Subject: + mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch added to -mm tree To: iamjoonsoo.kim@xxxxxxx,mgorman@xxxxxxx,riel@xxxxxxxxxx,vbabka@xxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Fri, 21 Feb 2014 14:52:54 -0800 The patch titled Subject: mm/compaction: change the timing to check to drop the spinlock has been added to the -mm tree. Its filename is mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Subject: mm/compaction: change the timing to check to drop the spinlock It is odd to drop the spinlock when we scan (SWAP_CLUSTER_MAX - 1) th pfn page. This may results in below situation while isolating migratepage. 1. try isolate 0x0 ~ 0x200 pfn pages. 2. When low_pfn is 0x1ff, ((low_pfn+1) % SWAP_CLUSTER_MAX) == 0, so drop the spinlock. 3. Then, to complete isolating, retry to aquire the lock. I think that it is better to use SWAP_CLUSTER_MAX th pfn for checking the criteria about dropping the lock. This has no harm 0x0 pfn, because, at this time, locked variable would be false. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/compaction.c~mm-compaction-change-the-timing-to-check-to-drop-the-spinlock mm/compaction.c --- a/mm/compaction.c~mm-compaction-change-the-timing-to-check-to-drop-the-spinlock +++ a/mm/compaction.c @@ -481,7 +481,7 @@ isolate_migratepages_range(struct zone * cond_resched(); for (; low_pfn < end_pfn; low_pfn++) { /* give a chance to irqs before checking need_resched() */ - if (locked && !((low_pfn+1) % SWAP_CLUSTER_MAX)) { + if (locked && !(low_pfn % SWAP_CLUSTER_MAX)) { if (should_release_lock(&zone->lru_lock)) { spin_unlock_irqrestore(&zone->lru_lock, flags); locked = false; _ Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are kthread-ensure-locality-of-task_struct-allocations.patch mm-hugetlb-unify-region-structure-handling.patch mm-hugetlb-improve-cleanup-resv_map-parameters.patch mm-hugetlb-fix-race-in-region-tracking.patch mm-hugetlb-remove-resv_map_put.patch mm-hugetlb-use-vma_resv_map-map-types.patch mm-hugetlb-improve-page-fault-scalability.patch mm-hugetlb-improve-page-fault-scalability-fix.patch mm-hugetlb-mark-some-bootstrap-functions-as-__init.patch mm-compaction-avoid-isolating-pinned-pages.patch mm-compaction-disallow-high-order-page-for-migration-target.patch mm-compaction-do-not-call-suitable_migration_target-on-every-page.patch mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch mm-compaction-check-pageblock-suitability-once-per-pageblock.patch mm-compaction-clean-up-code-on-success-of-ballon-isolation.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html