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Commit d05f3169 authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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mm: make expand_downwards() symmetrical with 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.

Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 248ac0e1

fs/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -200,7 +200,7 @@ static 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;

	}

include/linux/mm.h

+5 −3
Original line number Diff line number Diff line
@@ -1518,15 +1518,17 @@ 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);

mm/memory.c

+1 −1
Original line number Diff line number Diff line
@@ -2966,7 +2966,7 @@ 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;

mm/mmap.c

+1 −6
Original line number Diff line number Diff line
@@ -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.

 */

static int expand_downwards(struct vm_area_struct *vma,

int expand_downwards(struct vm_area_struct *vma,

				   unsigned long address)

{

	int error;
@@ -1821,11 +1821,6 @@ 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)

{