+ mm-memremap-remove-unused-get_dev_pagemap-parameter.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/memremap: remove unused get_dev_pagemap() parameter
has been added to the -mm mm-new branch.  Its filename is
     mm-memremap-remove-unused-get_dev_pagemap-parameter.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memremap-remove-unused-get_dev_pagemap-parameter.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
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fixup patches in mm-new.

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------------------------------------------------------
From: Alistair Popple <apopple@nvidia.com>
Subject: mm/memremap: remove unused get_dev_pagemap() parameter
Date: Thu, 4 Sep 2025 08:59:26 +1000

GUP no longer uses get_dev_pagemap().  As it was the only user of the
get_dev_pagemap() pgmap caching feature it can be removed.

Link: https://lkml.kernel.org/r/20250903225926.34702-2-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/memremap.h |    6 ++----
 mm/memory-failure.c      |    2 +-
 mm/memory_hotplug.c      |    2 +-
 mm/memremap.c            |   22 ++++------------------
 4 files changed, 8 insertions(+), 24 deletions(-)

--- a/include/linux/memremap.h~mm-memremap-remove-unused-get_dev_pagemap-parameter
+++ a/include/linux/memremap.h
@@ -211,8 +211,7 @@ void *memremap_pages(struct dev_pagemap
 void memunmap_pages(struct dev_pagemap *pgmap);
 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
-struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
-		struct dev_pagemap *pgmap);
+struct dev_pagemap *get_dev_pagemap(unsigned long pfn);
 bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
 
 unsigned long memremap_compat_align(void);
@@ -234,8 +233,7 @@ static inline void devm_memunmap_pages(s
 {
 }
 
-static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
-		struct dev_pagemap *pgmap)
+static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn)
 {
 	return NULL;
 }
--- a/mm/memory-failure.c~mm-memremap-remove-unused-get_dev_pagemap-parameter
+++ a/mm/memory-failure.c
@@ -2194,7 +2194,7 @@ int memory_failure(unsigned long pfn, in
 			goto unlock_mutex;
 
 		if (pfn_valid(pfn)) {
-			pgmap = get_dev_pagemap(pfn, NULL);
+			pgmap = get_dev_pagemap(pfn);
 			put_ref_page(pfn, flags);
 			if (pgmap) {
 				res = memory_failure_dev_pagemap(pfn, flags,
--- a/mm/memory_hotplug.c~mm-memremap-remove-unused-get_dev_pagemap-parameter
+++ a/mm/memory_hotplug.c
@@ -375,7 +375,7 @@ struct page *pfn_to_online_page(unsigned
 	 * the section may be 'offline' but 'valid'. Only
 	 * get_dev_pagemap() can determine sub-section online status.
 	 */
-	pgmap = get_dev_pagemap(pfn, NULL);
+	pgmap = get_dev_pagemap(pfn);
 	put_dev_pagemap(pgmap);
 
 	/* The presence of a pgmap indicates ZONE_DEVICE offline pfn */
--- a/mm/memremap.c~mm-memremap-remove-unused-get_dev_pagemap-parameter
+++ a/mm/memremap.c
@@ -153,14 +153,14 @@ static int pagemap_range(struct dev_page
 				"altmap not supported for multiple ranges\n"))
 		return -EINVAL;
 
-	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
+	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start));
 	if (conflict_pgmap) {
 		WARN(1, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
 		return -ENOMEM;
 	}
 
-	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
+	conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end));
 	if (conflict_pgmap) {
 		WARN(1, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
@@ -397,26 +397,12 @@ EXPORT_SYMBOL_GPL(devm_memunmap_pages);
 /**
  * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
  * @pfn: page frame number to lookup page_map
- * @pgmap: optional known pgmap that already has a reference
- *
- * If @pgmap is non-NULL and covers @pfn it will be returned as-is.  If @pgmap
- * is non-NULL but does not cover @pfn the reference to it will be released.
  */
-struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
-		struct dev_pagemap *pgmap)
+struct dev_pagemap *get_dev_pagemap(unsigned long pfn)
 {
+	struct dev_pagemap *pgmap;
 	resource_size_t phys = PFN_PHYS(pfn);
 
-	/*
-	 * In the cached case we're already holding a live reference.
-	 */
-	if (pgmap) {
-		if (phys >= pgmap->range.start && phys <= pgmap->range.end)
-			return pgmap;
-		put_dev_pagemap(pgmap);
-	}
-
-	/* fall back to slow path lookup */
 	rcu_read_lock();
 	pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
 	if (pgmap && !percpu_ref_tryget_live_rcu(&pgmap->ref))
_

Patches currently in -mm which might be from apopple@nvidia.com are

mm-gup-remove-dead-pgmap-refcounting-code.patch
mm-memremap-remove-unused-get_dev_pagemap-parameter.patch