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Thu, 9 Oct 2025 13:18:55 +0000 (GMT) From: Sumanth Korikkar To: Andrew Morton , David Hildenbrand , linux-mm Cc: LKML , linux-s390 , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sumanth Korikkar Subject: [PATCH v2 1/4] s390/mm: Support removal of boot-allocated virtual memory map Date: Thu, 9 Oct 2025 15:18:36 +0200 Message-ID: <20251009131839.3739108-2-sumanthk@linux.ibm.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251009131839.3739108-1-sumanthk@linux.ibm.com> References: <20251009131839.3739108-1-sumanthk@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=NsDcssdJ c=1 sm=1 tr=0 ts=68e7b644 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=x6icFKpwvdMA:10 a=VnNF1IyMAAAA:8 a=To8m7Vbe2ZeGRMaUrlAA:9 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-GUID: 0MT_MPCLfPTP8LJVQ9y6xIFGbashhyf8 X-Proofpoint-ORIG-GUID: 0MT_MPCLfPTP8LJVQ9y6xIFGbashhyf8 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDA4MDEyMSBTYWx0ZWRfX6Tea3Id5p7vv o3BN040OxR3h3sJ3xd3FNIb0HQysRsifcAYNwR1rI9YM1Z6J02qlpha0aPdnaZc378Y670Pdj7n SMt6Q4dzafF5xiFno2r30O3LS/W9HfBTsbmxPC3k6UuUAGCXFpctd9VS/ZIhlv1BO2shogShcQ9 OVRohzbafhKapyTRAoHBncYXukai4tTWXWNPKdK6jNg95Pl37YIllAd7f7ARpn84Y5915vF1soC O74+qSq+EYnZYpOsOlOfFQqTVWUVLVcR4IHmWl0u7tRqayfHkUYQfV7xKo0LrdwquNXM7rF/Y5N Y0U+PqZke+JnbyfNc9y8fOjSZuWleBPXOUROjFTMitNRwLsB8B2KDxB86C8XEmOCxtKGvhBuJBo XO5RMpUyRIBAyavtPZ3s2UbZsfNOvA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-09_04,2025-10-06_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 spamscore=0 impostorscore=0 adultscore=0 phishscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510080121 Content-Type: text/plain; charset="utf-8" On s390, memory blocks are not currently removed via arch_remove_memory(). With upcoming dynamic memory (de)configuration support, runtime removal of memory blocks is possible. This internally involves tearing down identity mapping, virtual memory mappings and freeing the physical memory backing the struct pages metadata. During early boot, physical memory used to back the struct pages metadata in vmemmap is allocated through: setup_arch() -> sparse_init() -> sparse_init_nid() -> __populate_section_memmap() -> vmemmap_alloc_block_buf() -> sparse_buffer_alloc() -> memblock_alloc() Here, sparse_init_nid() sets up virtual-to-physical mapping for struct pages backed by memblock_alloc(). This differs from runtime addition of hotplug memory which uses the buddy allocator later. To correctly free identity mappings, vmemmap mappings during hot-remove, boot-time and runtime allocations must be distinguished using the PageReserved bit: * Boot-time memory, such as identity-mapped page tables allocated via boot_crst_alloc() and reserved via reserve_pgtables() is marked PageReserved in memmap_init_reserved_pages(). * Physical memory backing vmemmap (struct pages from memblock_alloc()) is also marked PageReserved similarly. During teardown, PageReserved bit is checked to distinguish between boot-time allocation or buddy allocation. This is similar to commit 645d5ce2f7d6 ("powerpc/mm/radix: Fix PTE/PMD fragment count for early page table mappings") Reviewed-by: Heiko Carstens Signed-off-by: Sumanth Korikkar --- arch/s390/mm/pgalloc.c | 2 ++ arch/s390/mm/vmem.c | 21 ++++++++++++--------- 2 files changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c index 626fca116cd7..7df23528c01b 100644 --- a/arch/s390/mm/pgalloc.c +++ b/arch/s390/mm/pgalloc.c @@ -164,6 +164,8 @@ void page_table_free(struct mm_struct *mm, unsigned lon= g *table) { struct ptdesc *ptdesc =3D virt_to_ptdesc(table); =20 + if (pagetable_is_reserved(ptdesc)) + return free_reserved_ptdesc(ptdesc); pagetable_dtor_free(ptdesc); } =20 diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c index f48ef361bc83..d96587b84e81 100644 --- a/arch/s390/mm/vmem.c +++ b/arch/s390/mm/vmem.c @@ -4,6 +4,7 @@ */ =20 #include +#include #include #include #include @@ -39,15 +40,21 @@ static void __ref *vmem_alloc_pages(unsigned int order) =20 static void vmem_free_pages(unsigned long addr, int order, struct vmem_alt= map *altmap) { + unsigned int nr_pages =3D 1 << order; 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Thu, 9 Oct 2025 13:18:55 +0000 (GMT) From: Sumanth Korikkar To: Andrew Morton , David Hildenbrand , linux-mm Cc: LKML , linux-s390 , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sumanth Korikkar Subject: [PATCH v2 2/4] s390/sclp: Add support for dynamic (de)configuration of memory Date: Thu, 9 Oct 2025 15:18:37 +0200 Message-ID: <20251009131839.3739108-3-sumanthk@linux.ibm.