The patch titled
Subject: mm/ZONE_DEVICE: special case put_page() for device private pages
has been added to the -mm tree. Its filename is
mm-zone_device-special-case-put_page-for-device-private-pages-v4.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-zone_device-special-case-put_page-for-device-private-pages-v4.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-zone_device-special-case-put_page-for-device-private-pages-v4.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
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------------------------------------------------------
From: Jérôme Glisse <jglisse@xxxxxxxxxx>
Subject: mm/ZONE_DEVICE: special case put_page() for device private pages
A ZONE_DEVICE page that reach a refcount of 1 is free ie no longer have
any user. For device private pages this is important to catch and thus we
need to special case put_page() for this.
Link: http://lkml.kernel.org/r/20170817000548.32038-9-jglisse@xxxxxxxxxx
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: Aneesh Kumar <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: David Nellans <dnellans@xxxxxxxxxx>
Cc: Evgeny Baskakov <ebaskakov@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Mark Hairgrove <mhairgrove@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Sherry Cheung <SCheung@xxxxxxxxxx>
Cc: Subhash Gutti <sgutti@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memremap.h | 13 +++++++++++++
include/linux/mm.h | 31 ++++++++++++++++++++++---------
kernel/memremap.c | 25 ++++++++++++++++++++++++-
mm/hmm.c | 8 ++++++++
4 files changed, 67 insertions(+), 10 deletions(-)
diff -puN include/linux/memremap.h~mm-zone_device-special-case-put_page-for-device-private-pages-v4 include/linux/memremap.h
--- a/include/linux/memremap.h~mm-zone_device-special-case-put_page-for-device-private-pages-v4
+++ a/include/linux/memremap.h
@@ -126,6 +126,14 @@ struct dev_pagemap {
void *devm_memremap_pages(struct device *dev, struct resource *res,
struct percpu_ref *ref, struct vmem_altmap *altmap);
struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
+
+static inline bool is_zone_device_page(const struct page *page);
+
+static inline bool is_device_private_page(const struct page *page)
+{
+ return is_zone_device_page(page) &&
+ page->pgmap->type == MEMORY_DEVICE_PRIVATE;
+}
#else
static inline void *devm_memremap_pages(struct device *dev,
struct resource *res, struct percpu_ref *ref,
@@ -144,6 +152,11 @@ static inline struct dev_pagemap *find_d
{
return NULL;
}
+
+static inline bool is_device_private_page(const struct page *page)
+{
+ return false;
+}
#endif
/**
diff -puN include/linux/mm.h~mm-zone_device-special-case-put_page-for-device-private-pages-v4 include/linux/mm.h
--- a/include/linux/mm.h~mm-zone_device-special-case-put_page-for-device-private-pages-v4
+++ a/include/linux/mm.h
@@ -23,6 +23,7 @@
#include <linux/page_ext.h>
#include <linux/err.h>
#include <linux/page_ref.h>
+#include <linux/memremap.h>
struct mempolicy;
struct anon_vma;
@@ -792,25 +793,25 @@ static inline bool is_zone_device_page(c
{
return page_zonenum(page) == ZONE_DEVICE;
}
-
-static inline bool is_device_private_page(const struct page *page)
-{
- /* See MEMORY_DEVICE_PRIVATE in include/linux/memory_hotplug.h */
- return ((page_zonenum(page) == ZONE_DEVICE) &&
- (page->pgmap->type == MEMORY_DEVICE_PRIVATE));
-}
#else
static inline bool is_zone_device_page(const struct page *page)
{
return false;
}
+#endif
-static inline bool is_device_private_page(const struct page *page)
+#ifdef CONFIG_DEVICE_PRIVATE
+void put_zone_device_private_page(struct page *page);
+#else
+static inline void put_zone_device_private_page(struct page *page)
{
- return false;
}
#endif
+static inline bool is_device_private_page(const struct page *page);
+
+DECLARE_STATIC_KEY_FALSE(device_private_key);
+
static inline void get_page(struct page *page)
{
page = compound_head(page);
@@ -826,6 +827,18 @@ static inline void put_page(struct page
{
page = compound_head(page);
+ /*
+ * For private device pages we need to catch refcount transition from
+ * 2 to 1, when refcount reach one it means the private device page is
+ * free and we need to inform the device driver through callback. See
+ * include/linux/memremap.h and HMM for details.
