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Message-Id: <20110331115141.bd8f28d8.akpm@linux-foundation.org>
Date: Thu, 31 Mar 2011 11:51:41 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Namhyung Kim <namhyung@...il.com>
Cc: Paul Mundt <lethal@...ux-sh.org>,
David Howells <dhowells@...hat.com>,
Greg Ungerer <gerg@...pgear.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] nommu: sort mm->mmap list properly
On Mon, 28 Mar 2011 22:56:42 +0900
Namhyung Kim <namhyung@...il.com> wrote:
> @vma added into @mm should be sorted by start addr, end addr and VMA struct
> addr in that order because we may get identical VMAs in the @mm. However
> this was true only for the rbtree, not for the list.
>
> This patch fixes this by remembering 'rb_prev' during the tree traversal
> like find_vma_prepare() does and linking the @vma via __vma_link_list().
> After this patch, we can iterate the whole VMAs in correct order simply
> by using @mm->mmap list.
>
> Signed-off-by: Namhyung Kim <namhyung@...il.com>
> ---
> mm/nommu.c | 62 ++++++++++++++++++++++++++++++++++++++---------------------
> 1 files changed, 40 insertions(+), 22 deletions(-)
>
> diff --git a/mm/nommu.c b/mm/nommu.c
> index e7dbd3fae187..20d9c330eb0e 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -672,6 +672,30 @@ static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
> #endif
> }
>
> +/* borrowed from mm/mmap.c */
> +static inline void
> +__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
> + struct vm_area_struct *prev, struct rb_node *rb_parent)
> +{
> + struct vm_area_struct *next;
> +
> + vma->vm_prev = prev;
> + if (prev) {
> + next = prev->vm_next;
> + prev->vm_next = vma;
> + } else {
> + mm->mmap = vma;
> + if (rb_parent)
> + next = rb_entry(rb_parent,
> + struct vm_area_struct, vm_rb);
> + else
> + next = NULL;
> + }
> + vma->vm_next = next;
> + if (next)
> + next->vm_prev = vma;
> +}
Duplicating code is rather bad. And putting random vma functions into
mm/util.c is pretty ugly too, but I suppose it's less bad.
mm/internal.h | 4 ++++
mm/mmap.c | 22 ----------------------
mm/nommu.c | 24 ------------------------
mm/util.c | 24 ++++++++++++++++++++++++
4 files changed, 28 insertions(+), 46 deletions(-)
diff -puN mm/nommu.c~mm-nommu-sort-mm-mmap-list-properly-fix mm/nommu.c
--- a/mm/nommu.c~mm-nommu-sort-mm-mmap-list-properly-fix
+++ a/mm/nommu.c
@@ -672,30 +672,6 @@ static void protect_vma(struct vm_area_s
#endif
}
-/* borrowed from mm/mmap.c */
-static inline void
-__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
- struct vm_area_struct *prev, struct rb_node *rb_parent)
-{
- struct vm_area_struct *next;
-
- vma->vm_prev = prev;
- if (prev) {
- next = prev->vm_next;
- prev->vm_next = vma;
- } else {
- mm->mmap = vma;
- if (rb_parent)
- next = rb_entry(rb_parent,
- struct vm_area_struct, vm_rb);
- else
- next = NULL;
- }
- vma->vm_next = next;
- if (next)
- next->vm_prev = vma;
-}
-
/*
* add a VMA into a process's mm_struct in the appropriate place in the list
* and tree and add to the address space's page tree also if not an anonymous
diff -puN mm/util.c~mm-nommu-sort-mm-mmap-list-properly-fix mm/util.c
--- a/mm/util.c~mm-nommu-sort-mm-mmap-list-properly-fix
+++ a/mm/util.c
@@ -6,6 +6,8 @@
#include <linux/sched.h>
#include <asm/uaccess.h>
+#include "internal.h"
+
#define CREATE_TRACE_POINTS
#include <trace/events/kmem.h>
@@ -215,6 +217,28 @@ char *strndup_user(const char __user *s,
}
EXPORT_SYMBOL(strndup_user);
+void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
+ struct vm_area_struct *prev, struct rb_node *rb_parent)
+{
+ struct vm_area_struct *next;
+
+ vma->vm_prev = prev;
+ if (prev) {
+ next = prev->vm_next;
+ prev->vm_next = vma;
+ } else {
+ mm->mmap = vma;
+ if (rb_parent)
+ next = rb_entry(rb_parent,
+ struct vm_area_struct, vm_rb);
+ else
+ next = NULL;
+ }
+ vma->vm_next = next;
+ if (next)
+ next->vm_prev = vma;
+}
+
#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
void arch_pick_mmap_layout(struct mm_struct *mm)
{
diff -puN mm/internal.h~mm-nommu-sort-mm-mmap-list-properly-fix mm/internal.h
--- a/mm/internal.h~mm-nommu-sort-mm-mmap-list-properly-fix
+++ a/mm/internal.h
@@ -66,6 +66,10 @@ static inline unsigned long page_order(s
return page_private(page);
}
+/* mm/util.c */
+void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
+ struct vm_area_struct *prev, struct rb_node *rb_parent);
+
#ifdef CONFIG_MMU
extern long mlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
diff -puN mm/mmap.c~mm-nommu-sort-mm-mmap-list-properly-fix mm/mmap.c
--- a/mm/mmap.c~mm-nommu-sort-mm-mmap-list-properly-fix
+++ a/mm/mmap.c
@@ -398,28 +398,6 @@ find_vma_prepare(struct mm_struct *mm, u
return vma;
}
-void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
- struct vm_area_struct *prev, struct rb_node *rb_parent)
-{
- struct vm_area_struct *next;
-
- vma->vm_prev = prev;
- if (prev) {
- next = prev->vm_next;
- prev->vm_next = vma;
- } else {
- mm->mmap = vma;
- if (rb_parent)
- next = rb_entry(rb_parent,
- struct vm_area_struct, vm_rb);
- else
- next = NULL;
- }
- vma->vm_next = next;
- if (next)
- next->vm_prev = vma;
-}
-
void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
struct rb_node **rb_link, struct rb_node *rb_parent)
{
_
--
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