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Commit cea10a19 authored by Michel Lespinasse's avatar Michel Lespinasse Committed by Linus Torvalds
Browse files

mm: directly use __mlock_vma_pages_range() in find_extend_vma() 



In find_extend_vma(), we don't need mlock_vma_pages_range() to verify
the vma type - we know we're working with a stack.  So, we can call
directly into __mlock_vma_pages_range(), and remove the last
make_pages_present() call site.

Note that we don't use mm_populate() here, so we can't release the
mmap_sem while allocating new stack pages.  This is deemed acceptable,
because the stack vmas grow by a bounded number of pages at a time, and
these are anon pages so we don't have to read from disk to populate
them.

Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Tested-by: default avatarAndy Lutomirski <luto@amacapital.net>
Cc: Greg Ungerer <gregungerer@westnet.com.au>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c22c0d63

include/linux/mm.h

+0 −1
Original line number Diff line number Diff line
@@ -1035,7 +1035,6 @@ static inline int fixup_user_fault(struct task_struct *tsk, 
}

#endif



extern int make_pages_present(unsigned long addr, unsigned long end);

extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);

extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,

		void *buf, int len, int write);

mm/internal.h

+2 −2
Original line number Diff line number Diff line
@@ -162,8 +162,8 @@ void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 
		struct vm_area_struct *prev, struct rb_node *rb_parent);



#ifdef CONFIG_MMU

extern long mlock_vma_pages_range(struct vm_area_struct *vma,

			unsigned long start, unsigned long end);

extern long __mlock_vma_pages_range(struct vm_area_struct *vma,

		unsigned long start, unsigned long end, int *nonblocking);

extern void munlock_vma_pages_range(struct vm_area_struct *vma,

			unsigned long start, unsigned long end);

static inline void munlock_vma_pages_all(struct vm_area_struct *vma)

mm/memory.c

+0 −24
Original line number Diff line number Diff line
@@ -3824,30 +3824,6 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 
}

#endif /* __PAGETABLE_PMD_FOLDED */



int make_pages_present(unsigned long addr, unsigned long end)

{

	int ret, len, write;

	struct vm_area_struct * vma;



	vma = find_vma(current->mm, addr);

	if (!vma)

		return -ENOMEM;

	/*

	 * We want to touch writable mappings with a write fault in order

	 * to break COW, except for shared mappings because these don't COW

	 * and we would not want to dirty them for nothing.

	 */

	write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;

	BUG_ON(addr >= end);

	BUG_ON(end > vma->vm_end);

	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;

	ret = get_user_pages(current, current->mm, addr,

			len, write, 0, NULL, NULL);

	if (ret < 0)

		return ret;

	return ret == len ? 0 : -EFAULT;

}



#if !defined(__HAVE_ARCH_GATE_AREA)



#if defined(AT_SYSINFO_EHDR)

mm/mlock.c

+3 −54
Original line number Diff line number Diff line
@@ -155,9 +155,8 @@ void munlock_vma_page(struct page *page) 
 *

 * vma->vm_mm->mmap_sem must be held for at least read.

 */

static long __mlock_vma_pages_range(struct vm_area_struct *vma,

				    unsigned long start, unsigned long end,

				    int *nonblocking)

long __mlock_vma_pages_range(struct vm_area_struct *vma,

		unsigned long start, unsigned long end, int *nonblocking)

{

	struct mm_struct *mm = vma->vm_mm;

	unsigned long addr = start;
@@ -202,56 +201,6 @@ static int __mlock_posix_error_return(long retval) 
	return retval;

}



/**

 * mlock_vma_pages_range() - mlock pages in specified vma range.

 * @vma - the vma containing the specfied address range

 * @start - starting address in @vma to mlock

 * @end   - end address [+1] in @vma to mlock

 *

 * For mmap()/mremap()/expansion of mlocked vma.

 *

 * return 0 on success for "normal" vmas.

 *

 * return number of pages [> 0] to be removed from locked_vm on success

 * of "special" vmas.

 */

long mlock_vma_pages_range(struct vm_area_struct *vma,

			unsigned long start, unsigned long end)

{

	int nr_pages = (end - start) / PAGE_SIZE;

	BUG_ON(!(vma->vm_flags & VM_LOCKED));



	/*

	 * filter unlockable vmas

	 */

	if (vma->vm_flags & (VM_IO | VM_PFNMAP))

		goto no_mlock;



	if (!((vma->vm_flags & VM_DONTEXPAND) ||

			is_vm_hugetlb_page(vma) ||

			vma == get_gate_vma(current->mm))) {



		__mlock_vma_pages_range(vma, start, end, NULL);



		/* Hide errors from mmap() and other callers */

		return 0;

	}



	/*

	 * User mapped kernel pages or huge pages:

	 * make these pages present to populate the ptes, but

	 * fall thru' to reset VM_LOCKED--no need to unlock, and

	 * return nr_pages so these don't get counted against task's

	 * locked limit.  huge pages are already counted against

	 * locked vm limit.

	 */

	make_pages_present(start, end);



no_mlock:

	vma->vm_flags &= ~VM_LOCKED;	/* and don't come back! */

	return nr_pages;		/* error or pages NOT mlocked */

}



/*

 * munlock_vma_pages_range() - munlock all pages in the vma range.'

 * @vma - vma containing range to be munlock()ed.
@@ -303,7 +252,7 @@ void munlock_vma_pages_range(struct vm_area_struct *vma, 
 *

 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and

 * munlock is a no-op.  However, for some special vmas, we go ahead and

 * populate the ptes via make_pages_present().

 * populate the ptes.

 *

 * For vmas that pass the filters, merge/split as appropriate.

 */

mm/mmap.c

+4 −6
Original line number Diff line number Diff line
@@ -2204,9 +2204,8 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr) 
		return vma;

	if (!prev || expand_stack(prev, addr))

		return NULL;

	if (prev->vm_flags & VM_LOCKED) {

		mlock_vma_pages_range(prev, addr, prev->vm_end);

	}

	if (prev->vm_flags & VM_LOCKED)

		__mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);

	return prev;

}

#else
@@ -2232,9 +2231,8 @@ find_extend_vma(struct mm_struct * mm, unsigned long addr) 
	start = vma->vm_start;

	if (expand_stack(vma, addr))

		return NULL;

	if (vma->vm_flags & VM_LOCKED) {

		mlock_vma_pages_range(vma, addr, start);

	}

	if (vma->vm_flags & VM_LOCKED)

		__mlock_vma_pages_range(vma, addr, start, NULL);

	return vma;

}

#endif