dax: remove VM_MIXEDMAP for fsdax and device dax
This patch is reworked from an earlier patch that Dan has posted:
https://patchwork.kernel.org/patch/10131727/
VM_MIXEDMAP is used by dax to direct mm paths like vm_normal_page() that
the memory page it is dealing with is not typical memory from the linear
map. The get_user_pages_fast() path, since it does not resolve the vma,
is already using {pte,pmd}_devmap() as a stand-in for VM_MIXEDMAP, so we
use that as a VM_MIXEDMAP replacement in some locations. In the cases
where there is no pte to consult we fallback to using vma_is_dax() to
detect the VM_MIXEDMAP special case.
Now that we have explicit driver pfn_t-flag opt-in/opt-out for
get_user_pages() support for DAX we can stop setting VM_MIXEDMAP. This
also means we no longer need to worry about safely manipulating vm_flags
in a future where we support dynamically changing the dax mode of a
file.
DAX should also now be supported with madvise_behavior(), vma_merge(),
and copy_page_range().
This patch has been tested against ndctl unit test. It has also been
tested against xfstests commit: 625515d using fake pmem created by
memmap and no additional issues have been observed.
Link: http://lkml.kernel.org/r/152847720311.55924.16999195879201817653.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory.c b/mm/memory.c
index 348279f..7c3bd11 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -859,6 +859,10 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
return NULL;
}
}
+
+ if (pte_devmap(pte))
+ return NULL;
+
print_bad_pte(vma, addr, pte, NULL);
return NULL;
}
@@ -923,6 +927,8 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
}
}
+ if (pmd_devmap(pmd))
+ return NULL;
if (is_zero_pfn(pfn))
return NULL;
if (unlikely(pfn > highest_memmap_pfn))