From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 275302F12DA for ; Tue, 12 May 2026 06:54:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778568859; cv=none; b=rEN2yF26dnO4mSiyAhxkx9tmAZNiPITRqdSkK/cS9AqHabVRJsigg0nXRHEiKPRmdktPSmOSM/8vNI+3PL8wuc5Kv5Cal8wPqx1DIpVguGdwD6fvbjLWo98pGKaZHSVK7TsaJx3llFExUld+5O25UYCMN/Vv+GgTlnbBazb7kHQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778568859; c=relaxed/simple; bh=hSRNnVvjy42ucTL9yDNc9f+MiLC49s8FoJCJcX9mH2M=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TJakrL9J9ly1HfVIcPkTMzhoo4SVbT+kkACzOOVnwIR19/FyFERL68onTjwLdqLlbgX2Hk6JaeWX7qBIvFvQVzhU/IvyzP9Wfh7mi0XV/azpUf31fo/PplSgFwmx2qIC+UyoilBNFcNO96vn+oPBXi8EQQKcmPXO+Y98c5RSLes= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=idBAtUjK; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="idBAtUjK" Received: from pps.filterd (m0360083.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 64BK71hk3186917; Tue, 12 May 2026 06:53:09 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=z8usfq o9ZjJvq3jCjiATXiyRq9FwkYThylveTQxP7xU=; b=idBAtUjK87nQIqhxp+mR93 toYfFRwiCplGnCPzgQjH0OfRbw4LUmTaQJh0QsBN+bZQRstGw4lmkIIki6EPYSOg yHkpLP2EvJxEb/CXXGFyLKcaPGCI6SH8jdQN33FhswioIq9YS+rBZKModMM4jokb FhS7+PN8/pX64O4iGWjWRBmhVI+3t/X8nj0Lx/ZxSRkEw/2kBDBxOuqPNcim8X51 9kKaKtiE3xcLetwbTOTqdlYf4NB49fQe/EcDWTF4tSFrlOyzfK3IGLS8JNDvUwKe +DXMdAFi7wS7tx5zp3mAULIABQx0NCOX5XtRWAnRJa0BVqg5YRL6hB9Q5K3oCXAw == Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4e3nv59tv1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 12 May 2026 06:53:08 +0000 (GMT) Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 64C6dKxq015426; Tue, 12 May 2026 06:53:07 GMT Received: from smtprelay02.wdc07v.mail.ibm.com ([172.16.1.69]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4e3nfgj10c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 12 May 2026 06:53:07 +0000 (GMT) Received: from smtpav05.wdc07v.mail.ibm.com (smtpav05.wdc07v.mail.ibm.com [10.39.53.232]) by smtprelay02.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64C6r69V58851702 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 12 May 2026 06:53:06 GMT Received: from smtpav05.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8D0DB58053; Tue, 12 May 2026 06:53:06 +0000 (GMT) Received: from smtpav05.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2EB2E58043; Tue, 12 May 2026 06:52:57 +0000 (GMT) Received: from [9.123.6.34] (unknown [9.123.6.34]) by smtpav05.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 12 May 2026 06:52:56 +0000 (GMT) Message-ID: <943c5cd9-0796-45f5-9f8d-cb7e44457961@linux.ibm.com> Date: Tue, 12 May 2026 12:22:55 +0530 Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drivers/base/memory: make memory block get/put explicit To: Muchun Song , David Hildenbrand , Oscar Salvador , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich Cc: Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , linux-mm@kvack.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, muchun.song@linux.dev References: <20260511111800.2181785-1-songmuchun@bytedance.com> Content-Language: en-US From: Donet Tom In-Reply-To: <20260511111800.2181785-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=cPHQdFeN c=1 sm=1 tr=0 ts=6a02ce55 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=968KyxNXAAAA:8 a=VnNF1IyMAAAA:8 a=celaVYaThZoO3EmEkQQA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: 3iXNAsZwJoh2-sRW5JrH5NVNDGiEvKfW X-Proofpoint-GUID: 9-jgzV9kmWIieloOmYHSmmkqUMDM_L1h X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTEyMDA2MyBTYWx0ZWRfX6QWOWos8A3ve yaW+QAsAFoV0hzBslnPAGPSeVL6eU8SzDYftGBeUKOx7QDzmAy2et8+mLvYh1gXbmySUXYjsHXn QDafr0DriHgltGnffCMNhXa0hM+Vt4eIJ8tLFt+OKfysQ1AOTYIQ68xAcJHZFsECeN4x6zh/mET U1x2SwzpIwBzX0DPKtZrSBbiJk9fwwAV1LvzrMLCfzF0asgf4HQoWzoD5AqlczGN6QOJOzsyTAi otzDzyHftRkMB0SbIsax97vPwIlPl/HbwvJRih44vvO7vgaAH4jNKA1IPigtMmdrTMd+o7R5GYV Ot1WvkgdeVC1+waMINGAjft00XDW7NGd491lqxzILsKqTwAxa0rSTSOGElk0G1Hmw1bW3WPrEL9 /7WroWUFk1CfSA/oF/uDLyie0+0VCXFxC9/lvawCFlvKS3iGuVsmn2wzBKvd3LQXd+YxyR6c/65 4XtbCooWpUgXv+noiOA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-11_05,2026-05-08_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 phishscore=0 clxscore=1011 spamscore=0 impostorscore=0 lowpriorityscore=0 adultscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605050000 definitions=main-2605120063 On 5/11/26 4:48 PM, 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. > > Link: https://lore.kernel.org/linux-mm/7887915D-E598-42B3-9AFE-BFFBACE8DE2D@linux.dev/#t > Signed-off-by: Muchun Song > --- > .../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(-) Hi I did some basic DLPAR memory add/remove tests on PowerPC with this patch, and it is working fine. Initial memory ============== []# cat /proc/meminfo |grep -i MemTotal MemTotal:       205169920 kB After Add ========= []# cat /proc/meminfo |grep -i MemTotal MemTotal:       247112960 kB After Remove ============ []# cat /proc/meminfo |grep -i MemTotal MemTotal:       173729024 kB []# Tested-by: Donet Tom > 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)); > } > > 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) > +{ > + 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