diff options
| -rw-r--r-- | Documentation/filesystems/proc.txt | 7 | ||||
| -rw-r--r-- | Documentation/vm/soft-dirty.txt | 36 | ||||
| -rw-r--r-- | arch/Kconfig | 3 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 1 | ||||
| -rw-r--r-- | arch/x86/include/asm/pgtable.h | 24 | ||||
| -rw-r--r-- | arch/x86/include/asm/pgtable_types.h | 12 | ||||
| -rw-r--r-- | fs/proc/task_mmu.c | 47 | ||||
| -rw-r--r-- | include/asm-generic/pgtable.h | 22 | ||||
| -rw-r--r-- | mm/Kconfig | 12 | ||||
| -rw-r--r-- | mm/huge_memory.c | 2 | ||||
| -rw-r--r-- | mm/mremap.c | 2 |
11 files changed, 158 insertions, 10 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index fd8d0d5..fcc22c9 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -473,7 +473,8 @@ This file is only present if the CONFIG_MMU kernel configuration option is enabled. The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG -bits on both physical and virtual pages associated with a process. +bits on both physical and virtual pages associated with a process, and the +soft-dirty bit on pte (see Documentation/vm/soft-dirty.txt for details). To clear the bits for all the pages associated with the process > echo 1 > /proc/PID/clear_refs @@ -482,6 +483,10 @@ To clear the bits for the anonymous pages associated with the process To clear the bits for the file mapped pages associated with the process > echo 3 > /proc/PID/clear_refs + +To clear the soft-dirty bit + > echo 4 > /proc/PID/clear_refs + Any other value written to /proc/PID/clear_refs will have no effect. The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags diff --git a/Documentation/vm/soft-dirty.txt b/Documentation/vm/soft-dirty.txt new file mode 100644 index 0000000..9a12a59 --- /dev/null +++ b/Documentation/vm/soft-dirty.txt @@ -0,0 +1,36 @@ + SOFT-DIRTY PTEs + + The soft-dirty is a bit on a PTE which helps to track which pages a task +writes to. In order to do this tracking one should + + 1. Clear soft-dirty bits from the task's PTEs. + + This is done by writing "4" into the /proc/PID/clear_refs file of the + task in question. + + 2. Wait some time. + + 3. Read soft-dirty bits from the PTEs. + + This is done by reading from the /proc/PID/pagemap. The bit 55 of the + 64-bit qword is the soft-dirty one. If set, the respective PTE was + written to since step 1. + + + Internally, to do this tracking, the writable bit is cleared from PTEs +when the soft-dirty bit is cleared. So, after this, when the task tries to +modify a page at some virtual address the #PF occurs and the kernel sets +the soft-dirty bit on the respective PTE. + + Note, that although all the task's address space is marked as r/o after the +soft-dirty bits clear, the #PF-s that occur after that are processed fast. +This is so, since the pages are still mapped to physical memory, and thus all +the kernel does is finds this fact out and puts both writable and soft-dirty +bits on the PTE. + + + This feature is actively used by the checkpoint-restore project. You +can find more details about it on http://criu.org + + +-- Pavel Emelyanov, Apr 9, 2013 diff --git a/arch/Kconfig b/arch/Kconfig index a4429bc..8d2ae24 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -365,6 +365,9 @@ config HAVE_IRQ_TIME_ACCOUNTING config HAVE_ARCH_TRANSPARENT_HUGEPAGE bool +config HAVE_ARCH_SOFT_DIRTY + bool + config HAVE_MOD_ARCH_SPECIFIC bool help diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b094816..10764a3 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -102,6 +102,7 @@ config X86 select HAVE_ARCH_SECCOMP_FILTER select BUILDTIME_EXTABLE_SORT select GENERIC_CMOS_UPDATE + select HAVE_ARCH_SOFT_DIRTY select CLOCKSOURCE_WATCHDOG select GENERIC_CLOCKEVENTS select ARCH_CLOCKSOURCE_DATA if X86_64 diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 5b0818b..7dc305a 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -207,7 +207,7 @@ static inline pte_t pte_mkexec(pte_t pte) static inline pte_t pte_mkdirty(pte_t pte) { - return