Hi,
On 2021/12/10 07:04, Zi Yan wrote:
From: Zi Yan <ziy@nvidia.com>
alloc_migration_target() is used by alloc_contig_range() and non-LRU
movable compound pages can be migrated. Current code does not allocate the
right page size for such pages. Check THP precisely using
is_transparent_huge() and add allocation support for non-LRU compound
pages.
Could you elaborate on why the current code doesn't get the right size? how this patch fixes it.
The description sounds like it's an existing bug, if so, the patch subject should be changed to
"Fixes ..."?
quoted hunk ↗ jump to hunk
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
mm/migrate.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index d487a399253b..2ce3c771b1de 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1563,7 +1563,7 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask);
}
- if (PageTransHuge(page)) {
+ if (is_transparent_hugepage(page)) {
/*
* clear __GFP_RECLAIM to make the migration callback
* consistent with regular THP allocations.@@ -1572,13 +1572,17 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
if (PageTransHuge(page)) { // just give more code context
... gfp_mask |= GFP_TRANSHUGE;
order = HPAGE_PMD_ORDER;
order assigned here
quoted hunk ↗ jump to hunk
}
+ if (PageCompound(page)) {
+ gfp_mask |= __GFP_COMP;
+ order = compound_order(page);
re-assinged again as THP is a compound page?
Thanks,
Eric
quoted hunk ↗ jump to hunk
+ }
zidx = zone_idx(page_zone(page));
if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
gfp_mask |= __GFP_HIGHMEM;
new_page = __alloc_pages(gfp_mask, order, nid, mtc->nmask);
- if (new_page && PageTransHuge(new_page))
+ if (new_page && is_transparent_hugepage(page))
prep_transhuge_page(new_page);
return new_page;