On Thu, Aug 22, 2013 at 08:27:45AM +0100, Jan Beulich wrote: > >>> On 22.08.13 at 09:03, Cyrill Gorcunov <[email protected]> wrote: > > Ok, how about this? > > > > static inline pte_t pte_swp_mksoft_dirty(pte_t pte) > > { > > BUG_ON(pte_present(pte)); > > return pte_set_flags(pte, _PAGE_SWP_SOFT_DIRTY); > > } > > Sure, fine with me. Perhaps VM_BUG_ON() or some other similar > construct limiting the scope when any extra code gets generated > would do too.
Sorry for delay, the patch is below. > > But as said, even better would perhaps be to have it act on a > swp_entry_t. swp_entry_t is too small already to keep additional status bit, unfortunately. --- From: Cyrill Gorcunov <[email protected]> Subject: [PATCH] mm: Make sure _PAGE_SWP_SOFT_DIRTY bit is not set on present pte _PAGE_SOFT_DIRTY bit should never be set on present pte so add VM_BUG_ON to catch any potential future abuse. Also add a comment on _PAGE_SWP_SOFT_DIRTY definition explaining scope of its usage. Signed-off-by: Cyrill Gorcunov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Pavel Emelyanov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Matt Mackall <[email protected]> Cc: Xiao Guangrong <[email protected]> Cc: Marcelo Tosatti <[email protected]> Cc: KOSAKI Motohiro <[email protected]> Cc: Stephen Rothwell <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: "Aneesh Kumar K.V" <[email protected]> Cc: David Vrabel <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Cc: Boris Ostrovsky <[email protected]> Cc: Jan Beulich <[email protected]> --- arch/x86/include/asm/pgtable.h | 34 +++++++++++++++++++--------------- arch/x86/include/asm/pgtable_types.h | 3 +++ 2 files changed, 22 insertions(+), 15 deletions(-) Index: linux-2.6.git/arch/x86/include/asm/pgtable.h =================================================================== --- linux-2.6.git.orig/arch/x86/include/asm/pgtable.h +++ linux-2.6.git/arch/x86/include/asm/pgtable.h @@ -314,21 +314,6 @@ static inline pmd_t pmd_mksoft_dirty(pmd return pmd_set_flags(pmd, _PAGE_SOFT_DIRTY); } -static inline pte_t pte_swp_mksoft_dirty(pte_t pte) -{ - return pte_set_flags(pte, _PAGE_SWP_SOFT_DIRTY); -} - -static inline int pte_swp_soft_dirty(pte_t pte) -{ - return pte_flags(pte) & _PAGE_SWP_SOFT_DIRTY; -} - -static inline pte_t pte_swp_clear_soft_dirty(pte_t pte) -{ - return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY); -} - static inline pte_t pte_file_clear_soft_dirty(pte_t pte) { return pte_clear_flags(pte, _PAGE_SOFT_DIRTY); @@ -445,6 +430,7 @@ pte_t *populate_extra_pte(unsigned long #ifndef __ASSEMBLY__ #include <linux/mm_types.h> +#include <linux/mmdebug.h> #include <linux/log2.h> static inline int pte_none(pte_t pte) @@ -863,6 +849,24 @@ static inline void update_mmu_cache_pmd( { } +static inline pte_t pte_swp_mksoft_dirty(pte_t pte) +{ + VM_BUG_ON(pte_present(pte)); + return pte_set_flags(pte, _PAGE_SWP_SOFT_DIRTY); +} + +static inline int pte_swp_soft_dirty(pte_t pte) +{ + VM_BUG_ON(pte_present(pte)); + return pte_flags(pte) & _PAGE_SWP_SOFT_DIRTY; +} + +static inline pte_t pte_swp_clear_soft_dirty(pte_t pte) +{ + VM_BUG_ON(pte_present(pte)); + return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY); +} + #include <asm-generic/pgtable.h> #endif /* __ASSEMBLY__ */ Index: linux-2.6.git/arch/x86/include/asm/pgtable_types.h =================================================================== --- linux-2.6.git.orig/arch/x86/include/asm/pgtable_types.h +++ linux-2.6.git/arch/x86/include/asm/pgtable_types.h @@ -75,6 +75,9 @@ * with swap entry format. On x86 bits 6 and 7 are *not* involved * into swap entry computation, but bit 6 is used for nonlinear * file mapping, so we borrow bit 7 for soft dirty tracking. + * + * Please note that this bit must be treated as swap dirty page + * mark if and only if the PTE has present bit clear! */ #ifdef CONFIG_MEM_SOFT_DIRTY #define _PAGE_SWP_SOFT_DIRTY _PAGE_PSE -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