pte_set_flags(pte, _PAGE_DIRTY); + return pte_set_flags(pte, _PAGE_DIRTY | _PAGE_SOFT_DIRTY); } static inline pte_t pte_mkyoung(pte_t pte) @@ -271,7 +271,7 @@ static inline pmd_t pmd_wrprotect(pmd_t pmd) static inline pmd_t pmd_mkdirty(pmd_t pmd) { - return pmd_set_flags(pmd, _PAGE_DIRTY); + return pmd_set_flags(pmd, _PAGE_DIRTY | _PAGE_SOFT_DIRTY); } static inline pmd_t pmd_mkhuge(pmd_t pmd) @@ -294,6 +294,26 @@ static inline pmd_t pmd_mknotpresent(pmd_t pmd) return pmd_clear_flags(pmd, _PAGE_PRESENT); } +static inline int pte_soft_dirty(pte_t pte) +{ + return pte_flags(pte) & _PAGE_SOFT_DIRTY; +} + +static inline int pmd_soft_dirty(pmd_t pmd) +{ + return pmd_flags(pmd) & _PAGE_SOFT_DIRTY; +} + +static inline pte_t pte_mksoft_dirty(pte_t pte) +{ + return pte_set_flags(pte, _PAGE_SOFT_DIRTY); +} + +static inline pmd_t pmd_mksoft_dirty(pmd_t pmd) +{ + return pmd_set_flags(pmd, _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. diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index e642300..c98ac63 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -55,6 +55,18 @@ #define _PAGE_HIDDEN (_AT(pteval_t, 0)) #endif +/* + * The same hidden bit is used by kmemcheck, but since kmemcheck + * works on kernel pages while soft-dirty engine on user space, + * they do not conflict with each other. + */ + +#ifdef CONFIG_MEM_SOFT_DIRTY +#define _PAGE_SOFT_DIRTY (_AT(pteval_t, 1) << _PAGE_BIT_HIDDEN) +#else +#define _PAGE_SOFT_DIRTY (_AT(pteval_t, 0)) +#endif + #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) #define _PAGE_NX (_AT(pteval_t, 1) << _PAGE_BIT_NX) #else diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 39d6412..a18e065 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -11,6 +11,7 @@ #include <linux/rmap.h> #include <linux/swap.h> #include <linux/swapops.h> +#include <linux/mmu_notifier.h> #include <asm/elf.h> #include <asm/uaccess.h> @@ -692,13 +693,32 @@ enum clear_refs_types { CLEAR_REFS_ALL = 1, CLEAR_REFS_ANON, CLEAR_REFS_MAPPED, + CLEAR_REFS_SOFT_DIRTY, CLEAR_REFS_LAST, }; struct clear_refs_private { struct vm_area_struct *vma; + enum clear_refs_types type; }; +static inline void clear_soft_dirty(struct vm_area_struct *vma, + unsigned long addr, pte_t *pte) +{ +#ifdef CONFIG_MEM_SOFT_DIRTY + /* + * The soft-dirty tracker uses #PF-s to catch writes + * to pages, so write-protect the pte as well. See the + * Documentation/vm/soft-dirty.txt for full description + * of how soft-dirty works. + */ + pte_t ptent = *pte; + ptent = pte_wrprotect(ptent); + ptent = pte_clear_flags(ptent, _PAGE_SOFT_DIRTY); + set_pte_at(vma->vm_mm, addr, pte, ptent); +#endif +} + static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { @@ -718,6 +738,11 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr, if (!pte_present(ptent)) continue; + if (cp->type == CLEAR_REFS_SOFT_DIRTY) { + clear_soft_dirty(vma, addr, pte); + continue; + } + page = vm_normal_page(vma, addr, ptent); if (!page) continue; @@ -759,6 +784,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, mm = get_task_mm(task); if (mm) { struct clear_refs_private cp = { + .type = type, }; struct mm_walk clear_refs_walk = { .pmd_entry = clear_refs_pte_range, @@ -766,6 +792,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, .private = &cp, }; down_read(&mm->mmap_sem); + if (type == CLEAR_REFS_SOFT_DIRTY) + mmu_notifier_invalidate_range_start(mm, 0, -1); for (vma = mm->mmap; vma; vma = vma->vm_next) { cp.vma = vma; if (is_vm_hugetlb_page(vma)) @@ -786,6 +814,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, walk_page_range(vma->vm_start, vma->vm_end, &clear_refs_walk); } + if (type == CLEAR_REFS_SOFT_DIRTY) + mmu_notifier_invalidate_range_end(mm, 0, -1); flush_tlb_mm(mm); up_read(&mm->mmap_sem); mmput(mm); @@ -827,6 +857,7 @@ struct pagemapread { /* in "new" pagemap pshift bits are occupied with more status bits */ #define PM_STATUS2(v2, x) (__PM_PSHIFT(v2 ? x : PAGE_SHIFT)) +#define __PM_SOFT_DIRTY (1LL) #define PM_PRESENT PM_STATUS(4LL) #define PM_SWAP