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251009131839.3739108-1-sumanthk@linux.ibm.com> References: <20251009131839.3739108-1-sumanthk@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: XSeOwOWhV_ud2t3ZLD-3Ka6yVa7LN-bX X-Proofpoint-ORIG-GUID: XSeOwOWhV_ud2t3ZLD-3Ka6yVa7LN-bX X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDA4MDEyMSBTYWx0ZWRfX/M+SGmGCZbKk WUFt3L4RSI/eeog+Mbtn4yxHeR7JSER90LUccaSlOgmroeHByouTJMRuFsMKEeWTOWkGOg0hoif yHVEmQB4bhG5b21ggEYfNfsj7ic3jmkl/5aklGWeFDguBbKV19mGsLeYEBRGot2rrbRVqM6PQJt GWmglg2mlHI4tmH/G7X2tliCr3SoPbkXuUbk3N0HsvrP/Sw/EzpH76Kn8JVFtSiWI+rMxYwZIVZ 8Bgi1eNmLay/WoPRVWiZhdE/xSp7R0An/O4CHK9czK0G7j6JdfNno7oXfYFUqCDtA7U/9koUS0M R3N8w44k/9KDH3jJKEv4kO85GmBBOBJ07hlLeB6X+GD+KrdqPJm2MBJuB5FCpzdyaXVneeNd7v5 V6B+8/7rATRazw+2ktFF8oN/BxOmKw== X-Authority-Analysis: v=2.4 cv=FtwIPmrq c=1 sm=1 tr=0 ts=68e7b644 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=x6icFKpwvdMA:10 a=VwQbUJbxAAAA:8 a=20KFwNOVAAAA:8 a=VnNF1IyMAAAA:8 a=GHt7ZKPcJgLmr8k-lvIA:9 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-09_04,2025-10-06_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 clxscore=1015 phishscore=0 spamscore=0 bulkscore=0 priorityscore=1501 adultscore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510080121 Content-Type: text/plain; charset="utf-8" Provide a new interface for dynamic configuration and deconfiguration of hotplug memory, allowing with/without memmap_on_memory support. It is a follow up on the discussion with David when introducing memmap_on_memory support for s390 and support dynamic (de)configuration of memory: https://lore.kernel.org/all/ee492da8-74b4-4a97-8b24-73e07257f01d@redhat.com/ https://lore.kernel.org/all/20241202082732.3959803-1-sumanthk@linux.ibm.com/ The original motivation for introducing memmap_on_memory on s390 was to avoid using online memory to store struct pages metadata, particularly for standby memory blocks. This became critical in cases where there was an imbalance between standby and online memory, potentially leading to boot failures due to insufficient memory for metadata allocation. To address this, memmap_on_memory was utilized on s390. However, in its current form, it adds struct pages metadata at the start of each memory block at the time of addition and this configuration is static. It cannot be changed at runtime. (When the user needs continuous physical memory). Inorder to provide more flexibility to the user and overcome the above limitation, add option to dynamically configure and deconfigure hotpluggable memory block with/without memmap_on_memory. With the new interface, s390 will not add all possible hotplug memory in advance, like before, to make it visible in sysfs for online/offline actions. Instead, before memory block can be set online, it has to be configured via a new interface in /sys/firmware/memory/memoryX/config, which makes s390 similar to others. i.e. Adding of hotpluggable memory is controlled by the user instead of adding it at boottime. The s390 kernel sysfs interface to configure and deconfigure memory is as follows (considering the upcoming lsmem changes): * Initial memory layout: lsmem -o RANGE,SIZE,STATE,BLOCK,CONFIGURED,MEMMAP_ON_MEMORY RANGE SIZE STATE BLOCK CONFIGURED MEMMAP_ON_MEMORY 0x00000000-0x7fffffff 2G online 0-15 yes no 0x80000000-0xffffffff 2G offline 16-31 no yes * Configure memory sys=3D"/sys" echo 1 > $sys/firmware/memory/memory16/config lsmem -o RANGE,SIZE,STATE,BLOCK,CONFIGURED,MEMMAP_ON_MEMORY RANGE SIZE STATE BLOCK CONFIGURED MEMMAP_ON_MEMORY 0x00000000-0x7fffffff 2G online 0-15 yes no 0x80000000-0x87ffffff 128M offline 16 yes yes 0x88000000-0xffffffff 1.9G offline 17-31 no yes * Deconfigure memory echo 0 > $sys/firmware/memory/memory16/config lsmem -o RANGE,SIZE,STATE,BLOCK,CONFIGURED,MEMMAP_ON_MEMORY RANGE SIZE STATE BLOCK CONFIGURED MEMMAP_ON_MEMORY 0x00000000-0x7fffffff 2G online 0-15 yes no 0x80000000-0xffffffff 2G offline 16-31 no