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mm: make expand_downwards() symmetrical with expand_upwards()

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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.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2011-05-24 17:11:44 -07:00 • committed by Linus Torvalds
commit d05f3169c0
4 changed files with 8 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

2
fs/exec.c
View file

@ -200,7 +200,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
#ifdef CONFIG_STACK_GROWSUP #ifdef CONFIG_STACK_GROWSUP
if (write) { if (write) {
ret = expand_stack_downwards(bprm->vma, pos); ret = expand_downwards(bprm->vma, pos);
if (ret < 0) if (ret < 0)
return NULL; return NULL;
} }

8
include/linux/mm.h
View file

@ -1518,15 +1518,17 @@ unsigned long ra_submit(struct file_ra_state *ra,
struct address_space *mapping, struct address_space *mapping,
struct file *filp); 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); 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 #if VM_GROWSUP
extern int expand_upwards(struct vm_area_struct *vma, unsigned long address); extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
#else #else
#define expand_upwards(vma, address) do { } while (0) #define expand_upwards(vma, address) do { } while (0)
#endif #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. */ /* 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); extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);

2
mm/memory.c
View file

@ -2966,7 +2966,7 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo
if (prev && prev->vm_end == address) if (prev && prev->vm_end == address)
return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; 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) { if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
struct vm_area_struct *next = vma->vm_next; struct vm_area_struct *next = vma->vm_next;

7
mm/mmap.c
View file

@ -1774,7 +1774,7 @@ 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. * 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) unsigned long address)
{ {
int error; int error;
@ -1821,11 +1821,6 @@ static int expand_downwards(struct vm_area_struct *vma,
return error; return error;
} }
int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
{
return expand_downwards(vma, address);
}
#ifdef CONFIG_STACK_GROWSUP #ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address) int expand_stack(struct vm_area_struct *vma, unsigned long address)
{ {