Message-Id: <20220913195508.3511038-19-opendmb@gmail.com>
Date:   Tue, 13 Sep 2022 12:55:05 -0700
From:   Doug Berger <opendmb@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Jonathan Corbet <corbet@....net>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Frank Rowand <frowand.list@...il.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Mike Rapoport <rppt@...nel.org>,
        Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Borislav Petkov <bp@...e.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Doug Berger <opendmb@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Hildenbrand <david@...hat.com>, Zi Yan <ziy@...dia.com>,
        Oscar Salvador <osalvador@...e.de>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Kees Cook <keescook@...omium.org>,
        - <devicetree-spec@...r.kernel.org>,
        KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
        Mel Gorman <mgorman@...e.de>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-mm@...ck.org, iommu@...ts.linux.dev
Subject: [PATCH 18/21] mm/cma: support CMA in Designated Movable Blocks

This commit allows for different page allocator handling for
CMA areas that are within Designated Movable Blocks.

Specifically, the pageblocks are allowed to remain migratetype
MIGRATE_MOVABLE to allow more aggressive utilization by the
page allocator. This also means that the page allocator should
not consider these pages as part of the nr_free_cma metric it
uses for managing MIGRATE_CMA type pageblocks.

This leads to the decision to remove these areas from the
CmaTotal metrics after initialization to avoid confusion.

Signed-off-by: Doug Berger <opendmb@...il.com>
---
 include/linux/cma.h | 13 ++++++---
 mm/cma.c            | 55 +++++++++++++++++++++++++-----------
 mm/page_alloc.c     | 69 +++++++++++++++++++++++++++++----------------
 3 files changed, 92 insertions(+), 45 deletions(-)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index 63873b93deaa..ffbb8ea2c5f8 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -31,11 +31,13 @@ extern phys_addr_t cma_get_base(const struct cma *cma);
 extern unsigned long cma_get_size(const struct cma *cma);
 extern const char *cma_get_name(const struct cma *cma);
 
-extern int __init cma_declare_contiguous_nid(phys_addr_t base,
+extern int __init __cma_declare_contiguous_nid(phys_addr_t base,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
 			bool fixed, const char *name, struct cma **res_cma,
-			int nid);
+			int nid, bool in_dmb);
+#define cma_declare_contiguous_nid(b, s, l, a, o, f, n, r_c, nid)	\
+	__cma_declare_contiguous_nid(b, s, l, a, o, f, n, r_c, nid, false)
 static inline int __init cma_declare_contiguous(phys_addr_t base,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
@@ -44,10 +46,13 @@ static inline int __init cma_declare_contiguous(phys_addr_t base,
 	return cma_declare_contiguous_nid(base, size, limit, alignment,
 			order_per_bit, fixed, name, res_cma, NUMA_NO_NODE);
 }
-extern int cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
+extern int __cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
 					unsigned int order_per_bit,
 					const char *name,
-					struct cma **res_cma);
+					struct cma **res_cma,
+					bool in_dmb);
+#define cma_init_reserved_mem(base, size, order, name, res_cma)		\
+	__cma_init_reserved_mem(base, size, order, name, res_cma, 0)
 extern struct page *cma_alloc(struct cma *cma, unsigned long count, unsigned int align,
 			      bool no_warn);
 extern bool cma_pages_valid(struct cma *cma, const struct page *pages, unsigned long count);
diff --git a/mm/cma.c b/mm/cma.c
index 6208a3e1cd9d..4f33cd54db9e 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -33,6 +33,7 @@
 #include <linux/kmemleak.h>
 #include <linux/page-isolation.h>
 #include <trace/events/cma.h>
+#include <linux/dmb.h>
 
 #include "cma.h"
 
@@ -98,6 +99,10 @@ static void __init cma_activate_area(struct cma *cma)
 {
 	unsigned long base_pfn = cma->base_pfn, pfn;
 	struct zone *zone;
+	int is_dmb = dmb_intersects(base_pfn, base_pfn + cma->count);
+
+	if (is_dmb == DMB_MIXED)
+		goto out_error;
 
 	cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL);
 	if (!cma->bitmap)
@@ -116,13 +121,17 @@ static void __init cma_activate_area(struct cma *cma)
 			goto not_in_zone;
 	}
 