PM_STATUS(2LL) #define PM_FILE PM_STATUS(1LL) @@ -868,6 +899,7 @@ static void pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, { u64 frame, flags; struct page *page = NULL; + int flags2 = 0; if (pte_present(pte)) { frame = pte_pfn(pte); @@ -888,13 +920,15 @@ static void pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, if (page && !PageAnon(page)) flags |= PM_FILE; + if (pte_soft_dirty(pte)) + flags2 |= __PM_SOFT_DIRTY; - *pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, 0) | flags); + *pme = make_pme(PM_PFRAME(frame) | PM_STATUS2(pm->v2, flags2) | flags); } #ifdef CONFIG_TRANSPARENT_HUGEPAGE static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, - pmd_t pmd, int offset) + pmd_t pmd, int offset, int pmd_flags2) { /* * Currently pmd for thp is always present because thp can not be @@ -903,13 +937,13 @@ static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *p */ if (pmd_present(pmd)) *pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset) - | PM_STATUS2(pm->v2, 0) | PM_PRESENT); + | PM_STATUS2(pm->v2, pmd_flags2) | PM_PRESENT); else *pme = make_pme(PM_NOT_PRESENT(pm->v2)); } #else static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *pm, - pmd_t pmd, int offset) + pmd_t pmd, int offset, int pmd_flags2) { } #endif @@ -926,12 +960,15 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, /* find the first VMA at or above 'addr' */ vma = find_vma(walk->mm, addr); if (vma && pmd_trans_huge_lock(pmd, vma) == 1) { + int pmd_flags2; + + pmd_flags2 = (pmd_soft_dirty(*pmd) ? __PM_SOFT_DIRTY : 0); for (; addr != end; addr += PAGE_SIZE) { unsigned long offset; offset = (addr & ~PAGEMAP_WALK_MASK) >> PAGE_SHIFT; - thp_pmd_to_pagemap_entry(&pme, pm, *pmd, offset); + thp_pmd_to_pagemap_entry(&pme, pm, *pmd, offset, pmd_flags2); err = add_to_pagemap(addr, &pme, pm); if (err) break; diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index b183698..a7126d2 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -396,6 +396,28 @@ static inline void ptep_modify_prot_commit(struct mm_struct *mm, #define arch_start_context_switch(prev) do {} while (0) #endif +#ifndef CONFIG_HAVE_ARCH_SOFT_DIRTY +static inline int pte_soft_dirty(pte_t pte) +{ + return 0; +} + +static inline int pmd_soft_dirty(pmd_t pmd) +{ + return 0; +} + +static inline pte_t pte_mksoft_dirty(pte_t pte) +{ + return pte; +} + +static inline pmd_t pmd_mksoft_dirty(pmd_t pmd) +{ + return pmd; +} +#endif + #ifndef __HAVE_PFNMAP_TRACKING /* * Interfaces that can be used by architecture code to keep track of @@ -477,3 +477,15 @@ config FRONTSWAP and swap data is stored as normal on the matching swap device. If unsure, say Y to enable frontswap. + +config MEM_SOFT_DIRTY + bool "Track memory changes" + depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY + select PROC_PAGE_MONITOR + help + This option enables memory changes tracking by introducing a + soft-dirty bit on pte-s. This bit it set when someone writes + into a page just as regular dirty bit, but unlike the latter + it can be cleared by hands. + + See Documentation/vm/soft-dirty.txt for more details. diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 362c329..d8b3b85 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1429,7 +1429,7 @@ int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, if (ret == 1) { pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); VM_BUG_ON(!pmd_none(*new_pmd)); - set_pmd_at(mm, new_addr, new_pmd, pmd); + set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); spin_unlock(&mm->page_table_lock); } out: diff --git a/mm/mremap.c b/mm/mremap.c index 463a257..3708655 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -126,7 +126,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, continue; pte = ptep_get_and_clear(mm, old_addr, old_pte); pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); - set_pte_at(mm, new_addr, new_pte, pte); + set_pte_at(mm, new_addr, new_pte, pte_mksoft_dirty(pte)); } arch_leave_lazy_mmu_mode(); |
