diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/mm/memory.c b/mm/memory.c index 9e6608b50261..0ee13d3de88c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4405,13 +4405,13 @@ vm_fault_t finish_fault(struct vm_fault *vmf) return ret; } -static unsigned long fault_around_bytes __read_mostly = - rounddown_pow_of_two(65536); +static unsigned long fault_around_pages __read_mostly = + 65536 >> PAGE_SHIFT; #ifdef CONFIG_DEBUG_FS static int fault_around_bytes_get(void *data, u64 *val) { - *val = fault_around_bytes; + *val = fault_around_pages << PAGE_SHIFT; return 0; } @@ -4423,10 +4423,13 @@ static int fault_around_bytes_set(void *data, u64 val) { if (val / PAGE_SIZE > PTRS_PER_PTE) return -EINVAL; - if (val > PAGE_SIZE) - fault_around_bytes = rounddown_pow_of_two(val); - else - fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */ + + /* + * The minimum value is 1 page, however this results in no fault-around + * at all. See should_fault_around(). + */ + fault_around_pages = max(rounddown_pow_of_two(val) >> PAGE_SHIFT, 1UL); + return 0; } DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops, @@ -4452,18 +4455,18 @@ late_initcall(fault_around_debugfs); * This function doesn't cross VMA or page table boundaries, in order to call * map_pages() and acquire a PTE lock only once. * - * fault_around_bytes defines how many bytes we'll try to map. + * fault_around_pages defines how many pages we'll try to map. * do_fault_around() expects it to be set to a power of two less than or equal * to PTRS_PER_PTE. * * The virtual address of the area that we map is naturally aligned to - * fault_around_bytes rounded down to the machine page size + * fault_around_pages * PAGE_SIZE rounded down to the machine page size * (and therefore to page order). This way it's easier to guarantee * that we don't cross page table boundaries. */ static vm_fault_t do_fault_around(struct vm_fault *vmf) { - pgoff_t nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT; + pgoff_t nr_pages = READ_ONCE(fault_around_pages); pgoff_t pte_off = pte_index(vmf->address); /* The page offset of vmf->address within the VMA. */ pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff; @@ -4498,7 +4501,8 @@ static inline bool should_fault_around(struct vm_fault *vmf) if (uffd_disable_fault_around(vmf->vma)) return false; - return fault_around_bytes >> PAGE_SHIFT > 1; + /* A single page implies no faulting 'around' at all. */ + return fault_around_pages > 1; } static vm_fault_t do_read_fault(struct vm_fault *vmf) |