[RFC PATCH 01/21] mm: add {add|release}_memory_pages
From: Jonathan Lemon <hidden>
Date: 2020-06-18 16:10:06
Subsystem:
memory hot(un)plug, memory management, the rest · Maintainers:
David Hildenbrand, Oscar Salvador, Andrew Morton, Linus Torvalds
This allows creation of system pages at a specific physical address, which is useful for creating dummy backing pages which correspond to unaddressable external memory at specific locations. Signed-off-by: Jonathan Lemon <redacted> --- include/linux/memory_hotplug.h | 4 +++ mm/memory_hotplug.c | 65 ++++++++++++++++++++++++++++++++-- 2 files changed, 67 insertions(+), 2 deletions(-)
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 375515803cd8..05e012e1a203 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h@@ -138,6 +138,10 @@ extern void __remove_pages(unsigned long start_pfn, unsigned long nr_pages, extern int __add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages, struct mhp_params *params); +struct resource *add_memory_pages(int nid, u64 start, u64 size, + struct mhp_params *params); +void release_memory_pages(struct resource *res); + #ifndef CONFIG_ARCH_HAS_ADD_PAGES static inline int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages, struct mhp_params *params)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9b34e03e730a..926cd4a2f81f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c@@ -125,8 +125,8 @@ static struct resource *register_memory_resource(u64 start, u64 size, resource_name, flags); if (!res) { - pr_debug("Unable to reserve System RAM region: %016llx->%016llx\n", - start, start + size); + pr_debug("Unable to reserve %s region: %016llx->%016llx\n", + resource_name, start, start + size); return ERR_PTR(-EEXIST); } return res;
@@ -1109,6 +1109,67 @@ int add_memory(int nid, u64 start, u64 size) } EXPORT_SYMBOL_GPL(add_memory); +static int __ref add_memory_section(int nid, struct resource *res, + struct mhp_params *params) +{ + u64 start, end, section_size; + int ret; + + /* must align start/end with memory block size */ + end = res->start + resource_size(res); + section_size = memory_block_size_bytes(); + start = round_down(res->start, section_size); + end = round_up(end, section_size); + + mem_hotplug_begin(); + ret = __add_pages(nid, + PHYS_PFN(start), PHYS_PFN(end - start), params); + mem_hotplug_done(); + + return ret; +} + +/* requires device_hotplug_lock, see add_memory_resource() */ +static struct resource * __ref __add_memory_pages(int nid, u64 start, u64 size, + struct mhp_params *params) +{ + struct resource *res; + int ret; + + res = register_memory_resource(start, size, "Private RAM"); + if (IS_ERR(res)) + return res; + + ret = add_memory_section(nid, res, params); + if (ret < 0) { + release_memory_resource(res); + return ERR_PTR(ret); + } + + return res; +} + +struct resource *add_memory_pages(int nid, u64 start, u64 size, + struct mhp_params *params) +{ + struct resource *res; + + lock_device_hotplug(); + res = __add_memory_pages(nid, start, size, params); + unlock_device_hotplug(); + + return res; +} +EXPORT_SYMBOL_GPL(add_memory_pages); + +void release_memory_pages(struct resource *res) +{ + lock_device_hotplug(); + release_memory_resource(res); + unlock_device_hotplug(); +} +EXPORT_SYMBOL_GPL(release_memory_pages); + /* * Add special, driver-managed memory to the system as system RAM. Such * memory is not exposed via the raw firmware-provided memmap as system
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2.24.1