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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@redhat.com
Signed-off-by: Jérôme 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>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jérôme Glisse 2017-09-08 16:11:46 -07:00 committed by Linus Torvalds
parent 5042db43cc
commit 7b2d55d2c8
4 changed files with 67 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/memremap.h
View File

@ -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_dev_pagemap(resource_size_t phys)
{
return NULL;
}
static inline bool is_device_private_page(const struct page *page)
{
return false;
}
#endif
/**

31
include/linux/mm.h
View File

@ -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(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);
@ -826,6 +827,18 @@ 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);
}

25
kernel/memremap.c
View File

@ -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>
@ -500,3 +499,27 @@ 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) {
/* 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 */

8
mm/hmm.c
View File

@ -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;