[mm PATCH v6 0/7] Deferred page init improvements

[mm PATCH v6 0/7] Deferred page init improvements

[Alexander Duyck]

This patchset is essentially a refactor of the page initialization logic
that is meant to provide for better code reuse while providing a
significant improvement in deferred page initialization performance.

In my testing on an x86_64 system with 384GB of RAM and 3TB of persistent
memory per node I have seen the following. In the case of regular memory
initialization the deferred init time was decreased from 3.75s to 1.06s on
average. For the persistent memory the initialization time dropped from
24.17s to 19.12s on average. This amounts to a 253% improvement for the
deferred memory initialization performance, and a 26% improvement in the
persistent memory initialization performance.

I have called out the improvement observed with each patch.

Note: This patch set is meant as a replacment for the v5 set that is already
      in the MM tree.
      
      I had considered just doing incremental changes but Pavel at the time
      had suggested I submit it as a whole set, however that was almost 3
      weeks ago so if incremental changes are preferred let me know and
      I can submit the changes as incremental updates.

      I appologize for the delay in submitting this follow-on set. I had been
      trying to address the DAX PageReserved bit issue at the same time but
      that is taking more time than I anticipated so I decided to push this
      before the code sits too much longer.

      Commit bf416078f1d83 ("mm/page_alloc.c: memory hotplug: free pages as 
      higher order") causes issues with the revert of patch 7. It was
      necessary to replace all instances of __free_pages_boot_core with
      __free_pages_core.

v1->v2:
    Fixed build issue on PowerPC due to page struct size being 56
    Added new patch that removed __SetPageReserved call for hotplug
v2->v3:
    Rebased on latest linux-next
    Removed patch that had removed __SetPageReserved call from init
    Added patch that folded __SetPageReserved into set_page_links
    Tweaked __init_pageblock to use start_pfn to get section_nr instead of pfn
v3->v4:
    Updated patch description and comments for mm_zero_struct_page patch
        Replaced "default" with "case 64"
        Removed #ifndef mm_zero_struct_page
    Fixed typo in comment that ommited "_from" in kerneldoc for iterator
    Added Reviewed-by for patches reviewed by Pavel
    Added Acked-by from Michal Hocko
    Added deferred init times for patches that affect init performance
    Swapped patches 5 & 6, pulled some code/comments from 4 into 5
v4->v5:
    Updated Acks/Reviewed-by
    Rebased on latest linux-next
    Split core bits of zone iterator patch from MAX_ORDER_NR_PAGES init
v5->v6:
    Rebased on linux-next with previous v5 reverted
    Drop the "This patch" or "This change" from patch desriptions.
    Cleaned up patch descriptions for patches 3 & 4
    Fixed kerneldoc for __next_mem_pfn_range_in_zone
    Updated several Reviewed-by, and incorporated suggestions from Pavel
    Added __init_single_page_nolru to patch 5 to consolidate code
    Refactored iterator in patch 7 and fixed several issues

---

Alexander Duyck (7):
      mm: Use mm_zero_struct_page from SPARC on all 64b architectures
      mm: Drop meminit_pfn_in_nid as it is redundant
      mm: Implement new zone specific memblock iterator
      mm: Initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections
      mm: Move hot-plug specific memory init into separate functions and optimize
      mm: Add reserved flag setting to set_page_links
      mm: Use common iterator for deferred_init_pages and deferred_free_pages


 arch/sparc/include/asm/pgtable_64.h |   30 --
 include/linux/memblock.h            |   41 +++
 include/linux/mm.h                  |   50 +++
 mm/memblock.c                       |   64 ++++
 mm/page_alloc.c                     |  571 +++++++++++++++++++++--------------
 5 files changed, 498 insertions(+), 258 deletions(-)

--
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[mm PATCH v6 1/7] mm: Use mm_zero_struct_page from SPARC on all 64b architectures

[Alexander Duyck]

Use the same approach that was already in use on Sparc on all the
architectures that support a 64b long.

This is mostly motivated by the fact that 7 to 10 store/move instructions
are likely always going to be faster than having to call into a function
that is not specialized for handling page init.

An added advantage to doing it this way is that the compiler can get away
with combining writes in the __init_single_page call. As a result the
memset call will be reduced to only about 4 write operations, or at least
that is what I am seeing with GCC 6.2 as the flags, LRU pointers, and
count/mapcount seem to be cancelling out at least 4 of the 8 assignments on
my system.

One change I had to make to the function was to reduce the minimum page
size to 56 to support some powerpc64 configurations.

This change should introduce no change on SPARC since it already had this
code. In the case of x86_64 I saw a reduction from 3.75s to 2.80s when
initializing 384GB of RAM per node. Pavel Tatashin tested on a system with
Broadcom's Stingray CPU and 48GB of RAM and found that __init_single_page()
takes 19.30ns / 64-byte struct page before this patch and with this patch
it takes 17.33ns / 64-byte struct page. Mike Rapoport ran a similar test on
a OpenPower (S812LC 8348-21C) with Power8 processor and 128GB or RAM. His
results per 64-byte struct page were 4.68ns before, and 4.59ns after this
patch.

Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 arch/sparc/include/asm/pgtable_64.h |   30 --------------------------
 include/linux/mm.h                  |   41 ++++++++++++++++++++++++++++++++---
 2 files changed, 38 insertions(+), 33 deletions(-)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 1393a8ac596b..22500c3be7a9 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -231,36 +231,6 @@ extern unsigned long _PAGE_ALL_SZ_BITS;
 extern struct page *mem_map_zero;
 #define ZERO_PAGE(vaddr)	(mem_map_zero)
 
-/* This macro must be updated when the size of struct page grows above 80
- * or reduces below 64.
- * The idea that compiler optimizes out switch() statement, and only
- * leaves clrx instructions
- */
-#define	mm_zero_struct_page(pp) do {					\
-	unsigned long *_pp = (void *)(pp);				\
-									\
-	 /* Check that struct page is either 64, 72, or 80 bytes */	\
-	BUILD_BUG_ON(sizeof(struct page) & 7);				\
-	BUILD_BUG_ON(sizeof(struct page) < 64);				\
-	BUILD_BUG_ON(sizeof(struct page) > 80);				\
-									\
-	switch (sizeof(struct page)) {					\
-	case 80:							\
-		_pp[9] = 0;	/* fallthrough */			\
-	case 72:							\
-		_pp[8] = 0;	/* fallthrough */			\
-	default:							\
-		_pp[7] = 0;						\
-		_pp[6] = 0;						\
-		_pp[5] = 0;						\
-		_pp[4] = 0;						\
-		_pp[3] = 0;						\
-		_pp[2] = 0;						\
-		_pp[1] = 0;						\
-		_pp[0] = 0;						\
-	}								\
-} while (0)
-
 /* PFNs are real physical page numbers.  However, mem_map only begins to record
  * per-page information starting at pfn_base.  This is to handle systems where
  * the first physical page in the machine is at some huge physical address,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 692158d6c619..eb6e52b66bc2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -123,10 +123,45 @@ extern int mmap_rnd_compat_bits __read_mostly;
 
 /*
  * On some architectures it is expensive to call memset() for small sizes.
- * Those architectures should provide their own implementation of "struct page"
- * zeroing by defining this macro in <asm/pgtable.h>.
+ * If an architecture decides to implement their own version of
+ * mm_zero_struct_page they should wrap the defines below in a #ifndef and
+ * define their own version of this macro in <asm/pgtable.h>
  */
-#ifndef mm_zero_struct_page
+#if BITS_PER_LONG == 64
+/* This function must be updated when the size of struct page grows above 80
+ * or reduces below 56. The idea that compiler optimizes out switch()
+ * statement, and only leaves move/store instructions. Also the compiler can
+ * combine write statments if they are both assignments and can be reordered,
+ * this can result in several of the writes here being dropped.
+ */
+#define	mm_zero_struct_page(pp) __mm_zero_struct_page(pp)
+static inline void __mm_zero_struct_page(struct page *page)
+{
+	unsigned long *_pp = (void *)page;
+
+	 /* Check that struct page is either 56, 64, 72, or 80 bytes */
+	BUILD_BUG_ON(sizeof(struct page) & 7);
+	BUILD_BUG_ON(sizeof(struct page) < 56);
+	BUILD_BUG_ON(sizeof(struct page) > 80);
+
+	switch (sizeof(struct page)) {
+	case 80:
+		_pp[9] = 0;	/* fallthrough */
+	case 72:
+		_pp[8] = 0;	/* fallthrough */
+	case 64:
+		_pp[7] = 0;	/* fallthrough */
+	case 56:
+		_pp[6] = 0;
+		_pp[5] = 0;
+		_pp[4] = 0;
+		_pp[3] = 0;
+		_pp[2] = 0;
+		_pp[1] = 0;
+		_pp[0] = 0;
+	}
+}
+#else
 #define mm_zero_struct_page(pp)  ((void)memset((pp), 0, sizeof(struct page)))
 #endif
 

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[mm PATCH v6 2/7] mm: Drop meminit_pfn_in_nid as it is redundant

[Alexander Duyck]

As best as I can tell the meminit_pfn_in_nid call is completely redundant.
The deferred memory initialization is already making use of
for_each_free_mem_range which in turn will call into __next_mem_range which
will only return a memory range if it matches the node ID provided assuming
it is not NUMA_NO_NODE.

