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.

Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Link: http://lkml.kernel.org/r/1596180906-8442-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 30e1f14..d86c827 100644 (file)
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -710,6 +710,8 @@ static inline gfp_t htlb_modify_alloc_mask(struct hstate *h, gfp_t gfp_mask)
        /* Some callers might want to enforce node */
        modified_mask |= (gfp_mask & __GFP_THISNODE);
 
+       modified_mask |= (gfp_mask & __GFP_NOWARN);
+
        return modified_mask;
 }
 

diff --git a/mm/gup.c b/mm/gup.c
index d8a33dd..6c20c6e 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1620,10 +1620,12 @@ static struct page *new_non_cma_page(struct page *page, unsigned long private)
         * 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(struct page *page, unsigned long private)
 #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(struct page *page, unsigned long private)
                 */
                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 task_struct *tsk,
                                     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 task_struct *tsk,
 
                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;