diff options
Diffstat (limited to 'include/linux/mm_types.h')
-rw-r--r-- | include/linux/mm_types.h | 102 |
1 files changed, 72 insertions, 30 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3cadee0a3508..46f4ecf5479a 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -23,6 +23,7 @@ struct address_space; struct mem_cgroup; +struct hmm; /* * Each physical page in the system has a struct page associated with @@ -335,6 +336,7 @@ struct vm_area_struct { struct file * vm_file; /* File we map to (can be NULL). */ void * vm_private_data; /* was vm_pte (shared mem) */ + atomic_long_t swap_readahead_info; #ifndef CONFIG_MMU struct vm_region *vm_region; /* NOMMU mapping region */ #endif @@ -502,6 +504,11 @@ struct mm_struct { atomic_long_t hugetlb_usage; #endif struct work_struct async_put_work; + +#if IS_ENABLED(CONFIG_HMM) + /* HMM needs to track a few things per mm */ + struct hmm *hmm; +#endif } __randomize_layout; extern struct mm_struct init_mm; @@ -526,26 +533,6 @@ extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, extern void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end); -/* - * Memory barriers to keep this state in sync are graciously provided by - * the page table locks, outside of which no page table modifications happen. - * The barriers are used to ensure the order between tlb_flush_pending updates, - * which happen while the lock is not taken, and the PTE updates, which happen - * while the lock is taken, are serialized. - */ -static inline bool mm_tlb_flush_pending(struct mm_struct *mm) -{ - return atomic_read(&mm->tlb_flush_pending) > 0; -} - -/* - * Returns true if there are two above TLB batching threads in parallel. - */ -static inline bool mm_tlb_flush_nested(struct mm_struct *mm) -{ - return atomic_read(&mm->tlb_flush_pending) > 1; -} - static inline void init_tlb_flush_pending(struct mm_struct *mm) { atomic_set(&mm->tlb_flush_pending, 0); @@ -554,27 +541,82 @@ static inline void init_tlb_flush_pending(struct mm_struct *mm) static inline void inc_tlb_flush_pending(struct mm_struct *mm) { atomic_inc(&mm->tlb_flush_pending); - /* - * Guarantee that the tlb_flush_pending increase does not leak into the - * critical section updating the page tables + * The only time this value is relevant is when there are indeed pages + * to flush. And we'll only flush pages after changing them, which + * requires the PTL. + * + * So the ordering here is: + * + * atomic_inc(&mm->tlb_flush_pending); + * spin_lock(&ptl); + * ... + * set_pte_at(); + * spin_unlock(&ptl); + * + * spin_lock(&ptl) + * mm_tlb_flush_pending(); + * .... + * spin_unlock(&ptl); + * + * flush_tlb_range(); + * atomic_dec(&mm->tlb_flush_pending); + * + * Where the increment if constrained by the PTL unlock, it thus + * ensures that the increment is visible if the PTE modification is + * visible. After all, if there is no PTE modification, nobody cares + * about TLB flushes either. + * + * This very much relies on users (mm_tlb_flush_pending() and + * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and + * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc + * locks (PPC) the unlock of one doesn't order against the lock of + * another PTL. + * + * The decrement is ordered by the flush_tlb_range(), such that + * mm_tlb_flush_pending() will not return false unless all flushes have + * completed. */ - smp_mb__before_spinlock(); } -/* Clearing is done after a TLB flush, which also provides a barrier. */ static inline void dec_tlb_flush_pending(struct mm_struct *mm) { /* - * Guarantee that the tlb_flush_pending does not not leak into the - * critical section, since we must order the PTE change and changes to - * the pending TLB flush indication. We could have relied on TLB flush - * as a memory barrier, but this behavior is not clearly documented. + * See inc_tlb_flush_pending(). + * + * This cannot be smp_mb__before_atomic() because smp_mb() simply does + * not order against TLB invalidate completion, which is what we need. + * + * Therefore we must rely on tlb_flush_*() to guarantee order. */ - smp_mb__before_atomic(); atomic_dec(&mm->tlb_flush_pending); } +static inline bool mm_tlb_flush_pending(struct mm_struct *mm) +{ + /* + * Must be called after having acquired the PTL; orders against that + * PTLs release and therefore ensures that if we observe the modified + * PTE we must also observe the increment from inc_tlb_flush_pending(). + * + * That is, it only guarantees to return true if there is a flush + * pending for _this_ PTL. + */ + return atomic_read(&mm->tlb_flush_pending); +} + +static inline bool mm_tlb_flush_nested(struct mm_struct *mm) +{ + /* + * Similar to mm_tlb_flush_pending(), we must have acquired the PTL + * for which there is a TLB flush pending in order to guarantee + * we've seen both that PTE modification and the increment. + * + * (no requirement on actually still holding the PTL, that is irrelevant) + */ + return atomic_read(&mm->tlb_flush_pending) > 1; +} + struct vm_fault; struct vm_special_mapping { |