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Date: Fri, 01 Apr 2011 10:10:52 +0900
From: Namhyung Kim <namhyung@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
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
2011-03-31 (목), 11:51 -0700, Andrew Morton:
> 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.
>
Agreed. Thanks for doing this.
> 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)
> {
> _
>
>
--
Regards,
Namhyung Kim
--
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