Now that memmap_init_zone() knows how to split the init work into multiple threads, allow the tracking for those threads to be handled via a passed in 'struct memmap_async_state' instance.
This infrastructure allows devm_memremap_pages() users, like the pmem driver, to track memmap initialization in the backgroud, and use memmap_sync() when it performs an operation that may result in a pfn_to_page(), like dax mapping a pfn into userspace. The approach mirrors what is done for background memmap initialization and defers waiting for initialization to complete until the first userspace consumer arrives. Cc: Michal Hocko <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: "Jérôme Glisse" <[email protected]> Cc: Logan Gunthorpe <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Andrew Morton <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- include/linux/memmap_async.h | 10 ++++ include/linux/memremap.h | 29 ++++++++++++ kernel/memremap.c | 65 ++++++++++++++++----------- mm/page_alloc.c | 102 +++++++++++++++++++++++++++++++++++++----- 4 files changed, 169 insertions(+), 37 deletions(-) diff --git a/include/linux/memmap_async.h b/include/linux/memmap_async.h index d2011681a910..4633eca9290e 100644 --- a/include/linux/memmap_async.h +++ b/include/linux/memmap_async.h @@ -3,6 +3,9 @@ #define __LINUX_MEMMAP_ASYNC_H #include <linux/async.h> #include <linux/ioport.h> +#include <linux/async.h> +#include <linux/pfn_t.h> +#include <linux/radix-tree.h> struct dev_pagemap; struct vmem_altmap; @@ -32,14 +35,21 @@ struct memmap_init_memmap { }; struct memmap_init_pages { + int id; struct resource res; + async_cookie_t cookie; struct memmap_init_env *env; }; struct memmap_async_state { struct memmap_init_env env; struct memmap_init_memmap memmap; + struct memmap_init_pages page_init[NR_MEMMAP_THREADS]; + unsigned long active[BITS_TO_LONGS(NR_MEMMAP_THREADS)]; + struct radix_tree_root pfn_to_thread; }; extern struct async_domain memmap_init_domain; +extern void memmap_sync(pfn_t pfn, unsigned long nr_pages, + struct memmap_async_state *async); #endif /* __LINUX_MEMMAP_ASYNC_H */ diff --git a/include/linux/memremap.h b/include/linux/memremap.h index bfdc7363b13b..a2313fadd686 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -1,6 +1,7 @@ /* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_MEMREMAP_H_ #define _LINUX_MEMREMAP_H_ +#include <linux/pfn.h> #include <linux/ioport.h> #include <linux/percpu-refcount.h> @@ -101,6 +102,7 @@ typedef int (*dev_page_fault_t)(struct vm_area_struct *vma, pmd_t *pmdp); typedef void (*dev_page_free_t)(struct page *page, void *data); +struct memmap_async_state; /** * struct dev_pagemap - metadata for ZONE_DEVICE mappings * @page_fault: callback when CPU fault on an unaddressable device page @@ -112,6 +114,7 @@ typedef void (*dev_page_free_t)(struct page *page, void *data); * @dev: host device of the mapping for debug * @data: private data pointer for page_free() * @type: memory type: see MEMORY_* in memory_hotplug.h + * @async: async memmap init context */ struct dev_pagemap { dev_page_fault_t page_fault; @@ -124,8 +127,34 @@ struct dev_pagemap { struct device *dev; void *data; enum memory_type type; + struct memmap_async_state *async; }; +static inline unsigned long order_at(struct resource *res, unsigned long pgoff) +{ + unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff; + unsigned long nr_pages, mask; + + nr_pages = PHYS_PFN(resource_size(res)); + if (nr_pages == pgoff) + return ULONG_MAX; + + /* + * What is the largest aligned power-of-2 range available from + * this resource pgoff to the end of the resource range, + * considering the alignment of the current pgoff? + */ + mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff); + if (!mask) + return ULONG_MAX; + + return