yes 3. Enable memmap_on_memory and online it. echo 0 > $sys/devices/system/memory/memory5/online echo 0 > $sys/firmware/memory/memory5/config lsmem -o RANGE,SIZE,STATE,BLOCK,CONFIGURED,MEMMAP_ON_MEMORY RANGE SIZE STATE BLOCK CONFIGURED MEMMAP_ON_MEMORY 0x00000000-0x27ffffff 640M online 0-4 yes no 0x28000000-0x2fffffff 128M offline 5 no no 0x30000000-0x7fffffff 1.3G online 6-15 yes no 0x80000000-0xffffffff 2G offline 16-31 no yes echo 1 > $sys/firmware/memory/memory5/memmap_on_memory echo 1 > $sys/firmware/memory/memory5/config echo 1 > $sys/devices/system/memory/memory5/online lsmem -o RANGE,SIZE,STATE,BLOCK,CONFIGURED,MEMMAP_ON_MEMORY RANGE SIZE STATE BLOCK CONFIGURED MEMMAP_ON_MEMORY 0x00000000-0x27ffffff 640M online 0-4 yes no 0x28000000-0x2fffffff 128M online 5 yes yes 0x30000000-0x7fffffff 1.3G online 6-15 yes no 0x80000000-0xffffffff 2G offline 16-31 no yes 4. Disable memmap_on_memory and online it. echo 0 > $sys/devices/system/memory/memory5/online echo 0 > $sys/firmware/memory/memory5/config lsmem -o RANGE,SIZE,STATE,BLOCK,CONFIGURED,MEMMAP_ON_MEMORY RANGE SIZE STATE BLOCK CONFIGURED MEMMAP_ON_MEMORY 0x00000000-0x27ffffff 640M online 0-4 yes no 0x28000000-0x2fffffff 128M offline 5 no yes 0x30000000-0x7fffffff 1.3G online 6-15 yes no 0x80000000-0xffffffff 2G offline 16-31 no yes echo 0 > $sys/firmware/memory/memory5/memmap_on_memory echo 1 > $sys/firmware/memory/memory5/config echo 1 > $sys/devices/system/memory/memory5/online lsmem -o RANGE,SIZE,STATE,BLOCK,CONFIGURED,MEMMAP_ON_MEMORY RANGE SIZE STATE BLOCK CONFIGURED MEMMAP_ON_MEMORY 0x00000000-0x7fffffff 2G online 0-15 yes no 0x80000000-0xffffffff 2G offline 16-31 no yes Acked-by: Heiko Carstens Signed-off-by: Sumanth Korikkar Acked-by: David Hildenbrand --- drivers/s390/char/sclp_mem.c | 290 +++++++++++++++++++++++++---------- 1 file changed, 207 insertions(+), 83 deletions(-) diff --git a/drivers/s390/char/sclp_mem.c b/drivers/s390/char/sclp_mem.c index 27f49f5fd358..e1302b1c98ac 100644 --- a/drivers/s390/char/sclp_mem.c +++ b/drivers/s390/char/sclp_mem.c @@ -9,9 +9,12 @@ #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt =20 #include +#include #include #include #include +#include +#include #include #include #include @@ -27,7 +30,6 @@ #define SCLP_CMDW_ASSIGN_STORAGE 0x000d0001 #define SCLP_CMDW_UNASSIGN_STORAGE 0x000c0001 =20 -static DEFINE_MUTEX(sclp_mem_mutex); static LIST_HEAD(sclp_mem_list); static u8 sclp_max_storage_id; static DECLARE_BITMAP(sclp_storage_ids, 256); @@ -38,6 +40,18 @@ struct memory_increment { int standby; }; =20 +struct sclp_mem { + struct kobject kobj; + unsigned int id; + unsigned int memmap_on_memory; + unsigned int config; +}; + +struct sclp_mem_arg { + struct sclp_mem *sclp_mems; + struct kset *kset; +}; + struct assign_storage_sccb { struct sccb_header header; u16 rn; @@ -163,92 +177,165 @@ static int sclp_mem_change_state(unsigned long start= , unsigned long size, return rc ? -EIO : 0; } =20 -static bool contains_standby_increment(unsigned long start, unsigned long = end) +static ssize_t config_sclp_mem_show(struct kobject *kobj, struct kobj_attr= ibute *attr, char *buf) { - struct memory_increment *incr; - unsigned long istart; + struct sclp_mem *sclp_mem =3D container_of(kobj, struct sclp_mem, kobj); =20 - list_for_each_entry(incr, &sclp_mem_list, list) { - istart =3D rn2addr(incr->rn); - if (end - 1 < istart) - continue; - if (start > istart + sclp.rzm - 1) - continue; - if (incr->standby) - return true; - } - return false; + return sysfs_emit(buf, "%u\n", READ_ONCE(sclp_mem->config)); } =20 -static int sclp_mem_notifier(struct notifier_block *nb, - unsigned long action, void *data) +static ssize_t config_sclp_mem_store(struct kobject *kobj, struct kobj_att= ribute *attr, + const char *buf, size_t count) { - unsigned long start, size; - struct memory_notify *arg; + unsigned long addr, block_size; + struct sclp_mem *sclp_mem; + struct memory_block *mem; unsigned char id; - int rc =3D 0; + bool value; + int rc; =20 - arg =3D data; - start =3D arg->start_pfn << PAGE_SHIFT; - size =3D arg->nr_pages << PAGE_SHIFT; - mutex_lock(&sclp_mem_mutex); + rc =3D kstrtobool(buf, &value); + if (rc) + return rc; + sclp_mem =3D container_of(kobj, struct sclp_mem, kobj); + block_size =3D memory_block_size_bytes(); + addr =3D sclp_mem->id * block_size; + /* + * Hold device_hotplug_lock when adding/removing memory blocks. + * Additionally, also protect calls to find_memory_block() and + * sclp_attach_storage(). + */ + rc =3D lock_device_hotplug_sysfs(); + if (rc) + goto out; for_each_clear_bit(id, sclp_storage_ids, sclp_max_storage_id + 1) sclp_attach_storage(id); - switch (action) { - case MEM_GOING_OFFLINE: - /* - * Do not allow to set memory blocks offline that contain - * standby memory. This is done to simplify the "memory online" - * case. - */ - if (contains_standby_increment(start, start + size)) - rc =3D -EPERM; - break; - case MEM_PREPARE_ONLINE: + if (value) { + if (sclp_mem->config) + goto out_unlock; + rc =3D sclp_mem_change_state(addr, block_size, 1); + if (rc) + goto out_unlock; /* - * Access the altmap_start_pfn and altmap_nr_pages fields - * within the struct memory_notify specifically when dealing - * with only MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers. - * - * When altmap is in use, take the specified memory range - * online, which includes the altmap. + * Set entire memory block CMMA state to nodat. Later, when + * page tables pages are allocated via __add_memory(), those + * regions are marked __arch_set_page_dat(). */ - if (arg->altmap_nr_pages) { - start =3D PFN_PHYS(arg->altmap_start_pfn); - size +=3D PFN_PHYS(arg->altmap_nr_pages); + __arch_set_page_nodat((void *)__va(addr), block_size >> PAGE_SHIFT); + rc =3D __add_memory(0, addr, block_size, + sclp_mem->memmap_on_memory ? + MHP_MEMMAP_ON_MEMORY | MHP_OFFLINE_INACCESSIBLE : MHP_NONE); + if (rc) { + sclp_mem_change_state(addr, block_size, 0); + goto out_unlock; } - rc =3D sclp_mem_change_state(start, size, 1); - if (rc || !arg->altmap_nr_pages) - break; - /* - * Set CMMA state to nodat here, since the struct page memory - * at the beginning of the memory block will not go through the - * buddy allocator later. - */ - __arch_set_page_nodat((void *)__va(start), arg->altmap_nr_pages); - break; - case MEM_FINISH_OFFLINE: - /* - * When altmap is in use, take the specified memory range - * offline, which includes the altmap. - */ - if (arg->altmap_nr_pages) { - start =3D PFN_PHYS(arg->altmap_start_pfn); - size +=3D PFN_PHYS(arg->altmap_nr_pages); + mem =3D find_memory_block(pfn_to_section_nr(PFN_DOWN(addr))); + put_device(&mem->dev); + WRITE_ONCE(sclp_mem->config, 1); + } else { + if (!sclp_mem->config) + goto out_unlock; + mem =3D find_memory_block(pfn_to_section_nr(PFN_DOWN(addr))); + if (mem->state !=3D MEM_OFFLINE) { + put_device(&mem->dev); + rc =3D -EBUSY; + goto out_unlock; } - sclp_mem_change_state(start, size, 0); - break; - default: - break; + /* drop the ref just got via find_memory_block() */ + put_device(&mem->dev); + sclp_mem_change_state(addr, block_size, 0); + __remove_memory(addr, block_size); + WRITE_ONCE(sclp_mem->config, 0); } - mutex_unlock(&sclp_mem_mutex); - return rc ? NOTIFY_BAD : NOTIFY_OK; +out_unlock: + unlock_device_hotplug(); +out: + return rc ? rc : count; } =20 -static struct notifier_block sclp_mem_nb =3D { - .notifier_call =3D sclp_mem_notifier, +static ssize_t memmap_on_memory_show(struct kobject *kobj, struct kobj_att= ribute *attr, char *buf) +{ + struct sclp_mem *sclp_mem =3D container_of(kobj, struct sclp_mem, kobj); + + return sysfs_emit(buf, "%u\n", READ_ONCE(sclp_mem->memmap_on_memory)); +} + +static ssize_t memmap_on_memory_store(struct kobject *kobj, struct kobj_at= tribute *attr, + const char *buf, size_t count) +{ + struct sclp_mem *sclp_mem; + unsigned long block_size; + struct memory_block *mem; + bool value; + int rc; + + rc =3D kstrtobool(buf, &value); + if (rc) + return rc; + rc =3D lock_device_hotplug_sysfs(); + if (rc) + return rc; + block_size =3D memory_block_size_bytes(); + sclp_mem =3D container_of(kobj, struct sclp_mem, kobj); + mem =3D find_memory_block(pfn_to_section_nr(PFN_DOWN(sclp_mem->id * block= _size))); + if (!mem) { + WRITE_ONCE(sclp_mem->memmap_on_memory, value); + } else { + put_device(&mem->dev); + rc =3D -EBUSY; + } + unlock_device_hotplug(); + return rc ? rc : count; +} + +static const struct kobj_type ktype =3D { + .sysfs_ops =3D &kobj_sysfs_ops, }; =20 +static struct kobj_attribute memmap_attr =3D + __ATTR(memmap_on_memory, 0644, memmap_on_memory_show, memmap_on_memory_st= ore); +static struct kobj_attribute config_attr =3D + __ATTR(config, 0644, config_sclp_mem_show, config_sclp_mem_store); + +static struct attribute *sclp_mem_attrs[] =3D { + &memmap_attr.attr, + &config_attr.attr, + NULL, +}; + +static struct attribute_group sclp_mem_attr_group =3D { + .attrs =3D sclp_mem_attrs, +}; + +static int create_sclp_mem(struct sclp_mem *sclp_mem, struct kset *kset, + unsigned int id, bool config, bool memmap_on_memory) +{ + int rc; + + sclp_mem->memmap_on_memory =3D memmap_on_memory; + sclp_mem->config =3D config; + sclp_mem->id =3D id; + kobject_init(&sclp_mem->kobj, &ktype); + rc =3D kobject_add(&sclp_mem->kobj, &kset->kobj, "memory%d", id); + if (rc) + return rc; + return sysfs_create_group(&sclp_mem->kobj, &sclp_mem_attr_group); +} + +static int create_configured_sclp_mem(struct memory_block *mem, void *argu= ment) +{ + struct sclp_mem *sclp_mems; + struct sclp_mem_arg *arg; + struct kset *kset; + unsigned int id; + + id =3D mem->dev.id; + arg =3D (struct sclp_mem_arg *)argument; + sclp_mems =3D arg->sclp_mems; + kset =3D arg->kset; + return create_sclp_mem(&sclp_mems[id], kset, id, true, false); +} + static void __init align_to_block_size(unsigned long *start, unsigned long *size, unsigned long alignment) @@ -264,14 +351,17 @@ static void __init align_to_block_size(unsigned long = *start, *size =3D size_align; } =20 -static void __init add_memory_merged(u16 rn) +static int __init create_standby_sclp_mems_merged(struct sclp_mem *sclp_me= ms, + struct kset *kset, u16 rn) { unsigned long start, size, addr, block_size; static u16 first_rn, num; + unsigned int id; + int rc =3D 0; =20 if (rn && first_rn && (first_rn + num =3D=3D rn)) { num++; - return; + return rc; } if (!first_rn) goto skip_add; @@ -286,24 +376,61 @@ static void __init add_memory_merged(u16 rn) if (!size) goto skip_add; for (addr =3D start; addr < start + size; addr +=3D block_size) { - add_memory(0, addr, block_size, - cpu_has_edat1() ? - MHP_MEMMAP_ON_MEMORY | MHP_OFFLINE_INACCESSIBLE : MHP_NONE); + id =3D addr / block_size; + rc =3D create_sclp_mem(&sclp_mems[id], kset, id, false, + mhp_supports_memmap_on_memory()); + if (rc) + break; } skip_add: first_rn =3D rn; num =3D 1; + return rc; } =20 -static void __init sclp_add_standby_memory(void) +static int __init create_standby_sclp_mems(struct sclp_mem *sclp_mems, str= uct kset *kset) { struct memory_increment *incr; + int rc =3D 0; =20 list_for_each_entry(incr, &sclp_mem_list, list) { if (incr->standby) - add_memory_merged(incr->rn); + rc =3D create_standby_sclp_mems_merged(sclp_mems, kset, incr->rn); + if (rc) + goto out; } - add_memory_merged(0); + rc =3D create_standby_sclp_mems_merged(sclp_mems, kset, 0); +out: + return rc; +} + +static int __init init_sclp_mem(void) +{ + const u64 block_size =3D memory_block_size_bytes(); + const u64 max_sclp_mems =3D roundup(sclp.rnmax * sclp.rzm, block_size) / = block_size; + struct sclp_mem *sclp_mems; + struct sclp_mem_arg arg; + struct kset *kset; + int rc; + + /* Allocate memory for all blocks ahead of time. */ + sclp_mems =3D kcalloc(max_sclp_mems, sizeof(struct sclp_mem), GFP_KERNEL); + if (!sclp_mems) + return -ENOMEM; + + kset =3D kset_create_and_add("memory", NULL, firmware_kobj); + if (!kset) + return -ENOMEM; + + /* Initial memory is in the "configured" state already. */ + arg.sclp_mems =3D sclp_mems; + arg.kset =3D kset; + rc =3D for_each_memory_block(&arg, create_configured_sclp_mem); + if (rc) + return rc; + + /* Standby memory is "deconfigured". */ + return create_standby_sclp_mems(sclp_mems, kset); } =20 static void __init insert_increment(u16 rn, int standby, int assigned) @@ -336,7 +463,7 @@ static void __init insert_increment(u16 rn, int standby= , int assigned) list_add(&new_incr->list, prev); 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Thu, 9 Oct 2025 13:18:55 +0000 (GMT) From: Sumanth Korikkar To: Andrew Morton , David Hildenbrand , linux-mm Cc: LKML , linux-s390 , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sumanth Korikkar Subject: [PATCH v2 3/4] s390/sclp: Remove MHP_OFFLINE_INACCESSIBLE Date: Thu, 9 Oct 2025 15:18:38 +0200 Message-ID: <20251009131839.3739108-4-sumanthk@linux.ibm.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251009131839.3739108-1-sumanthk@linux.ibm.com> References: <20251009131839.3739108-1-sumanthk@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=NsDcssdJ c=1 sm=1 tr=0 ts=68e7b645 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=x6icFKpwvdMA:10 a=VnNF1IyMAAAA:8 a=20KFwNOVAAAA:8 a=f30ByJGsKnh_ESHQSg4A:9 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-GUID: Cb34PJeDiPm_thVi2hrKDmHPOp5HSuy7 X-Proofpoint-ORIG-GUID: Cb34PJeDiPm_thVi2hrKDmHPOp5HSuy7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDA4MDEyMSBTYWx0ZWRfX5tN/NaJQdW4q 0iwOvGH9gjQgfrNc390230OS8GSU/KCyVhDv+j+t/wpYOJ+R00bF2bdXjTlBCy/EJ39+1y+vFBa imNg2eJlswvknDznm/Kp45lptp9oK9pgDU9CnSLEE9i9hOq3YF0PsIuCr0iXwGTYFlgMWjlIbeg XrBRVmtL9EpdzxVvmUOny/K1S/1O9dziqZIMmeibkodseG/8b3keUF51wCL4a5fi9BeyTqltl4G OylClrDJalGkDe93SUfjwu7AIzEyvlvIZlkXElZzECSla+6FF4K10vY9dLUcxR6aXwfXYEbnIjx rza1ToJ7ISdc2wuUEgeePieO0HqsVvXQ/QhhZmzpos58sL4FHhmOvpFMlr6bSRrZuunR8zJgIHF jSqb8zMY84+sprtx1yyLXZZYBgT7GA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-09_04,2025-10-06_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 spamscore=0 impostorscore=0 adultscore=0 phishscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510080121 Content-Type: text/plain; charset="utf-8" mhp_flag MHP_OFFLINE_INACCESSIBLE was used to mark memory as not accessible until memory hotplug online phase begins. Earlier, standby memory blocks were added upfront during boottime and MHP_OFFLINE_INACCESSIBLE flag avoided page_init_poison() on memmap during mhp addtion phase. However with dynamic runtime configuration of memory, standby memory can be brought to accessible state before performing add_memory(). Hence, remove MHP_OFFLINE_INACCESSIBLE. Acked-by: Heiko Carstens Reviewed-by: David Hildenbrand Signed-off-by: Sumanth Korikkar --- drivers/s390/char/sclp_mem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/s390/char/sclp_mem.c b/drivers/s390/char/sclp_mem.c index e1302b1c98ac..0f8c0a4dbdd3 100644 --- a/drivers/s390/char/sclp_mem.c +++ b/drivers/s390/char/sclp_mem.c @@ -224,7 +224,7 @@ static ssize_t config_sclp_mem_store(struct kobject *ko= bj, struct kobj_attribute __arch_set_page_nodat((void *)__va(addr), block_size >> PAGE_SHIFT); rc =3D __add_memory(0, addr, block_size, sclp_mem->memmap_on_memory ? - MHP_MEMMAP_ON_MEMORY | MHP_OFFLINE_INACCESSIBLE : MHP_NONE); + MHP_MEMMAP_ON_MEMORY : MHP_NONE); if (rc) { sclp_mem_change_state(addr, block_size, 0); goto out_unlock; --=20 2.48.1 From nobody Sun Feb 8 06:49:49 2026 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 CEED9134AB; 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Thu, 9 Oct 2025 13:18:56 +0000 (GMT) From: Sumanth Korikkar To: Andrew Morton , David Hildenbrand , linux-mm Cc: LKML , linux-s390 , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sumanth Korikkar Subject: [PATCH v2 4/4] mm/memory_hotplug: Remove MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers Date: Thu, 9 Oct 2025 15:18:39 +0200 Message-ID: <20251009131839.3739108-5-sumanthk@linux.ibm.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251009131839.3739108-1-sumanthk@linux.ibm.com> References: <20251009131839.3739108-1-sumanthk@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: S-XrwK9RxNKLtc5UIvI2KOi1lSohAbZb X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMDA4MDEyMSBTYWx0ZWRfXzIQy3uj7SYU0 ticA8CMPXlhe01aF4bsdB6ZiMyF3qrp5km2dOdzWklTBfBaCCG8VH69v6PgPeDui9m7Ks/uoHv+ ycrvLgfbytpjJq6O4R2ak/tIlFemtgZ4M2iuu7mDP1zmpPZ3Vj+6vYFKCM8EUAmIIyzMyR+LCUh D78O87s11qqFvegQrRuPDeYsZBU81TynV1o5tBIHcX5awEv2kt3kblnXZhgPrDcRZTgPbAj44kt uotAwL55hSuJtf7sWMFdAgqvPDZY44B/ACMiJOo774ZMhc+M8TO2mokudQrziTBWzn+nADHknzR CUcfb3Ely+8iAL9QRn+6uWHu86vkw8Sz6ShFetiZT1bkKlcci2TXrXMaaFau4bwEizm/pSegh1D 3wN25CGy4zvjEhowwG+XEfkU14kMDA== X-Authority-Analysis: v=2.4 cv=cKntc1eN c=1 sm=1 tr=0 ts=68e7b645 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=x6icFKpwvdMA:10 a=VnNF1IyMAAAA:8 a=rQaNfnSK3a-WYbhgV1gA:9 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-GUID: S-XrwK9RxNKLtc5UIvI2KOi1lSohAbZb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-10-09_04,2025-10-06_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 bulkscore=0 phishscore=0 spamscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510020000 definitions=main-2510080121 