Commit 7b2d55d2 authored by Jérôme Glisse's avatar Jérôme Glisse Committed by Linus Torvalds
Browse files

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: default avatarJérôme 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5042db43

include/linux/memremap.h

+13 −0
Original line number Diff line number Diff line
@@ -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



/**

include/linux/mm.h

+22 −9
Original line number Diff line number Diff line
@@ -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);

}

kernel/memremap.c

+24 −1
Original line number Diff line number Diff line
@@ -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 */

mm/hmm.c

+8 −0
Original line number Diff line number Diff line
@@ -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;

CRA Git | Maintained and supported by SUSTech CRA and CCSE