Commit 6dec97dc authored by Cyrill Gorcunov's avatar Cyrill Gorcunov Committed by Linus Torvalds

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: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Analyzed-by: default avatarHugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9b506833
...@@ -15,6 +15,7 @@ ...@@ -15,6 +15,7 @@
#include <linux/swap.h> #include <linux/swap.h>
#include <linux/capability.h> #include <linux/capability.h>
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/swapops.h>
#include <linux/highmem.h> #include <linux/highmem.h>
#include <linux/security.h> #include <linux/security.h>
#include <linux/syscalls.h> #include <linux/syscalls.h>
...@@ -69,6 +70,23 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma, ...@@ -69,6 +70,23 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
return pmd; 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.
*/
#ifdef CONFIG_MEM_SOFT_DIRTY
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);
#endif
return pte;
}
static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
unsigned long old_addr, unsigned long old_end, unsigned long old_addr, unsigned long old_end,
struct vm_area_struct *new_vma, pmd_t *new_pmd, 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, ...@@ -126,7 +144,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
continue; continue;
pte = ptep_get_and_clear(mm, old_addr, old_pte); pte = ptep_get_and_clear(mm, old_addr, old_pte);
pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); 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);
} }
arch_leave_lazy_mmu_mode(); arch_leave_lazy_mmu_mode();
......
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