diff options
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/task_mmu.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 85ef60fdf2c0..5830b2e129ed 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -14,6 +14,7 @@ #include <linux/swapops.h> #include <linux/mmu_notifier.h> #include <linux/page_idle.h> +#include <linux/shmem_fs.h> #include <asm/elf.h> #include <asm/uaccess.h> @@ -717,8 +718,25 @@ static int show_smap(struct seq_file *m, void *v, int is_pid) #ifdef CONFIG_SHMEM if (vma->vm_file && shmem_mapping(vma->vm_file->f_mapping)) { - mss.check_shmem_swap = true; - smaps_walk.pte_hole = smaps_pte_hole; + /* + * For shared or readonly shmem mappings we know that all + * swapped out pages belong to the shmem object, and we can + * obtain the swap value much more efficiently. For private + * writable mappings, we might have COW pages that are + * not affected by the parent swapped out pages of the shmem + * object, so we have to distinguish them during the page walk. + * Unless we know that the shmem object (or the part mapped by + * our VMA) has no swapped out pages at all. + */ + unsigned long shmem_swapped = shmem_swap_usage(vma); + + if (!shmem_swapped || (vma->vm_flags & VM_SHARED) || + !(vma->vm_flags & VM_WRITE)) { + mss.swap = shmem_swapped; + } else { + mss.check_shmem_swap = true; + smaps_walk.pte_hole = smaps_pte_hole; + } } #endif |