Commit 941150a3 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

[PATCH] mbind: fix verify_pages pte_page 



Strict mbind's check that pages already mapped are on right node has been
using pte_page without checking if pfn_valid, and without page_table_lock
to prevent spurious failures when try_to_unmap_one intervenes between the
pte_present and the pte_page.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 400e6514

mm/mempolicy.c

+14 −5
Original line number Diff line number Diff line
@@ -242,6 +242,9 @@ static int 
verify_pages(struct mm_struct *mm,

	     unsigned long addr, unsigned long end, unsigned long *nodes)

{

	int err = 0;



	spin_lock(&mm->page_table_lock);

	while (addr < end) {

		struct page *p;

		pte_t *pte;
@@ -268,17 +271,23 @@ verify_pages(struct mm_struct *mm, 
		}

		p = NULL;

		pte = pte_offset_map(pmd, addr);

		if (pte_present(*pte))

			p = pte_page(*pte);

		if (pte_present(*pte)) {

			unsigned long pfn = pte_pfn(*pte);

			if (pfn_valid(pfn))

				p = pfn_to_page(pfn);

		}

		pte_unmap(pte);

		if (p) {

			unsigned nid = page_to_nid(p);

			if (!test_bit(nid, nodes))

				return -EIO;

			if (!test_bit(nid, nodes)) {

				err = -EIO;

				break;

			}

		}

		addr += PAGE_SIZE;

	}

	return 0;

	spin_unlock(&mm->page_table_lock);

	return err;

}



/* Step 1: check the range */