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![Andi Kleen](/assets/img/avatar_default.png)
Memory migration uses special swap entry types to trigger special actions on page faults. Extend this mechanism to also support poisoned swap entries, to trigger poison handling on page faults. This allows follow-on patches to prevent processes from faulting in poisoned pages again. v2: Fix overflow in MAX_SWAPFILES (Fengguang Wu) v3: Better overflow fix (Hidehiro Kawai) Signed-off-by: Andi Kleen <ak@linux.intel.com>
171 lines
4.2 KiB
C
171 lines
4.2 KiB
C
/*
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* swapcache pages are stored in the swapper_space radix tree. We want to
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* get good packing density in that tree, so the index should be dense in
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* the low-order bits.
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*
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* We arrange the `type' and `offset' fields so that `type' is at the five
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* high-order bits of the swp_entry_t and `offset' is right-aligned in the
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* remaining bits.
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*
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* swp_entry_t's are *never* stored anywhere in their arch-dependent format.
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*/
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#define SWP_TYPE_SHIFT(e) (sizeof(e.val) * 8 - MAX_SWAPFILES_SHIFT)
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#define SWP_OFFSET_MASK(e) ((1UL << SWP_TYPE_SHIFT(e)) - 1)
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/*
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* Store a type+offset into a swp_entry_t in an arch-independent format
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*/
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static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
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{
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swp_entry_t ret;
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ret.val = (type << SWP_TYPE_SHIFT(ret)) |
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(offset & SWP_OFFSET_MASK(ret));
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return ret;
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}
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/*
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* Extract the `type' field from a swp_entry_t. The swp_entry_t is in
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* arch-independent format
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*/
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static inline unsigned swp_type(swp_entry_t entry)
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{
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return (entry.val >> SWP_TYPE_SHIFT(entry));
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}
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/*
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* Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
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* arch-independent format
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*/
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static inline pgoff_t swp_offset(swp_entry_t entry)
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{
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return entry.val & SWP_OFFSET_MASK(entry);
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}
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#ifdef CONFIG_MMU
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/* check whether a pte points to a swap entry */
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static inline int is_swap_pte(pte_t pte)
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{
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return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
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}
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#endif
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/*
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* Convert the arch-dependent pte representation of a swp_entry_t into an
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* arch-independent swp_entry_t.
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*/
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static inline swp_entry_t pte_to_swp_entry(pte_t pte)
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{
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swp_entry_t arch_entry;
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BUG_ON(pte_file(pte));
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arch_entry = __pte_to_swp_entry(pte);
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return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
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}
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/*
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* Convert the arch-independent representation of a swp_entry_t into the
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* arch-dependent pte representation.
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*/
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static inline pte_t swp_entry_to_pte(swp_entry_t entry)
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{
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swp_entry_t arch_entry;
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arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
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BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
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return __swp_entry_to_pte(arch_entry);
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}
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#ifdef CONFIG_MIGRATION
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static inline swp_entry_t make_migration_entry(struct page *page, int write)
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{
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BUG_ON(!PageLocked(page));
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return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
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page_to_pfn(page));
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}
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static inline int is_migration_entry(swp_entry_t entry)
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{
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return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
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swp_type(entry) == SWP_MIGRATION_WRITE);
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}
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static inline int is_write_migration_entry(swp_entry_t entry)
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{
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return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
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}
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static inline struct page *migration_entry_to_page(swp_entry_t entry)
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{
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struct page *p = pfn_to_page(swp_offset(entry));
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/*
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* Any use of migration entries may only occur while the
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* corresponding page is locked
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*/
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BUG_ON(!PageLocked(p));
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return p;
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}
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static inline void make_migration_entry_read(swp_entry_t *entry)
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{
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*entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
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}
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extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
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unsigned long address);
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#else
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#define make_migration_entry(page, write) swp_entry(0, 0)
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static inline int is_migration_entry(swp_entry_t swp)
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{
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return 0;
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}
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#define migration_entry_to_page(swp) NULL
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static inline void make_migration_entry_read(swp_entry_t *entryp) { }
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static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
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unsigned long address) { }
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static inline int is_write_migration_entry(swp_entry_t entry)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_MEMORY_FAILURE
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/*
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* Support for hardware poisoned pages
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*/
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static inline swp_entry_t make_hwpoison_entry(struct page *page)
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{
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BUG_ON(!PageLocked(page));
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return swp_entry(SWP_HWPOISON, page_to_pfn(page));
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}
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static inline int is_hwpoison_entry(swp_entry_t entry)
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{
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return swp_type(entry) == SWP_HWPOISON;
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}
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#else
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static inline swp_entry_t make_hwpoison_entry(struct page *page)
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{
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return swp_entry(0, 0);
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}
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static inline int is_hwpoison_entry(swp_entry_t swp)
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{
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return 0;
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}
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#endif
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#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
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static inline int non_swap_entry(swp_entry_t entry)
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{
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return swp_type(entry) >= MAX_SWAPFILES;
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}
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#else
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static inline int non_swap_entry(swp_entry_t entry)
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{
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return 0;
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}
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#endif
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