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X-IronPort-AV: E=McAfee;i="6600,9927,10882"; a="419957274" X-IronPort-AV: E=Sophos;i="6.03,272,1694761200"; d="scan'208";a="419957274" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Nov 2023 17:38:58 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.03,272,1694761200"; d="scan'208";a="9193955" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Nov 2023 17:38:55 -0700 From: "Huang, Ying" To: Vishal Verma Cc: Andrew Morton , David Hildenbrand , Oscar Salvador , Dan Williams , Dave Jiang , , , , , Dave Hansen , "Aneesh Kumar K.V" , Michal Hocko , Jonathan Cameron , Jeff Moyer Subject: Re: [PATCH v9 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks In-Reply-To: <20231102-vv-kmem_memmap-v9-2-973d6b3a8f1a@intel.com> (Vishal Verma's message of "Thu, 2 Nov 2023 12:27:14 -0600") References: <20231102-vv-kmem_memmap-v9-0-973d6b3a8f1a@intel.com> <20231102-vv-kmem_memmap-v9-2-973d6b3a8f1a@intel.com> Date: Fri, 03 Nov 2023 08:36:52 +0800 Message-ID: <87wmuzzn8b.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 1135040015 X-Stat-Signature: 5daybad75muf5u3ostgue1f8ce5eukrd X-Rspam-User: X-HE-Tag: 1698971939-94818 X-HE-Meta: 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 QUEeu/Zo PuiGWl+IPMzSCWq7xyFszlY73aYIpZH38y1JQvrSEpiZuQdvKJJ9rPKpW9RGfwcQgueQRrQN+gDbRG7FqLmn0K5Uyjes+ZQjcb8oK8nFNiJqmKiQcNGUzMPLMEdTO/fgbPtrRygfQ+vFkGwegwbiiP2IkU27lAb9LNvOcOXmClkThgIYvI2d7t6IiE0ITaj87szuxcXGr/NHGebNA3BXtjtlSBzpZ7Fbeq/7TbF8ycfEHZNyuArV4wts34Me/t0uTqRWyjLg1JKAOCqy3VwoG1WKCV+7AAzpMQinn3RaBXW7K8mQd1a05X1s4/LHlNvKvVi5uHYy8hSG23ZyREcza84L1fEKi9Yyu+xggW9QghS2tRwsts5803BOe2MtcKfyZcbAVdgMPz+Tjbn2+MnyFJ1gSPqwM0LtJfUoNBY0bE3zL7FU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Vishal Verma writes: > The MHP_MEMMAP_ON_MEMORY flag for hotplugged memory is restricted to > 'memblock_size' chunks of memory being added. Adding a larger span of > memory precludes memmap_on_memory semantics. > > For users of hotplug such as kmem, large amounts of memory might get > added from the CXL subsystem. In some cases, this amount may exceed the > available 'main memory' to store the memmap for the memory being added. > In this case, it is useful to have a way to place the memmap on the > memory being added, even if it means splitting the addition into > memblock-sized chunks. > > Change add_memory_resource() to loop over memblock-sized chunks of > memory if caller requested memmap_on_memory, and if other conditions for > it are met. Teach try_remove_memory() to also expect that a memory > range being removed might have been split up into memblock sized chunks, > and to loop through those as needed. > > This does preclude being able to use PUD mappings in the direct map; a > proposal to how this could be optimized in the future is laid out > here[1]. > > [1]: https://lore.kernel.org/linux-mm/b6753402-2de9-25b2-36e9-eacd49752b19@redhat.com/ > > Cc: Andrew Morton > Cc: David Hildenbrand > Cc: Michal Hocko > Cc: Oscar Salvador > Cc: Dan Williams > Cc: Dave Jiang > Cc: Dave Hansen > Cc: Huang Ying > Suggested-by: David Hildenbrand > Reviewed-by: Dan Williams > Acked-by: David Hildenbrand > Signed-off-by: Vishal Verma LGTM, Thanks! Reviewed-by: "Huang, Ying" > --- > mm/memory_hotplug.c | 210 ++++++++++++++++++++++++++++++++++------------------ > 1 file changed, 136 insertions(+), 74 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 6be7de9efa55..b380675ab932 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1380,6 +1380,85 @@ static bool mhp_supports_memmap_on_memory(unsigned long size) > return arch_supports_memmap_on_memory(vmemmap_size); > } > > +static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size) > +{ > + unsigned