+ drivers-base-memory-make-memory-block-get-put-explicit.patch added to mm-new branch

+ drivers-base-memory-make-memory-block-get-put-explicit.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: drivers/base/memory: make memory block get/put explicit
has been added to the -mm mm-new branch.  Its filename is
     drivers-base-memory-make-memory-block-get-put-explicit.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/drivers-base-memory-make-memory-block-get-put-explicit.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
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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and is updated there most days

------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: drivers/base/memory: make memory block get/put explicit
Date: Tue, 12 May 2026 15:26:35 +0800

Rename the memory block lookup helper to make the acquired reference
explicit, add memory_block_put() to wrap put_device(), remove
find_memory_block(), and use memory_block_get() as the single block-id
based lookup interface.

This makes it clearer to callers that a successful lookup holds a
reference that must be dropped, reducing the chance of forgetting the
matching put and leaking the memory block device reference.

Link: https://lore.kernel.org/linux-mm/7887915D-E598-42B3-9AFE-BFFBACE8DE2D@linux.dev/#t
Link: https://lore.kernel.org/20260512072635.3969576-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Donet Tom <donettom@linux.ibm.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com> #s390
Cc: Richard Cheng <icheng@nvidia.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Doug Anderson <dianders@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/powerpc/platforms/pseries/hotplug-memory.c |   14 +----
 drivers/base/memory.c                           |   38 +++++---------
 drivers/base/node.c                             |    4 -
 drivers/s390/char/sclp_mem.c                    |   17 ++----
 include/linux/memory.h                          |    7 +-
 mm/memory_hotplug.c                             |    5 -
 6 files changed, 35 insertions(+), 50 deletions(-)

--- a/arch/powerpc/platforms/pseries/hotplug-memory.c~drivers-base-memory-make-memory-block-get-put-explicit
+++ a/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -164,13 +164,7 @@ static int update_lmb_associativity_inde
 
 static struct memory_block *lmb_to_memblock(struct drmem_lmb *lmb)
 {
-	unsigned long section_nr;
-	struct memory_block *mem_block;
-
-	section_nr = pfn_to_section_nr(PFN_DOWN(lmb->base_addr));
-
-	mem_block = find_memory_block(section_nr);
-	return mem_block;
+	return memory_block_get(phys_to_block_id(lmb->base_addr));
 }
 
 static int get_lmb_range(u32 drc_index, int n_lmbs,
@@ -220,7 +214,7 @@ static int dlpar_change_lmb_state(struct
 	else
 		rc = 0;
 
-	put_device(&mem_block->dev);
+	memory_block_put(mem_block);
 
 	return rc;
 }
@@ -319,12 +313,12 @@ static int dlpar_remove_lmb(struct drmem
 
 	rc = dlpar_offline_lmb(lmb);
 	if (rc) {
-		put_device(&mem_block->dev);
+		memory_block_put(mem_block);
 		return rc;
 	}
 
 	__remove_memory(lmb->base_addr, memory_block_size);
-	put_device(&mem_block->dev);
+	memory_block_put(mem_block);
 
 	/* Update memory regions for memory remove */
 	memblock_remove(lmb->base_addr, memory_block_size);
--- a/drivers/base/memory.c~drivers-base-memory-make-memory-block-get-put-explicit
+++ a/drivers/base/memory.c
@@ -649,7 +649,7 @@ int __weak arch_get_memory_phys_device(u
  *
  * Called under device_hotplug_lock.
  */
-struct memory_block *find_memory_block_by_id(unsigned long block_id)
+struct memory_block *memory_block_get(unsigned long block_id)
 {
 	struct memory_block *mem;
 
@@ -659,16 +659,6 @@ struct memory_block *find_memory_block_b
 	return mem;
 }
 
-/*
- * Called under device_hotplug_lock.
- */
-struct memory_block *find_memory_block(unsigned long section_nr)
-{
-	unsigned long block_id = memory_block_id(section_nr);
-
-	return find_memory_block_by_id(block_id);
-}
-
 static struct attribute *memory_memblk_attrs[] = {
 	&dev_attr_phys_index.attr,
 	&dev_attr_state.attr,
@@ -701,7 +691,7 @@ static int __add_memory_block(struct mem
 
 	ret = device_register(&memory->dev);
 	if (ret) {
-		put_device(&memory->dev);
+		memory_block_put(memory);
 		return ret;
 	}
 	ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory,
@@ -795,9 +785,9 @@ static int add_memory_block(unsigned lon
 	struct memory_block *mem;
 	int ret = 0;
 
