From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Michal Hocko <mhocko@suse.com>, Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm,memory_hotplug: Fix shrink_{zone,node}_span
Date: Wed, 17 Jul 2019 10:08:03 +0200 [thread overview]
Message-ID: <20190717080755.GA22661@linux> (raw)
In-Reply-To: <da07d964-fcfa-1406-bc12-faebbe38696e@redhat.com>
On Wed, Jul 17, 2019 at 10:01:01AM +0200, David Hildenbrand wrote:
> I'd also like to note that we should strive for making all zone-related
> changes when offlining in the future, not when removing memory. So
> ideally, any core changes we perform from now, should make that step
> (IOW implementing that) easier, not harder. Of course, BUGs have to be
> fixed.
>
> The rough idea would be to also mark ZONE_DEVICE sections as ONLINE (or
> rather rename it to "ACTIVE" to generalize).
>
> For each section we would then have
>
> - pfn_valid(): We have a valid "struct page" / memmap
> - pfn_present(): We have actually added that memory via an oficial
> interface to mm (e.g., arch_add_memory() )
> - pfn_online() / (or pfn_active()): Memory is active (online in "buddy"-
> speak, or memory that was moved to the ZONE_DEVICE zone)
>
> When resizing the zones (e.g., when offlining memory), we would then
> search for pfn_online(), not pfn_present().
>
> In addition to move_pfn_range_to_zone(), we would have
> remove_pfn_range_from_zone(), called during offline_pages() / by
> devmem/hmm/pmem code before removing.
>
> (I started to look into this, but I don't have any patches yet)
Yes, it seems like a good approach, and something that makes sense
to pursue.
FWIF, I sent a patchset [1] for that a long time ago, but I could not
follow-up due to time constraints.
[1] https://patchwork.kernel.org/cover/10700783/
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2019-07-17 8:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 8:15 [PATCH 0/2] Fixes for sub-section hotplug Oscar Salvador
2019-07-15 8:15 ` [PATCH 1/2] mm,sparse: Fix deactivate_section for early sections Oscar Salvador
2019-07-15 16:02 ` Aneesh Kumar K.V
2019-07-16 4:33 ` Dan Williams
2019-07-18 12:07 ` David Hildenbrand
2019-07-15 8:15 ` [PATCH 2/2] mm,memory_hotplug: Fix shrink_{zone,node}_span Oscar Salvador
2019-07-15 16:11 ` Aneesh Kumar K.V
2019-07-15 21:24 ` Oscar Salvador
2019-07-17 2:28 ` Dan Williams
2019-07-17 7:38 ` Oscar Salvador
2019-07-17 8:01 ` David Hildenbrand
2019-07-17 8:08 ` Oscar Salvador [this message]
2019-07-17 5:38 ` Aneesh Kumar K.V
2019-07-17 7:42 ` Oscar Salvador
2019-07-18 12:05 ` Oscar Salvador
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