I am operating on the assumption that there are no zones or pgdata_t
structures that have a NUMA node of NUMA_NO_NODE associated with them. If
that is the case then __next_mem_range will never return a memory range
that doesn't match the zone's node ID and as such the check is redundant.

So one piece I would like to verify on this is if this works for ia64.
Technically it was using a different approach to get the node ID, but it
seems to have the node ID also encoded into the memblock. So I am
assuming this is okay, but would like to get confirmation on that.

On my x86_64 test system with 384GB of memory per node I saw a reduction in
initialization time from 2.80s to 1.85s as a result of this patch.

Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 mm/page_alloc.c |   51 ++++++++++++++-------------------------------------
 1 file changed, 14 insertions(+), 37 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 20e1a8a2e98c..09969619ab48 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1308,36 +1308,22 @@ int __meminit early_pfn_to_nid(unsigned long pfn)
 #endif
 
 #ifdef CONFIG_NODES_SPAN_OTHER_NODES
-static inline bool __meminit __maybe_unused
-meminit_pfn_in_nid(unsigned long pfn, int node,
-		   struct mminit_pfnnid_cache *state)
+/* Only safe to use early in boot when initialisation is single-threaded */
+static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
 {
 	int nid;
 
-	nid = __early_pfn_to_nid(pfn, state);
+	nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
 	if (nid >= 0 && nid != node)
 		return false;
 	return true;
 }
 
-/* Only safe to use early in boot when initialisation is single-threaded */
-static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
-{
-	return meminit_pfn_in_nid(pfn, node, &early_pfnnid_cache);
-}
-
 #else
-
 static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
 {
 	return true;
 }
-static inline bool __meminit  __maybe_unused
-meminit_pfn_in_nid(unsigned long pfn, int node,
-		   struct mminit_pfnnid_cache *state)
-{
-	return true;
-}
 #endif
 
 
@@ -1466,21 +1452,13 @@ static inline void __init pgdat_init_report_one_done(void)
  *
  * Then, we check if a current large page is valid by only checking the validity
  * of the head pfn.
- *
- * Finally, meminit_pfn_in_nid is checked on systems where pfns can interleave
- * within a node: a pfn is between start and end of a node, but does not belong
- * to this memory node.
  */
-static inline bool __init
-deferred_pfn_valid(int nid, unsigned long pfn,
-		   struct mminit_pfnnid_cache *nid_init_state)
+static inline bool __init deferred_pfn_valid(unsigned long pfn)
 {
 	if (!pfn_valid_within(pfn))
 		return false;
 	if (!(pfn & (pageblock_nr_pages - 1)) && !pfn_valid(pfn))
 		return false;
-	if (!meminit_pfn_in_nid(pfn, nid, nid_init_state))
-		return false;
 	return true;
 }
 
@@ -1488,15 +1466,14 @@ deferred_pfn_valid(int nid, unsigned long pfn,
  * Free pages to buddy allocator. Try to free aligned pages in
  * pageblock_nr_pages sizes.
  */
-static void __init deferred_free_pages(int nid, int zid, unsigned long pfn,
+static void __init deferred_free_pages(unsigned long pfn,
 				       unsigned long end_pfn)
 {
-	struct mminit_pfnnid_cache nid_init_state = { };
 	unsigned long nr_pgmask = pageblock_nr_pages - 1;
 	unsigned long nr_free = 0;
 
 	for (; pfn < end_pfn; pfn++) {
-		if (!deferred_pfn_valid(nid, pfn, &nid_init_state)) {
+		if (!deferred_pfn_valid(pfn)) {
 			deferred_free_range(pfn - nr_free, nr_free);
 			nr_free = 0;
 		} else if (!(pfn & nr_pgmask)) {
@@ -1516,17 +1493,18 @@ static void __init deferred_free_pages(int nid, int zid, unsigned long pfn,
  * by performing it only once every pageblock_nr_pages.
  * Return number of pages initialized.
  */
-static unsigned long  __init deferred_init_pages(int nid, int zid,
+static unsigned long  __init deferred_init_pages(struct zone *zone,
 						 unsigned long pfn,
 						 unsigned long end_pfn)
 {
-	struct mminit_pfnnid_cache nid_init_state = { };
 	unsigned long nr_pgmask = pageblock_nr_pages - 1;
+	int nid = zone_to_nid(zone);
 	unsigned long nr_pages = 0;
+	int zid = zone_idx(zone);
 	struct page *page = NULL;
 
 	for (; pfn < end_pfn; pfn++) {
-		if (!deferred_pfn_valid(nid, pfn, &nid_init_state)) {
+		if (!deferred_pfn_valid(pfn)) {
 			page = NULL;
 			continue;
 		} else if (!page || !(pfn & nr_pgmask)) {
@@ -1589,12 +1567,12 @@ static int __init deferred_init_memmap(void *data)
 	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
 		spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
 		epfn = min_t(unsigned long, zone_end_pfn(zone), PFN_DOWN(epa));
-		nr_pages += deferred_init_pages(nid, zid, spfn, epfn);
+		nr_pages += deferred_init_pages(zone, spfn, epfn);
 	}
 	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
 		spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
 		epfn = min_t(unsigned long, zone_end_pfn(zone), PFN_DOWN(epa));
-		deferred_free_pages(nid, zid, spfn, epfn);
+		deferred_free_pages(spfn, epfn);
 	}
 	pgdat_resize_unlock(pgdat, &flags);
 
@@ -1633,7 +1611,6 @@ static DEFINE_STATIC_KEY_TRUE(deferred_pages);
 static noinline bool __init
 deferred_grow_zone(struct zone *zone, unsigned int order)
 {
-	int zid = zone_idx(zone);
 	int nid = zone_to_nid(zone);
 	pg_data_t *pgdat = NODE_DATA(nid);
 	unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
@@ -1683,7 +1660,7 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
 		while (spfn < epfn && nr_pages < nr_pages_needed) {
 			t = ALIGN(spfn + PAGES_PER_SECTION, PAGES_PER_SECTION);
 			first_deferred_pfn = min(t, epfn);
-			nr_pages += deferred_init_pages(nid, zid, spfn,
+			nr_pages += deferred_init_pages(zone, spfn,
 							first_deferred_pfn);
 			spfn = first_deferred_pfn;
 		}
@@ -1695,7 +1672,7 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
 	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
 		spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
 		epfn = min_t(unsigned long, first_deferred_pfn, PFN_DOWN(epa));
-		deferred_free_pages(nid, zid, spfn, epfn);
+		deferred_free_pages(spfn, epfn);
 
 		if (first_deferred_pfn == epfn)
 			break;

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[mm PATCH v6 3/7] mm: Implement new zone specific memblock iterator

[Alexander Duyck]

Introduce a new iterator for_each_free_mem_pfn_range_in_zone.

This iterator will take care of making sure a given memory range provided
is in fact contained within a zone. It takes are of all the bounds checking
we were doing in deferred_grow_zone, and deferred_init_memmap. In addition
it should help to speed up the search a bit by iterating until the end of a
range is greater than the start of the zone pfn range, and will exit
completely if the start is beyond the end of the zone.

Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 include/linux/memblock.h |   25 ++++++++++++++++++
 mm/memblock.c            |   64 ++++++++++++++++++++++++++++++++++++++++++++++
 mm/page_alloc.c          |   31 +++++++++-------------
 3 files changed, 101 insertions(+), 19 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 64c41cf45590..95d1aaa3f412 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -247,6 +247,31 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
 	     i >= 0; __next_mem_pfn_range(&i, nid, p_start, p_end, p_nid))
 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
 
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+void __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
+				  unsigned long *out_spfn,
+				  unsigned long *out_epfn);
+/**
+ * for_each_free_mem_range_in_zone - iterate through zone specific free
+ * memblock areas
+ * @i: u64 used as loop variable
+ * @zone: zone in which all of the memory blocks reside
+ * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ *
+ * Walks over free (memory && !reserved) areas of memblock in a specific
+ * zone. Available once memblock and an empty zone is initialized. The main
+ * assumption is that the zone start, end, and pgdat have been associated.
+ * This way we can use the zone to determine NUMA node, and if a given part
+ * of the memblock is valid for the zone.
+ */
+#define for_each_free_mem_pfn_range_in_zone(i, zone, p_start, p_end)	\
+	for (i = 0,							\
+	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end);	\
+	     i != U64_MAX;					\
+	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end))
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
+
 /**
  * for_each_free_mem_range - iterate through free memblock areas
  * @i: u64 used as loop variable
diff --git a/mm/memblock.c b/mm/memblock.c
index 57298abc7d98..0e49382033dd 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1247,6 +1247,70 @@ int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size,
 	return 0;
 }
 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+/**
+ * __next_mem_pfn_range_in_zone - iterator for for_each_*_range_in_zone()
+ *
+ * @idx: pointer to u64 loop variable
+ * @zone: zone in which all of the memory blocks reside
+ * @out_spfn: ptr to ulong for start pfn of the range, can be %NULL
+ * @out_epfn: ptr to ulong for end pfn of the range, can be %NULL
+ *
+ * This function is meant to be a zone/pfn specific wrapper for the
+ * for_each_mem_range type iterators. Specifically they are used in the
+ * deferred memory init routines and as such we were duplicating much of
+ * this logic throughout the code. So instead of having it in multiple
+ * locations it seemed like it would make more sense to centralize this to
+ * one new iterator that does everything they need.
+ */
+void __init_memblock
+__next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
+			     unsigned long *out_spfn, unsigned long *out_epfn)
+{
+	int zone_nid = zone_to_nid(zone);
+	phys_addr_t spa, epa;
+	int nid;
+
+	__next_mem_range(idx, zone_nid, MEMBLOCK_NONE,
+			 &memblock.memory, &memblock.reserved,
+			 &spa, &epa, &nid);
+
+	while (*idx != U64_MAX) {
+		unsigned long epfn = PFN_DOWN(epa);
+		unsigned long spfn = PFN_UP(spa);
+
+		/*
+		 * Verify the end is at least past the start of the zone and
+		 * that we have at least one PFN to initialize.
+		 */
+		if (zone->zone_start_pfn < epfn && spfn < epfn) {
+			/* if we went too far just stop searching */
+			if (zone_end_pfn(zone) <= spfn) {
+				*idx = U64_MAX;
+				break;
+			}
+
+			if (out_spfn)
+				*out_spfn = max(zone->zone_start_pfn, spfn);
+			if (out_epfn)
+				*out_epfn = min(zone_end_pfn(zone), epfn);
+
+			return;
+		}
+
+		__next_mem_range(idx, zone_nid, MEMBLOCK_NONE,
+				 &memblock.memory, &memblock.reserved,
+				 &spa, &epa, &nid);
+	}
+
+	/* signal end of iteration */
+	if (out_spfn)
+		*out_spfn = ULONG_MAX;
+	if (out_epfn)
+		*out_epfn = 0;
+}
+
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
 
 static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
 					phys_addr_t align, phys_addr_t start,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 09969619ab48..72f9889e3866 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1523,11 +1523,9 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
 static int __init deferred_init_memmap(void *data)
 {
 	pg_data_t *pgdat = data;
-	int nid = pgdat->node_id;
 	unsigned long start = jiffies;
 	unsigned long nr_pages = 0;
 	unsigned long spfn, epfn, first_init_pfn, flags;
-	phys_addr_t spa, epa;
 	int zid;
 	struct zone *zone;
 	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
@@ -1564,14 +1562,12 @@ static int __init deferred_init_memmap(void *data)
 	 * freeing pages we can access pages that are ahead (computing buddy
 	 * page in __free_one_page()).
 	 */
-	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
-		spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
-		epfn = min_t(unsigned long, zone_end_pfn(zone), PFN_DOWN(epa));
+	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
+		spfn = max_t(unsigned long, first_init_pfn, spfn);
 		nr_pages += deferred_init_pages(zone, spfn, epfn);
 	}
-	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
-		spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
-		epfn = min_t(unsigned long, zone_end_pfn(zone), PFN_DOWN(epa));
+	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
+		spfn = max_t(unsigned long, first_init_pfn, spfn);
 		deferred_free_pages(spfn, epfn);
 	}
 	pgdat_resize_unlock(pgdat, &flags);
@@ -1579,8 +1575,8 @@ static int __init deferred_init_memmap(void *data)
 	/* Sanity check that the next zone really is unpopulated */
 	WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
 
-	pr_info("node %d initialised, %lu pages in %ums\n", nid, nr_pages,
-					jiffies_to_msecs(jiffies - start));
+	pr_info("node %d initialised, %lu pages in %ums\n",
+		pgdat->node_id,	nr_pages, jiffies_to_msecs(jiffies - start));
 
 	pgdat_init_report_one_done();
 	return 0;
@@ -1611,13 +1607,11 @@ static DEFINE_STATIC_KEY_TRUE(deferred_pages);
 static noinline bool __init
 deferred_grow_zone(struct zone *zone, unsigned int order)
 {
-	int nid = zone_to_nid(zone);
-	pg_data_t *pgdat = NODE_DATA(nid);
 	unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
+	pg_data_t *pgdat = zone->zone_pgdat;
 	unsigned long nr_pages = 0;
 	unsigned long first_init_pfn, spfn, epfn, t, flags;
 	unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
-	phys_addr_t spa, epa;
 	u64 i;
 
 	/* Only the last zone may have deferred pages */
@@ -1653,9 +1647,8 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
 		return false;
 	}
 
-	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
-		spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
-		epfn = min_t(unsigned long, zone_end_pfn(zone), PFN_DOWN(epa));
+	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
+		spfn = max_t(unsigned long, first_init_pfn, spfn);
 
 		while (spfn < epfn && nr_pages < nr_pages_needed) {
 			t = ALIGN(spfn + PAGES_PER_SECTION, PAGES_PER_SECTION);
@@ -1669,9 +1662,9 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
 			break;
 	}
 
-	for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
-		spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
-		epfn = min_t(unsigned long, first_deferred_pfn, PFN_DOWN(epa));
+	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
+		spfn = max_t(unsigned long, first_init_pfn, spfn);
+		epfn = min_t(unsigned long, first_deferred_pfn, epfn);
 		deferred_free_pages(spfn, epfn);
 
 		if (first_deferred_pfn == epfn)

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[mm PATCH v6 4/7] mm: Initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections

[Alexander Duyck]

Add yet another iterator, for_each_free_mem_range_in_zone_from, and then
use it to support initializing and freeing pages in groups no larger than
MAX_ORDER_NR_PAGES. By doing this we can greatly improve the cache locality
of the pages while we do several loops over them in the init and freeing
process.

We are able to tighten the loops further as a result of the "from" iterator
as we can perform the initial checks for first_init_pfn in our first call
to the iterator, and continue without the need for those checks via the
"from" iterator. I have added this functionality in the function called
deferred_init_mem_pfn_range_in_zone that primes the iterator and causes us
to exit if we encounter any failure.

On my x86_64 test system with 384GB of memory per node I saw a reduction in
initialization time from 1.85s to 1.38s as a result of this patch.

Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 include/linux/memblock.h |   16 +++++
 mm/page_alloc.c          |  160 +++++++++++++++++++++++++++++++++-------------
 2 files changed, 132 insertions(+), 44 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 95d1aaa3f412..60e100fe5922 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -270,6 +270,22 @@ void __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
 	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end);	\
 	     i != U64_MAX;					\
 	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end))
+
+/**
+ * for_each_free_mem_range_in_zone_from - iterate through zone specific
+ * free memblock areas from a given point
+ * @i: u64 used as loop variable
+ * @zone: zone in which all of the memory blocks reside
+ * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
+ * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
+ *
+ * Walks over free (memory && !reserved) areas of memblock in a specific
+ * zone, continuing from current position. Available as soon as memblock is
+ * initialized.
+ */
+#define for_each_free_mem_pfn_range_in_zone_from(i, zone, p_start, p_end) \
+	for (; i != U64_MAX;					  \
+	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end))
 #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
 
 /**
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 72f9889e3866..fbd9bd2bc262 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1519,16 +1519,102 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
 	return (nr_pages);
 }
 
+/*
+ * This function is meant to pre-load the iterator for the zone init.
+ * Specifically it walks through the ranges until we are caught up to the
+ * first_init_pfn value and exits there. If we never encounter the value we
+ * return false indicating there are no valid ranges left.
+ */
+static bool __init
+deferred_init_mem_pfn_range_in_zone(u64 *i, struct zone *zone,
+				    unsigned long *spfn, unsigned long *epfn,
+				    unsigned long first_init_pfn)
+{
+	u64 j;
+
+	/*
+	 * Start out by walking through the ranges in this zone that have
+	 * already been initialized. We don't need to do anything with them
+	 * so we just need to flush them out of the system.
+	 */
+	for_each_free_mem_pfn_range_in_zone(j, zone, spfn, epfn) {
+		if (*epfn <= first_init_pfn)
+			continue;
+		if (*spfn < first_init_pfn)
+			*spfn = first_init_pfn;
+		*i = j;
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * Initialize and free pages. We do it in two loops: first we initialize
+ * struct page, than free to buddy allocator, because while we are
+ * freeing pages we can access pages that are ahead (computing buddy
+ * page in __free_one_page()).
+ *
+ * In order to try and keep some memory in the cache we have the loop
+ * broken along max page order boundaries. This way we will not cause
+ * any issues with the buddy page computation.
+ */
+static unsigned long __init
+deferred_init_maxorder(u64 *i, struct zone *zone, unsigned long *start_pfn,
+		       unsigned long *end_pfn)
+{
+	unsigned long mo_pfn = ALIGN(*start_pfn + 1, MAX_ORDER_NR_PAGES);
+	unsigned long spfn = *start_pfn, epfn = *end_pfn;
+	unsigned long nr_pages = 0;
+	u64 j = *i;
+
+	/* First we loop through and initialize the page values */
+	for_each_free_mem_pfn_range_in_zone_from(j, zone, &spfn, &epfn) {
+		unsigned long t;
+
+		if (mo_pfn <= spfn)
+			break;
+
+		t = min(mo_pfn, epfn);
+		nr_pages += deferred_init_pages(zone, spfn, t);
+
+		if (mo_pfn <= epfn)
+			break;
+	}
+
+	/* Reset values and now loop through freeing pages as needed */
+	j = *i;
+
+	for_each_free_mem_pfn_range_in_zone_from(j, zone, start_pfn, end_pfn) {
+		unsigned long t;
+
+		if (mo_pfn <= *start_pfn)
+			break;
+
+		t = min(mo_pfn, *end_pfn);
+		deferred_free_pages(*start_pfn, t);
+		*start_pfn = t;
+
+		if (mo_pfn < *end_pfn)
+			break;
+	}
+
+	/* Store our current values to be reused on the next iteration */
+	*i = j;
+
+	return nr_pages;
+}
+
 /* Initialise remaining memory on a node */
 static int __init deferred_init_memmap(void *data)
 {
 	pg_data_t *pgdat = data;
+	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
+	unsigned long spfn = 0, epfn = 0, nr_pages = 0;
+	unsigned long first_init_pfn, flags;
 	unsigned long start = jiffies;
-	unsigned long nr_pages = 0;
-	unsigned long spfn, epfn, first_init_pfn, flags;
-	int zid;
 	struct zone *zone;
-	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
+	int zid;
 	u64 i;
 
 	/* Bind memory initialisation thread to a local node if possible */
@@ -1554,22 +1640,20 @@ static int __init deferred_init_memmap(void *data)
 		if (first_init_pfn < zone_end_pfn(zone))
 			break;
 	}
-	first_init_pfn = max(zone->zone_start_pfn, first_init_pfn);
+
+	/* If the zone is empty somebody else may have cleared out the zone */
+	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
+						 first_init_pfn))
+		goto zone_empty;
 
 	/*
-	 * Initialize and free pages. We do it in two loops: first we initialize
-	 * struct page, than free to buddy allocator, because while we are
-	 * freeing pages we can access pages that are ahead (computing buddy
-	 * page in __free_one_page()).
+	 * Initialize and free pages in MAX_ORDER sized increments so
+	 * that we can avoid introducing any issues with the buddy
+	 * allocator.
 	 */
-	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
-		spfn = max_t(unsigned long, first_init_pfn, spfn);
-		nr_pages += deferred_init_pages(zone, spfn, epfn);
-	}
-	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
-		spfn = max_t(unsigned long, first_init_pfn, spfn);
-		deferred_free_pages(spfn, epfn);
-	}
+	while (spfn < epfn)
+		nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
+zone_empty:
 	pgdat_resize_unlock(pgdat, &flags);
 
 	/* Sanity check that the next zone really is unpopulated */
@@ -1609,9 +1693,9 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
 {
 	unsigned long nr_pages_needed = ALIGN(1 << order, PAGES_PER_SECTION);
 	pg_data_t *pgdat = zone->zone_pgdat;
-	unsigned long nr_pages = 0;
-	unsigned long first_init_pfn, spfn, epfn, t, flags;
 	unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
+	unsigned long spfn, epfn, flags;
+	unsigned long nr_pages = 0;
 	u64 i;
 
 	/* Only the last zone may have deferred pages */
@@ -1640,36 +1724,24 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
 		return true;
 	}
 
-	first_init_pfn = max(zone->zone_start_pfn, first_deferred_pfn);
-
-	if (first_init_pfn >= pgdat_end_pfn(pgdat)) {
+	/* If the zone is empty somebody else may have cleared out the zone */
+	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
+						 first_deferred_pfn)) {
+		pgdat->first_deferred_pfn = ULONG_MAX;
 		pgdat_resize_unlock(pgdat, &flags);
-		return false;
+		return true;
 	}
 
-	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
-		spfn = max_t(unsigned long, first_init_pfn, spfn);
-
-		while (spfn < epfn && nr_pages < nr_pages_needed) {
-			t = ALIGN(spfn + PAGES_PER_SECTION, PAGES_PER_SECTION);
-			first_deferred_pfn = min(t, epfn);
-			nr_pages += deferred_init_pages(zone, spfn,
-							first_deferred_pfn);
-			spfn = first_deferred_pfn;
-		}
-
-		if (nr_pages >= nr_pages_needed)
-			break;
+	/*
+	 * Initialize and free pages in MAX_ORDER sized increments so
+	 * that we can avoid introducing any issues with the buddy
+	 * allocator.
+	 */
+	while (spfn < epfn && nr_pages < nr_pages_needed) {
+		nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
+		first_deferred_pfn = spfn;
 	}
 
-	for_each_free_mem_pfn_range_in_zone(i, zone, &spfn, &epfn) {
-		spfn = max_t(unsigned long, first_init_pfn, spfn);
-		epfn = min_t(unsigned long, first_deferred_pfn, epfn);
-		deferred_free_pages(spfn, epfn);
-
-		if (first_deferred_pfn == epfn)
-			break;
-	}
 	pgdat->first_deferred_pfn = first_deferred_pfn;
 	pgdat_resize_unlock(pgdat, &flags);
 

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[mm PATCH v6 5/7] mm: Move hot-plug specific memory init into separate functions and optimize

[Alexander Duyck]

Combine the bits in memmap_init_zone and memmap_init_zone_device that are
related to hotplug into a single function called __memmap_init_hotplug.

