From 06dac2f467fe9269a433aa5056dd2ee1d20475e9 Mon Sep 17 00:00:00 2001 From: Charan Teja Reddy Date: Tue, 4 May 2021 18:36:51 -0700 Subject: mm: compaction: update the COMPACT[STALL|FAIL] events properly By definition, COMPACT[STALL|FAIL] events needs to be counted when there is 'At least in one zone compaction wasn't deferred or skipped from the direct compaction'. And when compaction is skipped or deferred, COMPACT_SKIPPED will be returned but it will still go and update these compaction events which is wrong in the sense that COMPACT[STALL|FAIL] is counted without even trying the compaction. Correct this by skipping the counting of these events when COMPACT_SKIPPED is returned for compaction. This indirectly also avoid the unnecessary try into the get_page_from_freelist() when compaction is not even tried. There is a corner case where compaction is skipped but still count COMPACTSTALL event, which is that IRQ came and freed the page and the same is captured in capture_control. Link: https://lkml.kernel.org/r/1613151184-21213-1-git-send-email-charante@codeaurora.org Signed-off-by: Charan Teja Reddy Acked-by: Vlastimil Babka Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/compaction.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'mm/compaction.c') diff --git a/mm/compaction.c b/mm/compaction.c index 027eb794e747..1be7928af62b 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2529,6 +2529,14 @@ static enum compact_result compact_zone_order(struct zone *zone, int order, */ WRITE_ONCE(current->capture_control, NULL); *capture = READ_ONCE(capc.page); + /* + * Technically, it is also possible that compaction is skipped but + * the page is still captured out of luck(IRQ came and freed the page). + * Returning COMPACT_SUCCESS in such cases helps in properly accounting + * the COMPACT[STALL|FAIL] when compaction is skipped. + */ + if (*capture) + ret = COMPACT_SUCCESS; return ret; } -- cgit 1.4.1