find_first_bit(&mask, BITS_PER_LONG); +} + +#define foreach_order_pgoff(res, order, pgoff) \ + for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \ + pgoff += 1UL << order, order = order_at((res), pgoff)) + #ifdef CONFIG_ZONE_DEVICE void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap, void (*kill)(struct percpu_ref *)); diff --git a/kernel/memremap.c b/kernel/memremap.c index 85e4a7c576b2..18719a596be5 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -7,6 +7,7 @@ #include <linux/io.h> #include <linux/mm.h> #include <linux/memory_hotplug.h> +#include <linux/memmap_async.h> #include <linux/swap.h> #include <linux/swapops.h> #include <linux/wait_bit.h> @@ -16,31 +17,6 @@ static RADIX_TREE(pgmap_radix, GFP_KERNEL); #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1) #define SECTION_SIZE (1UL << PA_SECTION_SHIFT) -static unsigned long order_at(struct resource *res, unsigned long pgoff) -{ - unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff; - unsigned long nr_pages, mask; - - nr_pages = PHYS_PFN(resource_size(res)); - if (nr_pages == pgoff) - return ULONG_MAX; - - /* - * What is the largest aligned power-of-2 range available from - * this resource pgoff to the end of the resource range, - * considering the alignment of the current pgoff? - */ - mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff); - if (!mask) - return ULONG_MAX; - - return find_first_bit(&mask, BITS_PER_LONG); -} - -#define foreach_order_pgoff(res, order, pgoff) \ - for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \ - pgoff += 1UL << order, order = order_at((res), pgoff)) - #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) int device_private_entry_fault(struct vm_area_struct *vma, unsigned long addr, @@ -113,15 +89,46 @@ static unsigned long pfn_next(unsigned long pfn) #define for_each_device_pfn(pfn, map) \ for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn)) +static void kill_memmap_async(struct memmap_async_state *async) +{ + struct radix_tree_iter iter; + void *slot; + int i; + + if (!async) + return; + + for (i = 0; i < NR_MEMMAP_THREADS; i++) { + async_cookie_t cookie; + + if (!test_bit(i, async->active)) + continue; + + cookie = async->page_init[i].cookie; + async_synchronize_cookie_domain(cookie+1, &memmap_init_domain); + } + radix_tree_for_each_slot(slot, &async->pfn_to_thread, &iter, 0) + radix_tree_delete(&async->pfn_to_thread, iter.index); +} + static void devm_memremap_pages_release(void *data) { struct dev_pagemap *pgmap = data; struct device *dev = pgmap->dev; struct resource *res = &pgmap->res; resource_size_t align_start, align_size; + struct memmap_async_state *async = pgmap->async; unsigned long pfn; + /* + * Once the pgmap is killed pgmap owners must disallow new + * direct_access / page mapping requests. I.e. memmap_sync() + * users must not race the teardown of the async->pfn_to_thread + * radix. + */ pgmap->kill(pgmap->ref); + kill_memmap_async(async); + for_each_device_pfn(pfn, pgmap) put_page(pfn_to_page(pfn)); @@ -240,7 +247,13 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap, struct zone *zone; error = arch_add_memory(nid, align_start, align_size, altmap, - false, NULL); + false, pgmap->async); + if (error == -EWOULDBLOCK) { + /* fall back to synchronous */ + pgmap->async = NULL; + error = arch_add_memory(nid, align_start, align_size, + altmap, false, NULL); + } zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE]; if (!error) move_pfn_range_to_zone(zone, align_start >> PAGE_SHIFT, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6d0ed17cf305..d1466dd82bc2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -68,6 +68,7 @@ #include <linux/ftrace.h> #include <linux/lockdep.h> #include <linux/async.h> +#include <linux/pfn_t.h> #include <linux/nmi.h> #include <asm/sections.h> @@ -5510,12 +5511,80 @@ static void __ref memmap_init_async(void *data, async_cookie_t cookie) { struct memmap_init_pages *args = data; struct memmap_init_env *env = args->env; + struct dev_pagemap *pgmap = env->pgmap; + struct memmap_async_state *async = pgmap ? pgmap->async : NULL; struct resource *res = &args->res; unsigned long pfn; + if (async) + async_synchronize_cookie_domain(async->memmap.cookie+1, + &memmap_init_domain); + for (pfn = PHYS_PFN(res->start); pfn < PHYS_PFN(res->end+1); pfn++) memmap_init_one(pfn, env->zone, env->nid, env->context, - env->pgmap); + pgmap); + if (async) + clear_bit(args->id, async->active); +} + +void memmap_sync(pfn_t pfn, unsigned long nr_pages, + struct memmap_async_state *async) +{ + struct memmap_init_pages *args, *start, *end; + unsigned long raw_pfn = pfn_t_to_pfn(pfn); + + if (!async || !pfn_t_has_page(pfn) + || !bitmap_weight(async->active, NR_MEMMAP_THREADS)) + return; + + start = radix_tree_lookup(&async->pfn_to_thread, raw_pfn); + end = radix_tree_lookup(&async->pfn_to_thread, raw_pfn + nr_pages - 1); + if (!start || !end) { + WARN_ON_ONCE(1); + return; + } + + for (args = start; args <= end; args++) { + int id = args - &async->page_init[0]; + + async_synchronize_cookie_domain(args->cookie+1, + &memmap_init_domain); + pr_debug("%s: pfn: %#lx nr: %ld thread: %d\n", + __func__, raw_pfn, nr_pages, id); + } +} +EXPORT_SYMBOL_GPL(memmap_sync); + +static bool run_memmap_init(struct memmap_init_pages *thread, + struct memmap_async_state *async, struct async_domain *domain) +{ + struct resource *res = &thread->res; + unsigned long pgoff; + int order; + + if (!async) { + async_schedule_domain(memmap_init_async, thread, domain); + return false; + } + + thread->cookie = async_schedule_domain(memmap_init_async, + thread, domain); + set_bit(thread->id, async->active); + foreach_order_pgoff(res, order, pgoff) { + int rc = __radix_tree_insert(&async->pfn_to_thread, + PHYS_PFN(res->start) + pgoff, order, thread); + if (rc) { + /* + * Mark all threads inactive, and by returning + * false we'll sync all threads before returning + * from memmap_init_zone(). + */ + memset(async->active, 0, sizeof(unsigned long) + * BITS_TO_LONGS(NR_MEMMAP_THREADS)); + return false; + } + } + return true; } /* @@ -5554,33 +5623,44 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, * function. They do not exist on hotplugged memory. */ ASYNC_DOMAIN_EXCLUSIVE(local); - struct memmap_init_pages args[NR_MEMMAP_THREADS]; - struct memmap_init_env env = { - .nid = nid, - .zone = zone, - .pgmap = pgmap, - .context = context, - }; + struct memmap_async_state *async = pgmap ? pgmap->async : NULL; + struct memmap_init_pages _args[NR_MEMMAP_THREADS]; + struct memmap_init_pages *args = async ? async->page_init : _args; + struct async_domain *domain; + struct memmap_init_env _env; + struct memmap_init_env *env = async ? &async->env : &_env; unsigned long step, rem; + bool sync = !async; int i; + domain = async ? &memmap_init_domain : &local; + env->pgmap = pgmap; + env->nid = nid; + env->zone = zone; + env->context = context; + size = end_pfn - start_pfn; step = size / NR_MEMMAP_THREADS; rem = size % NR_MEMMAP_THREADS; + if (async) + INIT_RADIX_TREE(&async->pfn_to_thread, GFP_KERNEL); for (i = 0; i < NR_MEMMAP_THREADS; i++) { struct memmap_init_pages *t = &args[i]; - t->env = &env; + t->id = i; + t->env = env; t->res.start = PFN_PHYS(start_pfn); t->res.end = PFN_PHYS(start_pfn + step) - 1; if (i == NR_MEMMAP_THREADS-1) t->res.end += PFN_PHYS(rem); - async_schedule_domain(memmap_init_async, t, &local); + if (!run_memmap_init(t, async, domain)) + sync = true; start_pfn += step; } - async_synchronize_full_domain(&local); + if (sync) + async_synchronize_full_domain(domain); return; } _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