Content-Type: text/plain; charset="utf-8" MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers were introduced to prepare the transition of memory to and from a physically accessible state. This enhancement was crucial for implementing the "memmap on memory" feature for s390. With introduction of dynamic (de)configuration of hotpluggable memory, memory can be brought to accessible state before add_memory(). Memory can be brought to inaccessible state before remove_memory(). Hence, there is no need of MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers anymore. This basically reverts commit c5f1e2d18909 ("mm/memory_hotplug: introduce MEM_PREPARE_ONLINE/MEM_FINISH_O= FFLINE notifiers") Additionally, apply minor adjustments to the function parameters of move_pfn_range_to_zone() and mhp_supports_memmap_on_memory() to ensure compatibility with the latest branch. Signed-off-by: Sumanth Korikkar Acked-by: David Hildenbrand --- drivers/base/memory.c | 23 +---------------------- include/linux/memory.h | 9 --------- include/linux/memory_hotplug.h | 18 +----------------- include/linux/memremap.h | 1 - mm/memory_hotplug.c | 17 +++-------------- mm/sparse.c | 3 +-- 6 files changed, 6 insertions(+), 65 deletions(-) diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 6d84a02cfa5d..fc43f2703ae0 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -226,7 +226,6 @@ static int memory_block_online(struct memory_block *mem) unsigned long start_pfn =3D section_nr_to_pfn(mem->start_section_nr); unsigned long nr_pages =3D PAGES_PER_SECTION * sections_per_block; unsigned long nr_vmemmap_pages =3D 0; - struct memory_notify arg; struct zone *zone; int ret; =20 @@ -246,19 +245,9 @@ static int memory_block_online(struct memory_block *me= m) if (mem->altmap) nr_vmemmap_pages =3D mem->altmap->free; =20 - arg.altmap_start_pfn =3D start_pfn; - arg.altmap_nr_pages =3D nr_vmemmap_pages; - arg.start_pfn =3D start_pfn + nr_vmemmap_pages; - arg.nr_pages =3D nr_pages - nr_vmemmap_pages; mem_hotplug_begin(); - ret =3D memory_notify(MEM_PREPARE_ONLINE, &arg); - ret =3D notifier_to_errno(ret); - if (ret) - goto out_notifier; - if (nr_vmemmap_pages) { - ret =3D mhp_init_memmap_on_memory(start_pfn, nr_vmemmap_pages, - zone, mem->altmap->inaccessible); + ret =3D mhp_init_memmap_on_memory(start_pfn, nr_vmemmap_pages, zone); if (ret) goto out; } @@ -280,11 +269,7 @@ static int memory_block_online(struct memory_block *me= m) nr_vmemmap_pages); =20 mem->zone =3D zone; - mem_hotplug_done(); - return ret; out: - memory_notify(MEM_FINISH_OFFLINE, &arg); -out_notifier: mem_hotplug_done(); return ret; } @@ -297,7 +282,6 @@ static int memory_block_offline(struct memory_block *me= m) unsigned long start_pfn =3D section_nr_to_pfn(mem->start_section_nr); unsigned long nr_pages =3D PAGES_PER_SECTION * sections_per_block; unsigned long nr_vmemmap_pages =3D 0; - struct memory_notify arg; int ret; =20 if (!mem->zone) @@ -329,11 +313,6 @@ static int memory_block_offline(struct memory_block *m= em) mhp_deinit_memmap_on_memory(start_pfn, nr_vmemmap_pages); =20 mem->zone =3D NULL; - arg.altmap_start_pfn =3D start_pfn; - arg.altmap_nr_pages =3D nr_vmemmap_pages; - arg.start_pfn =3D start_pfn + nr_vmemmap_pages; - arg.nr_pages =3D nr_pages - nr_vmemmap_pages; - memory_notify(MEM_FINISH_OFFLINE, &arg); out: mem_hotplug_done(); return ret; diff --git a/include/linux/memory.h b/include/linux/memory.h index 0c214256216f..ba1515160894 100644 --- a/include/linux/memory.h +++ b/include/linux/memory.h @@ -96,17 +96,8 @@ int set_memory_block_size_order(unsigned int order); #define MEM_GOING_ONLINE (1<<3) #define MEM_CANCEL_ONLINE (1<<4) #define MEM_CANCEL_OFFLINE (1<<5) -#define MEM_PREPARE_ONLINE (1<<6) -#define MEM_FINISH_OFFLINE (1<<7) =20 struct memory_notify { - /* - * The altmap_start_pfn and altmap_nr_pages fields are designated for - * specifying the altmap range and are exclusively intended for use in - * MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers. - */ - unsigned long altmap_start_pfn; - unsigned long altmap_nr_pages; unsigned long start_pfn; unsigned long nr_pages; }; diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 23f038a16231..f2f16cdd73ee 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -58,22 +58,6 @@ typedef int __bitwise mhp_t; * implies the node id (nid). */ #define MHP_NID_IS_MGID ((__force mhp_t)BIT(2)) -/* - * The hotplugged memory is completely inaccessible while the memory is - * offline. The memory provider will handle MEM_PREPARE_ONLINE / - * MEM_FINISH_OFFLINE notifications and make the memory accessible. - * - * This flag is only relevant when used along with MHP_MEMMAP_ON_MEMORY, - * because the altmap cannot be written (e.g., poisoned) when adding - * memory -- before it is set online. - * - * This allows for adding memory with an altmap that is not currently - * made available by a hypervisor. When onlining that memory, the - * hypervisor can be instructed to make that memory available, and - * the onlining phase will not require any memory allocations, which is - * helpful in low-memory situations. - */ -#define MHP_OFFLINE_INACCESSIBLE ((__force mhp_t)BIT(3)) =20 /* * Extended parameters for memory hotplug: @@ -123,7 +107,7 @@ extern void adjust_present_page_count(struct page *page, long nr_pages); /* VM interface that may be used by firmware interface */ extern int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_p= ages, - struct zone *zone, bool mhp_off_inaccessible); + struct zone *zone); extern void mhp_deinit_memmap_on_memory(unsigned long pfn, unsigned long n= r_pages); extern int online_pages(unsigned long pfn, unsigned long nr_pages, struct zone *zone, struct memory_group *group); diff --git a/include/linux/memremap.h b/include/linux/memremap.h index e5951ba12a28..30c7aecbd245 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -25,7 +25,6 @@ struct vmem_altmap { unsigned long free; unsigned long align; unsigned long alloc; - bool inaccessible; }; =20 /* diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 0be83039c3b5..238a6712738e 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1088,7 +1088,7 @@ void adjust_present_page_count(struct page *page, str= uct memory_group *group, } =20 int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages, - struct zone *zone, bool mhp_off_inaccessible) + struct zone *zone) { unsigned long end_pfn =3D pfn + nr_pages; int ret, i; @@ -1097,15 +1097,6 @@ int mhp_init_memmap_on_memory(unsigned long pfn, uns= igned long nr_pages, if (ret) return ret; =20 - /* - * Memory block is accessible at this stage and hence poison the struct - * pages now. If the memory block is accessible during memory hotplug - * addition phase, then page poisining is already performed in - * sparse_add_section(). - */ - if (mhp_off_inaccessible) - page_init_poison(pfn_to_page(pfn), sizeof(struct page) * nr_pages); - move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_UNMOVABLE, false); =20 @@ -1444,7 +1435,7 @@ static void remove_memory_blocks_and_altmaps(u64 star= t, u64 size) } =20 static int create_altmaps_and_memory_blocks(int nid, struct memory_group *= group, - u64 start, u64 size, mhp_t mhp_flags) + u64 start, u64 size) { unsigned long memblock_size =3D memory_block_size_bytes(); u64 cur_start; @@ -1460,8 +1451,6 @@ static int create_altmaps_and_memory_blocks(int nid, = struct memory_group *group, }; =20 mhp_altmap.free =3D memory_block_memmap_on_memory_pages(); - if (mhp_flags & MHP_OFFLINE_INACCESSIBLE) - mhp_altmap.inaccessible =3D true; params.altmap =3D kmemdup(&mhp_altmap, sizeof(struct vmem_altmap), GFP_KERNEL); if (!params.altmap) { @@ -1555,7 +1544,7 @@ int add_memory_resource(int nid, struct resource *res= , mhp_t mhp_flags) */ if ((mhp_flags & MHP_MEMMAP_ON_MEMORY) && mhp_supports_memmap_on_memory()) { - ret =3D create_altmaps_and_memory_blocks(nid, group, start, size, mhp_fl= ags); + ret =3D create_altmaps_and_memory_blocks(nid, group, start, size); if (ret) goto error; } else { diff --git a/mm/sparse.c b/mm/sparse.c index 17c50a6415c2..b5b2b6f7041b 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -951,8 +951,7 @@ int __meminit sparse_add_section(int nid, unsigned long= start_pfn, * Poison uninitialized struct pages in order to catch invalid flags * combinations. */ - if (!altmap || !altmap->inaccessible) - page_init_poison(memmap, sizeof(struct page) * nr_pages); + page_init_poison(memmap, sizeof(struct page) * nr_pages); =20 ms =3D __nr_to_section(section_nr); set_section_nid(section_nr, nid); --=20 2.48.1