long memblock_size = memory_block_size_bytes(); > + u64 cur_start; > + > + /* > + * For memmap_on_memory, the altmaps were added on a per-memblock > + * basis; we have to process each individual memory block. > + */ > + for (cur_start = start; cur_start < start + size; > + cur_start += memblock_size) { > + struct vmem_altmap *altmap = NULL; > + struct memory_block *mem; > + > + mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(cur_start))); > + if (WARN_ON_ONCE(!mem)) > + continue; > + > + altmap = mem->altmap; > + mem->altmap = NULL; > + > + remove_memory_block_devices(cur_start, memblock_size); > + > + arch_remove_memory(cur_start, memblock_size, altmap); > + > + /* Verify that all vmemmap pages have actually been freed. */ > + WARN(altmap->alloc, "Altmap not fully unmapped"); > + kfree(altmap); > + } > +} > + > +static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group, > + u64 start, u64 size) > +{ > + unsigned long memblock_size = memory_block_size_bytes(); > + u64 cur_start; > + int ret; > + > + for (cur_start = start; cur_start < start + size; > + cur_start += memblock_size) { > + struct mhp_params params = { .pgprot = > + pgprot_mhp(PAGE_KERNEL) }; > + struct vmem_altmap mhp_altmap = { > + .base_pfn = PHYS_PFN(cur_start), > + .end_pfn = PHYS_PFN(cur_start + memblock_size - 1), > + }; > + > + mhp_altmap.free = memory_block_memmap_on_memory_pages(); > + params.altmap = kmemdup(&mhp_altmap, sizeof(struct vmem_altmap), > + GFP_KERNEL); > + if (!params.altmap) { > + ret = -ENOMEM; > + goto out; > + } > + > + /* call arch's memory hotadd */ > + ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms); > + if (ret < 0) { > + kfree(params.altmap); > + goto out; > + } > + > + /* create memory block devices after memory was added */ > + ret = create_memory_block_devices(cur_start, memblock_size, > + params.altmap, group); > + if (ret) { > + arch_remove_memory(cur_start, memblock_size, NULL); > + kfree(params.altmap); > + goto out; > + } > + } > + > + return 0; > +out: > + if (ret && cur_start != start) > + remove_memory_blocks_and_altmaps(start, cur_start - start); > + return ret; > +} > + > /* > * NOTE: The caller must call lock_device_hotplug() to serialize hotplug > * and online/offline operations (triggered e.g. by sysfs). > @@ -1390,10 +1469,6 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > { > struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) }; > enum memblock_flags memblock_flags = MEMBLOCK_NONE; > - struct vmem_altmap mhp_altmap = { > - .base_pfn = PHYS_PFN(res->start), > - .end_pfn = PHYS_PFN(res->end), > - }; > struct memory_group *group = NULL; > u64 start, size; > bool new_node = false; > @@ -1436,28 +1511,22 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > /* > * Self hosted memmap array > */ > - if (mhp_flags & MHP_MEMMAP_ON_MEMORY) { > - if (mhp_supports_memmap_on_memory(size)) { > - mhp_altmap.free = memory_block_memmap_on_memory_pages(); > - params.altmap = kmemdup(&mhp_altmap, > - sizeof(struct vmem_altmap), > - GFP_KERNEL); > - if (!params.altmap) > - goto error; > + if ((mhp_flags & MHP_MEMMAP_ON_MEMORY) && > + mhp_supports_memmap_on_memory(memory_block_size_bytes())) { > + ret = create_altmaps_and_memory_blocks(nid, group, start, size); > + if (ret) > + goto error; > + } else { > + ret = arch_add_memory(nid, start, size, ¶ms); > + if (ret < 0) > + goto error; > + > + /* create memory block devices after memory was added */ > + ret = create_memory_block_devices(start, size, NULL, group); > + if (ret) { > + arch_remove_memory(start, size, NULL); > + goto error; > } > - /* fallback to not using altmap */ > - } > - > - /* call arch's memory hotadd */ > - ret = arch_add_memory(nid, start, size, ¶ms); > - if (ret < 0) > - goto error_free; > - > - /* create memory block devices after memory was added */ > - ret = create_memory_block_devices(start, size, params.altmap, group); > - if (ret) { > - arch_remove_memory(start, size, NULL); > - goto error_free; > } > > if (new_node) { > @@ -1494,8 +1563,6 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > walk_memory_blocks(start, size, NULL, online_memory_block); > > return ret; > -error_free: > - kfree(params.altmap); > error: > if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) > memblock_remove(start, size); > @@ -2062,17 +2129,13 @@ static int check_memblock_offlined_cb(struct memory_block *mem, void *arg) > return 0; > } > > -static int test_has_altmap_cb(struct memory_block *mem, void *arg) > +static int count_memory_range_altmaps_cb(struct memory_block *mem, void *arg) > { > - struct memory_block **mem_ptr = (struct memory_block **)arg; > - /* > - * return the memblock if we have altmap > - * and break callback. > - */ > - if (mem->altmap) { > - *mem_ptr = mem; > - return 1; > - } > + u64 *num_altmaps = (u64 *)arg; > + > + if (mem->altmap) > + *num_altmaps += 1; > + > return 0; > } > > @@ -2146,11 +2209,29 @@ void try_offline_node(int nid) > } > EXPORT_SYMBOL(try_offline_node); > > +static int memory_blocks_have_altmaps(u64 start, u64 size) > +{ > + u64 num_memblocks = size / memory_block_size_bytes(); > + u64 num_altmaps = 0; > + > + if (!mhp_memmap_on_memory()) > + return 0; > + > + walk_memory_blocks(start, size, &num_altmaps, > + count_memory_range_altmaps_cb); > + > + if (num_altmaps == 0) > + return 0; > + > + if (WARN_ON_ONCE(num_memblocks != num_altmaps)) > + return -EINVAL; > + > + return 1; > +} > + > static int __ref try_remove_memory(u64 start, u64 size) > { > - struct memory_block *mem; > - int rc = 0, nid = NUMA_NO_NODE; > - struct vmem_altmap *altmap = NULL; > + int rc, nid = NUMA_NO_NODE; > > BUG_ON(check_hotplug_memory_range(start, size)); > > @@ -2167,45 +2248,26 @@ static int __ref try_remove_memory(u64 start, u64 size) > if (rc) > return rc; > > - /* > - * We only support removing memory added with MHP_MEMMAP_ON_MEMORY in > - * the same granularity it was added - a single memory block. > - */ > - if (mhp_memmap_on_memory()) { > - rc = walk_memory_blocks(start, size, &mem, test_has_altmap_cb); > - if (rc) { > - if (size != memory_block_size_bytes()) { > - pr_warn("Refuse to remove %#llx - %#llx," > - "wrong granularity\n", > - start, start + size); > - return -EINVAL; > - } > - altmap = mem->altmap; > - /* > - * Mark altmap NULL so that we can add a debug > - * check on memblock free. > - */ > - mem->altmap = NULL; > - } > - } > - > /* remove memmap entry */ > firmware_map_remove(start, start + size, "System RAM"); > > - /* > - * Memory block device removal under the device_hotplug_lock is > - * a barrier against racing online attempts. > - */ > - remove_memory_block_devices(start, size); > - > mem_hotplug_begin(); > > - arch_remove_memory(start, size, altmap); > - > - /* Verify that all vmemmap pages have actually been freed. */ > - if (altmap) { > - WARN(altmap->alloc, "Altmap not fully unmapped"); > - kfree(altmap); > + rc = memory_blocks_have_altmaps(start, size); > + if (rc < 0) { > + mem_hotplug_done(); > + return rc; > + } else if (!rc) { > + /* > + * Memory block device removal under the device_hotplug_lock is > + * a barrier against racing online attempts. > + * No altmaps present, do the removal directly > + */ > + remove_memory_block_devices(start, size); > + arch_remove_memory(start, size, NULL); > + } else { > + /* all memblocks in the range have altmaps */ > + remove_memory_blocks_and_altmaps(start, size); > } > > if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {