mm, page_alloc: pass preferred nid instead of zonelist to allocator

The main allocator function __alloc_pages_nodemask() takes a zonelist
pointer as one of its parameters.  All of its callers directly or
indirectly obtain the zonelist via node_zonelist() using a preferred
node id and gfp_mask.  We can make the code a bit simpler by doing the
zonelist lookup in __alloc_pages_nodemask(), passing it a preferred node
id instead (gfp_mask is already another parameter).

There are some code size benefits thanks to removal of inlined
node_zonelist():

  bloat-o-meter add/remove: 2/2 grow/shrink: 4/36 up/down: 399/-1351 (-952)

This will also make things simpler if we proceed with converting cpusets
to zonelists.

Link: http://lkml.kernel.org/r/20170517081140.30654-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Christoph Lameter <cl@linux.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/gfp.h

@@ -432,14 +432,13 @@ static inline void arch_alloc_page(struct page *page, int order) { }
 #endif
 
 struct page *
-__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
-		       struct zonelist *zonelist, nodemask_t *nodemask);
+__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
+							nodemask_t *nodemask);
 
 static inline struct page *
-__alloc_pages(gfp_t gfp_mask, unsigned int order,
-		struct zonelist *zonelist)
+__alloc_pages(gfp_t gfp_mask, unsigned int order, int preferred_nid)
 {
-	return __alloc_pages_nodemask(gfp_mask, order, zonelist, NULL);
+	return __alloc_pages_nodemask(gfp_mask, order, preferred_nid, NULL);
 }
 
 /*
@@ -452,7 +451,7 @@ __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
 	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
 	VM_WARN_ON(!node_online(nid));
 
-	return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
+	return __alloc_pages(gfp_mask, order, nid);
 }
 
 /*

include/linux/mempolicy.h

@@ -146,7 +146,7 @@ extern void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new,
 				enum mpol_rebind_step step);
 extern void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new);
 
-extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
+extern int huge_node(struct vm_area_struct *vma,
 				unsigned long addr, gfp_t gfp_flags,
 				struct mempolicy **mpol, nodemask_t **nodemask);
 extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
@@ -269,13 +269,13 @@ static inline void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
 {
 }
 
-static inline struct zonelist *huge_zonelist(struct vm_area_struct *vma,
+static inline int huge_node(struct vm_area_struct *vma,
 				unsigned long addr, gfp_t gfp_flags,
 				struct mempolicy **mpol, nodemask_t **nodemask)
 {
 	*mpol = NULL;
 	*nodemask = NULL;
-	return node_zonelist(0, gfp_flags);
+	return 0;
 }
 
 static inline bool init_nodemask_of_mempolicy(nodemask_t *m)

mm/hugetlb.c

@@ -920,6 +920,8 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
 	struct page *page = NULL;
 	struct mempolicy *mpol;
 	nodemask_t *nodemask;
+	gfp_t gfp_mask;
+	int nid;
 	struct zonelist *zonelist;
 	struct zone *zone;
 	struct zoneref *z;
@@ -940,12 +942,13 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
 
 retry_cpuset:
 	cpuset_mems_cookie = read_mems_allowed_begin();
-	zonelist = huge_zonelist(vma, address,
-					htlb_alloc_mask(h), &mpol, &nodemask);
+	gfp_mask = htlb_alloc_mask(h);
+	nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
+	zonelist = node_zonelist(nid, gfp_mask);
 
 	for_each_zone_zonelist_nodemask(zone, z, zonelist,
 						MAX_NR_ZONES - 1, nodemask) {
-		if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
+		if (cpuset_zone_allowed(zone, gfp_mask)) {
 			page = dequeue_huge_page_node(h, zone_to_nid(zone));
 			if (page) {
 				if (avoid_reserve)
@@ -1558,13 +1561,13 @@ static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
 	do {
 		struct page *page;
 		struct mempolicy *mpol;
-		struct zonelist *zl;
+		int nid;
 		nodemask_t *nodemask;
 
 		cpuset_mems_cookie = read_mems_allowed_begin();
-		zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
+		nid = huge_node(vma, addr, gfp, &mpol, &nodemask);
 		mpol_cond_put(mpol);
-		page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
+		page = __alloc_pages_nodemask(gfp, order, nid, nodemask);
 		if (page)
 			return page;
 	} while (read_mems_allowed_retry(cpuset_mems_cookie));

mm/memory_hotplug.c

@@ -1459,11 +1459,9 @@ static struct page *new_node_page(struct page *page, unsigned long private,
 		gfp_mask |= __GFP_HIGHMEM;
 
 	if (!nodes_empty(nmask))
-		new_page = __alloc_pages_nodemask(gfp_mask, 0,
-					node_zonelist(nid, gfp_mask), &nmask);
+		new_page = __alloc_pages_nodemask(gfp_mask, 0, nid, &nmask);
 	if (!new_page)
-		new_page = __alloc_pages(gfp_mask, 0,
-					node_zonelist(nid, gfp_mask));
+		new_page = __alloc_pages(gfp_mask, 0, nid);
 
 	return new_page;
 }

mm/mempolicy.c

@@ -1669,9 +1669,9 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
 	return NULL;
 }
 
-/* Return a zonelist indicated by gfp for node representing a mempolicy */
-static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
-	int nd)
+/* Return the node id preferred by the given mempolicy, or the given id */
+static int policy_node(gfp_t gfp, struct mempolicy *policy,
+								int nd)
 {
 	if (policy->mode == MPOL_PREFERRED && !(policy->flags & MPOL_F_LOCAL))
 		nd = policy->v.preferred_node;
@@ -1684,7 +1684,7 @@ static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
 		WARN_ON_ONCE(policy->mode == MPOL_BIND && (gfp & __GFP_THISNODE));
 	}
 
-	return node_zonelist(nd, gfp);
+	return nd;
 }
 
 /* Do dynamic interleaving for a process */
@@ -1791,38 +1791,37 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
 
 #ifdef CONFIG_HUGETLBFS
 /*
- * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)
+ * huge_node(@vma, @addr, @gfp_flags, @mpol)
  * @vma: virtual memory area whose policy is sought
  * @addr: address in @vma for shared policy lookup and interleave policy
  * @gfp_flags: for requested zone
  * @mpol: pointer to mempolicy pointer for reference counted mempolicy
  * @nodemask: pointer to nodemask pointer for MPOL_BIND nodemask
  *
- * Returns a zonelist suitable for a huge page allocation and a pointer
+ * Returns a nid suitable for a huge page allocation and a pointer
  * to the struct mempolicy for conditional unref after allocation.
  * If the effective policy is 'BIND, returns a pointer to the mempolicy's
  * @nodemask for filtering the zonelist.
  *
  * Must be protected by read_mems_allowed_begin()
  */
-struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
-				gfp_t gfp_flags, struct mempolicy **mpol,
-				nodemask_t **nodemask)
+int huge_node(struct vm_area_struct *vma, unsigned long addr, gfp_t gfp_flags,
+				struct mempolicy **mpol, nodemask_t **nodemask)
 {
-	struct zonelist *zl;
+	int nid;
 
 	*mpol = get_vma_policy(vma, addr);
 	*nodemask = NULL;	/* assume !MPOL_BIND */
 
 	if (unlikely((*mpol)->mode == MPOL_INTERLEAVE)) {
-		zl = node_zonelist(interleave_nid(*mpol, vma, addr,
-				huge_page_shift(hstate_vma(vma))), gfp_flags);
+		nid = interleave_nid(*mpol, vma, addr,
+					huge_page_shift(hstate_vma(vma)));
 	} else {
-		zl = policy_zonelist(gfp_flags, *mpol, numa_node_id());
+		nid = policy_node(gfp_flags, *mpol, numa_node_id());
 		if ((*mpol)->mode == MPOL_BIND)
 			*nodemask = &(*mpol)->v.nodes;
 	}
-	return zl;
+	return nid;
 }
 
 /*
@@ -1924,12 +1923,10 @@ out:
 static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
 					unsigned nid)
 {
-	struct zonelist *zl;
 	struct page *page;
 
-	zl = node_zonelist(nid, gfp);
-	page = __alloc_pages(gfp, order, zl);
-	if (page && page_zone(page) == zonelist_zone(&zl->_zonerefs[0]))
+	page = __alloc_pages(gfp, order, nid);
+	if (page && page_to_nid(page) == nid)
 		inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
 	return page;
 }
@@ -1963,8 +1960,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
 {
 	struct mempolicy *pol;
 	struct page *page;
+	int preferred_nid;
 	unsigned int cpuset_mems_cookie;
-	struct zonelist *zl;
 	nodemask_t *nmask;
 
 retry_cpuset:
@@ -2007,8 +2004,8 @@ retry_cpuset:
 	}
 
 	nmask = policy_nodemask(gfp, pol);
-	zl = policy_zonelist(gfp, pol, node);
-	page = __alloc_pages_nodemask(gfp, order, zl, nmask);
+	preferred_nid = policy_node(gfp, pol, node);
+	page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask);
 	mpol_cond_put(pol);
 out:
 	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
@@ -2055,7 +2052,7 @@ retry_cpuset:
 		page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
 	else
 		page = __alloc_pages_nodemask(gfp, order,
-				policy_zonelist(gfp, pol, numa_node_id()),
+				policy_node(gfp, pol, numa_node_id()),
 				policy_nodemask(gfp, pol));
 
 	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))

mm/page_alloc.c

@@ -3980,12 +3980,12 @@ got_pg:
 }
 
 static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
-		struct zonelist *zonelist, nodemask_t *nodemask,
+		int preferred_nid, nodemask_t *nodemask,
 		struct alloc_context *ac, gfp_t *alloc_mask,
 		unsigned int *alloc_flags)
 {
 	ac->high_zoneidx = gfp_zone(gfp_mask);
-	ac->zonelist = zonelist;
+	ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
 	ac->nodemask = nodemask;
 	ac->migratetype = gfpflags_to_migratetype(gfp_mask);
 
@@ -4030,8 +4030,8 @@ static inline void finalise_ac(gfp_t gfp_mask,
  * This is the 'heart' of the zoned buddy allocator.
  */
 struct page *
-__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
-			struct zonelist *zonelist, nodemask_t *nodemask)
+__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
+							nodemask_t *nodemask)
 {
 	struct page *page;
 	unsigned int alloc_flags = ALLOC_WMARK_LOW;
@@ -4039,7 +4039,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	struct alloc_context ac = { };
 
 	gfp_mask &= gfp_allowed_mask;
-	if (!prepare_alloc_pages(gfp_mask, order, zonelist, nodemask, &ac, &alloc_mask, &alloc_flags))
+	if (!prepare_alloc_pages(gfp_mask, order, preferred_nid, nodemask, &ac, &alloc_mask, &alloc_flags))
 		return NULL;
 
 	finalise_ac(gfp_mask, order, &ac);