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mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS

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In preparation for fixing dax-dma-vs-unmap issues, filesystems need to
be able to rely on the fact that they will get wakeups on dev_pagemap
page-idle events. Introduce MEMORY_DEVICE_FS_DAX and
generic_dax_page_free() as common indicator / infrastructure for dax
filesytems to require. With this change there are no users of the
MEMORY_DEVICE_HOST designation, so remove it.

The HMM sub-system extended dev_pagemap to arrange a callback when a
dev_pagemap managed page is freed. Since a dev_pagemap page is free /
idle when its reference count is 1 it requires an additional branch to
check the page-type at put_page() time. Given put_page() is a hot-path
we do not want to incur that check if HMM is not in use, so a static
branch is used to avoid that overhead when not necessary.

Now, the FS_DAX implementation wants to reuse this mechanism for
receiving dev_pagemap ->page_free() callbacks. Rework the HMM-specific
static-key into a generic mechanism that either HMM or FS_DAX code paths
can enable.

For ARCH=um builds, and any other arch that lacks ZONE_DEVICE support,
care must be taken to compile out the DEV_PAGEMAP_OPS infrastructure.
However, we still need to support FS_DAX in the FS_DAX_LIMITED case
implemented by the s390/dcssblk driver.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Thomas Meyer <thomas@m3y3r.de>
Reported-by: Dave Jiang <dave.jiang@intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2018-05-16 11:46:08 -07:00
parent 5981690ddb
commit e763848843
10 changed files with 137 additions and 65 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/dax/super.c
View File

@ -86,6 +86,7 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
{
struct block_device *bdev = sb->s_bdev;
struct dax_device *dax_dev;
bool dax_enabled = false;
pgoff_t pgoff;
int err, id;
void *kaddr;
@ -134,14 +135,21 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
* on being able to do (page_address(pfn_to_page())).
*/
WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
dax_enabled = true;
} else if (pfn_t_devmap(pfn)) {
/* pass */;
} else {
struct dev_pagemap *pgmap;
pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX)
dax_enabled = true;
put_dev_pagemap(pgmap);
}
if (!dax_enabled) {
pr_debug("VFS (%s): error: dax support not enabled\n",
sb->s_id);
return -EOPNOTSUPP;
}
return 0;
}
EXPORT_SYMBOL_GPL(__bdev_dax_supported);

2
drivers/nvdimm/pfn_devs.c
View File

@ -561,8 +561,6 @@ static int __nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
res->start += start_pad;
res->end -= end_trunc;
pgmap->type = MEMORY_DEVICE_HOST;
if (nd_pfn->mode == PFN_MODE_RAM) {
if (offset < SZ_8K)
return -EINVAL;

25
drivers/nvdimm/pmem.c
View File

@ -294,6 +294,27 @@ static void pmem_release_disk(void *__pmem)
put_disk(pmem->disk);
}
static void pmem_release_pgmap_ops(void *__pgmap)
{
dev_pagemap_put_ops();
}
static void fsdax_pagefree(struct page *page, void *data)
{
wake_up_var(&page->_refcount);
}
static int setup_pagemap_fsdax(struct device *dev, struct dev_pagemap *pgmap)
{
dev_pagemap_get_ops();
if (devm_add_action_or_reset(dev, pmem_release_pgmap_ops, pgmap))
return -ENOMEM;
pgmap->type = MEMORY_DEVICE_FS_DAX;
pgmap->page_free = fsdax_pagefree;
return 0;
}
static int pmem_attach_disk(struct device *dev,
struct nd_namespace_common *ndns)
{
@ -353,6 +374,8 @@ static int pmem_attach_disk(struct device *dev,
pmem->pfn_flags = PFN_DEV;
pmem->pgmap.ref = &q->q_usage_counter;
if (is_nd_pfn(dev)) {
if (setup_pagemap_fsdax(dev, &pmem->pgmap))
return -ENOMEM;
addr = devm_memremap_pages(dev, &pmem->pgmap);
pfn_sb = nd_pfn->pfn_sb;
pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
@ -364,6 +387,8 @@ static int pmem_attach_disk(struct device *dev,
} else if (pmem_should_map_pages(dev)) {
memcpy(&pmem->pgmap.res, &nsio->res, sizeof(pmem->pgmap.res));
pmem->pgmap.altmap_valid = false;
if (setup_pagemap_fsdax(dev, &pmem->pgmap))
return -ENOMEM;
addr = devm_memremap_pages(dev, &pmem->pgmap);
pmem->pfn_flags |= PFN_MAP;
memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));

1
fs/Kconfig
View File

@ -38,6 +38,7 @@ config FS_DAX
bool "Direct Access (DAX) support"
depends on MMU
depends on !(ARM || MIPS || SPARC)
select DEV_PAGEMAP_OPS if (ZONE_DEVICE && !FS_DAX_LIMITED)
select FS_IOMAP
select DAX
help

