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Don't lock guardpage if the stack is growing up

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Linux kernel excludes guard page when performing mlock on a VMA with
down-growing stack. However, some architectures have up-growing stack
and locking the guard page should be excluded in this case too.

This patch fixes lvm2 on PA-RISC (and possibly other architectures with
up-growing stack). lvm2 calculates number of used pages when locking and
when unlocking and reports an internal error if the numbers mismatch.

[ Patch changed fairly extensively to also fix /proc/<pid>/maps for the
  grows-up case, and to move things around a bit to clean it all up and
  share the infrstructure with the /proc bits.

  Tested on ia64 that has both grow-up and grow-down segments  - Linus ]

Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Tested-by: Tony Luck <tony.luck@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mikulas Patocka 2011-05-09 13:01:09 +02:00 • committed by Linus Torvalds
parent 26822eebb2
commit a09a79f668
3 changed files with 37 additions and 15 deletions
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24
include/linux/mm.h
View file

@ -1011,11 +1011,33 @@ 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)
static inline int vma_growsdown(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_start(struct vm_area_struct *vma,
unsigned long addr)
{
return (vma->vm_flags & VM_GROWSDOWN) &&
(vma->vm_start == addr) &&
!vma_growsdown(vma->vm_prev, addr);
}
/* Is the vma a continuation of the stack vma below it? */
static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
{
return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
}
static inline int stack_guard_page_end(struct vm_area_struct *vma,
unsigned long addr)
{
return (vma->vm_flags & VM_GROWSUP) &&
(vma->vm_end == addr) &&
!vma_growsup(vma->vm_next, addr);
}
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);