From: "Jérôme Glisse" <jglisse@redhat.com>
To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Cc: "Dan Williams" <dan.j.williams@intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Ross Zwisler" <ross.zwisler@linux.intel.com>
Subject: [HMM 08/15] mm/ZONE_DEVICE: special case put_page() for device private pages v2
Date: Wed, 24 May 2017 13:20:17 -0400 [thread overview]
Message-ID: <20170524172024.30810-9-jglisse@redhat.com> (raw)
In-Reply-To: <20170524172024.30810-1-jglisse@redhat.com>
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.
Changed since v1:
- use static key to disable special code path in put_page() by
default
- uninline put_zone_device_private_page()
- fix build issues with some kernel config related to header
inter-dependency
Signed-off-by: JA(C)rA'me Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
---
include/linux/memremap.h | 13 +++++++++++++
include/linux/mm.h | 31 ++++++++++++++++++++++---------
kernel/memremap.c | 19 ++++++++++++++++++-
mm/hmm.c | 8 ++++++++
4 files changed, 61 insertions(+), 10 deletions(-)
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 0fcf840..0e0d2e6 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -125,6 +125,14 @@ 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,
@@ -143,6 +151,11 @@ static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
{
return NULL;
}
+
+static inline bool is_device_private_page(const struct page *page)
+{
+ return false;
+}
#endif
/**
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a825dab..7f0656f 100644
--- a/include/linux/mm.h
+++ b/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;
@@ -788,25 +789,25 @@ static inline bool is_zone_device_page(const struct page *page)
{
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);
@@ -822,6 +823,18 @@ static inline void put_page(struct page *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 --git a/kernel/memremap.c b/kernel/memremap.c
index cd596d4..b9baa6c 100644
--- a/kernel/memremap.c
+++ b/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>
@@ -464,3 +463,21 @@ struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
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)
+ 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 --git a/mm/hmm.c b/mm/hmm.c
index e7d5a36..ff9011e 100644
--- a/mm/hmm.c
+++ b/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;
--
2.9.4
--
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next prev parent reply other threads:[~2017-05-24 17:20 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 17:20 [HMM 00/15] HMM (Heterogeneous Memory Management) v23 Jérôme Glisse
2017-05-24 17:20 ` [HMM 01/15] hmm: heterogeneous memory management documentation Jérôme Glisse
2017-06-24 6:15 ` John Hubbard
2017-05-24 17:20 ` [HMM 02/15] mm/hmm: heterogeneous memory management (HMM for short) v4 Jérôme Glisse
2017-05-31 2:10 ` Balbir Singh
2017-06-01 22:35 ` Jerome Glisse
2017-05-24 17:20 ` [HMM 03/15] mm/hmm/mirror: mirror process address space on device with HMM helpers v3 Jérôme Glisse
2017-05-24 17:20 ` [HMM 04/15] mm/hmm/mirror: helper to snapshot CPU page table v3 Jérôme Glisse
2017-05-24 17:20 ` [HMM 05/15] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-05-24 17:20 ` [HMM 06/15] mm/memory_hotplug: introduce add_pages Jérôme Glisse
2017-05-31 1:31 ` Balbir Singh
2017-05-24 17:20 ` [HMM 07/15] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v3 Jérôme Glisse
2017-05-30 16:43 ` Ross Zwisler
2017-05-30 21:43 ` Jerome Glisse
2017-05-31 1:23 ` Balbir Singh
2017-06-09 3:55 ` John Hubbard
2017-06-12 17:57 ` Jerome Glisse
2017-06-15 3:41 ` zhong jiang
2017-06-15 17:43 ` Jerome Glisse
2017-05-24 17:20 ` Jérôme Glisse [this message]
2017-05-24 17:20 ` [HMM 09/15] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v5 Jérôme Glisse
2017-06-24 3:54 ` John Hubbard
2017-05-24 17:20 ` [HMM 10/15] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v3 Jérôme Glisse
2017-05-24 17:20 ` [HMM 11/15] mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY Jérôme Glisse
2017-05-24 17:20 ` [HMM 12/15] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-05-31 3:59 ` Balbir Singh
2017-06-01 22:35 ` Jerome Glisse
2017-06-07 9:02 ` Balbir Singh
2017-06-07 14:06 ` Jerome Glisse
2017-05-24 17:20 ` [HMM 13/15] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-05-24 17:20 ` [HMM 14/15] mm/migrate: support un-addressable ZONE_DEVICE page in migration v2 Jérôme Glisse
2017-05-31 4:09 ` Balbir Singh
2017-05-31 8:39 ` Balbir Singh
2017-05-24 17:20 ` [HMM 15/15] mm/migrate: allow migrate_vma() to alloc new page on empty entry v2 Jérôme Glisse
2017-06-16 7:22 ` [HMM 00/15] HMM (Heterogeneous Memory Management) v23 Bridgman, John
2017-06-16 14:47 ` Jerome Glisse
2017-06-16 17:55 ` Bridgman, John
2017-06-16 18:04 ` Jerome Glisse
2017-06-23 15:00 ` Bob Liu
2017-06-23 15:28 ` Jerome Glisse
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