From: Vlastimil Babka <vbabka@suse.cz>
To: Mike Rapoport <rppt@kernel.org>
Cc: "Michal Hocko" <mhocko@suse.com>, "Mel Gorman" <mgorman@suse.de>,
"David Hildenbrand" <david@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"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>,
"Mike Rapoport" <rppt@linux.ibm.com>, "Qian Cai" <cai@lca.pw>,
"Sarvela, Tomi P" <tomi.p.sarvela@intel.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
stable@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v5 1/1] mm: refactor initialization of struct page for holes in memory layout
Date: Wed, 17 Feb 2021 13:27:37 +0100 [thread overview]
Message-ID: <0255912b-19af-e8fc-9a04-06a519287716@suse.cz> (raw)
In-Reply-To: <20210216174914.GD1307762@kernel.org>
On 2/16/21 6:49 PM, Mike Rapoport wrote:
> Hi Vlastimil,
>
> On Tue, Feb 16, 2021 at 05:39:12PM +0100, Vlastimil Babka wrote:
>>
>>
>> So, Andrea could you please check if this fixes the original
>> fast_isolate_around() issue for you? With the VM_BUG_ON not removed, DEBUG_VM
>> enabled, no changes to struct page initialization...
>> It relies on pageblock_pfn_to_page as the rest of the compaction code.
>
> Pardon my ignorance of compaction internals, but does this mean that with
> your patch we'll never call set_pfnblock_flags_mask() for a pfn in a hole?
No it doesn't mean that kind of guarantee. But we will not call it anymore (if
my patch is correct) from a path which we currently know it's doing that and
triggering the VM_BUG_ON. So that's a targetted fix that matches stable backport
criteria. It doesn't contradict your patch as a way to improve mainline, I still
agree it's best long-term if we initialize the struct pages without such
surprises. But I also agree with Michal that there's a risk of replacing one
corner case with another and thus we shouldn't do that as a stable fix.
prev parent reply other threads:[~2021-02-17 12:28 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 11:08 [PATCH v5 1/1] mm: refactor initialization of struct page for holes in memory layout Mike Rapoport
2021-02-08 21:11 ` Andrew Morton
2021-02-08 21:25 ` Mike Rapoport
2021-02-12 9:55 ` David Hildenbrand
2021-02-12 9:56 ` David Hildenbrand
2021-02-12 10:11 ` Michal Hocko
2021-02-12 10:16 ` David Hildenbrand
2021-02-12 10:37 ` Michal Hocko
2021-02-14 17:29 ` Mike Rapoport
2021-02-15 8:45 ` David Hildenbrand
2021-02-16 11:13 ` Mike Rapoport
2021-02-12 10:33 ` Michal Hocko
2021-02-12 10:42 ` David Hildenbrand
2021-02-12 13:18 ` Michal Hocko
2021-02-14 18:00 ` Mike Rapoport
2021-02-15 9:00 ` Michal Hocko
2021-02-15 9:05 ` David Hildenbrand
2021-02-15 21:24 ` Mike Rapoport
2021-02-16 8:33 ` Michal Hocko
2021-02-16 11:01 ` Mike Rapoport
2021-02-16 11:39 ` Michal Hocko
2021-02-16 12:34 ` Vlastimil Babka
2021-02-16 12:59 ` Vlastimil Babka
2021-02-16 13:11 ` Michal Hocko
2021-02-16 16:39 ` Vlastimil Babka
2021-02-16 17:49 ` Mike Rapoport
2021-02-17 12:27 ` Vlastimil Babka [this message]
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