A dax mapping establishes a pte with _PAGE_DEVMAP set when the driver has established a devm_memremap_pages() mapping, i.e. when the pfn_t return from ->direct_access() has PFN_DEV and PFN_MAP set. Later, when encountering _PAGE_DEVMAP during a page table walk we lookup and pin a struct dev_pagemap instance to keep the result of pfn_to_page() valid until put_page(). Signed-off-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Logan Gunthorpe <logang@deltatee.com> Cc: Dave Hansen <dave@sr71.net> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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uapi/asm |