diff options
| author | Dan Williams | 2022-05-20 13:41:24 -0700 |
|---|---|---|
| committer | Dan Williams | 2022-07-21 17:19:25 -0700 |
| commit | 14b80582c43e4f550acfd93c2b2cadbe36ea0874 (patch) | |
| tree | 3dc431e60aa40621c05388d9431de45c03b2974d /mm | |
| parent | 7f8faf96a2fb562833db73595640329ca8da7b1d (diff) | |
resource: Introduce alloc_free_mem_region()
The core of devm_request_free_mem_region() is a helper that searches for
free space in iomem_resource and performs __request_region_locked() on
the result of that search. The policy choices of the implementation
conform to what CONFIG_DEVICE_PRIVATE users want which is memory that is
immediately marked busy, and a preference to search for the first-fit
free range in descending order from the top of the physical address
space.
CXL has a need for a similar allocator, but with the following tweaks:
1/ Search for free space in ascending order
2/ Search for free space relative to a given CXL window
3/ 'insert' rather than 'request' the new resource given downstream
drivers from the CXL Region driver (like the pmem or dax drivers) are
responsible for request_mem_region() when they activate the memory
range.
Rework __request_free_mem_region() into get_free_mem_region() which
takes a set of GFR_* (Get Free Region) flags to control the allocation
policy (ascending vs descending), and "busy" policy (insert_resource()
vs request_region()).
As part of the consolidation of the legacy GFR_REQUEST_REGION case with
the new default of just inserting a new resource into the free space
some minor cleanups like not checking for NULL before calling
devres_free() (which does its own check) is included.
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/linux-cxl/20220420143406.GY2120790@nvidia.com/
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/165784333333.1758207.13703329337805274043.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index 169e64192e48..a5b4fee2e3fd 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -994,9 +994,14 @@ config HMM_MIRROR bool depends on MMU +config GET_FREE_REGION + depends on SPARSEMEM + bool + config DEVICE_PRIVATE bool "Unaddressable device memory (GPU memory, ...)" depends on ZONE_DEVICE + select GET_FREE_REGION help Allows creation of struct pages to represent unaddressable device |