Andy reported that if file page get reclaimed we loose 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 Signed-off-by: Cyrill Gorcunov Cc: Pavel Emelyanov Cc: Andrew Morton Cc: Matt Mackall Cc: Xiao Guangrong Cc: Marcelo Tosatti Cc: KOSAKI Motohiro Cc: Stephen Rothwell Cc: Peter Zijlstra Cc: "Aneesh Kumar K.V" --- arch/x86/include/asm/pgtable-2level.h | 48 +++++++++++++++++++++++++++++++++- arch/x86/include/asm/pgtable-3level.h | 3 ++ arch/x86/include/asm/pgtable.h | 15 ++++++++++ arch/x86/include/asm/pgtable_types.h | 4 ++ fs/proc/task_mmu.c | 2 + include/asm-generic/pgtable.h | 15 ++++++++++ mm/fremap.c | 11 +++++-- mm/memory.c | 11 +++++-- mm/rmap.c | 8 ++++- 9 files changed, 107 insertions(+), 10 deletions(-) Index: linux-2.6.git/arch/x86/include/asm/pgtable-2level.h =================================================================== --- linux-2.6.git.orig/arch/x86/include/asm/pgtable-2level.h +++ linux-2.6.git/arch/x86/include/asm/pgtable-2level.h @@ -55,9 +55,53 @@ static inline pmd_t native_pmdp_get_and_ #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_ << 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) Index: linux-2.6.git/arch/x86/include/asm/pgtable-3level.h =================================================================== --- linux-2.6.git.orig/arch/x86/include/asm/pgtable-3level.h +++ linux-2.6.git/arch/x86/include/asm/pgtable-3level.h @@ -179,6 +179,9 @@ static inline pmd_t native_pmdp_get_and_ /* * Bits 0, 6 and 7 are taken in the low part of the pte, * put the 32 bits of offset into the high part. + * + * For soft-dirty tracking 11 bit is taken from + * the low part of pte as well. */ #define pte_to_pgoff(pte) ((pte).pte_high) #define pgoff_to_pte(off) \ 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 @@ -329,6 +329,21 @@ static inline pte_t pte_swp_clear_soft_d 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); +} + +static inline pte_t pte_file_mksoft_dirty(pte_t pte) +{ + return pte_set_flags(pte, _PAGE_SOFT_DIRTY); +} + +static inline int pte_file_soft_dirty(pte_t pte) +{ + return pte_flags(pte) & _PAGE_SOFT_DIRTY; +} + /* * Mask out unsupported bits in a present pgprot. Non-present pgprots * can use those bits for other purposes, so leave them be. 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 @@ -61,8 +61,10 @@ * they do not conflict with each other. */ +#define _PAGE_BIT_SOFT_DIRTY _PAGE_BIT_HIDDEN + #ifdef CONFIG_MEM_SOFT_DIRTY -#define _PAGE_SOFT_DIRTY (_AT(pteval_t, 1) << _PAGE_BIT_HIDDEN) +#define _PAGE_SOFT_DIRTY (_AT(pteval_t, 1) << _PAGE_BIT_SOFT_DIRTY) #else #define _PAGE_SOFT_DIRTY (_AT(pteval_t, 0)) #endif Index: linux-2.6.git/fs/proc/task_mmu.c =================================================================== --- linux-2.6.git.orig/fs/proc/task_mmu.c +++ linux-2.6.git/fs/proc/task_mmu.c @@ -736,6 +736,8 @@ static inline void clear_soft_dirty(stru ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY); } else if (is_swap_pte(ptent)) { ptent = pte_swp_clear_soft_dirty(ptent); + } else if (pte_file(ptent)) { + ptent = pte_file_clear_soft_dirty(ptent); } set_pte_at(vma->vm_mm, addr, pte, ptent); Index: linux-2.6.git/include/asm-generic/pgtable.h =================================================================== --- linux-2.6.git.orig/include/asm-generic/pgtable.h +++ linux-2.6.git/include/asm-generic/pgtable.h @@ -432,6 +432,21 @@ static inline pte_t pte_swp_clear_soft_d { return pte; } + +static inline pte_t pte_file_clear_soft_dirty(pte_t pte) +{ + return pte; +} + +static inline pte_t pte_file_mksoft_dirty(pte_t pte) +{ + return pte; +} + +static inline int pte_file_soft_dirty(pte_t pte) +{ + return 0; +} #endif #ifndef __HAVE_PFNMAP_TRACKING Index: linux-2.6.git/mm/fremap.c =================================================================== --- linux-2.6.git.orig/mm/fremap.c +++ linux-2.6.git/mm/fremap.c @@ -57,17 +57,22 @@ static int install_file_pte(struct mm_st unsigned long addr, unsigned long pgoff, pgprot_t prot) { int err = -ENOMEM; - pte_t *pte; + pte_t *pte, ptfile; spinlock_t *ptl; pte = get_locked_pte(mm, addr, &ptl); if (!pte) goto out; - if (!pte_none(*pte)) + ptfile = pgoff_to_pte(pgoff); + + if (!pte_none(*pte)) { + if (pte_present(*pte) && pte_soft_dirty(*pte)) + pte_file_mksoft_dirty(ptfile); zap_pte(mm, vma, addr, pte); + } - set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff)); + set_pte_at(mm, addr, pte, ptfile); /* * We don't need to run update_mmu_cache() here because the "file pte" * being installed by install_file_pte() is not a real pte - it's a Index: linux-2.6.git/mm/memory.c =================================================================== --- linux-2.6.git.orig/mm/memory.c +++ linux-2.6.git/mm/memory.c @@ -1141,9 +1141,12 @@ again: continue; if (unlikely(details) && details->nonlinear_vma && linear_page_index(details->nonlinear_vma, - addr) != page->index) - set_pte_at(mm, addr, pte, - pgoff_to_pte(page->index)); + addr) != page->index) { + pte_t ptfile = pgoff_to_pte(page->index); + if (pte_soft_dirty(ptent)) + pte_file_mksoft_dirty(ptfile); + set_pte_at(mm, addr, pte, ptfile); + } if (PageAnon(page)) rss[MM_ANONPAGES]--; else { @@ -3410,6 +3413,8 @@ static int __do_fault(struct mm_struct * entry = mk_pte(page, vma->vm_page_prot); if (flags & FAULT_FLAG_WRITE) entry = maybe_mkwrite(pte_mkdirty(entry), vma); + else if (pte_file(orig_pte) && pte_file_soft_dirty(orig_pte)) + pte_mksoft_dirty(entry); if (anon) { inc_mm_counter_fast(mm, MM_ANONPAGES); page_add_new_anon_rmap(page, vma, address); Index: linux-2.6.git/mm/rmap.c =================================================================== --- linux-2.6.git.orig/mm/rmap.c +++ linux-2.6.git/mm/rmap.c @@ -1405,8 +1405,12 @@ static int try_to_unmap_cluster(unsigned pteval = ptep_clear_flush(vma, address, pte); /* If nonlinear, store the file page offset in the pte. */ - if (page->index != linear_page_index(vma, address)) - set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); + if (page->index != linear_page_index(vma, address)) { + pte_t ptfile = pgoff_to_pte(page->index); + if (pte_soft_dirty(pteval)) + pte_file_mksoft_dirty(ptfile); + set_pte_at(mm, address, pte, ptfile); + } /* Move the dirty bit to the physical page now the pte is gone. */ if (pte_dirty(pteval)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/