diff options
| -rw-r--r-- | include/linux/sched.h | 7 | ||||
| -rw-r--r-- | mm/internal.h | 4 | ||||
| -rw-r--r-- | mm/rmap.c | 28 | ||||
| -rw-r--r-- | mm/vmscan.c | 7 |
4 files changed, 38 insertions, 8 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 3c602c20c717..a4ab9daa387c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1354,6 +1354,13 @@ struct tlbflush_unmap_batch { /* True if any bit in cpumask is set */ bool flush_required; + + /* + * If true then the PTE was dirty when unmapped. The entry must be + * flushed before IO is initiated or a stale TLB entry potentially + * allows an update without redirtying the page. + */ + bool writable; }; struct task_struct { diff --git a/mm/internal.h b/mm/internal.h index bd6372ac5f7f..1195dd2d6a2b 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -431,10 +431,14 @@ struct tlbflush_unmap_batch; #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH void try_to_unmap_flush(void); +void try_to_unmap_flush_dirty(void); #else static inline void try_to_unmap_flush(void) { } +static inline void try_to_unmap_flush_dirty(void) +{ +} #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */ #endif /* __MM_INTERNAL_H */ diff --git a/mm/rmap.c b/mm/rmap.c index 326d5d89e45c..0db38e7d0a72 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -626,16 +626,34 @@ void try_to_unmap_flush(void) } cpumask_clear(&tlb_ubc->cpumask); tlb_ubc->flush_required = false; + tlb_ubc->writable = false; put_cpu(); } +/* Flush iff there are potentially writable TLB entries that can race with IO */ +void try_to_unmap_flush_dirty(void) +{ + struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; + + if (tlb_ubc->writable) + try_to_unmap_flush(); +} + static void set_tlb_ubc_flush_pending(struct mm_struct *mm, - struct page *page) + struct page *page, bool writable) { struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; cpumask_or(&tlb_ubc->cpumask, &tlb_ubc->cpumask, mm_cpumask(mm)); tlb_ubc->flush_required = true; + + /* + * If the PTE was dirty then it's best to assume it's writable. The + * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush() + * before the page is queued for IO. + */ + if (writable) + tlb_ubc->writable = true; } /* @@ -658,7 +676,7 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) } #else static void set_tlb_ubc_flush_pending(struct mm_struct *mm, - struct page *page) + struct page *page, bool writable) { } @@ -1315,11 +1333,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, */ pteval = ptep_get_and_clear(mm, address, pte); - /* Potentially writable TLBs must be flushed before IO */ - if (pte_dirty(pteval)) - flush_tlb_page(vma, address); - else - set_tlb_ubc_flush_pending(mm, page); + set_tlb_ubc_flush_pending(mm, page, pte_dirty(pteval)); } else { pteval = ptep_clear_flush(vma, address, pte); } diff --git a/mm/vmscan.c b/mm/vmscan.c index 99ec00d6a5dd..b1139039122a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1098,7 +1098,12 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (!sc->may_writepage) goto keep_locked; - /* Page is dirty, try to write it out here */ + /* + * Page is dirty. Flush the TLB if a writable entry + * potentially exists to avoid CPU writes after IO + * starts and then write it out here. + */ + try_to_unmap_flush_dirty(); switch (pageout(page, mapping, sc)) { case PAGE_KEEP: goto keep_locked; |