Re: [PATCH] mm: Fix hiding the stack guard page in proc

[Stefan Bader <stefan.bader@canonical.com>]

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On 08/31/2010 03:33 PM, Linus Torvalds wrote:
> On Tuesday, August 31, 2010, Stefan Bader <stefan.bader@canonical.com> wrote:
>>
>> Maybe its would be worth moving the inlines to mm.h.
> 
> Yes, I think it would be a good idea to try to abstract it out a bit...
> 
>        Linus

Quick and dirty (and very untested)

Stefan

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>From 33f7a4a8d572628dd82c8953d434b2806a1c448e Mon Sep 17 00:00:00 2001
From: Stefan Bader <stefan.bader@canonical.com>
Date: Tue, 31 Aug 2010 15:52:27 +0200
Subject: [PATCH] mm: Move vma_stack_continue into mm.h

So it can be used by all that need to check for that.

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
 fs/proc/task_mmu.c |    3 +--
 include/linux/mm.h |    7 +++++++
 mm/mlock.c         |    6 ------
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2e302b4..ac0101a 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -224,8 +224,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 	/* We don't show the stack guard page in /proc/maps */
 	start = vma->vm_start;
 	if (vma->vm_flags & VM_GROWSDOWN)
-		if (!vma->vm_prev || vma->vm_prev->vm_flags != VM_GROWSDOWN ||
-		    vma->vm_start != vma->vm_prev->vm_end)
+		if(!vma_stack_continue(vma->vm_prev, vma->vm_start))
 			start += PAGE_SIZE;
 
 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e6b1210..4f4773a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -864,6 +864,13 @@ int set_page_dirty(struct page *page);
 int set_page_dirty_lock(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
 
+/* Is the vma a continuation of the stack vma above it? */
+static inline int vma_stack_continue(struct vm_area_struct *vma,
+				     unsigned long addr)
+{
+	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
+}
+
 extern unsigned long move_page_tables(struct vm_area_struct *vma,
 		unsigned long old_addr, struct vm_area_struct *new_vma,
 		unsigned long new_addr, unsigned long len);
diff --git a/mm/mlock.c b/mm/mlock.c
index cbae7c5..b70919c 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -135,12 +135,6 @@ void munlock_vma_page(struct page *page)
 	}
 }
 
-/* Is the vma a continuation of the stack vma above it? */
-static inline int vma_stack_continue(struct vm_area_struct *vma, unsigned long addr)
-{
-	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
-}
-
 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
 {
 	return (vma->vm_flags & VM_GROWSDOWN) &&
-- 
1.7.0.4