Also take the opportunity to integrate __init_single_page's functionality
into this function. In doing so we can get rid of some of the redundancy
such as the LRU pointers versus the pgmap.

Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 mm/page_alloc.c |  208 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 135 insertions(+), 73 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fbd9bd2bc262..416bbb6f05ab 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1181,8 +1181,9 @@ static void free_one_page(struct zone *zone,
 	spin_unlock(&zone->lock);
 }
 
-static void __meminit __init_single_page(struct page *page, unsigned long pfn,
-				unsigned long zone, int nid)
+static void __meminit __init_struct_page_nolru(struct page *page,
+					       unsigned long pfn,
+					       unsigned long zone, int nid)
 {
 	mm_zero_struct_page(page);
 	set_page_links(page, zone, nid, pfn);
@@ -1191,7 +1192,6 @@ static void __meminit __init_single_page(struct page *page, unsigned long pfn,
 	page_cpupid_reset_last(page);
 	page_kasan_tag_reset(page);
 
-	INIT_LIST_HEAD(&page->lru);
 #ifdef WANT_PAGE_VIRTUAL
 	/* The shift won't overflow because ZONE_NORMAL is below 4G. */
 	if (!is_highmem_idx(zone))
@@ -1199,6 +1199,80 @@ static void __meminit __init_single_page(struct page *page, unsigned long pfn,
 #endif
 }
 
+static void __meminit __init_single_page(struct page *page, unsigned long pfn,
+				unsigned long zone, int nid)
+{
+	__init_struct_page_nolru(page, pfn, zone, nid);
+	INIT_LIST_HEAD(&page->lru);
+}
+
+static void __meminit __init_pageblock(unsigned long start_pfn,
+				       unsigned long nr_pages,
+				       unsigned long zone, int nid,
+				       struct dev_pagemap *pgmap)
+{
+	unsigned long nr_pgmask = pageblock_nr_pages - 1;
+	struct page *start_page = pfn_to_page(start_pfn);
+	unsigned long pfn = start_pfn + nr_pages - 1;
+	struct page *page;
+
+	/*
+	 * Enforce the following requirements:
+	 * size > 0
+	 * size < pageblock_nr_pages
+	 * start_pfn -> pfn does not cross pageblock_nr_pages boundary
+	 */
+	VM_BUG_ON(((start_pfn ^ pfn) | (nr_pages - 1)) > nr_pgmask);
+
+	/*
+	 * Work from highest page to lowest, this way we will still be
+	 * warm in the cache when we call set_pageblock_migratetype
+	 * below.
+	 *
+	 * The loop is based around the page pointer as the main index
+	 * instead of the pfn because pfn is not used inside the loop if
+	 * the section number is not in page flags and WANT_PAGE_VIRTUAL
+	 * is not defined.
+	 */
+	for (page = start_page + nr_pages; page-- != start_page; pfn--) {
+		__init_struct_page_nolru(page, pfn, zone, nid);
+		/*
+		 * Mark page reserved as it will need to wait for onlining
+		 * phase for it to be fully associated with a zone.
+		 *
+		 * We can use the non-atomic __set_bit operation for setting
+		 * the flag as we are still initializing the pages.
+		 */
+		__SetPageReserved(page);
+		/*
+		 * ZONE_DEVICE pages union ->lru with a ->pgmap back
+		 * pointer and hmm_data.  It is a bug if a ZONE_DEVICE
+		 * page is ever freed or placed on a driver-private list.
+		 */
+		page->pgmap = pgmap;
+		if (!pgmap)
+			INIT_LIST_HEAD(&page->lru);
+	}
+
+	/*
+	 * Mark the block movable so that blocks are reserved for
+	 * movable at startup. This will force kernel allocations
+	 * to reserve their blocks rather than leaking throughout
+	 * the address space during boot when many long-lived
+	 * kernel allocations are made.
+	 *
+	 * bitmap is created for zone's valid pfn range. but memmap
+	 * can be created for invalid pages (for alignment)
+	 * check here not to call set_pageblock_migratetype() against
+	 * pfn out of zone.
+	 *
+	 * Please note that MEMMAP_HOTPLUG path doesn't clear memmap
+	 * because this is done early in sparse_add_one_section
+	 */
+	if (!(start_pfn & nr_pgmask))
+		set_pageblock_migratetype(start_page, MIGRATE_MOVABLE);
+}
+
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
 static void __meminit init_reserved_page(unsigned long pfn)
 {
@@ -5693,6 +5767,25 @@ overlap_memmap_init(unsigned long zone, unsigned long *pfn)
 	return false;
 }
 
+static void __meminit __memmap_init_hotplug(unsigned long size, int nid,
+					    unsigned long zone,
+					    unsigned long start_pfn,
+					    struct dev_pagemap *pgmap)
+{
+	unsigned long pfn = start_pfn + size;
+
+	while (pfn != start_pfn) {
+		unsigned long stride = pfn;
+
+		pfn = max(ALIGN_DOWN(pfn - 1, pageblock_nr_pages), start_pfn);
+		stride -= pfn;
+
+		__init_pageblock(pfn, stride, zone, nid, pgmap);
+
+		cond_resched();
+	}
+}
+
 /*
  * Initially all pages are reserved - free ones are freed
  * up by memblock_free_all() once the early boot process is
@@ -5703,49 +5796,59 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		struct vmem_altmap *altmap)
 {
 	unsigned long pfn, end_pfn = start_pfn + size;
-	struct page *page;
 
 	if (highest_memmap_pfn < end_pfn - 1)
 		highest_memmap_pfn = end_pfn - 1;
 
+	if (context == MEMMAP_HOTPLUG) {
 #ifdef CONFIG_ZONE_DEVICE
-	/*
-	 * Honor reservation requested by the driver for this ZONE_DEVICE
-	 * memory. We limit the total number of pages to initialize to just
-	 * those that might contain the memory mapping. We will defer the
-	 * ZONE_DEVICE page initialization until after we have released
-	 * the hotplug lock.
-	 */
-	if (zone == ZONE_DEVICE) {
-		if (!altmap)
-			return;
+		/*
+		 * Honor reservation requested by the driver for this
+		 * ZONE_DEVICE memory. We limit the total number of pages to
+		 * initialize to just those that might contain the memory
+		 * mapping. We will defer the ZONE_DEVICE page initialization
+		 * until after we have released the hotplug lock.
+		 */
+		if (zone == ZONE_DEVICE) {
+			if (!altmap)
+				return;
+
+			if (start_pfn == altmap->base_pfn)
+				start_pfn += altmap->reserve;
+			end_pfn = altmap->base_pfn +
+				  vmem_altmap_offset(altmap);
+		}
+#endif
+		/*
+		 * For these ZONE_DEVICE pages we don't need to record the
+		 * pgmap as they should represent only those pages used to
+		 * store the memory map. The actual ZONE_DEVICE pages will
+		 * be initialized later.
+		 */
+		__memmap_init_hotplug(end_pfn - start_pfn, nid, zone,
+				      start_pfn, NULL);
 
-		if (start_pfn == altmap->base_pfn)
-			start_pfn += altmap->reserve;
-		end_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
+		return;
 	}
-#endif
 
 	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
+		struct page *page;
+
 		/*
 		 * There can be holes in boot-time mem_map[]s handed to this
 		 * function.  They do not exist on hotplugged memory.
 		 */
-		if (context == MEMMAP_EARLY) {
-			if (!early_pfn_valid(pfn))
-				continue;
-			if (!early_pfn_in_nid(pfn, nid))
-				continue;
-			if (overlap_memmap_init(zone, &pfn))
-				continue;
-			if (defer_init(nid, pfn, end_pfn))
-				break;
-		}
+		if (!early_pfn_valid(pfn))
+			continue;
+		if (!early_pfn_in_nid(pfn, nid))
+			continue;
+		if (overlap_memmap_init(zone, &pfn))
+			continue;
+		if (defer_init(nid, pfn, end_pfn))
+			break;
 
 		page = pfn_to_page(pfn);
 		__init_single_page(page, pfn, zone, nid);
-		if (context == MEMMAP_HOTPLUG)
-			__SetPageReserved(page);
 
 		/*
 		 * Mark the block movable so that blocks are reserved for
@@ -5772,7 +5875,6 @@ void __ref memmap_init_zone_device(struct zone *zone,
 				   unsigned long size,
 				   struct dev_pagemap *pgmap)
 {
-	unsigned long pfn, end_pfn = start_pfn + size;
 	struct pglist_data *pgdat = zone->zone_pgdat;
 	unsigned long zone_idx = zone_idx(zone);
 	unsigned long start = jiffies;
@@ -5788,53 +5890,13 @@ void __ref memmap_init_zone_device(struct zone *zone,
 	 */
 	if (pgmap->altmap_valid) {
 		struct vmem_altmap *altmap = &pgmap->altmap;
+		unsigned long end_pfn = start_pfn + size;
 
 		start_pfn = altmap->base_pfn + vmem_altmap_offset(altmap);
 		size = end_pfn - start_pfn;
 	}
 
-	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
-		struct page *page = pfn_to_page(pfn);
-
-		__init_single_page(page, pfn, zone_idx, nid);
-
-		/*
-		 * Mark page reserved as it will need to wait for onlining
-		 * phase for it to be fully associated with a zone.
-		 *
-		 * We can use the non-atomic __set_bit operation for setting
-		 * the flag as we are still initializing the pages.
-		 */
-		__SetPageReserved(page);
-
-		/*
-		 * ZONE_DEVICE pages union ->lru with a ->pgmap back
-		 * pointer and hmm_data.  It is a bug if a ZONE_DEVICE
-		 * page is ever freed or placed on a driver-private list.
-		 */
-		page->pgmap = pgmap;
-		page->hmm_data = 0;
-
-		/*
-		 * Mark the block movable so that blocks are reserved for
-		 * movable at startup. This will force kernel allocations
-		 * to reserve their blocks rather than leaking throughout
-		 * the address space during boot when many long-lived
-		 * kernel allocations are made.
-		 *
-		 * bitmap is created for zone's valid pfn range. but memmap
-		 * can be created for invalid pages (for alignment)
-		 * check here not to call set_pageblock_migratetype() against
-		 * pfn out of zone.
-		 *
-		 * Please note that MEMMAP_HOTPLUG path doesn't clear memmap
-		 * because this is done early in sparse_add_one_section
-		 */
-		if (!(pfn & (pageblock_nr_pages - 1))) {
-			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-			cond_resched();
-		}
-	}
+	__memmap_init_hotplug(size, nid, zone_idx, start_pfn, pgmap);
 
 	pr_info("%s initialised, %lu pages in %ums\n", dev_name(pgmap->dev),
 		size, jiffies_to_msecs(jiffies - start));

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[mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Alexander Duyck]

Modify the set_page_links function to include the setting of the reserved
flag via a simple AND and OR operation. The motivation for this is the fact
that the existing __set_bit call still seems to have effects on performance
as replacing the call with the AND and OR can reduce initialization time.

Looking over the assembly code before and after the change the main
difference between the two is that the reserved bit is stored in a value
that is generated outside of the main initialization loop and is then
written with the other flags field values in one write to the page->flags
value. Previously the generated value was written and then then a btsq
instruction was issued.

On my x86_64 test system with 3TB of persistent memory per node I saw the
persistent memory initialization time on average drop from 23.49s to
19.12s per node.

Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 include/linux/mm.h |    9 ++++++++-
 mm/page_alloc.c    |   39 +++++++++++++++++++++++++--------------
 2 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index eb6e52b66bc2..5faf66dd4559 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1238,11 +1238,18 @@ static inline void set_page_node(struct page *page, unsigned long node)
 	page->flags |= (node & NODES_MASK) << NODES_PGSHIFT;
 }
 
+static inline void set_page_reserved(struct page *page, bool reserved)
+{
+	page->flags &= ~(1ul << PG_reserved);
+	page->flags |= (unsigned long)(!!reserved) << PG_reserved;
+}
+
 static inline void set_page_links(struct page *page, enum zone_type zone,
-	unsigned long node, unsigned long pfn)
+	unsigned long node, unsigned long pfn, bool reserved)
 {
 	set_page_zone(page, zone);
 	set_page_node(page, node);
+	set_page_reserved(page, reserved);
 #ifdef SECTION_IN_PAGE_FLAGS
 	set_page_section(page, pfn_to_section_nr(pfn));
 #endif
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 416bbb6f05ab..61eb9945d805 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1183,10 +1183,16 @@ static void free_one_page(struct zone *zone,
 
 static void __meminit __init_struct_page_nolru(struct page *page,
 					       unsigned long pfn,
-					       unsigned long zone, int nid)
+					       unsigned long zone, int nid,
+					       bool is_reserved)
 {
 	mm_zero_struct_page(page);
-	set_page_links(page, zone, nid, pfn);
+
+	/*
+	 * We can use a non-atomic operation for setting the
+	 * PG_reserved flag as we are still initializing the pages.
+	 */
+	set_page_links(page, zone, nid, pfn, is_reserved);
 	init_page_count(page);
 	page_mapcount_reset(page);
 	page_cpupid_reset_last(page);
@@ -1202,14 +1208,15 @@ static void __meminit __init_struct_page_nolru(struct page *page,
 static void __meminit __init_single_page(struct page *page, unsigned long pfn,
 				unsigned long zone, int nid)
 {
-	__init_struct_page_nolru(page, pfn, zone, nid);
+	__init_struct_page_nolru(page, pfn, zone, nid, false);
 	INIT_LIST_HEAD(&page->lru);
 }
 
 static void __meminit __init_pageblock(unsigned long start_pfn,
 				       unsigned long nr_pages,
 				       unsigned long zone, int nid,
-				       struct dev_pagemap *pgmap)
+				       struct dev_pagemap *pgmap,
+				       bool is_reserved)
 {
 	unsigned long nr_pgmask = pageblock_nr_pages - 1;
 	struct page *start_page = pfn_to_page(start_pfn);
@@ -1235,15 +1242,8 @@ static void __meminit __init_pageblock(unsigned long start_pfn,
 	 * is not defined.
 	 */
 	for (page = start_page + nr_pages; page-- != start_page; pfn--) {
-		__init_struct_page_nolru(page, pfn, zone, nid);
-		/*
-		 * Mark page reserved as it will need to wait for onlining
-		 * phase for it to be fully associated with a zone.
-		 *
-		 * We can use the non-atomic __set_bit operation for setting
-		 * the flag as we are still initializing the pages.
-		 */
-		__SetPageReserved(page);
+		__init_struct_page_nolru(page, pfn, zone, nid, is_reserved);
+
 		/*
 		 * ZONE_DEVICE pages union ->lru with a ->pgmap back
 		 * pointer and hmm_data.  It is a bug if a ZONE_DEVICE
@@ -5780,7 +5780,18 @@ static void __meminit __memmap_init_hotplug(unsigned long size, int nid,
 		pfn = max(ALIGN_DOWN(pfn - 1, pageblock_nr_pages), start_pfn);
 		stride -= pfn;
 
-		__init_pageblock(pfn, stride, zone, nid, pgmap);
+		/*
+		 * The last argument of __init_pageblock is a boolean
+		 * value indicating if the page will be marked as reserved.
+		 *
+		 * Mark page reserved as it will need to wait for onlining
+		 * phase for it to be fully associated with a zone.
+		 *
+		 * Under certain circumstances ZONE_DEVICE pages may not
+		 * need to be marked as reserved, however there is still
+		 * code that is depending on this being set for now.
+		 */
+		__init_pageblock(pfn, stride, zone, nid, pgmap, true);
 
 		cond_resched();
 	}

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Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Michal Hocko]

On Fri 30-11-18 13:53:18, Alexander Duyck wrote:
> Modify the set_page_links function to include the setting of the reserved
> flag via a simple AND and OR operation. The motivation for this is the fact
> that the existing __set_bit call still seems to have effects on performance
> as replacing the call with the AND and OR can reduce initialization time.
> 
> Looking over the assembly code before and after the change the main
> difference between the two is that the reserved bit is stored in a value
> that is generated outside of the main initialization loop and is then
> written with the other flags field values in one write to the page->flags
> value. Previously the generated value was written and then then a btsq
> instruction was issued.
> 
> On my x86_64 test system with 3TB of persistent memory per node I saw the
> persistent memory initialization time on average drop from 23.49s to
> 19.12s per node.

