From: Baoquan He <bhe@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
"Michael S . Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH v1 1/6] mm/page_alloc: tweak comments in has_unmovable_pages()
Date: Tue, 28 Jul 2020 21:48:26 +0800 [thread overview]
Message-ID: <20200728134826.GC14854@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20200630142639.22770-2-david@redhat.com>
On 06/30/20 at 04:26pm, David Hildenbrand wrote:
> Let's move the split comment regarding bootmem allocations and memory
> holes, especially in the context of ZONE_MOVABLE, to the PageReserved()
> check.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> mm/page_alloc.c | 22 ++++++----------------
> 1 file changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 48eb0f1410d47..bd3ebf08f09b9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8207,14 +8207,6 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page,
> unsigned long iter = 0;
> unsigned long pfn = page_to_pfn(page);
>
> - /*
> - * TODO we could make this much more efficient by not checking every
> - * page in the range if we know all of them are in MOVABLE_ZONE and
> - * that the movable zone guarantees that pages are migratable but
> - * the later is not the case right now unfortunatelly. E.g. movablecore
> - * can still lead to having bootmem allocations in zone_movable.
> - */
> -
> if (is_migrate_cma_page(page)) {
> /*
> * CMA allocations (alloc_contig_range) really need to mark
> @@ -8233,6 +8225,12 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page,
>
> page = pfn_to_page(pfn + iter);
>
> + /*
> + * Both, bootmem allocations and memory holes are marked
> + * PG_reserved and are unmovable. We can even have unmovable
> + * allocations inside ZONE_MOVABLE, for example when
> + * specifying "movable_core".
~~~~ should be 'movablecore', we don't
have kernel parameter 'movable_core'.
Otherwise, this looks good to me. Esp the code comment at below had been
added very long time ago and obsolete.
Reviewed-by: Baoquan He <bhe@redhat.com>
By the way, David, do you know what is the situation of having unmovable
allocations inside ZONE_MOVABLE when specifying 'movablecore'? I quickly
went through find_zone_movable_pfns_for_nodes(), but didn't get why.
Could you tell a little more detail about it?
Thanks
Baoquan
> + */
> if (PageReserved(page))
> return page;
>
> @@ -8306,14 +8304,6 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page,
> * it. But now, memory offline itself doesn't call
> * shrink_node_slabs() and it still to be fixed.
> */
> - /*
> - * If the page is not RAM, page_count()should be 0.
> - * we don't need more check. This is an _used_ not-movable page.
> - *
> - * The problematic thing here is PG_reserved pages. PG_reserved
> - * is set to both of a memory hole page and a _used_ kernel
> - * page at boot.
> - */
> return page;
> }
> return NULL;
> --
> 2.26.2
>
>
next prev parent reply other threads:[~2020-07-28 13:48 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-30 14:26 [PATCH v1 0/6] mm / virtio-mem: support ZONE_MOVABLE David Hildenbrand
2020-06-30 14:26 ` [PATCH v1 1/6] mm/page_alloc: tweak comments in has_unmovable_pages() David Hildenbrand
2020-07-28 13:48 ` Baoquan He [this message]
2020-07-28 14:07 ` David Hildenbrand
2020-07-29 10:47 ` Baoquan He
2020-07-29 12:29 ` David Hildenbrand
2020-06-30 14:26 ` [PATCH v1 2/6] mm/page_isolation: don't dump_page(NULL) in set_migratetype_isolate() David Hildenbrand
2020-07-28 13:56 ` Baoquan He
2020-07-29 17:31 ` Mike Kravetz
2020-07-29 18:08 ` David Hildenbrand
2020-07-29 18:35 ` Mike Kravetz
2020-07-29 18:41 ` David Hildenbrand
2020-07-30 4:21 ` Pankaj Gupta
2020-06-30 14:26 ` [PATCH v1 3/6] mm/page_isolation: drop WARN_ON_ONCE() " David Hildenbrand
2020-07-29 13:24 ` Baoquan He
2020-07-29 13:37 ` David Hildenbrand
2020-07-29 14:05 ` Baoquan He
2020-06-30 14:26 ` [PATCH v1 4/6] mm/page_isolation: cleanup set_migratetype_isolate() David Hildenbrand
2020-07-29 14:06 ` Baoquan He
2020-07-30 4:31 ` Pankaj Gupta
2020-06-30 14:26 ` [PATCH v1 5/6] mm/page_alloc: restrict ZONE_MOVABLE optimization in has_unmovable_pages() to memory offlining David Hildenbrand
2020-07-27 12:23 ` David Hildenbrand
2020-06-30 14:26 ` [PATCH v1 6/6] virtio-mem: don't special-case ZONE_MOVABLE David Hildenbrand
2020-07-21 9:59 ` [PATCH v1 0/6] mm / virtio-mem: support ZONE_MOVABLE David Hildenbrand
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