36
include/linux/memremap.h
View File

@ -1,7 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_MEMREMAP_H_
#define _LINUX_MEMREMAP_H_
#include <linux/mm.h>
#include <linux/ioport.h>
#include <linux/percpu-refcount.h>
@ -30,13 +29,6 @@ struct vmem_altmap {
* Specialize ZONE_DEVICE memory into multiple types each having differents
* usage.
*
* MEMORY_DEVICE_HOST:
* Persistent device memory (pmem): struct page might be allocated in different
* memory and architecture might want to perform special actions. It is similar
* to regular memory, in that the CPU can access it transparently. However,
* it is likely to have different bandwidth and latency than regular memory.
* See Documentation/nvdimm/nvdimm.txt for more information.
*
* MEMORY_DEVICE_PRIVATE:
* Device memory that is not directly addressable by the CPU: CPU can neither
* read nor write private memory. In this case, we do still have struct pages
@ -53,11 +45,19 @@ struct vmem_altmap {
* driver can hotplug the device memory using ZONE_DEVICE and with that memory
* type. Any page of a process can be migrated to such memory. However no one
* should be allow to pin such memory so that it can always be evicted.
*
* MEMORY_DEVICE_FS_DAX:
* Host memory that has similar access semantics as System RAM i.e. DMA
* coherent and supports page pinning. In support of coordinating page
* pinning vs other operations MEMORY_DEVICE_FS_DAX arranges for a
* wakeup event whenever a page is unpinned and becomes idle. This
* wakeup is used to coordinate physical address space management (ex:
* fs truncate/hole punch) vs pinned pages (ex: device dma).
*/
enum memory_type {
MEMORY_DEVICE_HOST = 0,
MEMORY_DEVICE_PRIVATE,
MEMORY_DEVICE_PRIVATE = 1,
MEMORY_DEVICE_PUBLIC,
MEMORY_DEVICE_FS_DAX,
};
/*
@ -129,8 +129,6 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
static inline bool is_zone_device_page(const struct page *page);
#else
static inline void *devm_memremap_pages(struct device *dev,
struct dev_pagemap *pgmap)
@ -161,20 +159,6 @@ static inline void vmem_altmap_free(struct vmem_altmap *altmap,
}
#endif /* CONFIG_ZONE_DEVICE */
#if defined(CONFIG_DEVICE_PRIVATE) || defined(CONFIG_DEVICE_PUBLIC)
static inline bool is_device_private_page(const struct page *page)
{
return is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_PRIVATE;
}
static inline bool is_device_public_page(const struct page *page)
{
return is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_PUBLIC;
}
#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
{
if (pgmap)

71
include/linux/mm.h
View File

@ -821,27 +821,65 @@ static inline bool is_zone_device_page(const struct page *page)
}
#endif
#if defined(CONFIG_DEVICE_PRIVATE) || defined(CONFIG_DEVICE_PUBLIC)
void put_zone_device_private_or_public_page(struct page *page);
DECLARE_STATIC_KEY_FALSE(device_private_key);
#define IS_HMM_ENABLED static_branch_unlikely(&device_private_key)
static inline bool is_device_private_page(const struct page *page);
static inline bool is_device_public_page(const struct page *page);
#else /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
static inline void put_zone_device_private_or_public_page(struct page *page)
#ifdef CONFIG_DEV_PAGEMAP_OPS
void dev_pagemap_get_ops(void);
void dev_pagemap_put_ops(void);
void __put_devmap_managed_page(struct page *page);
DECLARE_STATIC_KEY_FALSE(devmap_managed_key);
static inline bool put_devmap_managed_page(struct page *page)
{
if (!static_branch_unlikely(&devmap_managed_key))
return false;
if (!is_zone_device_page(page))
return false;
switch (page->pgmap->type) {
case MEMORY_DEVICE_PRIVATE:
case MEMORY_DEVICE_PUBLIC:
case MEMORY_DEVICE_FS_DAX:
__put_devmap_managed_page(page);
return true;
default:
break;
}
return false;
}
static inline bool is_device_private_page(const struct page *page)
{
return is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_PRIVATE;
}
static inline bool is_device_public_page(const struct page *page)
{
return is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_PUBLIC;
}
#else /* CONFIG_DEV_PAGEMAP_OPS */
static inline void dev_pagemap_get_ops(void)
{
}
#define IS_HMM_ENABLED 0
static inline void dev_pagemap_put_ops(void)
{
}
static inline bool put_devmap_managed_page(struct page *page)
{
return false;
}
static inline bool is_device_private_page(const struct page *page)
{
return false;
}
static inline bool is_device_public_page(const struct page *page)
{
return false;
}
#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
#endif /* CONFIG_DEV_PAGEMAP_OPS */
static inline void get_page(struct page *page)
{
@ -859,16 +897,13 @@ 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
* For devmap managed pages we need to catch refcount transition from
* 2 to 1, when refcount reach one it means the page is free and we
* need to inform the device driver through callback. See
* include/linux/memremap.h and HMM for details.
*/
if (IS_HMM_ENABLED && unlikely(is_device_private_page(page) ||
unlikely(is_device_public_page(page)))) {
put_zone_device_private_or_public_page(page);
if (put_devmap_managed_page(page))
return;
}
if (put_page_testzero(page))
__put_page(page);

