From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org,
linux-acpi@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Wei Yang <richard.weiyang@linux.alibaba.com>,
Mike Rapoport <rppt@kernel.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>
Subject: Re: [PATCH RFC 4/4] mm/page_alloc: place pages to tail in __free_pages_core()
Date: Mon, 28 Sep 2020 09:58:24 +0200 [thread overview]
Message-ID: <20200928075820.GA4082@linux> (raw)
In-Reply-To: <20200916183411.64756-5-david@redhat.com>
On Wed, Sep 16, 2020 at 08:34:11PM +0200, David Hildenbrand wrote:
> @@ -1523,7 +1524,13 @@ void __free_pages_core(struct page *page, unsigned int order)
>
> atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
> set_page_refcounted(page);
> - __free_pages(page, order);
> +
> + /*
> + * Bypass PCP and place fresh pages right to the tail, primarily
> + * relevant for memory onlining.
> + */
> + page_ref_dec(page);
> + __free_pages_ok(page, order, FOP_TO_TAIL);
Sorry, I must be missing something obvious here, but I am a bit confused here.
I get the part of placing them at the tail so rmqueue_bulk() won't
find them, but I do not get why we decrement page's refcount.
IIUC, its refcount will be 0, but why do we want to do that?
Another thing a bit unrelated... we mess three times with page's refcount
(two before this patch).
Why do we have this dance in place?
Thanks
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2020-09-28 7:58 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 18:34 [PATCH RFC 0/4] mm: place pages to the freelist tail when onling and undoing isolation David Hildenbrand
2020-09-16 18:34 ` [PATCH RFC 1/4] mm/page_alloc: convert "report" flag of __free_one_page() to a proper flag David Hildenbrand
2020-09-16 21:44 ` Alexander Duyck
2020-09-18 1:53 ` Wei Yang
2020-09-18 7:23 ` David Hildenbrand
2020-09-24 10:19 ` Vlastimil Babka
2020-09-25 10:34 ` Oscar Salvador
2020-09-16 18:34 ` [PATCH RFC 2/4] mm/page_alloc: place pages to tail in __putback_isolated_page() David Hildenbrand
2020-09-16 21:50 ` Alexander Duyck
2020-09-18 2:07 ` Wei Yang
2020-09-18 7:27 ` David Hildenbrand
2020-09-21 1:57 ` Wei Yang
2020-09-18 2:16 ` Wei Yang
2020-09-18 7:29 ` David Hildenbrand
2020-09-24 10:37 ` Vlastimil Babka
2020-09-25 8:10 ` David Hildenbrand
2020-09-25 13:19 ` Oscar Salvador
2020-09-25 13:30 ` David Hildenbrand
2020-09-16 18:34 ` [PATCH RFC 3/4] mm/page_alloc: always move pages to the tail of the freelist in unset_migratetype_isolate() David Hildenbrand
2020-09-18 2:29 ` Wei Yang
2020-09-18 7:30 ` David Hildenbrand
2020-09-24 11:13 ` Vlastimil Babka
2020-09-25 2:45 ` Wei Yang
2020-09-25 8:05 ` David Hildenbrand
2020-09-25 8:39 ` Vlastimil Babka
2020-09-25 13:13 ` David Hildenbrand
2020-09-25 13:57 ` Oscar Salvador
2020-09-16 18:34 ` [PATCH RFC 4/4] mm/page_alloc: place pages to tail in __free_pages_core() David Hildenbrand
2020-09-24 13:44 ` Vlastimil Babka
2020-09-28 7:58 ` Oscar Salvador [this message]
2020-09-28 8:36 ` David Hildenbrand
2020-09-28 12:53 ` Oscar Salvador
2020-09-16 18:50 ` [PATCH RFC 0/4] mm: place pages to the freelist tail when onling and undoing isolation osalvador
2020-09-16 19:31 ` David Hildenbrand
2020-09-18 2:30 ` Wei Yang
2020-09-18 7:32 ` David Hildenbrand
2020-09-23 14:31 ` Vlastimil Babka
2020-09-23 15:26 ` David Hildenbrand
2020-09-24 9:40 ` Mel Gorman
2020-09-24 9:54 ` David Hildenbrand
2020-09-24 13:59 ` Vlastimil Babka
2020-09-24 14:29 ` David Hildenbrand
2020-09-24 1:57 ` Wei Yang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200928075820.GA4082@linux \
--to=osalvador@suse.de \
--cc=akpm@linux-foundation.org \
--cc=alexander.h.duyck@linux.intel.com \
--cc=dave.hansen@intel.com \
--cc=david@redhat.com \
--cc=haiyangz@microsoft.com \
--cc=kys@microsoft.com \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@kernel.org \
--cc=richard.weiyang@linux.alibaba.com \
--cc=rppt@kernel.org \
--cc=sthemmin@microsoft.com \
--cc=vbabka@suse.cz \
--cc=wei.liu@kernel.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.