linux-kernel - Re: [PATCH v4 0/6] mm / virtio-mem: support ZONE

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Date:   Mon, 10 Aug 2020 09:56:32 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        Baoquan He <bhe@...hat.com>, Jason Wang <jasowang@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Michal Hocko <mhocko@...e.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Qian Cai <cai@....pw>
Subject: Re: [PATCH v4 0/6] mm / virtio-mem: support ZONE_MOVABLE

On 04.08.20 21:41, David Hildenbrand wrote:
> @Andrew can we give this a churn and consider it for v5.9 in case there
> are no more comments?

@Andrew, Ping, so I assume we'll target v5.10?


> 
> Patch #1-#4,#6 have RBss or ACKs, patch #5 is virtio-mem stuff maintained
> by me (and MST is aware).
> 
> ---
> 
> When introducing virtio-mem, the semantics of ZONE_MOVABLE were rather
> unclear, which is why we special-cased ZONE_MOVABLE such that partially
> plugged blocks would never end up in ZONE_MOVABLE.
> 
> Now that the semantics are much clearer (and are documented in patch #6),
> let's support partially plugged memory blocks in ZONE_MOVABLE, allowing
> partially plugged memory blocks to be online to ZONE_MOVABLE and also
> unplugging from such memory blocks. This avoids surprises when onlining
> of memory blocks suddenly fails, just because they are not completely
> populated by virtio-mem (yet).
> 
> This is especially helpful for testing, but also paves the way for
> virtio-mem optimizations, allowing more memory to get reliably unplugged.
> 
> Cleanup has_unmovable_pages() and set_migratetype_isolate(), providing
> better documentation of how ZONE_MOVABLE interacts with different kind of
> unmovable pages (memory offlining vs. alloc_contig_range()).
> 
> v3 -> v4:
> - "mm/page_isolation: drop WARN_ON_ONCE() in set_migratetype_isolate()"
> -- Fix typo in description
> - "virtio-mem: don't special-case ZONE_MOVABLE"
> -- Add more details why we initialli special-cased ZONE_MOVABLE (via MST)
> - "mm: document semantics of ZONE_MOVABLE"
> -- Rephrase some parts of documentation (via Mike)
> 
> v2 -> v3:
> - "mm: document semantics of ZONE_MOVABLE"
> -- Fix a typo
> 
> v1 -> v2:
> - "mm/page_isolation: don't dump_page(NULL) in set_migratetype_isolate()"
> -- Move to position 1, add Fixes: tag
> -- Drop unused "out:" label
> - "mm/page_isolation: drop WARN_ON_ONCE() in set_migratetype_isolate()"
> -- Keep curly braces on "else" case
> - Replace "[PATCH v1 5/6] mm/page_alloc: restrict ZONE_MOVABLE optimization
>            in has_unmovable_pages() to memory offlining"
>   by "mm: document semantics of ZONE_MOVABLE"
> -- Brain dump of what I know about ZONE_MOVABLE
> 
> David Hildenbrand (6):
>   mm/page_isolation: don't dump_page(NULL) in set_migratetype_isolate()
>   mm/page_alloc: tweak comments in has_unmovable_pages()
>   mm/page_isolation: drop WARN_ON_ONCE() in set_migratetype_isolate()
>   mm/page_isolation: cleanup set_migratetype_isolate()
>   virtio-mem: don't special-case ZONE_MOVABLE
>   mm: document semantics of ZONE_MOVABLE
> 
>  drivers/virtio/virtio_mem.c | 47 +++++++------------------------------
>  include/linux/mmzone.h      | 35 +++++++++++++++++++++++++++
>  mm/page_alloc.c             | 22 +++++------------
>  mm/page_isolation.c         | 39 ++++++++++++++----------------
>  4 files changed, 66 insertions(+), 77 deletions(-)
> 


-- 
Thanks,

David / dhildenb