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Message-ID: <20200819125850.GK5422@dhcp22.suse.cz>
Date: Wed, 19 Aug 2020 14:58:50 +0200
From: Michal Hocko <mhocko@...e.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Andrew Morton <akpm@...ux-foundation.org>,
Wei Yang <richard.weiyang@...ux.alibaba.com>,
Baoquan He <bhe@...hat.com>,
Pankaj Gupta <pankaj.gupta.linux@...il.com>,
Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH v1 06/11] mm/memory_hotplug: drop nr_isolate_pageblock in
offline_pages()
On Wed 19-08-20 12:11:52, David Hildenbrand wrote:
> We make sure that we cannot have any memory holes right at the beginning
> of offline_pages() and we only support to online/offline full sections.
> Both, sections and pageblocks are a power of two in size, and sections
> always span full pageblocks.
>
> We can directly calculate the number of isolated pageblocks from nr_pages.
>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Wei Yang <richard.weiyang@...ux.alibaba.com>
> Cc: Baoquan He <bhe@...hat.com>
> Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
> Cc: Oscar Salvador <osalvador@...e.de>
> Signed-off-by: David Hildenbrand <david@...hat.com>
Acked-by: Michal Hocko <mhocko@...e.com>
> ---
> mm/memory_hotplug.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 50aa5df696e9d..098361fcb4504 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1460,10 +1460,10 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
> {
> const unsigned long end_pfn = start_pfn + nr_pages;
> unsigned long pfn, system_ram_pages = 0;
> - int ret, node, nr_isolate_pageblock;
> unsigned long flags;
> struct zone *zone;
> struct memory_notify arg;
> + int ret, node;
> char *reason;
>
> /* We can only offline full sections (e.g., SECTION_IS_ONLINE) */
> @@ -1507,7 +1507,6 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
> reason = "failure to isolate range";
> goto failed_removal;
> }
> - nr_isolate_pageblock = ret;
>
> arg.start_pfn = start_pfn;
> arg.nr_pages = nr_pages;
> @@ -1569,7 +1568,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
> * pageblocks zone counter here.
> */
> spin_lock_irqsave(&zone->lock, flags);
> - zone->nr_isolate_pageblock -= nr_isolate_pageblock;
> + zone->nr_isolate_pageblock -= nr_pages / pageblock_nr_pages;
> spin_unlock_irqrestore(&zone->lock, flags);
>
> /* removal success */
> --
> 2.26.2
>
--
Michal Hocko
SUSE Labs
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