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FROMLIST: mm: failfast mode with __GFP_NORETRY in alloc_contig_range

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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.

Bug: 170340257
Bug: 120293424
Link: https://lore.kernel.org/linux-mm/YAnM5PbNJZlk%2F%2FiX@google.com/T/#m1362218ebb69e6e10c20d9361008b079745c4e6f
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Minchan Kim <minchan@google.com>
Change-Id: I42ba8dd5aeb065d936978ab205e4baf84bf9a321
This commit is contained in:
Minchan Kim
2020-12-21 18:01:56 -08:00
committed by Minchan Kim
parent 23ba990a3e
commit 20512940b8
1 changed files with 6 additions and 2 deletions
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8
mm/page_alloc.c
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@@ -8480,12 +8480,16 @@ 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)) {
@@ -8502,7 +8506,7 @@ 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;
}
@@ -8553,7 +8557,7 @@ 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),