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Date: Tue, 31 Jul 2012 14:42:17 +0400
From: Konstantin Khlebnikov <khlebnikov@...nvz.org>
To: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Cc: Carsten Otte <cotte@...ibm.com>, Ingo Molnar <mingo@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Nick Piggin <npiggin@...nel.dk>
Subject: [PATCH v3 05/10] mm: kill vma flag VM_INSERTPAGE
This patch merges VM_INSERTPAGE into VM_MIXEDMAP.
VM_MIXEDMAP VMA can mix pure-pfn ptes, special ptes and normal ptes.
Now copy_page_range() always copies VM_MIXEDMAP VMA on fork like VM_PFNMAP.
If driver populates whole VMA at mmap() it probably not expects page-faults.
This patch removes special check from vma_wants_writenotify() which disables
pages write tracking for VMA populated via vm_instert_page(). BDI below mapped
file should not use dirty-accounting, moreover do_wp_page() can handle this.
vm_insert_page() still marks vma after first usage. Usually it is called from
f_op->mmap() handler under mm->mmap_sem write-lock, so it able to change
vma->vm_flags. Caller must set VM_MIXEDMAP at mmap time if it wants to call
this function from other places, for example from page-fault handler.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@...nvz.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Nick Piggin <npiggin@...nel.dk>
Cc: Carsten Otte <cotte@...ibm.com>
Cc: Ingo Molnar <mingo@...hat.com>
---
include/linux/mm.h | 1 -
mm/huge_memory.c | 3 +--
mm/ksm.c | 2 +-
mm/memory.c | 14 ++++++++++++--
mm/mmap.c | 2 +-
5 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 22c945b..cdff0ed 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -103,7 +103,6 @@ extern unsigned int kobjsize(const void *objp);
#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */
#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
#define VM_ARCH_1 0x01000000 /* Architecture-specific flag */
-#define VM_INSERTPAGE 0x02000000 /* The vma has had "vm_insert_page()" done on it */
#define VM_NODUMP 0x04000000 /* Do not include in the core dump */
#define VM_CAN_NONLINEAR 0x08000000 /* Has ->fault & does nonlinear pages */
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 67721f8..8b3c55a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1491,8 +1491,7 @@ out:
return ret;
}
-#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP| \
- VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
+#define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
int hugepage_madvise(struct vm_area_struct *vma,
unsigned long *vm_flags, int advice)
diff --git a/mm/ksm.c b/mm/ksm.c
index d1cbe2a..f9ccb16 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1469,7 +1469,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
*/
if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE |
VM_PFNMAP | VM_IO | VM_DONTEXPAND |
- VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE |
+ VM_RESERVED | VM_HUGETLB |
VM_NONLINEAR | VM_MIXEDMAP))
return 0; /* just ignore the advice */
diff --git a/mm/memory.c b/mm/memory.c
index aca6f22..2fb27a0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1047,7 +1047,8 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
* readonly mappings. The tradeoff is that copy_page_range is more
* efficient than faulting.
*/
- if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
+ if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
+ VM_PFNMAP | VM_MIXEDMAP))) {
if (!vma->anon_vma)
return 0;
}
@@ -2082,6 +2083,11 @@ out:
* ask for a shared writable mapping!
*
* The page does not need to be reserved.
+ *
+ * Usually this function is called from f_op->mmap() handler
+ * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
+ * Caller must set VM_MIXEDMAP on vma if it wants to call this
+ * function from other places, for example from page-fault handler.
*/
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
struct page *page)
@@ -2090,7 +2096,11 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
return -EFAULT;
if (!page_count(page))
return -EINVAL;
- vma->vm_flags |= VM_INSERTPAGE;
+ if (!(vma->vm_flags & VM_MIXEDMAP)) {
+ BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
+ BUG_ON(vma->vm_flags & VM_PFNMAP);
+ vma->vm_flags |= VM_MIXEDMAP;
+ }
return insert_page(vma, addr, page, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_insert_page);
diff --git a/mm/mmap.c b/mm/mmap.c
index 3edfcdf..47a74c4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1188,7 +1188,7 @@ int vma_wants_writenotify(struct vm_area_struct *vma)
return 0;
/* Specialty mapping? */
- if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
+ if (vm_flags & VM_PFNMAP)
return 0;
/* Can the mapping track the dirty pages? */
--
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