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mm,thp,compaction,cma: allow THP migration for CMA allocations

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The code to implement THP migrations already exists, and the code for CMA
to clear out a region of memory already exists.

Only a few small tweaks are needed to allow CMA to move THP memory when
attempting an allocation from alloc_contig_range.

With these changes, migrating THPs from a CMA area works when allocating a
1GB hugepage from CMA memory.

[riel@surriel.com: fix hugetlbfs pages per Mike, cleanup per Vlastimil]
  Link: http://lkml.kernel.org/r/20200228104700.0af2f18d@imladris.surriel.com
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Link: http://lkml.kernel.org/r/20200227213238.1298752-2-riel@surriel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rik van Riel 2020-04-01 21:10:31 -07:00 committed by Linus Torvalds
parent b06eda091e
commit 1da2f328fa
2 changed files with 20 additions and 11 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

22
mm/compaction.c
View file

@ -894,12 +894,13 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
/* /*
* Regardless of being on LRU, compound pages such as THP and * Regardless of being on LRU, compound pages such as THP and
* hugetlbfs are not to be compacted. We can potentially save * hugetlbfs are not to be compacted unless we are attempting
* a lot of iterations if we skip them at once. The check is * an allocation much larger than the huge page size (eg CMA).
* racy, but we can consider only valid values and the only * We can potentially save a lot of iterations if we skip them
* danger is skipping too much. * at once. The check is racy, but we can consider only valid
* values and the only danger is skipping too much.
*/ */
if (PageCompound(page)) { if (PageCompound(page) && !cc->alloc_contig) {
const unsigned int order = compound_order(page); const unsigned int order = compound_order(page);
if (likely(order < MAX_ORDER)) if (likely(order < MAX_ORDER))
@ -969,7 +970,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
* and it's on LRU. It can only be a THP so the order * and it's on LRU. It can only be a THP so the order
* is safe to read and it's 0 for tail pages. * is safe to read and it's 0 for tail pages.
*/ */
if (unlikely(PageCompound(page))) { if (unlikely(PageCompound(page) && !cc->alloc_contig)) {
low_pfn += compound_nr(page) - 1; low_pfn += compound_nr(page) - 1;
goto isolate_fail; goto isolate_fail;
} }
@ -981,12 +982,15 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
if (__isolate_lru_page(page, isolate_mode) != 0) if (__isolate_lru_page(page, isolate_mode) != 0)
goto isolate_fail; goto isolate_fail;
VM_BUG_ON_PAGE(PageCompound(page), page); /* The whole page is taken off the LRU; skip the tail pages. */
if (PageCompound(page))
low_pfn += compound_nr(page) - 1;
/* Successfully isolated */ /* Successfully isolated */
del_page_from_lru_list(page, lruvec, page_lru(page)); del_page_from_lru_list(page, lruvec, page_lru(page));
inc_node_page_state(page, mod_node_page_state(page_pgdat(page),
NR_ISOLATED_ANON + page_is_file_cache(page)); NR_ISOLATED_ANON + page_is_file_cache(page),
hpage_nr_pages(page));
isolate_success: isolate_success:
list_add(&page->lru, &cc->migratepages); list_add(&page->lru, &cc->migratepages);

7
mm/page_alloc.c
View file

@ -8251,15 +8251,20 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page,
/* /*
* Hugepages are not in LRU lists, but they're movable. * Hugepages are not in LRU lists, but they're movable.
* THPs are on the LRU, but need to be counted as #small pages.
* We need not scan over tail pages because we don't * We need not scan over tail pages because we don't
* handle each tail page individually in migration. * handle each tail page individually in migration.
*/ */
if (PageHuge(page)) { if (PageHuge(page) || PageTransCompound(page)) {
struct page *head = compound_head(page); struct page *head = compound_head(page);
unsigned int skip_pages; unsigned int skip_pages;
if (PageHuge(page)) {
if (!hugepage_migration_supported(page_hstate(head))) if (!hugepage_migration_supported(page_hstate(head)))
return page; return page;
} else if (!PageLRU(head) && !__PageMovable(head)) {
return page;
}
skip_pages = compound_nr(head) - (page - head); skip_pages = compound_nr(head) - (page - head);
iter += skip_pages - 1; iter += skip_pages - 1;