-	for (pfn = base_pfn; pfn < base_pfn + cma->count;
-	     pfn += pageblock_nr_pages) {
-		struct page *page = pfn_to_page(pfn);
+	if (is_dmb == DMB_INTERSECTS) {
+		totalcma_pages -= cma->count;
+	} else {
+		for (pfn = base_pfn; pfn < base_pfn + cma->count;
+		     pfn += pageblock_nr_pages) {
+			struct page *page = pfn_to_page(pfn);
 
-		set_pageblock_migratetype(page, MIGRATE_CMA);
-		init_reserved_pageblock(page);
-		page_zone(page)->cma_pages += pageblock_nr_pages;
+			set_pageblock_migratetype(page, MIGRATE_CMA);
+			init_reserved_pageblock(page);
+			page_zone(page)->cma_pages += pageblock_nr_pages;
+		}
 	}
 
 	spin_lock_init(&cma->lock);
@@ -141,7 +150,8 @@ static void __init cma_activate_area(struct cma *cma)
 	if (!cma->reserve_pages_on_error) {
 		for (pfn = base_pfn; pfn < base_pfn + cma->count;
 		     pfn += pageblock_nr_pages)
-			init_reserved_pageblock(pfn_to_page(pfn));
+			if (!dmb_intersects(pfn, pfn + pageblock_nr_pages))
+				init_reserved_pageblock(pfn_to_page(pfn));
 	}
 	totalcma_pages -= cma->count;
 	cma->count = 0;
@@ -166,7 +176,7 @@ void __init cma_reserve_pages_on_error(struct cma *cma)
 }
 
 /**
- * cma_init_reserved_mem() - create custom contiguous area from reserved memory
+ * __cma_init_reserved_mem() - create custom contiguous area in reserved memory
  * @base: Base address of the reserved area
  * @size: Size of the reserved area (in bytes),
  * @order_per_bit: Order of pages represented by one bit on bitmap.
@@ -174,15 +184,18 @@ void __init cma_reserve_pages_on_error(struct cma *cma)
  *        the area will be set to "cmaN", where N is a running counter of
  *        used areas.
  * @res_cma: Pointer to store the created cma region.
+ * @in_dmb: Designate the reserved memory as a Designated Movable Block.
  *
  * This function creates custom contiguous area from already reserved memory.
  */
-int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
-				 unsigned int order_per_bit,
-				 const char *name,
-				 struct cma **res_cma)
+int __init __cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
+				   unsigned int order_per_bit,
+				   const char *name,
+				   struct cma **res_cma,
+				   bool in_dmb)
 {
 	struct cma *cma;
+	int err;
 
 	/* Sanity checks */
 	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
@@ -201,6 +214,14 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
 	if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
 		return -EINVAL;
 
+	if (in_dmb) {
+		err = dmb_reserve(base, size, NULL);
+		if (err) {
+			pr_err("Cannot reserve DMB for CMA!\n");
+			return err;
+		}
+	}
+
 	/*
 	 * Each reserved area must be initialised later, when more kernel
 	 * subsystems (like slab allocator) are available.
@@ -223,7 +244,7 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
 }
 
 /**
- * cma_declare_contiguous_nid() - reserve custom contiguous area
+ * __cma_declare_contiguous_nid() - reserve custom contiguous area
  * @base: Base address of the reserved area optional, use 0 for any
  * @size: Size of the reserved area (in bytes),
  * @limit: End address of the reserved memory (optional, 0 for any).
@@ -233,6 +254,7 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
  * @name: The name of the area. See function cma_init_reserved_mem()
  * @res_cma: Pointer to store the created cma region.
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
+ * @in_dmb: Designate the reserved memory as a Designated Movable Block.
  *
  * This function reserves memory from early allocator. It should be
  * called by arch specific code once the early allocator (memblock or bootmem)
@@ -242,11 +264,11 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
  * If @fixed is true, reserve contiguous area at exactly @base.  If false,
  * reserve in range from @base to @limit.
  */
-int __init cma_declare_contiguous_nid(phys_addr_t base,
+int __init __cma_declare_contiguous_nid(phys_addr_t base,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
 			bool fixed, const char *name, struct cma **res_cma,
-			int nid)
+			int nid, bool in_dmb)
 {
 	phys_addr_t memblock_end = memblock_end_of_DRAM();
 	phys_addr_t highmem_start;
@@ -374,7 +396,8 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
 		base = addr;
 	}
 
