Quoting Gleb Natapov <[email protected]>:
> It seams now you broke MADV_NORMAL.
Right. How's this?
---
Add madvise options to control whether memory range is inherited across fork.
Useful e.g. for when hardware is doing DMA from/into these pages.
Signed-off-by: Michael S. Tsirkin <[email protected]>
Index: linux-2.6.14-dontcopy/kernel/fork.c
===================================================================
--- linux-2.6.14-dontcopy.orig/kernel/fork.c 2005-11-08 23:41:30.000000000 +0200
+++ linux-2.6.14-dontcopy/kernel/fork.c 2005-11-14 16:59:05.000000000 +0200
@@ -209,7 +209,7 @@ static inline int dup_mmap(struct mm_str
for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
struct file *file;
- if (mpnt->vm_flags & VM_DONTCOPY) {
+ if (mpnt->vm_flags & (VM_DONTCOPY | VM_DONTFORK)) {
long pages = vma_pages(mpnt);
mm->total_vm -= pages;
__vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
Index: linux-2.6.14-dontcopy/mm/mmap.c
===================================================================
--- linux-2.6.14-dontcopy.orig/mm/mmap.c 2005-11-08 23:42:01.000000000 +0200
+++ linux-2.6.14-dontcopy/mm/mmap.c 2005-11-14 17:02:37.000000000 +0200
@@ -840,7 +840,7 @@ void __vm_stat_account(struct mm_struct
#ifdef CONFIG_HUGETLB
if (flags & VM_HUGETLB) {
- if (!(flags & VM_DONTCOPY))
+ if (!(flags & (VM_DONTCOPY|VM_DONTFORK)))
mm->shared_vm += pages;
return;
}
Index: linux-2.6.14-dontcopy/mm/madvise.c
===================================================================
--- linux-2.6.14-dontcopy.orig/mm/madvise.c 2005-10-28 02:02:08.000000000 +0200
+++ linux-2.6.14-dontcopy/mm/madvise.c 2005-11-14 22:40:43.000000000 +0200
@@ -22,16 +22,23 @@ static long madvise_behavior(struct vm_a
struct mm_struct * mm = vma->vm_mm;
int error = 0;
pgoff_t pgoff;
- int new_flags = vma->vm_flags & ~VM_READHINTMASK;
+ int new_flags = vma->vm_flags;
switch (behavior) {
+ case MADV_NORMAL:
+ new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
+ break;
case MADV_SEQUENTIAL:
- new_flags |= VM_SEQ_READ;
+ new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
break;
case MADV_RANDOM:
- new_flags |= VM_RAND_READ;
+ new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
break;
- default:
+ case MADV_DONTFORK:
+ new_flags |= VM_DONTFORK;
+ break;
+ case MADV_DOFORK:
+ new_flags &= ~VM_DONTFORK;
break;
}
@@ -150,6 +157,8 @@ madvise_vma(struct vm_area_struct *vma,
case MADV_NORMAL:
case MADV_SEQUENTIAL:
case MADV_RANDOM:
+ case MADV_DONTFORK:
+ case MADV_DOFORK:
error = madvise_behavior(vma, prev, start, end, behavior);
break;
Index: linux-2.6.14-dontcopy/include/linux/mm.h
===================================================================
--- linux-2.6.14-dontcopy.orig/include/linux/mm.h 2005-11-08 23:24:58.000000000 +0200
+++ linux-2.6.14-dontcopy/include/linux/mm.h 2005-11-14 16:58:51.000000000 +0200
@@ -162,6 +162,7 @@ extern unsigned int kobjsize(const void
#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */
#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
+#define VM_DONTFORK 0x02000000 /* App wants to set VM_DONTCOPY */
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
Index: linux-2.6.14-dontcopy/include/asm-x86_64/mman.h
===================================================================
--- linux-2.6.14-dontcopy.orig/include/asm-x86_64/mman.h 2005-11-08 23:19:35.000000000 +0200
+++ linux-2.6.14-dontcopy/include/asm-x86_64/mman.h 2005-11-14 16:57:29.000000000 +0200
@@ -36,6 +36,8 @@
#define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */
#define MADV_WILLNEED 0x3 /* pre-fault pages */
#define MADV_DONTNEED 0x4 /* discard these pages */
+#define MADV_DONTFORK 0x30 /* dont inherit across fork */
+#define MADV_DOFORK 0x31 /* do inherit across fork */
/* compatibility flags */
#define MAP_ANON MAP_ANONYMOUS
--
MST
-
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