[PATCH 05/15] dax: stop using VM_MIXEDMAP for dax
From: Dan Williams
Date: Tue Oct 31 2017 - 19:28:36 EST
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.
Cc: Jan Kara <jack@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/dax/device.c | 2 +-
fs/ext2/file.c | 1 -
fs/ext4/file.c | 2 +-
fs/xfs/xfs_file.c | 2 +-
include/linux/mm.h | 1 +
include/linux/vma.h | 33 +++++++++++++++++++++++++++++++++
mm/huge_memory.c | 8 ++++----
mm/ksm.c | 3 +++
mm/madvise.c | 2 +-
mm/memory.c | 8 ++++++--
mm/migrate.c | 3 ++-
mm/mlock.c | 5 +++--
mm/mmap.c | 8 ++++----
13 files changed, 60 insertions(+), 18 deletions(-)
create mode 100644 include/linux/vma.h
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index e9f3b3e4bbf4..ed79d006026e 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -450,7 +450,7 @@ 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 ff3a3636a5ca..70657e8550ed 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -125,7 +125,6 @@ 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 b1da660ac3bc..0cc9d205bd96 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -352,7 +352,7 @@ 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 309e26c9dddb..c419c6fdb769 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1134,7 +1134,7 @@ 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/include/linux/mm.h b/include/linux/mm.h
index 065d99deb847..8c1e3ac77285 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2338,6 +2338,7 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
+bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/include/linux/vma.h b/include/linux/vma.h
new file mode 100644
index 000000000000..135ad5262cd1
--- /dev/null
+++ b/include/linux/vma.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright(c) 2017 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#ifndef __VMA_H__
+#define __VMA_H__
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/mm_types.h>
+#include <linux/hugetlb_inline.h>
+
+/*
+ * There are several vma types that have special handling in the
+ * get_user_pages() path and other core mm paths that must not assume
+ * normal pages. vma_is_special() consolidates checks for VM_SPECIAL,
+ * hugetlb and dax vmas, but note that there are 'special' vmas and
+ * special circumstances beyond these types. In other words this helper
+ * is not exhaustive.
+ */
+static inline bool vma_is_special(struct vm_area_struct *vma)
+{
+ return vma && (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)
+ || vma_is_dax(vma));
+}
+#endif /* __VMA_H__ */
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 269b5df58543..3cabd682da1c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -765,11 +765,11 @@ 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))
+ || vm_mixed_ok(vma, 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;
@@ -824,11 +824,11 @@ int vmf_insert_pfn_pud(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))
+ || vm_mixed_ok(vma, 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 6cb60f46cce5..72f196a36503 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2361,6 +2361,9 @@ 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/madvise.c b/mm/madvise.c
index 25bade36e9ca..50513a7a11f6 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -95,7 +95,7 @@ static long madvise_behavior(struct vm_area_struct *vma,
new_flags |= VM_DONTDUMP;
break;
case MADV_DODUMP:
- if (new_flags & VM_SPECIAL) {
+ if (vma_is_dax(vma) || (new_flags & VM_SPECIAL)) {
error = -EINVAL;
goto out;
}
diff --git a/mm/memory.c b/mm/memory.c
index e764dc5d8a87..150c9194db27 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -830,6 +830,8 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
return vma->vm_ops->find_special_page(vma, addr);
if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
return NULL;
+ if (pte_devmap(pte))
+ return NULL;
if (is_zero_pfn(pfn))
return NULL;
@@ -917,6 +919,8 @@ 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))
@@ -1227,7 +1231,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* efficient than faulting.
*/
if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
- !vma->anon_vma)
+ !vma->anon_vma && !vma_is_dax(vma))
return 0;
if (is_vm_hugetlb_page(vma))
@@ -1896,7 +1900,7 @@ int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
}
EXPORT_SYMBOL(vm_insert_pfn_prot);
-static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
+bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
{
/* these checks mirror the abort conditions in vm_normal_page */
if (vma->vm_flags & VM_MIXEDMAP)
diff --git a/mm/migrate.c b/mm/migrate.c
index 6954c1435833..13f8748e7cba 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -45,6 +45,7 @@
#include <linux/page_owner.h>
#include <linux/sched/mm.h>
#include <linux/ptrace.h>
+#include <linux/vma.h>
#include <asm/tlbflush.h>
@@ -2927,7 +2928,7 @@ 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 || vma_is_special(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 dfc6f1912176..4e20915ddfef 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -22,6 +22,7 @@
#include <linux/hugetlb.h>
#include <linux/memcontrol.h>
#include <linux/mm_inline.h>
+#include <linux/vma.h>
#include "internal.h"
@@ -519,8 +520,8 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
int lock = !!(newflags & VM_LOCKED);
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))
+ if (newflags == vma->vm_flags || vma_is_special(vma)
+ || vma == get_gate_vma(current->mm))
/* 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 680506faceae..c28996f74320 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -45,6 +45,7 @@
#include <linux/moduleparam.h>
#include <linux/pkeys.h>
#include <linux/oom.h>
+#include <linux/vma.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
@@ -1722,11 +1723,10 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
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 (vma_is_special(vma) || vma == get_gate_vma(current->mm))
vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
+ else
+ mm->locked_vm += (len >> PAGE_SHIFT);
}
if (file)