I have tried to explain why the whole reserved bit doesn't make much
sense in this code several times already. You keep ignoring that and
that is highly annoying. Especially when you add a tricky code to
optimize something that is not really needed.

Based on that I am not going to waste my time on other patches in this
series to review and give feedback which might be ignored again.

-- 
Michal Hocko
SUSE Labs

Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Alexander Duyck]

On Wed, 2018-12-05 at 18:22 +0100, Michal Hocko wrote:
> On Fri 30-11-18 13:53:18, Alexander Duyck wrote:
> > Modify the set_page_links function to include the setting of the reserved
> > flag via a simple AND and OR operation. The motivation for this is the fact
> > that the existing __set_bit call still seems to have effects on performance
> > as replacing the call with the AND and OR can reduce initialization time.
> > 
> > Looking over the assembly code before and after the change the main
> > difference between the two is that the reserved bit is stored in a value
> > that is generated outside of the main initialization loop and is then
> > written with the other flags field values in one write to the page->flags
> > value. Previously the generated value was written and then then a btsq
> > instruction was issued.
> > 
> > On my x86_64 test system with 3TB of persistent memory per node I saw the
> > persistent memory initialization time on average drop from 23.49s to
> > 19.12s per node.
> 
> I have tried to explain why the whole reserved bit doesn't make much
> sense in this code several times already. You keep ignoring that and
> that is highly annoying. Especially when you add a tricky code to
> optimize something that is not really needed.
> 
> Based on that I am not going to waste my time on other patches in this
> series to review and give feedback which might be ignored again.

I got your explanation. However Andrew had already applied the patches
and I had some outstanding issues in them that needed to be addressed.
So I thought it best to send out this set of patches with those fixes
before the code in mm became too stale. I am still working on what to
do about the Reserved bit, and plan to submit it as a follow-up set.



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Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Michal Hocko]

On Wed 05-12-18 09:55:17, Alexander Duyck wrote:
> On Wed, 2018-12-05 at 18:22 +0100, Michal Hocko wrote:
> > On Fri 30-11-18 13:53:18, Alexander Duyck wrote:
> > > Modify the set_page_links function to include the setting of the reserved
> > > flag via a simple AND and OR operation. The motivation for this is the fact
> > > that the existing __set_bit call still seems to have effects on performance
> > > as replacing the call with the AND and OR can reduce initialization time.
> > > 
> > > Looking over the assembly code before and after the change the main
> > > difference between the two is that the reserved bit is stored in a value
> > > that is generated outside of the main initialization loop and is then
> > > written with the other flags field values in one write to the page->flags
> > > value. Previously the generated value was written and then then a btsq
> > > instruction was issued.
> > > 
> > > On my x86_64 test system with 3TB of persistent memory per node I saw the
> > > persistent memory initialization time on average drop from 23.49s to
> > > 19.12s per node.
> > 
> > I have tried to explain why the whole reserved bit doesn't make much
> > sense in this code several times already. You keep ignoring that and
> > that is highly annoying. Especially when you add a tricky code to
> > optimize something that is not really needed.
> > 
> > Based on that I am not going to waste my time on other patches in this
> > series to review and give feedback which might be ignored again.
> 
> I got your explanation. However Andrew had already applied the patches
> and I had some outstanding issues in them that needed to be addressed.
> So I thought it best to send out this set of patches with those fixes
> before the code in mm became too stale. I am still working on what to
> do about the Reserved bit, and plan to submit it as a follow-up set.

>From my experience Andrew can drop patches between different versions of
the patchset. Things can change a lot while they are in mmotm and under
the discussion.
-- 
Michal Hocko
SUSE Labs
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Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Andrew Morton]

On Wed, 5 Dec 2018 21:42:47 +0100 Michal Hocko <mhocko@kernel.org> wrote:

> > I got your explanation. However Andrew had already applied the patches
> > and I had some outstanding issues in them that needed to be addressed.
> > So I thought it best to send out this set of patches with those fixes
> > before the code in mm became too stale. I am still working on what to
> > do about the Reserved bit, and plan to submit it as a follow-up set.
> 
> >From my experience Andrew can drop patches between different versions of
> the patchset. Things can change a lot while they are in mmotm and under
> the discussion.

It's been a while and everyone has forgotten everything, so I'll drop
this version of the patchset.

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Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Alexander Duyck]

On Tue, 2019-03-12 at 15:07 -0700, Andrew Morton wrote:
> On Wed, 5 Dec 2018 21:42:47 +0100 Michal Hocko <mhocko@kernel.org> wrote:
> 
> > > I got your explanation. However Andrew had already applied the patches
> > > and I had some outstanding issues in them that needed to be addressed.
> > > So I thought it best to send out this set of patches with those fixes
> > > before the code in mm became too stale. I am still working on what to
> > > do about the Reserved bit, and plan to submit it as a follow-up set.
> > > From my experience Andrew can drop patches between different versions of
> > the patchset. Things can change a lot while they are in mmotm and under
> > the discussion.
> 
> It's been a while and everyone has forgotten everything, so I'll drop
> this version of the patchset.
> 

As far as getting to the reserved bit I probably won't have the time in
the near future. If I were to resubmit the first 4 patches as a
standalone patch set would that be acceptable, or would they be held up
as well until the reserved bit issues is addressed?

- Alex



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Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Andrew Morton]

On Tue, 12 Mar 2019 15:50:36 -0700 Alexander Duyck <alexander.h.duyck@linux.intel.com> wrote:

> On Tue, 2019-03-12 at 15:07 -0700, Andrew Morton wrote:
> > On Wed, 5 Dec 2018 21:42:47 +0100 Michal Hocko <mhocko@kernel.org> wrote:
> > 
> > > > I got your explanation. However Andrew had already applied the patches
> > > > and I had some outstanding issues in them that needed to be addressed.
> > > > So I thought it best to send out this set of patches with those fixes
> > > > before the code in mm became too stale. I am still working on what to
> > > > do about the Reserved bit, and plan to submit it as a follow-up set.
> > > > From my experience Andrew can drop patches between different versions of
> > > the patchset. Things can change a lot while they are in mmotm and under
> > > the discussion.
> > 
> > It's been a while and everyone has forgotten everything, so I'll drop
> > this version of the patchset.
> > 
> 
> As far as getting to the reserved bit I probably won't have the time in
> the near future. If I were to resubmit the first 4 patches as a
> standalone patch set would that be acceptable, or would they be held up
> as well until the reserved bit issues is addressed?
> 

Yes, I think that merging the first four will be OK.  As long as they
don't add some bug which [5/5] corrects, which happens sometimes!

Please redo, retest and resend sometime?
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Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links

[Alexander Duyck]

On Wed, 2019-03-13 at 09:33 -0700, Andrew Morton wrote:
> On Tue, 12 Mar 2019 15:50:36 -0700 Alexander Duyck <alexander.h.duyck@linux.intel.com> wrote:
> 
> > On Tue, 2019-03-12 at 15:07 -0700, Andrew Morton wrote:
> > > On Wed, 5 Dec 2018 21:42:47 +0100 Michal Hocko <mhocko@kernel.org> wrote:
> > > 
> > > > > I got your explanation. However Andrew had already applied the patches
> > > > > and I had some outstanding issues in them that needed to be addressed.
> > > > > So I thought it best to send out this set of patches with those fixes
> > > > > before the code in mm became too stale. I am still working on what to
> > > > > do about the Reserved bit, and plan to submit it as a follow-up set.
> > > > > From my experience Andrew can drop patches between different versions of
> > > > the patchset. Things can change a lot while they are in mmotm and under
> > > > the discussion.
> > > 
> > > It's been a while and everyone has forgotten everything, so I'll drop
> > > this version of the patchset.
> > > 
> > 
> > As far as getting to the reserved bit I probably won't have the time in
> > the near future. If I were to resubmit the first 4 patches as a
> > standalone patch set would that be acceptable, or would they be held up
> > as well until the reserved bit issues is addressed?
> > 
> 
> Yes, I think that merging the first four will be OK.  As long as they
> don't add some bug which [5/5] corrects, which happens sometimes!
> 
> Please redo, retest and resend sometime?

I had gone through and tested with each patch applied individually when
I was performance testing them, and I am fairly certain there wasn't a
bug introduced between any two patches.

The issue that I recall Michal had was the fact that I was essentially
embedding the setting of the reserved page under several layers of
function calls, which would make it harder to remove. I started that
work at about patch 5 which is why I figured I would resend the first
4, and hold off on 5-7 until I can get the reserved bit removal for
hotplug done.

I can probably have the patches ready to go in a couple days. I'll send
updates once linux-next and mmotm with the patches dropped have been
posted.

Thanks.

- Alex

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[mm PATCH v6 7/7] mm: Use common iterator for deferred_init_pages and deferred_free_pages

[Alexander Duyck]

Create a common iterator to be used by both deferred_init_pages and
deferred_free_pages. By doing this we can cut down a bit on code overhead
as they will likely both be inlined into the same function anyway.

This new approach allows deferred_init_pages to make use of
__init_pageblock. By doing this we can cut down on the code size by sharing
code between both the hotplug and deferred memory init code paths.

An additional benefit to this approach is that we improve in cache locality
of the memory init as we can focus on the memory areas related to
identifying if a given PFN is valid and keep that warm in the cache until
we transition to a region of a different type. So we will stream through a
chunk of valid blocks before we turn to initializing page structs.

On my x86_64 test system with 384GB of memory per node I saw a reduction in
initialization time from 1.38s to 1.06s as a result of this patch.

Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 mm/page_alloc.c |  146 +++++++++++++++++++++++++++++--------------------------
 1 file changed, 77 insertions(+), 69 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 61eb9945d805..48c6fc73a70d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1481,32 +1481,6 @@ void clear_zone_contiguous(struct zone *zone)
 }
 
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
-static void __init deferred_free_range(unsigned long pfn,
-				       unsigned long nr_pages)
-{
-	struct page *page;
-	unsigned long i;
-
-	if (!nr_pages)
-		return;
-
-	page = pfn_to_page(pfn);
-
-	/* Free a large naturally-aligned chunk if possible */
-	if (nr_pages == pageblock_nr_pages &&
-	    (pfn & (pageblock_nr_pages - 1)) == 0) {
-		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-		__free_pages_core(page, pageblock_order);
-		return;
-	}
-
-	for (i = 0; i < nr_pages; i++, page++, pfn++) {
-		if ((pfn & (pageblock_nr_pages - 1)) == 0)
-			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-		__free_pages_core(page, 0);
-	}
-}
-
 /* Completion tracking for deferred_init_memmap() threads */
 static atomic_t pgdat_init_n_undone __initdata;
 static __initdata DECLARE_COMPLETION(pgdat_init_all_done_comp);
@@ -1518,48 +1492,89 @@ static inline void __init pgdat_init_report_one_done(void)
 }
 
 /*
- * Returns true if page needs to be initialized or freed to buddy allocator.
+ * Returns count if page range needs to be initialized or freed
  *
- * First we check if pfn is valid on architectures where it is possible to have
- * holes within pageblock_nr_pages. On systems where it is not possible, this
- * function is optimized out.
+ * First we check if the contiguous pfns are valid on architectures where it
+ * is possible to have holes within pageblock_nr_pages. On systems where it
+ * is not possible, this function is optimized out.
+ *
+ * Then, we check if a current large page is valid by only checking the
+ * validity of the head pfn.
  *
- * Then, we check if a current large page is valid by only checking the validity
- * of the head pfn.
  */
-static inline bool __init deferred_pfn_valid(unsigned long pfn)
+static unsigned long __next_pfn_valid_range(unsigned long *pfn,
+					    unsigned long *i,
+					    unsigned long end_pfn)
 {
-	if (!pfn_valid_within(pfn))
-		return false;
-	if (!(pfn & (pageblock_nr_pages - 1)) && !pfn_valid(pfn))
-		return false;
-	return true;
+	unsigned long start_pfn = *i;
+
+	while (start_pfn < end_pfn) {
+		unsigned long t = ALIGN(start_pfn + 1, pageblock_nr_pages);
+		unsigned long pageblock_pfn = min(t, end_pfn);
+		unsigned long count = 0;
+
+#ifndef CONFIG_HOLES_IN_ZONE
+		if (pfn_valid(start_pfn))
+			count = pageblock_pfn - start_pfn;
+		start_pfn = pageblock_pfn;
+#else
+		while (start_pfn < pageblock_pfn) {
+			if (pfn_valid(start_pfn++)) {
+				count++;
+				continue;
+			}
+
+			if (!count)
+				continue;
+
+			/*
+			 * The last PFN was invalid, report the block of
+			 * PFNs we currently have available and skip over
+			 * the invalid one.
+			 */
+			*pfn = start_pfn - (count + 1);
+			*i = start_pfn;
+			return count;
+		}
+#endif
+		if (!count)
+			continue;
+
+		*pfn = start_pfn - count;
+		*i = start_pfn;
+		return count;
+	}
+
+	return 0;
 }
 
+#define for_each_deferred_pfn_valid_range(pfn, count, i, start_pfn, end_pfn) \
+	for (i = (start_pfn),						     \
+	     count = __next_pfn_valid_range(&pfn, &i, (end_pfn));	     \
+	     count;							     \
+	     count = __next_pfn_valid_range(&pfn, &i, (end_pfn)))
+
 /*
  * Free pages to buddy allocator. Try to free aligned pages in
  * pageblock_nr_pages sizes.
  */
-static void __init deferred_free_pages(unsigned long pfn,
+static void __init deferred_free_pages(unsigned long start_pfn,
 				       unsigned long end_pfn)
 {
-	unsigned long nr_pgmask = pageblock_nr_pages - 1;
-	unsigned long nr_free = 0;
-
-	for (; pfn < end_pfn; pfn++) {
-		if (!deferred_pfn_valid(pfn)) {
-			deferred_free_range(pfn - nr_free, nr_free);
-			nr_free = 0;
-		} else if (!(pfn & nr_pgmask)) {
-			deferred_free_range(pfn - nr_free, nr_free);
-			nr_free = 1;
-			touch_nmi_watchdog();
+	unsigned long i, pfn, count;
+
+	for_each_deferred_pfn_valid_range(pfn, count, i, start_pfn, end_pfn) {
+		struct page *page = pfn_to_page(pfn);
+
+		if (count == pageblock_nr_pages) {
+			__free_pages_core(page, pageblock_order);
 		} else {
-			nr_free++;
+			while (count--)
+				__free_pages_core(page++, 0);
 		}
+
+		touch_nmi_watchdog();
 	}
-	/* Free the last block of pages to allocator */
-	deferred_free_range(pfn - nr_free, nr_free);
 }
 
 /*
@@ -1568,29 +1583,22 @@ static void __init deferred_free_pages(unsigned long pfn,
  * Return number of pages initialized.
  */
 static unsigned long  __init deferred_init_pages(struct zone *zone,
-						 unsigned long pfn,
+						 unsigned long start_pfn,
 						 unsigned long end_pfn)
 {
-	unsigned long nr_pgmask = pageblock_nr_pages - 1;
 	int nid = zone_to_nid(zone);
+	unsigned long i, pfn, count;
 	unsigned long nr_pages = 0;
 	int zid = zone_idx(zone);
-	struct page *page = NULL;
 
-	for (; pfn < end_pfn; pfn++) {
-		if (!deferred_pfn_valid(pfn)) {
-			page = NULL;
-			continue;
-		} else if (!page || !(pfn & nr_pgmask)) {
-			page = pfn_to_page(pfn);
-			touch_nmi_watchdog();
-		} else {
-			page++;
-		}
-		__init_single_page(page, pfn, zid, nid);
-		nr_pages++;
+	for_each_deferred_pfn_valid_range(pfn, count, i, start_pfn, end_pfn) {
+		nr_pages += count;
+		__init_pageblock(pfn, count, zid, nid, NULL, false);
+
+		touch_nmi_watchdog();
 	}
-	return (nr_pages);
+
+	return nr_pages;
 }
 
 /*

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