[PATCH v2 1/3] mm/mm_init.c: get the highest zone directly

[PATCH v2 1/3] mm/mm_init.c: get the highest zone directly

[Wei Yang]

We have recorded nr_zones in pgdat, just get it directly.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
---
 mm/mm_init.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/mm/mm_init.c b/mm/mm_init.c
index aa83105b3a1b..2bcf87eab0c6 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2136,7 +2136,7 @@ static int __init deferred_init_memmap(void *data)
 	unsigned long first_init_pfn, flags;
 	unsigned long start = jiffies;
 	struct zone *zone;
-	int zid, max_threads;
+	int max_threads;
 	u64 i;
 
 	/* Bind memory initialisation thread to a local node if possible */
@@ -2163,12 +2163,8 @@ static int __init deferred_init_memmap(void *data)
 	 */
 	pgdat_resize_unlock(pgdat, &flags);
 
-	/* Only the highest zone is deferred so find it */
-	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
-		zone = pgdat->node_zones + zid;
-		if (first_init_pfn < zone_end_pfn(zone))
-			break;
-	}
+	/* Only the highest zone is deferred */
+	zone = pgdat->node_zones + pgdat->nr_zones - 1;
 
 	/* 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,
@@ -2196,7 +2192,7 @@ static int __init deferred_init_memmap(void *data)
 	}
 zone_empty:
 	/* Sanity check that the next zone really is unpopulated */
-	WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
+	WARN_ON(pgdat->nr_zones < MAX_NR_ZONES && populated_zone(++zone));
 
 	pr_info("node %d deferred pages initialised in %ums\n",
 		pgdat->node_id, jiffies_to_msecs(jiffies - start));
-- 
2.34.1

[PATCH v2 2/3] mm/mm_init.c: use deferred_init_mem_pfn_range_in_zone() to decide loop condition

[Wei Yang]

If deferred_init_mem_pfn_range_in_zone() return true, we know it finds
some range in (spfn, epfn). Then we can use it directly for the loop
condition.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
---
 mm/mm_init.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 2bcf87eab0c6..d05a4c38310f 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2166,20 +2166,15 @@ static int __init deferred_init_memmap(void *data)
 	/* Only the highest zone is deferred */
 	zone = pgdat->node_zones + pgdat->nr_zones - 1;
 
-	/* 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;
-
 	max_threads = deferred_page_init_max_threads(cpumask);
 
-	while (spfn < epfn) {
-		unsigned long epfn_align = ALIGN(epfn, PAGES_PER_SECTION);
+	while (deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, first_init_pfn)) {
+		first_init_pfn = ALIGN(epfn, PAGES_PER_SECTION);
 		struct padata_mt_job job = {
 			.thread_fn   = deferred_init_memmap_chunk,
 			.fn_arg      = zone,
 			.start       = spfn,
-			.size        = epfn_align - spfn,
+			.size        = first_init_pfn - spfn,
 			.align       = PAGES_PER_SECTION,
 			.min_chunk   = PAGES_PER_SECTION,
 			.max_threads = max_threads,
@@ -2187,10 +2182,8 @@ static int __init deferred_init_memmap(void *data)
 		};
 
 		padata_do_multithreaded(&job);
-		deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
-						    epfn_align);
 	}
-zone_empty:
+
 	/* Sanity check that the next zone really is unpopulated */
 	WARN_ON(pgdat->nr_zones < MAX_NR_ZONES && populated_zone(++zone));
 
-- 
2.34.1

[PATCH v2 3/3] mm/mm_init.c: not always search next deferred_init_pfn from very beginning

[Wei Yang]

In function deferred_init_memmap(), we call
deferred_init_mem_pfn_range_in_zone() to get the next deferred_init_pfn.
But we always search it from the very beginning.

Since we save the index in i, we can leverage this to search from i next
time.

[rppt refine the comment]

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>

---
v2: update comment instead of rename function name
---
 include/linux/memblock.h | 19 -------------------
 mm/mm_init.c             | 23 ++++++++++++++---------
 2 files changed, 14 insertions(+), 28 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 6cf18dc2b4d0..45cac33334c8 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -299,25 +299,6 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
 void __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
 				  unsigned long *out_spfn,
 				  unsigned long *out_epfn);
-/**
- * for_each_free_mem_pfn_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))
 
 /**
  * for_each_free_mem_pfn_range_in_zone_from - iterate through zone specific
diff --git a/mm/mm_init.c b/mm/mm_init.c
index d05a4c38310f..c152c60eca3d 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2017,24 +2017,29 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
 }
 
 /*
- * 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.
+ * This function is meant to pre-load the iterator for the zone init from
+ * a given point.
+ * Specifically it walks through the ranges starting with initial index
+ * passed to it 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;
+	u64 j = *i;
+
+	if (j == 0)
+		__next_mem_pfn_range_in_zone(&j, zone, spfn, epfn);
 
 	/*
 	 * 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) {
+	for_each_free_mem_pfn_range_in_zone_from(j, zone, spfn, epfn) {
 		if (*epfn <= first_init_pfn)
 			continue;
 		if (*spfn < first_init_pfn)
@@ -2106,7 +2111,7 @@ deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn,
 {
 	unsigned long spfn, epfn;
 	struct zone *zone = arg;
-	u64 i;
+	u64 i = 0;
 
 	deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, start_pfn);
 
@@ -2137,7 +2142,7 @@ static int __init deferred_init_memmap(void *data)
 	unsigned long start = jiffies;
 	struct zone *zone;
 	int max_threads;
-	u64 i;
+	u64 i = 0;
 
 	/* Bind memory initialisation thread to a local node if possible */
 	if (!cpumask_empty(cpumask))
@@ -2212,7 +2217,7 @@ bool __init deferred_grow_zone(struct zone *zone, unsigned int order)
 	unsigned long first_deferred_pfn = pgdat->first_deferred_pfn;
 	unsigned long spfn, epfn, flags;
 	unsigned long nr_pages = 0;
-	u64 i;
+	u64 i = 0;
 
 	/* Only the last zone may have deferred pages */
 	if (zone_end_pfn(zone) != pgdat_end_pfn(pgdat))
-- 
2.34.1

Re: [PATCH v2 1/3] mm/mm_init.c: get the highest zone directly

[Mike Rapoport]

From: Mike Rapoport (IBM) <rppt@kernel.org>

On Wed, 05 Jun 2024 07:13:37 +0000, Wei Yang wrote:
> We have recorded nr_zones in pgdat, just get it directly.
> 
> 

Applied to for-next branch of memblock.git tree, thanks!

[1/3] mm/mm_init.c: get the highest zone directly
      commit: e62a627e845de79104e7fb6661eb69162aa91a21
[2/3] mm/mm_init.c: use deferred_init_mem_pfn_range_in_zone() to decide loop condition
      commit: 731b1168481978f56e81e1866758356387e4c23d
[3/3] mm/mm_init.c: not always search next deferred_init_pfn from very beginning
      commit: 8887ee905d0889d491e88b12f8134d31c8a21b11

tree: https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock
branch: for-next

--
Sincerely yours,
Mike.