diff mbox series

[v5,2/8] mm: pagewalk: Take the pagetable lock in walk_pte_range()

Message ID 20191010124314.40067-3-thomas_os@shipmail.org (mailing list archive)
State New, archived
Headers show
Series Emulated coherent graphics memory take 2 | expand

Commit Message

Thomas Hellström (Intel) Oct. 10, 2019, 12:43 p.m. UTC 
From: Thomas Hellstrom <thellstrom@vmware.com>

Without the lock, anybody modifying a pte from within this function might
have it concurrently modified by someone else.

Cc: Matthew Wilcox <willy@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 mm/pagewalk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Kirill A . Shutemov Oct. 11, 2019, 12:56 p.m. UTC | #1 
On Thu, Oct 10, 2019 at 02:43:08PM +0200, Thomas Hellström (VMware) wrote:
> From: Thomas Hellstrom <thellstrom@vmware.com>
> 
> Without the lock, anybody modifying a pte from within this function might
> have it concurrently modified by someone else.
> 
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Rik van Riel <riel@surriel.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Cc: Jérôme Glisse <jglisse@redhat.com>
> Cc: Kirill A. Shutemov <kirill@shutemov.name>
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
diff mbox series

Patch

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index d48c2a986ea3..c5fa42cab14f 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -10,8 +10,9 @@  static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 	pte_t *pte;
 	int err = 0;
 	const struct mm_walk_ops *ops = walk->ops;
+	spinlock_t *ptl;
 
-	pte = pte_offset_map(pmd, addr);
+	pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
 	for (;;) {
 		err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
 		if (err)
@@ -22,7 +23,7 @@  static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		pte++;
 	}
 
-	pte_unmap(pte);
+	pte_unmap_unlock(pte, ptl);
 	return err;
 }