-	mem = find_memory_block_by_id(block_id);
+	mem = memory_block_get(block_id);
 	if (mem) {
-		put_device(&mem->dev);
+		memory_block_put(mem);
 		return -EEXIST;
 	}
 	mem = kzalloc_obj(*mem);
@@ -845,8 +835,8 @@ static void remove_memory_block(struct m
 		memory->group = NULL;
 	}
 
-	/* drop the ref. we got via find_memory_block() */
-	put_device(&memory->dev);
+	/* drop the ref. we got via memory_block_get() */
+	memory_block_put(memory);
 	device_unregister(&memory->dev);
 }
 
@@ -880,7 +870,7 @@ int create_memory_block_devices(unsigned
 		end_block_id = block_id;
 		for (block_id = start_block_id; block_id != end_block_id;
 		     block_id++) {
-			mem = find_memory_block_by_id(block_id);
+			mem = memory_block_get(block_id);
 			if (WARN_ON_ONCE(!mem))
 				continue;
 			remove_memory_block(mem);
@@ -908,7 +898,7 @@ void remove_memory_block_devices(unsigne
 		return;
 
 	for (block_id = start_block_id; block_id != end_block_id; block_id++) {
-		mem = find_memory_block_by_id(block_id);
+		mem = memory_block_get(block_id);
 		if (WARN_ON_ONCE(!mem))
 			continue;
 		num_poisoned_pages_sub(-1UL, memblk_nr_poison(mem));
@@ -1015,12 +1005,12 @@ int walk_memory_blocks(unsigned long sta
 		return 0;
 
 	for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
-		mem = find_memory_block_by_id(block_id);
+		mem = memory_block_get(block_id);
 		if (!mem)
 			continue;
 
 		ret = func(mem, arg);
-		put_device(&mem->dev);
+		memory_block_put(mem);
 		if (ret)
 			break;
 	}
@@ -1228,22 +1218,22 @@ int walk_dynamic_memory_groups(int nid,
 void memblk_nr_poison_inc(unsigned long pfn)
 {
 	const unsigned long block_id = pfn_to_block_id(pfn);
-	struct memory_block *mem = find_memory_block_by_id(block_id);
+	struct memory_block *mem = memory_block_get(block_id);
 
 	if (mem) {
 		atomic_long_inc(&mem->nr_hwpoison);
-		put_device(&mem->dev);
+		memory_block_put(mem);
 	}
 }
 
 void memblk_nr_poison_sub(unsigned long pfn, long i)
 {
 	const unsigned long block_id = pfn_to_block_id(pfn);
-	struct memory_block *mem = find_memory_block_by_id(block_id);
+	struct memory_block *mem = memory_block_get(block_id);
 
 	if (mem) {
 		atomic_long_sub(i, &mem->nr_hwpoison);
-		put_device(&mem->dev);
+		memory_block_put(mem);
 	}
 }
 
--- a/drivers/base/node.c~drivers-base-memory-make-memory-block-get-put-explicit
+++ a/drivers/base/node.c
@@ -849,13 +849,13 @@ static void register_memory_blocks_under
 		for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
 			struct memory_block *mem;
 
-			mem = find_memory_block_by_id(block_id);
+			mem = memory_block_get(block_id);
 			if (!mem)
 				continue;
 
 			memory_block_add_nid_early(mem, nid);
 			do_register_memory_block_under_node(nid, mem);
-			put_device(&mem->dev);
+			memory_block_put(mem);
 		}
 
