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 <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: "Jérôme Glisse" <jglisse@xxxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
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;
}
