[mm PATCH v7 0/4] Deferred page init improvements

[mm PATCH v7 0/4] 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 I have seen the
following. In the case of regular memory initialization the deferred init
time was decreased from 3.75s to 1.38s on average. This amounts to a 172%
improvement for the deferred memory initialization performance.

I have called out the improvement observed with each patch.

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 descriptions.
    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
v6->v7:
    Updated MAX_ORDER_NR_PAGES patch to stop on section aligned boundaries
    Dropped patches 5-7
        Will follow-up later with reserved bit rework before resubmitting

---

Alexander Duyck (4):
      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


 arch/sparc/include/asm/pgtable_64.h |   30 -----
 include/linux/memblock.h            |   41 +++++++
 include/linux/mm.h                  |   41 ++++++-
 mm/memblock.c                       |   64 ++++++++++
 mm/page_alloc.c                     |  218 ++++++++++++++++++++++-------------
 5 files changed, 277 insertions(+), 117 deletions(-)

--

[mm PATCH v7 1/4] mm: Use mm_zero_struct_page from SPARC on all 64b architectures

[Alexander Duyck]

From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

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 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 fe52e266016e..f391c2d7c180 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -124,10 +124,45 @@ static inline void totalram_pages_set(long val)
 
 /*
  * 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
 

[mm PATCH v7 2/4] mm: Drop meminit_pfn_in_nid as it is redundant

[Alexander Duyck]

From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

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 0c53807a2943..2d2bca9803d2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1398,36 +1398,22 @@ 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
 
 
@@ -1556,21 +1542,13 @@ 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;
 }
 
@@ -1578,15 +1556,14 @@ static inline void __init pgdat_init_report_one_done(void)
  * 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)) {
@@ -1606,17 +1583,18 @@ 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)) {
@@ -1679,12 +1657,12 @@ 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);
 
@@ -1716,7 +1694,6 @@ static int __init deferred_init_memmap(void *data)
 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);
@@ -1766,7 +1743,7 @@ static int __init deferred_init_memmap(void *data)
 		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;
 		}
@@ -1778,7 +1755,7 @@ 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, first_deferred_pfn, PFN_DOWN(epa));
-		deferred_free_pages(nid, zid, spfn, epfn);
+		deferred_free_pages(spfn, epfn);
 
 		if (first_deferred_pfn == epfn)
 			break;

[mm PATCH v7 3/4] mm: Implement new zone specific memblock iterator

[Alexander Duyck]

From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

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 294d5d80e150..f8b78892b977 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -240,6 +240,31 @@ 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 e7665cf914b1..28fa8926d9f8 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1255,6 +1255,70 @@ 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 */
 
 /**
  * memblock_alloc_range_nid - allocate boot memory block
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2d2bca9803d2..61467e28c966 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1613,11 +1613,9 @@ 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);
@@ -1654,14 +1652,12 @@ 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);
@@ -1669,8 +1665,8 @@ 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;
@@ -1694,13 +1690,11 @@ static int __init deferred_init_memmap(void *data)
 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 */
@@ -1736,9 +1730,8 @@ static int __init deferred_init_memmap(void *data)
 		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);
@@ -1752,9 +1745,9 @@ static int __init deferred_init_memmap(void *data)
 			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)

Re: [mm PATCH v7 3/4] mm: Implement new zone specific memblock iterator

[Mike Rapoport]

On Fri, Apr 05, 2019 at 03:12:25PM -0700, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> 
> 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>

Reviewed-by: Mike Rapoport <rppt@linux.ibm.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 294d5d80e150..f8b78892b977 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -240,6 +240,31 @@ 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 e7665cf914b1..28fa8926d9f8 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1255,6 +1255,70 @@ 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 */
> 
>  /**
>   * memblock_alloc_range_nid - allocate boot memory block
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 2d2bca9803d2..61467e28c966 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1613,11 +1613,9 @@ 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);
> @@ -1654,14 +1652,12 @@ 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);
> @@ -1669,8 +1665,8 @@ 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;
> @@ -1694,13 +1690,11 @@ static int __init deferred_init_memmap(void *data)
>  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 */
> @@ -1736,9 +1730,8 @@ static int __init deferred_init_memmap(void *data)
>  		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);
> @@ -1752,9 +1745,9 @@ static int __init deferred_init_memmap(void *data)
>  			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)
> 

-- 
Sincerely yours,
Mike.

[mm PATCH v7 4/4] mm: Initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections

[Alexander Duyck]

From: Alexander Duyck <alexander.h.duyck@linux.intel.com>

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          |  162 ++++++++++++++++++++++++++++++++++------------
 2 files changed, 137 insertions(+), 41 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index f8b78892b977..47e3c0612592 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -263,6 +263,22 @@ 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 61467e28c966..06fbec9edf84 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1609,16 +1609,100 @@ 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, then 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, start_pfn, end_pfn) {
+		unsigned long t;
+
+		if (mo_pfn <= *start_pfn)
+			break;
+
+		t = min(mo_pfn, *end_pfn);
+		nr_pages += deferred_init_pages(zone, *start_pfn, t);
+
+		if (mo_pfn < *end_pfn) {
+			*start_pfn = mo_pfn;
+			break;
+		}
+	}
+
+	/* Reset values and now loop through freeing pages as needed */
+	swap(j, *i);
+
+	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);
+		deferred_free_pages(spfn, t);
+
+		if (mo_pfn <= epfn)
+			break;
+	}
+
+	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 */
@@ -1644,22 +1728,20 @@ 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 */
@@ -1692,9 +1774,9 @@ static int __init deferred_init_memmap(void *data)
 {
 	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 */
@@ -1723,37 +1805,35 @@ static int __init deferred_init_memmap(void *data)
 		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);
+	/*
+	 * Initialize and free pages in MAX_ORDER sized increments so
+	 * that we can avoid introducing any issues with the buddy
+	 * allocator.
+	 */
+	while (spfn < epfn) {
+		/* update our first deferred PFN for this section */
+		first_deferred_pfn = spfn;
+
+		nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
 
-		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;
-		}
+		/* We should only stop along section boundaries */
+		if ((first_deferred_pfn ^ spfn) < PAGES_PER_SECTION)
+			continue;
 
+		/* If our quota has been met we can stop here */
 		if (nr_pages >= nr_pages_needed)
 			break;
 	}
 
-	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->first_deferred_pfn = spfn;
 	pgdat_resize_unlock(pgdat, &flags);
 
 	return nr_pages > 0;