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Date: Fri, 6 May 2011 09:50:27 +0200
From: Michal Hocko <mhocko@...e.cz>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Hugh Dickins <hughd@...gle.com>, linux-mm@...ck.org,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v4] mm: make expand_downwards symmetrical to expand_upwards
Hi Andrew,
I am sorry to repost this kind of trivial cleanup for the 4th time,
but after recent discussion (https://lkml.org/lkml/2011/5/3/323)
with Hugh I think that it makes sense to keep the original
expand_{upwards,downwards} without being explicit about the stack in the
name. As Hugh pointed out, IA64 uses expand_upwards for something that
is not really a stack (it is a backing storage for registers).
The following patch reworks the original one so it is not incremental.
If you prefer incremental one I can send that one instead.
Just for record this patch obsoletes:
mm-make-expand_downwards-symmetrical-with-expand_upwards.patch
mm-make-expand_downwards-symmetrical-with-expand_upwards-v3.patch
in your current (2011-04-29-16-25) mm tree.
---
>From 1b679558f464530c59c93930b958a3436a250c25 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@...e.cz>
Date: Fri, 15 Apr 2011 14:56:26 +0200
Subject: [PATCH] mm: make expand_downwards symmetrical to expand_upwards
Currently we have expand_upwards exported while expand_downwards is
accessible only via expand_stack or expand_stack_downwards.
check_stack_guard_page is a nice example of the asymmetry. It uses
expand_stack for VM_GROWSDOWN while expand_upwards is called for
VM_GROWSUP case.
Let's clean this up by exporting both functions and make those names
consistent. Let's use expand_{upwards,downwards} because expanding
doesn't always involve stack manipulation (an example is
ia64_do_page_fault which uses expand_upwards for registers backing store
expansion).
expand_downwards has to be defined for both CONFIG_STACK_GROWS{UP,DOWN}
because get_arg_page calls the downwards version in the early process
initialization phase for growsup configuration.
CC: Hugh Dickins <hughd@...gle.com>
Signed-off-by: Michal Hocko <mhocko@...e.cz>
---
fs/exec.c | 2 +-
include/linux/mm.h | 8 +++++---
mm/memory.c | 2 +-
mm/mmap.c | 7 +------
4 files changed, 8 insertions(+), 11 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 5e62d26..c2668ff 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -194,7 +194,7 @@ struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
#ifdef CONFIG_STACK_GROWSUP
if (write) {
- ret = expand_stack_downwards(bprm->vma, pos);
+ ret = expand_downwards(bprm->vma, pos);
if (ret < 0)
return NULL;
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 692dbae..2d4f62b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1494,15 +1494,17 @@ unsigned long ra_submit(struct file_ra_state *ra,
struct address_space *mapping,
struct file *filp);
-/* Do stack extension */
+/* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
+
+/* CONFIG_STACK_GROWSUP still needs to to grow downwards at some places */
+extern int expand_downwards(struct vm_area_struct *vma,
+ unsigned long address);
#if VM_GROWSUP
extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
#else
#define expand_upwards(vma, address) do { } while (0)
#endif
-extern int expand_stack_downwards(struct vm_area_struct *vma,
- unsigned long address);
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);
diff --git a/mm/memory.c b/mm/memory.c
index ce22a25..f404fb6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2969,7 +2969,7 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo
if (prev && prev->vm_end == address)
return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
- expand_stack(vma, address - PAGE_SIZE);
+ expand_downwards(vma, address - PAGE_SIZE);
}
if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
struct vm_area_struct *next = vma->vm_next;
diff --git a/mm/mmap.c b/mm/mmap.c
index e27e0cf..4c10287 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1782,7 +1782,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
/*
* vma is the first one with address < vma->vm_start. Have to extend vma.
*/
-static int expand_downwards(struct vm_area_struct *vma,
+int expand_downwards(struct vm_area_struct *vma,
unsigned long address)
{
int error;
@@ -1829,11 +1829,6 @@ static int expand_downwards(struct vm_area_struct *vma,
return error;
}
-int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
-{
- return expand_downwards(vma, address);
-}
-
#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
--
1.7.4.4
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
--
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