From: Muchun Song <songmuchun@bytedance.com>
To: akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Muchun Song <songmuchun@bytedance.com>,
Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v2] mm/page_isolation: do not isolate the max order page
Date: Fri, 4 Dec 2020 00:22:37 +0800 [thread overview]
Message-ID: <20201203162237.21885-1-songmuchun@bytedance.com> (raw)
The max order page has no buddy page and never merge to other order.
So isolating and then freeing it is pointless. And if order == MAX_ORDER
- 1, then the buddy can actually be a !pfn_valid() in some corner case?
pfn_valid_within(buddy_pfn) that follows would only catch it on archs
with holes in zone. Then is_migrate_isolate_page(buddy) might access an
invalid buddy. So this is also a bug fix.
Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
Changes in v2:
- Add Fixes tag in the commit log.
mm/page_isolation.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index a254e1f370a3..bddf788f45bf 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -88,7 +88,7 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
*/
if (PageBuddy(page)) {
order = buddy_order(page);
- if (order >= pageblock_order) {
+ if (order >= pageblock_order && order < MAX_ORDER - 1) {
pfn = page_to_pfn(page);
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
--
2.11.0
next reply other threads:[~2020-12-03 16:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 16:22 Muchun Song [this message]
2020-12-03 16:28 ` [PATCH v2] mm/page_isolation: do not isolate the max order page David Hildenbrand
2020-12-04 16:12 ` [External] " Muchun Song
2020-12-04 17:12 ` David Hildenbrand
2020-12-07 13:42 ` Oscar Salvador
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=20201203162237.21885-1-songmuchun@bytedance.com \
--to=songmuchun@bytedance.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--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).