From: Lecopzer Chen <lecopzer.chen@mediatek.com>
To: <akpm@linux-foundation.org>, <mgorman@techsingularity.net>
Cc: <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<vbabka@suse.cz>, <nsaenzju@redhat.com>, <yj.chiang@mediatek.com>,
Lecopzer Chen <lecopzer.chen@mediatek.com>,
Mark-pk Tsai <mark-pk.tsai@mediatek.com>,
Joe Liu <joe.liu@mediatek.com>
Subject: [PATCH] mm: page_alloc: fix cma pageblock was stolen in rmqueue fallback
Date: Wed, 30 Aug 2023 19:13:33 +0800 [thread overview]
Message-ID: <20230830111332.7599-1-lecopzer.chen@mediatek.com> (raw)
commit 4b23a68f9536 ("mm/page_alloc: protect PCP lists with a
spinlock") fallback freeing page to free_one_page() if pcp trylock
failed. This make MIGRATE_CMA be able to fallback and be stolen
whole pageblock by MIGRATE_UNMOVABLE in the page allocation.
PCP free is fine because free_pcppages_bulk() will always get
migratetype again before freeing the page, thus this only happen when
someone tried to put CMA page in to other MIGRATE_TYPE's freelist.
Fixes: 4b23a68f9536 ("mm/page_alloc: protect PCP lists with a spinlock")
Reported-by: Joe Liu <joe.liu@mediatek.com>
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Mark-pk Tsai <mark-pk.tsai@mediatek.com>
Cc: Joe Liu <joe.liu@mediatek.com>
---
mm/page_alloc.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 452459836b71..0ea88c031838 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2428,6 +2428,14 @@ void free_unref_page(struct page *page, unsigned int order)
free_unref_page_commit(zone, pcp, page, migratetype, order);
pcp_spin_unlock(pcp);
} else {
+#ifdef CONFIG_CMA
+ /*
+ * CMA must be back to its freelist. Otherwise CMA pageblock may
+ * be stolen by fallback flow while getting free page.
+ */
+ if (get_pcppage_migratetype(page) == MIGRATE_CMA)
+ migratetype = MIGRATE_CMA;
+#endif
free_one_page(zone, page, pfn, order, migratetype, FPI_NONE);
}
pcp_trylock_finish(UP_flags);
--
2.18.0
next reply other threads:[~2023-08-30 11:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-30 11:13 Lecopzer Chen [this message]
2023-09-05 9:09 ` [PATCH] mm: page_alloc: fix cma pageblock was stolen in rmqueue fallback Mel Gorman
2023-09-05 9:22 ` Lecopzer Chen
2023-09-05 9:37 ` Vlastimil Babka
2023-09-05 12:28 ` Mel Gorman
2023-09-11 15:57 ` Johannes Weiner
2023-09-11 16:13 ` Vlastimil Babka
2023-09-11 18:11 ` Johannes Weiner
2023-09-11 19:59 ` Vlastimil Babka
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