dax: remove VM_MIXEDMAP for fsdax and device dax (e1fb4a08) · Commits · 戴 / test

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>

drivers/dax/device.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -474,7 +474,7 @@ static int dax_mmap(struct file filp, struct vm_area_struct vma)
		return rc;

		vma->vm_ops = &dax_vm_ops;
		vma->vm_flags \|= VM_MIXEDMAP \| VM_HUGEPAGE;
		vma->vm_flags \|= VM_HUGEPAGE;
		return 0;
		}

fs/ext2/file.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -126,7 +126,6 @@ static int ext2_file_mmap(struct file file, struct vm_area_struct vma)

		file_accessed(file);
		vma->vm_ops = &ext2_dax_vm_ops;
		vma->vm_flags \|= VM_MIXEDMAP;
		return 0;
		}
		#else

fs/ext4/file.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -374,7 +374,7 @@ static int ext4_file_mmap(struct file file, struct vm_area_struct vma)
		file_accessed(file);
		if (IS_DAX(file_inode(file))) {
		vma->vm_ops = &ext4_dax_vm_ops;
		vma->vm_flags \|= VM_MIXEDMAP \| VM_HUGEPAGE;
		vma->vm_flags \|= VM_HUGEPAGE;
		} else {
		vma->vm_ops = &ext4_file_vm_ops;
		}

fs/xfs/xfs_file.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1169,7 +1169,7 @@ xfs_file_mmap(
		file_accessed(filp);
		vma->vm_ops = &xfs_file_vm_ops;
		if (IS_DAX(file_inode(filp)))
		vma->vm_flags \|= VM_MIXEDMAP \| VM_HUGEPAGE;
		vma->vm_flags \|= VM_HUGEPAGE;
		return 0;
		}

mm/hmm.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -676,7 +676,8 @@ int hmm_vma_get_pfns(struct hmm_range *range)
		return -EINVAL;

		/* FIXME support hugetlb fs */
		if (is_vm_hugetlb_page(vma) \|\| (vma->vm_flags & VM_SPECIAL)) {
		if (is_vm_hugetlb_page(vma) \|\| (vma->vm_flags & VM_SPECIAL) \|\|
		vma_is_dax(vma)) {
		hmm_pfns_special(range);
		return -EINVAL;
		}
		@@ -849,7 +850,8 @@ int hmm_vma_fault(struct hmm_range *range, bool block)
		return -EINVAL;

		/* FIXME support hugetlb fs */
		if (is_vm_hugetlb_page(vma) \|\| (vma->vm_flags & VM_SPECIAL)) {
		if (is_vm_hugetlb_page(vma) \|\| (vma->vm_flags & VM_SPECIAL) \|\|
		vma_is_dax(vma)) {
		hmm_pfns_special(range);
		return -EINVAL;
		}

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