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authorCharan Teja Reddy <charante@codeaurora.org>2021-05-05 04:36:51 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 21:27:24 +0300
commit06dac2f467fe9269a433aa5056dd2ee1d20475e9 (patch)
tree95f275981034d644d9a329e8bfe00dd8c2dc39ff /mm
parentef4984384172e93cc95e0e8cd102536d67e8a787 (diff)
downloadlinux-06dac2f467fe9269a433aa5056dd2ee1d20475e9.tar.xz
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 <charante@codeaurora.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/compaction.c8
-rw-r--r--mm/page_alloc.c2
2 files changed, 10 insertions, 0 deletions
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;
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 19cdd8a829dc..64d4aae2a78a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4204,6 +4204,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
memalloc_noreclaim_restore(noreclaim_flag);
psi_memstall_leave(&pflags);
+ if (*compact_result == COMPACT_SKIPPED)
+ return NULL;
/*
* At least in one zone compaction wasn't deferred or skipped, so let's
* count a compaction stall