mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma

The previous commit ("mm/thp: Allocate transparent hugepages on local
node") introduced alloc_hugepage_vma() to mm/mempolicy.c to perform a
special policy for THP allocations.  The function has the same interface
as alloc_pages_vma(), shares a lot of boilerplate code and a long
comment.

This patch merges the hugepage special case into alloc_pages_vma.  The
extra if condition should be cheap enough price to pay.  We also prevent
a (however unlikely) race with parallel mems_allowed update, which could
make hugepage allocation restart only within the fallback call to
alloc_hugepage_vma() and not reconsider the special rule in
alloc_hugepage_vma().

Also by making sure mpol_cond_put(pol) is always called before actual
allocation attempt, we can use a single exit path within the function.

Also update the comment for missing node parameter and obsolete reference
to mm_sem.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 60110e06419d..51bd1e72a917 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -334,22 +334,22 @@ alloc_pages(gfp_t gfp_mask, unsigned int order)
 }
 extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
                         struct vm_area_struct *vma, unsigned long addr,
-                        int node);
-extern struct page *alloc_hugepage_vma(gfp_t gfp, struct vm_area_struct *vma,
-                                       unsigned long addr, int order);
+                        int node, bool hugepage);
+#define alloc_hugepage_vma(gfp_mask, vma, addr, order)  \
+        alloc_pages_vma(gfp_mask, order, vma, addr, numa_node_id(), true)
 #else
 #define alloc_pages(gfp_mask, order) \
                 alloc_pages_node(numa_node_id(), gfp_mask, order)
-#define alloc_pages_vma(gfp_mask, order, vma, addr, node)       \
+#define alloc_pages_vma(gfp_mask, order, vma, addr, node, false)\
         alloc_pages(gfp_mask, order)
 #define alloc_hugepage_vma(gfp_mask, vma, addr, order)  \
         alloc_pages(gfp_mask, order)
 #endif
 #define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
 #define alloc_page_vma(gfp_mask, vma, addr)                     \
-        alloc_pages_vma(gfp_mask, 0, vma, addr, numa_node_id())
+        alloc_pages_vma(gfp_mask, 0, vma, addr, numa_node_id(), false)
 #define alloc_page_vma_node(gfp_mask, vma, addr, node)          \
-        alloc_pages_vma(gfp_mask, 0, vma, addr, node)
+        alloc_pages_vma(gfp_mask, 0, vma, addr, node, false)
 
 extern struct page *alloc_kmem_pages(gfp_t gfp_mask, unsigned int order);
 extern struct page *alloc_kmem_pages_node(int nid, gfp_t gfp_mask,