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author | Cyrill Gorcunov <gorcunov@gmail.com> | 2013-08-13 16:00:49 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-08-13 17:57:47 -0700 |
commit | 179ef71cbc085252e3fe6b8159263a7ed1d88ea4 (patch) | |
tree | 423b58912b0bf0dc9697fff3d2205b8ca653968e /include/asm-generic/pgtable.h | |
parent | 3e6b11df245180949938734bc192eaf32f3a06b3 (diff) | |
download | linux-179ef71cbc085252e3fe6b8159263a7ed1d88ea4.tar.gz linux-179ef71cbc085252e3fe6b8159263a7ed1d88ea4.tar.xz |
mm: save soft-dirty bits on swapped pages
Andy Lutomirski reported that if a page with _PAGE_SOFT_DIRTY bit set
get swapped out, the bit is getting lost and no longer available when
pte read back.
To resolve this we introduce _PTE_SWP_SOFT_DIRTY bit which is saved in
pte entry for the page being swapped out. When such page is to be read
back from a swap cache we check for bit presence and if it's there we
clear it and restore the former _PAGE_SOFT_DIRTY bit back.
One of the problem was to find a place in pte entry where we can save
the _PTE_SWP_SOFT_DIRTY bit while page is in swap. The _PAGE_PSE was
chosen for that, it doesn't intersect with swap entry format stored in
pte.
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>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: 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>
Diffstat (limited to 'include/asm-generic/pgtable.h')
-rw-r--r-- | include/asm-generic/pgtable.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 2f47ade1b567..2a7e0d10ad9a 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -417,6 +417,21 @@ static inline pmd_t pmd_mksoft_dirty(pmd_t pmd) { return pmd; } + +static inline pte_t pte_swp_mksoft_dirty(pte_t pte) +{ + return pte; +} + +static inline int pte_swp_soft_dirty(pte_t pte) +{ + return 0; +} + +static inline pte_t pte_swp_clear_soft_dirty(pte_t pte) +{ + return pte; +} #endif #ifndef __HAVE_PFNMAP_TRACKING |