+ */
+ if (static_branch_unlikely(&device_private_key) &&
+ unlikely(is_device_private_page(page))) {
+ put_zone_device_private_page(page);
+ return;
+ }
+
if (put_page_testzero(page))
__put_page(page);
}
diff -puN kernel/memremap.c~mm-zone_device-special-case-put_page-for-device-private-pages-v4 kernel/memremap.c
--- a/kernel/memremap.c~mm-zone_device-special-case-put_page-for-device-private-pages-v4
+++ a/kernel/memremap.c
@@ -11,7 +11,6 @@
* General Public License for more details.
*/
#include <linux/radix-tree.h>
-#include <linux/memremap.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/pfn_t.h>
@@ -488,3 +487,27 @@ struct vmem_altmap *to_vmem_altmap(unsig
return pgmap ? pgmap->altmap : NULL;
}
#endif /* CONFIG_ZONE_DEVICE */
+
+
+#ifdef CONFIG_DEVICE_PRIVATE
+void put_zone_device_private_page(struct page *page)
+{
+ int count = page_ref_dec_return(page);
+
+ /*
+ * If refcount is 1 then page is freed and refcount is stable as nobody
+ * holds a reference on the page.
+ */
+ if (count == 1) {
+ /* Clear Active bit in case of parallel mark_page_accessed */
+ __ClearPageActive(page);
+ __ClearPageWaiters(page);
+
+ page->mapping = NULL;
+
+ page->pgmap->page_free(page, page->pgmap->data);
+ } else if (!count)
+ __put_page(page);
+}
+EXPORT_SYMBOL(put_zone_device_private_page);
+#endif /* CONFIG_DEVICE_PRIVATE */
diff -puN mm/hmm.c~mm-zone_device-special-case-put_page-for-device-private-pages-v4 mm/hmm.c
--- a/mm/hmm.c~mm-zone_device-special-case-put_page-for-device-private-pages-v4
+++ a/mm/hmm.c
@@ -25,9 +25,17 @@
#include <linux/sched.h>
#include <linux/swapops.h>
#include <linux/hugetlb.h>
+#include <linux/jump_label.h>
#include <linux/mmu_notifier.h>
+/*
+ * Device private memory see HMM (Documentation/vm/hmm.txt) or hmm.h
+ */
+DEFINE_STATIC_KEY_FALSE(device_private_key);
+EXPORT_SYMBOL(device_private_key);
+
+
#ifdef CONFIG_HMM
static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
_
Patches currently in -mm which might be from jglisse@xxxxxxxxxx are
hmm-heterogeneous-memory-management-documentation-v3.patch
mm-hmm-heterogeneous-memory-management-hmm-for-short-v5.patch
mm-hmm-mirror-mirror-process-address-space-on-device-with-hmm-helpers-v3.patch
mm-hmm-mirror-helper-to-snapshot-cpu-page-table-v4.patch
mm-hmm-mirror-device-page-fault-handler.patch
mm-zone_device-new-type-of-zone_device-for-unaddressable-memory-v5.patch
mm-zone_device-special-case-put_page-for-device-private-pages-v4.patch
mm-memcontrol-allow-to-uncharge-page-without-using-page-lru-field.patch
mm-memcontrol-support-memory_device_private-v4.patch
mm-hmm-devmem-device-memory-hotplug-using-zone_device-v7.patch
mm-hmm-devmem-dummy-hmm-device-for-zone_device-memory-v3.patch
mm-migrate-new-migrate-mode-migrate_sync_no_copy.patch
mm-migrate-new-memory-migration-helper-for-use-with-device-memory-v5.patch
mm-migrate-migrate_vma-unmap-page-from-vma-while-collecting-pages.patch
mm-migrate-support-un-addressable-zone_device-page-in-migration-v3.patch
mm-migrate-allow-migrate_vma-to-alloc-new-page-on-empty-entry-v4.patch
mm-device-public-memory-device-memory-cache-coherent-with-cpu-v5.patch
mm-hmm-add-new-helper-to-hotplug-cdm-memory-region-v3.patch
lib-interval_tree-fast-overlap-detection-fix.patch
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