From 9476df7d80dfc425b37bfecf1d89edf8ec81fcb6 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 15 Jan 2016 16:56:19 -0800 Subject: mm: introduce find_dev_pagemap() There are several scenarios where we need to retrieve and update metadata associated with a given devm_memremap_pages() mapping, and the only lookup key available is a pfn in the range: 1/ We want to augment vmemmap_populate() (called via arch_add_memory()) to allocate memmap storage from pre-allocated pages reserved by the device driver. At vmemmap_alloc_block_buf() time it grabs device pages rather than page allocator pages. This is in support of devm_memremap_pages() mappings where the memmap is too large to fit in main memory (i.e. large persistent memory devices). 2/ Taking a reference against the mapping when inserting device pages into the address_space radix of a given inode. This facilitates unmap_mapping_range() and truncate_inode_pages() operations when the driver is tearing down the mapping. 3/ get_user_pages() operations on ZONE_DEVICE memory require taking a reference against the mapping so that the driver teardown path can revoke and drain usage of device pages. Signed-off-by: Dan Williams Tested-by: Logan Gunthorpe Cc: Christoph Hellwig Cc: Dave Chinner Cc: Ross Zwisler Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memremap.h | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 include/linux/memremap.h (limited to 'include/linux/memremap.h') diff --git a/include/linux/memremap.h b/include/linux/memremap.h new file mode 100644 index 000000000000..d90721c178bb --- /dev/null +++ b/include/linux/memremap.h @@ -0,0 +1,38 @@ +#ifndef _LINUX_MEMREMAP_H_ +#define _LINUX_MEMREMAP_H_ +#include + +struct resource; +struct device; +/** + * struct dev_pagemap - metadata for ZONE_DEVICE mappings + * @dev: host device of the mapping for debug + */ +struct dev_pagemap { + /* TODO: vmem_altmap and percpu_ref count */ + struct device *dev; +}; + +#ifdef CONFIG_ZONE_DEVICE +void *devm_memremap_pages(struct device *dev, struct resource *res); +struct dev_pagemap *find_dev_pagemap(resource_size_t phys); +#else +static inline void *devm_memremap_pages(struct device *dev, + struct resource *res) +{ + /* + * Fail attempts to call devm_memremap_pages() without + * ZONE_DEVICE support enabled, this requires callers to fall + * back to plain devm_memremap() based on config + */ + WARN_ON_ONCE(1); + return ERR_PTR(-ENXIO); +} + +static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys) +{ + return NULL; +} +#endif + +#endif /* _LINUX_MEMREMAP_H_ */ -- cgit