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/drivers/dax/device.c b/drivers/dax/device.c
index 108c37f..0a2acd7 100644 (file)
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -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;
 }
 

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 047c327..28b2609 100644 (file)
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -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

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 7f80233..69d65d4 100644 (file)
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -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;
        }

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 181e908..5eaef2c 100644 (file)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -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;
 }
 

diff --git a/mm/hmm.c b/mm/hmm.c
index de7b6bf..f40e8ad 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -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;
        }

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a9e1e09..1ce44e8 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -762,11 +762,11 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
         * but we need to be consistent with PTEs and architectures that
         * can't support a 'special' bit.
         */
-       BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
+       BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
+                       !pfn_t_devmap(pfn));
        BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
                                                (VM_PFNMAP|VM_MIXEDMAP));
        BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
-       BUG_ON(!pfn_t_devmap(pfn));
 
        if (addr < vma->vm_start || addr >= vma->vm_end)
                return VM_FAULT_SIGBUS;

diff --git a/mm/ksm.c b/mm/ksm.c
index a6d43cf..9b855a8 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2430,6 +2430,9 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
                                 VM_HUGETLB | VM_MIXEDMAP))
                        return 0;               /* just ignore the advice */
 
+               if (vma_is_dax(vma))
+                       return 0;
+
 #ifdef VM_SAO
                if (*vm_flags & VM_SAO)
                        return 0;

diff --git a/mm/memory.c b/mm/memory.c
index 348279f..7c3bd11 100644 (file)
--- 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))

diff --git a/mm/migrate.c b/mm/migrate.c
index 8c0af0f..4a83268 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2951,7 +2951,8 @@ int migrate_vma(const struct migrate_vma_ops *ops,
        /* Sanity check the arguments */
        start &= PAGE_MASK;
        end &= PAGE_MASK;
-       if (!vma || is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL))
+       if (!vma || is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL) ||
+                       vma_is_dax(vma))
                return -EINVAL;
        if (start < vma->vm_start || start >= vma->vm_end)
                return -EINVAL;

diff --git a/mm/mlock.c b/mm/mlock.c
index 74e5a65..41cc47e 100644 (file)
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -527,7 +527,8 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
        vm_flags_t old_flags = vma->vm_flags;
 
        if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
-           is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm))
+           is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
+           vma_is_dax(vma))
                /* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
                goto out;
 

diff --git a/mm/mmap.c b/mm/mmap.c
index 17bbf4d..8d6449e 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1796,11 +1796,12 @@ out:
 
        vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
        if (vm_flags & VM_LOCKED) {
-               if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
-                                       vma == get_gate_vma(current->mm)))
-                       mm->locked_vm += (len >> PAGE_SHIFT);
-               else
+               if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
+                                       is_vm_hugetlb_page(vma) ||
+                                       vma == get_gate_vma(current->mm))
                        vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
+               else
+                       mm->locked_vm += (len >> PAGE_SHIFT);
        }
 
        if (file)