[138/165] mm/gup: restrict CMA region by using allocation scope API

Commit Message

Andrew Morton Aug. 12, 2020, 1:37 a.m. UTC

From: Joonsoo Kim <[e-mail]>
Subject: mm/gup: restrict CMA region by using allocation scope API

We have well defined scope API to exclude CMA region.  Use it rather than
manipulating gfp_mask manually.  With this change, we can now restore
__GFP_MOVABLE for gfp_mask like as usual migration target allocation.  It
would result in that the ZONE_MOVABLE is also searched by page allocator. 
For hugetlb, gfp_mask is redefined since it has a regular allocation mask
filter for migration target.  __GPF_NOWARN is added to hugetlb gfp_mask
filter since a new user for gfp_mask filter, gup, want to be silent when
allocation fails.

Note that this can be considered as a fix for the commit 9a4e9f3b2d73
("mm: update get_user_pages_longterm to migrate pages allocated from CMA
region").  However, "Fixes" tag isn't added here since it is just
suboptimal but it doesn't cause any problem.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Joonsoo Kim <[e-mail]>
Suggested-by: Michal Hocko <[e-mail]>
Acked-by: Vlastimil Babka <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Roman Gushchin <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Naoya Horiguchi <[e-mail]>
Cc: "Aneesh Kumar K . V" <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 include/linux/hugetlb.h |    2 ++
 mm/gup.c                |   17 ++++++++---------
 2 files changed, 10 insertions(+), 9 deletions(-)

Patch

--- a/include/linux/hugetlb.h~mm-gup-restrict-cma-region-by-using-allocation-scope-api
+++ a/include/linux/hugetlb.h
@@ -710,6 +710,8 @@  static inline gfp_t htlb_modify_alloc_ma
 	/* Some callers might want to enforce node */
 	modified_mask |= (gfp_mask & __GFP_THISNODE);
 
+	modified_mask |= (gfp_mask & __GFP_NOWARN);
+
 	return modified_mask;
 }
 
--- a/mm/gup.c~mm-gup-restrict-cma-region-by-using-allocation-scope-api
+++ a/mm/gup.c
@@ -1620,10 +1620,12 @@  static struct page *new_non_cma_page(str
 	 * Trying to allocate a page for migration. Ignore allocation
 	 * failure warnings. We don't force __GFP_THISNODE here because
 	 * this node here is the node where we have CMA reservation and
-	 * in some case these nodes will have really less non movable
+	 * in some case these nodes will have really less non CMA
 	 * allocation memory.
+	 *
+	 * Note that CMA region is prohibited by allocation scope.
 	 */
-	gfp_t gfp_mask = GFP_USER | __GFP_NOWARN;
+	gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_NOWARN;
 
 	if (PageHighMem(page))
 		gfp_mask |= __GFP_HIGHMEM;
@@ -1631,6 +1633,8 @@  static struct page *new_non_cma_page(str
 #ifdef CONFIG_HUGETLB_PAGE
 	if (PageHuge(page)) {
 		struct hstate *h = page_hstate(page);
+
+		gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
 		/*
 		 * We don't want to dequeue from the pool because pool pages will
 		 * mostly be from the CMA region.
@@ -1645,11 +1649,6 @@  static struct page *new_non_cma_page(str
 		 */
 		gfp_t thp_gfpmask = GFP_TRANSHUGE | __GFP_NOWARN;
 
-		/*
-		 * Remove the movable mask so that we don't allocate from
-		 * CMA area again.
-		 */
-		thp_gfpmask &= ~__GFP_MOVABLE;
 		thp = __alloc_pages_node(nid, thp_gfpmask, HPAGE_PMD_ORDER);
 		if (!thp)
 			return NULL;
@@ -1795,7 +1794,6 @@  static long __gup_longterm_locked(struct
 				     vmas_tmp, NULL, gup_flags);
 
 	if (gup_flags & FOLL_LONGTERM) {
-		memalloc_nocma_restore(flags);
 		if (rc < 0)
 			goto out;
 
@@ -1808,9 +1806,10 @@  static long __gup_longterm_locked(struct
 
 		rc = check_and_migrate_cma_pages(tsk, mm, start, rc, pages,
 						 vmas_tmp, gup_flags);
+out:
+		memalloc_nocma_restore(flags);
 	}
 
-out:
 	if (vmas_tmp != vmas)
 		kfree(vmas_tmp);
 	return rc;