 	}
--- a/drivers/s390/char/sclp_mem.c~drivers-base-memory-make-memory-block-get-put-explicit
+++ a/drivers/s390/char/sclp_mem.c
@@ -204,7 +204,7 @@ static ssize_t sclp_config_mem_store(str
 	addr = sclp_mem->id * block_size;
 	/*
 	 * Hold device_hotplug_lock when adding/removing memory blocks.
-	 * Additionally, also protect calls to find_memory_block() and
+	 * Additionally, also protect calls to memory_block_get() and
 	 * sclp_attach_storage().
 	 */
 	rc = lock_device_hotplug_sysfs();
@@ -231,20 +231,19 @@ static ssize_t sclp_config_mem_store(str
 			sclp_mem_change_state(addr, block_size, 0);
 			goto out_unlock;
 		}
-		mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(addr)));
-		put_device(&mem->dev);
+		mem = memory_block_get(phys_to_block_id(addr));
+		memory_block_put(mem);
 		WRITE_ONCE(sclp_mem->config, 1);
 	} else {
 		if (!sclp_mem->config)
 			goto out_unlock;
-		mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(addr)));
+		mem = memory_block_get(phys_to_block_id(addr));
 		if (mem->state != MEM_OFFLINE) {
-			put_device(&mem->dev);
+			memory_block_put(mem);
 			rc = -EBUSY;
 			goto out_unlock;
 		}
-		/* drop the ref just got via find_memory_block() */
-		put_device(&mem->dev);
+		memory_block_put(mem);
 		sclp_mem_change_state(addr, block_size, 0);
 		__remove_memory(addr, block_size);
 #ifdef CONFIG_KASAN
@@ -294,11 +293,11 @@ static ssize_t sclp_memmap_on_memory_sto
 		return rc;
 	block_size = memory_block_size_bytes();
 	sclp_mem = container_of(kobj, struct sclp_mem, kobj);
-	mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(sclp_mem->id * block_size)));
+	mem = memory_block_get(phys_to_block_id(sclp_mem->id * block_size));
 	if (!mem) {
 		WRITE_ONCE(sclp_mem->memmap_on_memory, value);
 	} else {
-		put_device(&mem->dev);
+		memory_block_put(mem);
 		rc = -EBUSY;
 	}
 	unlock_device_hotplug();
--- a/include/linux/memory.h~drivers-base-memory-make-memory-block-get-put-explicit
+++ a/include/linux/memory.h
@@ -158,7 +158,11 @@ int create_memory_block_devices(unsigned
 void remove_memory_block_devices(unsigned long start, unsigned long size);
 extern void memory_dev_init(void);
 extern int memory_notify(enum memory_block_state state, void *v);
-extern struct memory_block *find_memory_block(unsigned long section_nr);
+struct memory_block *memory_block_get(unsigned long block_id);
+static inline void memory_block_put(struct memory_block *mem)
+{
+	put_device(&mem->dev);
+}
 typedef int (*walk_memory_blocks_func_t)(struct memory_block *, void *);
 extern int walk_memory_blocks(unsigned long start, unsigned long size,
 			      void *arg, walk_memory_blocks_func_t func);
@@ -171,7 +175,6 @@ struct memory_group *memory_group_find_b
 typedef int (*walk_memory_groups_func_t)(struct memory_group *, void *);
 int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func,
 			       struct memory_group *excluded, void *arg);
-struct memory_block *find_memory_block_by_id(unsigned long block_id);
 #define hotplug_memory_notifier(fn, pri) ({		\
 	static __meminitdata struct notifier_block fn##_mem_nb =\
 		{ .notifier_call = fn, .priority = pri };\
--- a/mm/memory_hotplug.c~drivers-base-memory-make-memory-block-get-put-explicit
+++ a/mm/memory_hotplug.c
@@ -1423,14 +1423,13 @@ static void remove_memory_blocks_and_alt
 		struct vmem_altmap *altmap = NULL;
 		struct memory_block *mem;
 
-		mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(cur_start)));
+		mem = memory_block_get(phys_to_block_id(cur_start));
 		if (WARN_ON_ONCE(!mem))
 			continue;
 
 		altmap = mem->altmap;
 		mem->altmap = NULL;
-		/* drop the ref. we got via find_memory_block() */
-		put_device(&mem->dev);
+		memory_block_put(mem);
 
 		remove_memory_block_devices(cur_start, memblock_size);
 		arch_remove_memory(cur_start, memblock_size, altmap, NULL);
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-memory_hotplug-fix-memory-block-reference-leak-on-remove.patch
drivers-base-memory-fix-memory-block-reference-leak-in-poison-accounting.patch
mm-sparse-remove-sparse-buffer-pre-allocation-mechanism.patch
mm-sparse-vmemmap-fix-vmemmap-accounting-underflow.patch
mm-memory_hotplug-fix-incorrect-altmap-passing-in-error-path.patch
mm-sparse-vmemmap-pass-pgmap-argument-to-memory-deactivation-paths.patch
mm-sparse-vmemmap-fix-dax-vmemmap-accounting-with-optimization.patch
mm-mm_init-fix-pageblock-migratetype-for-zone_device-compound-pages.patch
mm-mm_init-fix-uninitialized-struct-pages-for-zone_device.patch
mm-memory_hotplug-factor-out-altmap-freeing-checks.patch
drivers-base-memory-make-memory-block-get-put-explicit.patch