From: Michal Hocko <mhocko@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Oscar Salvador <osalvador@suse.de>,
Mel Gorman <mgorman@techsingularity.net>,
Mike Rapoport <rppt@linux.ibm.com>,
Dan Williams <dan.j.williams@intel.com>,
Wei Yang <richard.weiyang@gmail.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Pavel Tatashin <pavel.tatashin@microsoft.com>
Subject: Re: [PATCH v1 1/2] mm/page_alloc.c: Don't set pages PageReserved() when offlining
Date: Mon, 21 Oct 2019 17:47:12 +0200 [thread overview]
Message-ID: <20191021154712.GW9379@dhcp22.suse.cz> (raw)
In-Reply-To: <b6a392c9-1cb8-321e-b7ba-d483d928a3cc@redhat.com>
On Mon 21-10-19 17:39:36, David Hildenbrand wrote:
> On 21.10.19 16:43, Michal Hocko wrote:
[...]
> > We still set PageReserved before onlining pages and that one should be
> > good to go as well (memmap_init_zone).
> > Thanks!
>
> memmap_init_zone() is called when onlining memory. There, set all pages to
> reserved right now (on context == MEMMAP_HOTPLUG). We clear PG_reserved when
> onlining a page to the buddy (e.g., generic_online_page). If we would online
> a memory block with holes, we would want to keep all such pages
> (!pfn_valid()) set to reserved. Also, there might be other side effects.
Isn't it sufficient to have those pages in a poisoned state? They are
not onlined so their state is basically undefined anyway. I do not see
how PageReserved makes this any better.
Also is the hole inside a hotplugable memory something we really have to
care about. Has anybody actually seen a platform to require that?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-10-21 15:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-21 14:19 [PATCH v1 0/2] mm: Memory offlining + page isolation cleanups David Hildenbrand
2019-10-21 14:19 ` [PATCH v1 1/2] mm/page_alloc.c: Don't set pages PageReserved() when offlining David Hildenbrand
2019-10-21 14:43 ` Michal Hocko
2019-10-21 15:39 ` David Hildenbrand
2019-10-21 15:47 ` Michal Hocko [this message]
2019-10-21 15:54 ` David Hildenbrand
2019-10-22 8:20 ` Michal Hocko
2019-10-22 8:23 ` David Hildenbrand
2019-10-22 8:58 ` Michal Hocko
2019-10-22 9:03 ` David Hildenbrand
2019-10-21 14:19 ` [PATCH v1 2/2] mm/page_isolation.c: Convert SKIP_HWPOISON to MEMORY_OFFLINE David Hildenbrand
2019-10-21 15:02 ` Michal Hocko
2019-10-21 15:04 ` David Hildenbrand
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