On Mon, May 11, 2026 at 07:18:00PM +0800, Muchun Song wrote: > Rename the memory block lookup helper to make the acquired reference > explicit, add memory_block_put() to wrap put_device(), and collapse the > redundant section-number wrapper into a 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.
As David said, let's reference more of what you've done in the various refactorings. > > Link: > https://lore.kernel.org/linux-mm/[email protected]/#t > Signed-off-by: Muchun Song <[email protected]> LGTM overall, so: Reviewed-by: Lorenzo Stoakes <[email protected]> > --- > .../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(-) > > diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c > b/arch/powerpc/platforms/pseries/hotplug-memory.c > index 75f85a5da981..94f3b57054b6 100644 > --- a/arch/powerpc/platforms/pseries/hotplug-memory.c > +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c > @@ -164,13 +164,7 @@ static int update_lmb_associativity_index(struct > drmem_lmb *lmb) > > 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)); Ah nice I see this does the equivalent via phys_to_block_id() and pfn_to_block_id() so that's a nice cleanup. > } > > static int get_lmb_range(u32 drc_index, int n_lmbs, > @@ -220,7 +214,7 @@ static int dlpar_change_lmb_state(struct drmem_lmb *lmb, > bool online) > 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_lmb *lmb) > > 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); > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 11d57cfa8d72..5b5d41089e81 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -649,7 +649,7 @@ int __weak arch_get_memory_phys_device(unsigned long > start_pfn) > * > * 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_by_id(unsigned > long block_id) > 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 memory_block *memory) > > 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 long block_id, int > nid, unsigned long state > 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 memory_block > *memory) > 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 long start, > unsigned long size, > 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(unsigned long start, > unsigned long size) > 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 start, unsigned > long size, > 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, > walk_memory_groups_func_t func, > 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); > } > } > > diff --git a/drivers/base/node.c b/drivers/base/node.c > index 126f66aa2c3e..b3333ca92090 100644 > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -847,13 +847,13 @@ static void register_memory_blocks_under_nodes(void) > 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); > } > > } > diff --git a/drivers/s390/char/sclp_mem.c b/drivers/s390/char/sclp_mem.c > index 78c054e26d17..6df1926d4c62 100644 > --- a/drivers/s390/char/sclp_mem.c > +++ b/drivers/s390/char/sclp_mem.c > @@ -204,7 +204,7 @@ static ssize_t sclp_config_mem_store(struct kobject > *kobj, struct kobj_attribute > 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(struct kobject > *kobj, struct kobj_attribute > 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_store(struct > kobject *kobj, struct kobj_att > 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(); > diff --git a/include/linux/memory.h b/include/linux/memory.h > index 5bb5599c6b2b..29edef1f975c 100644 > --- a/include/linux/memory.h > +++ b/include/linux/memory.h > @@ -158,7 +158,11 @@ int create_memory_block_devices(unsigned long start, > unsigned long size, > 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); > +extern struct memory_block *memory_block_get(unsigned long block_id); > +static inline void memory_block_put(struct memory_block *mem) Yeah as David says, we remove extern's now as and when we touch that code :) > +{ > + 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_by_id(int mgid); > 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 };\ > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 462d8dcd636d..890c6453e887 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1417,14 +1417,13 @@ static void remove_memory_blocks_and_altmaps(u64 > start, u64 size) > 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); > > > base-commit: e98d21c170b01ddef366f023bbfcf6b31509fa83 > -- > 2.54.0 >