-	ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
+	ret = __cma_init_reserved_mem(base, size, order_per_bit, name, res_cma,
+				      in_dmb);
 	if (ret)
 		goto free_mem;
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e38dd1b32771..09d00c178bc8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -9233,29 +9233,8 @@ int __alloc_contig_migrate_range(struct compact_control *cc,
 	return 0;
 }
 
-/**
- * alloc_contig_range() -- tries to allocate given range of pages
- * @start:	start PFN to allocate
- * @end:	one-past-the-last PFN to allocate
- * @migratetype:	migratetype of the underlying pageblocks (either
- *			#MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
- *			in range must have the same migratetype and it must
- *			be either of the two.
- * @gfp_mask:	GFP mask to use during compaction
- *
- * The PFN range does not have to be pageblock aligned. The PFN range must
- * belong to a single zone.
- *
- * The first thing this routine does is attempt to MIGRATE_ISOLATE all
- * pageblocks in the range.  Once isolated, the pageblocks should not
- * be modified by others.
- *
- * Return: zero on success or negative error code.  On success all
- * pages which PFN is in [start, end) are allocated for the caller and
- * need to be freed with free_contig_range().
- */
-int alloc_contig_range(unsigned long start, unsigned long end,
-		       unsigned migratetype, gfp_t gfp_mask)
+int _alloc_contig_range(unsigned long start, unsigned long end,
+			unsigned int migratetype, gfp_t gfp_mask)
 {
 	unsigned long outer_start, outer_end;
 	int order;
@@ -9379,6 +9358,46 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 	undo_isolate_page_range(start, end, migratetype);
 	return ret;
 }
+
+/**
+ * alloc_contig_range() -- tries to allocate given range of pages
+ * @start:	start PFN to allocate
+ * @end:	one-past-the-last PFN to allocate
+ * @migratetype:	migratetype of the underlying pageblocks (either
+ *			#MIGRATE_MOVABLE or #MIGRATE_CMA).  All pageblocks
+ *			in range must have the same migratetype and it must
+ *			be either of the two.
+ * @gfp_mask:	GFP mask to use during compaction
+ *
+ * The PFN range does not have to be pageblock aligned. The PFN range must
+ * belong to a single zone.
+ *
+ * The first thing this routine does is attempt to MIGRATE_ISOLATE all
+ * pageblocks in the range.  Once isolated, the pageblocks should not
+ * be modified by others.
+ *
+ * Return: zero on success or negative error code.  On success all
+ * pages which PFN is in [start, end) are allocated for the caller and
+ * need to be freed with free_contig_range().
+ */
+int alloc_contig_range(unsigned long start, unsigned long end,
+		       unsigned int migratetype, gfp_t gfp_mask)
+{
+	switch (dmb_intersects(start, end)) {
+	case DMB_DISJOINT:
+		break;
+	case DMB_INTERSECTS:
+		if (migratetype == MIGRATE_CMA)
+			migratetype = MIGRATE_MOVABLE;
+		else
+			return -EBUSY;
+		break;
+	default:
+		return -EBUSY;
+	}
+
+	return _alloc_contig_range(start, end, migratetype, gfp_mask);
+}
 EXPORT_SYMBOL(alloc_contig_range);
 
 static int __alloc_contig_pages(unsigned long start_pfn,
@@ -9386,8 +9405,8 @@ static int __alloc_contig_pages(unsigned long start_pfn,
 {
 	unsigned long end_pfn = start_pfn + nr_pages;
 
-	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
-				  gfp_mask);
+	return _alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
+				   gfp_mask);
 }
 
 static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn,
-- 
2.25.1

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