memremap: lift the devmap_enable manipulation into devm_memremap_pages

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.
Also check that a ->page_free is provided for the pgmaps types that
require it, and check for a valid type as well while we are at it.

Note that this also fixes the fact that hmm never called
dev_pagemap_put_ops and thus would leave the slow path enabled forever,
even after a device driver unload or disable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 9dac48359353b80db51027354c10999b13739721..48767171a4dfa24ecc38e8e722e77e2dbb2bd093 100644 (file)
--- 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_pagemap_page_free(struct page *page, void *data)
 {
        wake_up_var(&page->_refcount);
@@ -350,16 +345,6 @@ static const struct dev_pagemap_ops fsdax_pagemap_ops = {
        .cleanup                = pmem_pagemap_cleanup,
 };
 
-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)
 {
@@ -415,8 +400,8 @@ 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);
@@ -428,8 +413,8 @@ 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 7399f9f08de6c584143e0ead8926bae08fcfe4e0..2425f4167ec217124774d42b6e806d509844e369 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -932,8 +932,6 @@ 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)
@@ -973,14 +971,6 @@ 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 00c1ceb60c1944aae89e4823af1c10c1892cbb9a..3219a4c91d0731609cbc54947fcd1be37cae28c0 100644 (file)
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -17,6 +17,35 @@ 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_managed_enable;
+
+static void devmap_managed_enable_put(void *data)
+{
+       if (atomic_dec_and_test(&devmap_managed_enable))
+               static_branch_disable(&devmap_managed_key);
+}
+
+static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
+{
+       if (!pgmap->ops->page_free) {
+               WARN(1, "Missing page_free method\n");
+               return -EINVAL;
+       }
+
+       if (atomic_inc_return(&devmap_managed_enable) == 1)
+               static_branch_enable(&devmap_managed_key);
+       return devm_add_action_or_reset(dev, devmap_managed_enable_put, NULL);
+}
+#else
+static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap)
+{
+       return -EINVAL;
+}
+#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,
@@ -156,6 +185,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
        };
        pgprot_t pgprot = PAGE_KERNEL;
        int error, nid, is_ram;
+       bool need_devmap_managed = true;
 
        switch (pgmap->type) {
        case MEMORY_DEVICE_PRIVATE:
@@ -173,6 +203,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
                break;
        case MEMORY_DEVICE_DEVDAX:
        case MEMORY_DEVICE_PCI_P2PDMA:
+               need_devmap_managed = false;
                break;
        default:
                WARN(1, "Invalid pgmap type %d\n", pgmap->type);
@@ -185,6 +216,12 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
                return ERR_PTR(-EINVAL);
        }
 
+       if (need_devmap_managed) {
+               error = devmap_managed_enable_get(dev, pgmap);
+               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;
@@ -351,28 +388,6 @@ 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 987793fba923aa9aa9023d1cfd9709fe42ef67c1..5b0bd5f6a74f56ed834102e38797264fc574c220 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -1415,8 +1415,6 @@ 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);