[PATCH 09/22] memremap: lift the devmap_enable manipulation into devm_memremap_pages

Christoph Hellwig
2019-06-13T09:43:58Z

Just check if there is a ->page_free operation set and take care of the
static key enable, as well as the put using device managed resources.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/nvdimm/pmem.c | 23 +++--------------
include/linux/mm.h | 10 --------
kernel/memremap.c | 59 +++++++++++++++++++++++++++----------------
mm/hmm.c | 2 --
4 files changed, 41 insertions(+), 53 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index b9638c6553a1..66837eed6375 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -334,11 +334,6 @@ 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 pmem_fsdax_page_free(struct page *page, void *data)
{
wake_up_var(&page->_refcount);
@@ -353,16 +348,6 @@ static const struct dev_pagemap_ops pmem_legacy_pagemap_ops = {
.kill = pmem_kill,
};

-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->ops = &fsdax_pagemap_ops;
- return 0;
-}
-
static int pmem_attach_disk(struct device *dev,
struct nd_namespace_common *ndns)
{
@@ -421,8 +406,8 @@ 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;
+ pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
+ pmem->pgmap.ops = &fsdax_pagemap_ops;
addr = devm_memremap_pages(dev, &pmem->pgmap);
pfn_sb = nd_pfn->pfn_sb;
pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
@@ -434,8 +419,8 @@ 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;
+ pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
+ pmem->pgmap.ops = &fsdax_pagemap_ops;
addr = devm_memremap_pages(dev, &pmem->pgmap);
pmem->pfn_flags |= PFN_MAP;
memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e8834ac32b7..edcf2b821647 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -921,8 +921,6 @@ static inline bool is_zone_device_page(const struct page *page)
#endif

#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)
@@ -969,14 +967,6 @@ static inline bool is_pci_p2pdma_page(const struct page *page)
#endif /* CONFIG_PCI_P2PDMA */

#else /* CONFIG_DEV_PAGEMAP_OPS */
-static inline void dev_pagemap_get_ops(void)
-{
-}
-
-static inline void dev_pagemap_put_ops(void)
-{
-}
-
static inline bool put_devmap_managed_page(struct page *page)
{
return false;
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 94b830b6eca5..6a3183cac764 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -17,6 +17,37 @@ static DEFINE_XARRAY(pgmap_array);
#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)

+#ifdef CONFIG_DEV_PAGEMAP_OPS
+DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
+EXPORT_SYMBOL(devmap_managed_key);
+static atomic_t devmap_enable;
+
+static void dev_pagemap_put_ops(void *data)
+{
+ if (atomic_dec_and_test(&devmap_enable))
+ static_branch_disable(&devmap_managed_key);
+}
+
+/*
+ * Toggle the static key for ->page_free() callbacks when dev_pagemap
+ * pages go idle.
+ */
+static int dev_pagemap_enable(struct device *dev)
+{
+ if (atomic_inc_return(&devmap_enable) == 1)
+ static_branch_enable(&devmap_managed_key);
+
+ if (devm_add_action_or_reset(dev, dev_pagemap_put_ops, NULL))
+ return -ENOMEM;
+ return 0;
+}
+#else
+static inline int dev_pagemap_enable(struct device *dev)
+{
+ return 0;
+}
+#endif /* CONFIG_DEV_PAGEMAP_OPS */
+
#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
unsigned long addr,
@@ -159,6 +190,12 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
if (!pgmap->ref || !pgmap->ops || !pgmap->ops->kill)
return ERR_PTR(-EINVAL);

+ if (pgmap->ops->page_free) {
+ error = dev_pagemap_enable(dev);
+ if (error)
+ return ERR_PTR(error);
+ }
+
align_start = res->start & ~(SECTION_SIZE - 1);
align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
- align_start;
@@ -316,28 +353,6 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
EXPORT_SYMBOL_GPL(get_dev_pagemap);

#ifdef CONFIG_DEV_PAGEMAP_OPS
-DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
-EXPORT_SYMBOL(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);
diff --git a/mm/hmm.c b/mm/hmm.c
index c76a1b5defda..6dc769feb2e1 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -1378,8 +1378,6 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
void *result;
int ret;

- dev_pagemap_get_ops();
-
devmem = devm_kzalloc(device, sizeof(*devmem), GFP_KERNEL);
if (!devmem)
return ERR_PTR(-ENOMEM);
--
2.20.1