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mm: save soft-dirty bits on file pages

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Andy reported that if file page get reclaimed we lose the soft-dirty bit
if it was there, so save _PAGE_BIT_SOFT_DIRTY bit when page address get
encoded into pte entry.  Thus when #pf happens on such non-present pte
we can restore it back.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Cyrill Gorcunov
2013-08-13 16:00:51 -07:00
committed by Linus Torvalds
parent 179ef71cbc
commit 41bb3476b3
9 changed files with 108 additions and 11 deletions
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48
arch/x86/include/asm/pgtable-2level.h
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@@ -55,9 +55,53 @@ static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
#define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
#endif
#ifdef CONFIG_MEM_SOFT_DIRTY
/*
* Bits _PAGE_BIT_PRESENT, _PAGE_BIT_FILE, _PAGE_BIT_SOFT_DIRTY and
* _PAGE_BIT_PROTNONE are taken, split up the 28 bits of offset
* into this range.
*/
#define PTE_FILE_MAX_BITS 28
#define PTE_FILE_SHIFT1 (_PAGE_BIT_PRESENT + 1)
#define PTE_FILE_SHIFT2 (_PAGE_BIT_FILE + 1)
#define PTE_FILE_SHIFT3 (_PAGE_BIT_PROTNONE + 1)
#define PTE_FILE_SHIFT4 (_PAGE_BIT_SOFT_DIRTY + 1)
#define PTE_FILE_BITS1 (PTE_FILE_SHIFT2 - PTE_FILE_SHIFT1 - 1)
#define PTE_FILE_BITS2 (PTE_FILE_SHIFT3 - PTE_FILE_SHIFT2 - 1)
#define PTE_FILE_BITS3 (PTE_FILE_SHIFT4 - PTE_FILE_SHIFT3 - 1)
#define pte_to_pgoff(pte) \
((((pte).pte_low >> (PTE_FILE_SHIFT1)) \
& ((1U << PTE_FILE_BITS1) - 1))) \
+ ((((pte).pte_low >> (PTE_FILE_SHIFT2)) \
& ((1U << PTE_FILE_BITS2) - 1)) \
<< (PTE_FILE_BITS1)) \
+ ((((pte).pte_low >> (PTE_FILE_SHIFT3)) \
& ((1U << PTE_FILE_BITS3) - 1)) \
<< (PTE_FILE_BITS1 + PTE_FILE_BITS2)) \
+ ((((pte).pte_low >> (PTE_FILE_SHIFT4))) \
<< (PTE_FILE_BITS1 + PTE_FILE_BITS2 + PTE_FILE_BITS3))
#define pgoff_to_pte(off) \
((pte_t) { .pte_low = \
((((off)) & ((1U << PTE_FILE_BITS1) - 1)) << PTE_FILE_SHIFT1) \
+ ((((off) >> PTE_FILE_BITS1) \
& ((1U << PTE_FILE_BITS2) - 1)) \
<< PTE_FILE_SHIFT2) \
+ ((((off) >> (PTE_FILE_BITS1 + PTE_FILE_BITS2)) \
& ((1U << PTE_FILE_BITS3) - 1)) \
<< PTE_FILE_SHIFT3) \
+ ((((off) >> \
(PTE_FILE_BITS1 + PTE_FILE_BITS2 + PTE_FILE_BITS3))) \
<< PTE_FILE_SHIFT4) \
+ _PAGE_FILE })
#else /* CONFIG_MEM_SOFT_DIRTY */
/*
* Bits _PAGE_BIT_PRESENT, _PAGE_BIT_FILE and _PAGE_BIT_PROTNONE are taken,
* split up the 29 bits of offset into this range:
* split up the 29 bits of offset into this range.
*/
#define PTE_FILE_MAX_BITS 29
#define PTE_FILE_SHIFT1 (_PAGE_BIT_PRESENT + 1)
@@ -88,6 +132,8 @@ static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
<< PTE_FILE_SHIFT3) \
+ _PAGE_FILE })
#endif /* CONFIG_MEM_SOFT_DIRTY */
/* Encode and de-code a swap entry */
#if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE
#define SWP_TYPE_BITS (_PAGE_BIT_FILE - _PAGE_BIT_PRESENT - 1)