path: root/mm/mremap.c
diff options
authorCyrill Gorcunov <gorcunov@gmail.com>2013-08-27 12:37:18 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-08-27 09:36:17 -0700
commit6dec97dc92946eb479e6ebb54a61f8226cceefec (patch)
tree7065d6d5f27b19ce4773460d50c1502610848f64 /mm/mremap.c
parent9b506833210fdaea2cd00e39368805e28f49492d (diff)
mm: move_ptes -- Set soft dirty bit depending on pte type
Dave reported corrupted swap entries | [ 4588.541886] swap_free: Unused swap offset entry 00002d15 | [ 4588.541952] BUG: Bad page map in process trinity-kid12 pte:005a2a80 pmd:22c01f067 and Hugh pointed that in move_ptes _PAGE_SOFT_DIRTY bit set regardless the type of entry pte consists of. The trick here is that when we carry soft dirty status in swap entries we are to use _PAGE_SWP_SOFT_DIRTY instead, because this is the only place in pte which can be used for own needs without intersecting with bits owned by swap entry type/offset. Reported-and-tested-by: Dave Jones <davej@redhat.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@parallels.com> Analyzed-by: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mremap.c')
1 files changed, 20 insertions, 1 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index 457d34ef3bf..0843feb66f3 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -15,6 +15,7 @@
#include <linux/swap.h>
#include <linux/capability.h>
#include <linux/fs.h>
+#include <linux/swapops.h>
#include <linux/highmem.h>
#include <linux/security.h>
#include <linux/syscalls.h>
@@ -69,6 +70,23 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
return pmd;
+static pte_t move_soft_dirty_pte(pte_t pte)
+ /*
+ * Set soft dirty bit so we can notice
+ * in userspace the ptes were moved.
+ */
+ if (pte_present(pte))
+ pte = pte_mksoft_dirty(pte);
+ else if (is_swap_pte(pte))
+ pte = pte_swp_mksoft_dirty(pte);
+ else if (pte_file(pte))
+ pte = pte_file_mksoft_dirty(pte);
+ return pte;
static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
unsigned long old_addr, unsigned long old_end,
struct vm_area_struct *new_vma, pmd_t *new_pmd,
@@ -126,7 +144,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
pte = ptep_get_and_clear(mm, old_addr, old_pte);
pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
- set_pte_at(mm, new_addr, new_pte, pte_mksoft_dirty(pte));
+ pte = move_soft_dirty_pte(pte);
+ set_pte_at(mm, new_addr, new_pte, pte);