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From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	hyesoo.yu@samsung.com, david@redhat.com, mhocko@suse.com,
	surenb@google.com, pullip.cho@samsung.com, joaodias@google.com,
	hridya@google.com, john.stultz@linaro.org,
	sumit.semwal@linaro.org, linux-media@vger.kernel.org,
	devicetree@vger.kernel.org, hch@infradead.org,
	robh+dt@kernel.org, linaro-mm-sig@lists.linaro.org,
	Minchan Kim <minchan@kernel.org>
Subject: [PATCH v4 2/4] mm: failfast mode with __GFP_NORETRY in alloc_contig_range
Date: Thu, 21 Jan 2021 09:55:00 -0800
Message-ID: <20210121175502.274391-3-minchan@kernel.org> (raw)
In-Reply-To: <20210121175502.274391-1-minchan@kernel.org>

Contiguous memory allocation can be stalled due to waiting
on page writeback and/or page lock which causes unpredictable
delay. It's a unavoidable cost for the requestor to get *big*
contiguous memory but it's expensive for *small* contiguous
memory(e.g., order-4) because caller could retry the request
in different range where would have easy migratable pages
without stalling.

This patch introduce __GFP_NORETRY as compaction gfp_mask in
alloc_contig_range so it will fail fast without blocking
when it encounters pages needed waiting.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 mm/page_alloc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b031a5ae0bd5..1cdc3ee0b22e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8491,12 +8491,16 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 	unsigned int nr_reclaimed;
 	unsigned long pfn = start;
 	unsigned int tries = 0;
+	unsigned int max_tries = 5;
 	int ret = 0;
 	struct migration_target_control mtc = {
 		.nid = zone_to_nid(cc->zone),
 		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
 	};
 
+	if (cc->alloc_contig && cc->mode == MIGRATE_ASYNC)
+		max_tries = 1;
+
 	migrate_prep();
 
 	while (pfn < end || !list_empty(&cc->migratepages)) {
@@ -8513,7 +8517,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 				break;
 			}
 			tries = 0;
-		} else if (++tries == 5) {
+		} else if (++tries == max_tries) {
 			ret = ret < 0 ? ret : -EBUSY;
 			break;
 		}
@@ -8564,7 +8568,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 		.nr_migratepages = 0,
 		.order = -1,
 		.zone = page_zone(pfn_to_page(start)),
-		.mode = MIGRATE_SYNC,
+		.mode = gfp_mask & __GFP_NORETRY ? MIGRATE_ASYNC : MIGRATE_SYNC,
 		.ignore_skip_hint = true,
 		.no_set_skip_hint = true,
 		.gfp_mask = current_gfp_context(gfp_mask),
-- 
2.30.0.296.g2bfb1c46d8-goog


  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-21 17:54 [PATCH v4 0/4] Chunk Heap Support on DMA-HEAP Minchan Kim
2021-01-21 17:54 ` [PATCH v4 1/4] mm: cma: introduce gfp flag in cma_alloc instead of no_warn Minchan Kim
2021-01-21 18:46   ` David Hildenbrand
2021-01-21 18:50   ` Minchan Kim
2021-01-25 13:07   ` Michal Hocko
2021-01-25 19:42     ` Minchan Kim
2021-01-26  7:38       ` Michal Hocko
2021-01-26 19:12         ` Minchan Kim
2021-01-27 20:21           ` Minchan Kim
2021-01-21 17:55 ` Minchan Kim [this message]
2021-01-25 13:12   ` [PATCH v4 2/4] mm: failfast mode with __GFP_NORETRY in alloc_contig_range Michal Hocko
2021-01-25 13:13     ` Michal Hocko
2021-01-25 19:33     ` Minchan Kim
2021-01-26  7:44       ` Michal Hocko
2021-01-26 19:10         ` Minchan Kim
2021-01-27  8:14           ` Michal Hocko
2021-01-27 20:42         ` Minchan Kim
2021-01-28  7:53           ` Michal Hocko
2021-01-28 16:56             ` Minchan Kim
2021-01-21 17:55 ` [PATCH v4 3/4] dt-bindings: reserved-memory: Make DMA-BUF CMA heap DT-configurable Minchan Kim
2021-01-26  7:07   ` John Stultz
2021-01-27 20:25     ` Hridya Valsaraju
2021-02-05 22:55   ` Rob Herring
2021-01-21 17:55 ` [PATCH v4 4/4] dma-buf: heaps: add chunk heap to dmabuf heaps Minchan Kim
2021-01-26  7:07   ` Christoph Hellwig
2021-01-26 19:27     ` Minchan Kim
2021-01-26  7:32   ` John Stultz
2021-01-26 19:24     ` Minchan Kim
2021-01-26  7:46   ` Michal Hocko
2021-01-26 19:25     ` Minchan Kim
2021-01-27  8:09       ` Michal Hocko

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