PATCH v6 1/1] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout Mike Rapoport
2021-02-22 11:12 ` Mike Rapoport
2021-02-23 1:15 ` Baoquan He
2021-02-23 8:04 ` David Hildenbrand [this message]
2021-02-23 9:48 ` Mike Rapoport
2021-02-23 9:49 ` David Hildenbrand
2021-02-23 10:06 ` Mike Rapoport
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