32
kernel/memremap.c
View File

@ -9,6 +9,7 @@
#include <linux/memory_hotplug.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/wait_bit.h>
static DEFINE_MUTEX(pgmap_lock);
static RADIX_TREE(pgmap_radix, GFP_KERNEL);
@ -300,9 +301,32 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
return pgmap;
}
EXPORT_SYMBOL_GPL(get_dev_pagemap);
#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) || IS_ENABLED(CONFIG_DEVICE_PUBLIC)
void put_zone_device_private_or_public_page(struct page *page)
#ifdef CONFIG_DEV_PAGEMAP_OPS
DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
EXPORT_SYMBOL_GPL(devmap_managed_key);
static atomic_t devmap_enable;
/*
* Toggle the static key for ->page_free() callbacks when dev_pagemap
* pages go idle.
*/
void dev_pagemap_get_ops(void)
{
if (atomic_inc_return(&devmap_enable) == 1)
static_branch_enable(&devmap_managed_key);
}
EXPORT_SYMBOL_GPL(dev_pagemap_get_ops);
void dev_pagemap_put_ops(void)
{
if (atomic_dec_and_test(&devmap_enable))
static_branch_disable(&devmap_managed_key);
}
EXPORT_SYMBOL_GPL(dev_pagemap_put_ops);
void __put_devmap_managed_page(struct page *page)
{
int count = page_ref_dec_return(page);
@ -322,5 +346,5 @@ void put_zone_device_private_or_public_page(struct page *page)
} else if (!count)
__put_page(page);
}
EXPORT_SYMBOL(put_zone_device_private_or_public_page);
#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
EXPORT_SYMBOL_GPL(__put_devmap_managed_page);
#endif /* CONFIG_DEV_PAGEMAP_OPS */

5
mm/Kconfig
View File

@ -692,6 +692,9 @@ config ARCH_HAS_HMM
config MIGRATE_VMA_HELPER
bool
config DEV_PAGEMAP_OPS
bool
config HMM
bool
select MIGRATE_VMA_HELPER
@ -712,6 +715,7 @@ config DEVICE_PRIVATE
bool "Unaddressable device memory (GPU memory, ...)"
depends on ARCH_HAS_HMM
select HMM
select DEV_PAGEMAP_OPS
help
Allows creation of struct pages to represent unaddressable device
@ -722,6 +726,7 @@ config DEVICE_PUBLIC
bool "Addressable device memory (like GPU memory)"
depends on ARCH_HAS_HMM
select HMM
select DEV_PAGEMAP_OPS
help
Allows creation of struct pages to represent addressable device

13
mm/hmm.c
View File

@ -35,15 +35,6 @@
#define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT)
#if defined(CONFIG_DEVICE_PRIVATE) || defined(CONFIG_DEVICE_PUBLIC)
/*
* Device private memory see HMM (Documentation/vm/hmm.txt) or hmm.h
*/
DEFINE_STATIC_KEY_FALSE(device_private_key);
EXPORT_SYMBOL(device_private_key);
#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
#if IS_ENABLED(CONFIG_HMM_MIRROR)
static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
@ -1167,7 +1158,7 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
resource_size_t addr;
int ret;
static_branch_enable(&device_private_key);
dev_pagemap_get_ops();
devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem),
GFP_KERNEL, dev_to_node(device));
@ -1261,7 +1252,7 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY)
return ERR_PTR(-EINVAL);
static_branch_enable(&device_private_key);
dev_pagemap_get_ops();
devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem),
GFP_KERNEL, dev_to_node(device));

3
mm/swap.c
View File

@ -29,6 +29,7 @@
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/backing-dev.h>
#include <linux/memremap.h>
#include <linux/memcontrol.h>
#include <linux/gfp.h>
#include <linux/uio.h>
@ -743,7 +744,7 @@ void release_pages(struct page **pages, int nr)
flags);
locked_pgdat = NULL;
}
put_zone_device_private_or_public_page(page);
put_devmap_managed_page(page);
continue;
}