From: Michal Hocko <mhocko@suse.com>
To: js1304@gmail.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Vlastimil Babka <vbabka@suse.cz>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Mel Gorman <mgorman@techsingularity.net>,
kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs
Date: Tue, 29 Sep 2020 10:08:14 +0200 [thread overview]
Message-ID: <20200929080814.GB22035@dhcp22.suse.cz> (raw)
In-Reply-To: <1601283046-15329-1-git-send-email-iamjoonsoo.kim@lge.com>
On Mon 28-09-20 17:50:46, Joonsoo Kim wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> memalloc_nocma_{save/restore} APIs can be used to skip page allocation
> on CMA area, but, there is a missing case and the page on CMA area could
> be allocated even if APIs are used. This patch handles this case to fix
> the potential issue.
>
> Missing case is an allocation from the pcplist. MIGRATE_MOVABLE pcplist
> could have the pages on CMA area so we need to skip it if ALLOC_CMA isn't
> specified.
>
> Fixes: 8510e69c8efe (mm/page_alloc: fix memalloc_nocma_{save/restore} APIs)
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> ---
> mm/page_alloc.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index fab5e97..104d2e1 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3367,9 +3367,16 @@ struct page *rmqueue(struct zone *preferred_zone,
> struct page *page;
>
> if (likely(order == 0)) {
> - page = rmqueue_pcplist(preferred_zone, zone, gfp_flags,
> + /*
> + * MIGRATE_MOVABLE pcplist could have the pages on CMA area and
> + * we need to skip it when CMA area isn't allowed.
> + */
> + if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
> + migratetype != MIGRATE_MOVABLE) {
> + page = rmqueue_pcplist(preferred_zone, zone, gfp_flags,
> migratetype, alloc_flags);
> - goto out;
> + goto out;
> + }
> }
This approach looks definitely better than the previous version.
>
> /*
> @@ -3381,7 +3388,7 @@ struct page *rmqueue(struct zone *preferred_zone,
>
> do {
> page = NULL;
> - if (alloc_flags & ALLOC_HARDER) {
> + if (order > 0 && alloc_flags & ALLOC_HARDER) {
> page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
> if (page)
> trace_mm_page_alloc_zone_locked(page, order, migratetype);
But this condition is not clear to me. __rmqueue_smallest doesn't access
pcp lists. Maybe I have missed the point in the original discussion but
this deserves a comment at least.
> --
> 2.7.4
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-09-29 8:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 8:50 [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs js1304
2020-09-28 23:52 ` Andrew Morton
2020-09-29 1:28 ` Joonsoo Kim
2020-09-29 4:50 ` Andrew Morton
2020-09-29 6:46 ` Joonsoo Kim
2020-09-29 8:08 ` Michal Hocko [this message]
2020-09-29 8:38 ` Joonsoo Kim
2020-09-29 9:53 ` Michal Hocko
2020-09-29 8:13 ` Vlastimil Babka
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=20200929080814.GB22035@dhcp22.suse.cz \
--to=mhocko@suse.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.ibm.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=js1304@gmail.com \
--cc=kernel-team@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=vbabka@suse.cz \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).