From: Michal Hocko <mhocko@suse.com>
To: Charan Teja Reddy <charante@codeaurora.org>
Cc: akpm@linux-foundation.org, vbabka@suse.cz, david@redhat.com,
rientjes@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, vinmenon@codeaurora.org
Subject: Re: [PATCH V2] mm, page_alloc: fix core hung in free_pcppages_bulk()
Date: Thu, 13 Aug 2020 13:41:05 +0200 [thread overview]
Message-ID: <20200813114105.GI9477@dhcp22.suse.cz> (raw)
In-Reply-To: <1597150703-19003-1-git-send-email-charante@codeaurora.org>
On Tue 11-08-20 18:28:23, Charan Teja Reddy wrote:
[...]
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index e4896e6..839039f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1304,6 +1304,11 @@ static void free_pcppages_bulk(struct zone *zone, int count,
> struct page *page, *tmp;
> LIST_HEAD(head);
>
> + /*
> + * Ensure proper count is passed which otherwise would stuck in the
> + * below while (list_empty(list)) loop.
> + */
> + count = min(pcp->count, count);
> while (count) {
> struct list_head *list;
How does this prevent the race actually? Don't we need something like
the following instead?
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e028b87ce294..45bcc7ba37c4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1317,9 +1317,16 @@ static void free_pcppages_bulk(struct zone *zone, int count,
* lists
*/
do {
+ bool looped = false;
+
batch_free++;
- if (++migratetype == MIGRATE_PCPTYPES)
+ if (++migratetype == MIGRATE_PCPTYPES) {
+ if (looped)
+ goto free;
+
migratetype = 0;
+ looped = true;
+ }
list = &pcp->lists[migratetype];
} while (list_empty(list));
@@ -1352,6 +1359,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
} while (--count && --batch_free && !list_empty(list));
}
+free:
spin_lock(&zone->lock);
isolated_pageblocks = has_isolate_pageblock(zone);
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-08-13 11:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 12:58 [PATCH V2] mm, page_alloc: fix core hung in free_pcppages_bulk() Charan Teja Reddy
2020-08-11 21:05 ` David Hildenbrand
2020-08-12 9:46 ` Charan Teja Kalla
2020-08-12 10:00 ` David Hildenbrand
2020-08-12 10:11 ` Charan Teja Kalla
2020-08-13 9:32 ` David Hildenbrand
2020-08-12 18:53 ` David Rientjes
2020-08-13 11:41 ` Michal Hocko [this message]
2020-08-13 16:21 ` Charan Teja Kalla
2020-08-13 16:30 ` Michal Hocko
2020-08-13 17:27 ` Charan Teja Kalla
2020-08-14 6:39 ` Michal Hocko
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