diff options
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 49 |
1 files changed, 28 insertions, 21 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 5020b28..000a220 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -906,8 +906,8 @@ EXPORT_SYMBOL(page_cache_prev_hole); * Looks up the page cache slot at @mapping & @offset. If there is a * page cache page, it is returned with an increased refcount. * - * If the slot holds a shadow entry of a previously evicted page, it - * is returned. + * If the slot holds a shadow entry of a previously evicted page, or a + * swap entry from shmem/tmpfs, it is returned. * * Otherwise, %NULL is returned. */ @@ -928,9 +928,9 @@ repeat: if (radix_tree_deref_retry(page)) goto repeat; /* - * Otherwise, shmem/tmpfs must be storing a swap entry - * here as an exceptional entry: so return it without - * attempting to raise page count. + * A shadow entry of a recently evicted page, + * or a swap entry from shmem/tmpfs. Return + * it without attempting to raise page count. */ goto out; } @@ -983,8 +983,8 @@ EXPORT_SYMBOL(find_get_page); * page cache page, it is returned locked and with an increased * refcount. * - * If the slot holds a shadow entry of a previously evicted page, it - * is returned. + * If the slot holds a shadow entry of a previously evicted page, or a + * swap entry from shmem/tmpfs, it is returned. * * Otherwise, %NULL is returned. * @@ -1099,8 +1099,8 @@ EXPORT_SYMBOL(find_or_create_page); * with ascending indexes. There may be holes in the indices due to * not-present pages. * - * Any shadow entries of evicted pages are included in the returned - * array. + * Any shadow entries of evicted pages, or swap entries from + * shmem/tmpfs, are included in the returned array. * * find_get_entries() returns the number of pages and shadow entries * which were found. @@ -1128,9 +1128,9 @@ repeat: if (radix_tree_deref_retry(page)) goto restart; /* - * Otherwise, we must be storing a swap entry - * here as an exceptional entry: so return it - * without attempting to raise page count. + * A shadow entry of a recently evicted page, + * or a swap entry from shmem/tmpfs. Return + * it without attempting to raise page count. */ goto export; } @@ -1198,9 +1198,9 @@ repeat: goto restart; } /* - * Otherwise, shmem/tmpfs must be storing a swap entry - * here as an exceptional entry: so skip over it - - * we only reach this from invalidate_mapping_pages(). + * A shadow entry of a recently evicted page, + * or a swap entry from shmem/tmpfs. Skip + * over it. */ continue; } @@ -1265,9 +1265,9 @@ repeat: goto restart; } /* - * Otherwise, shmem/tmpfs must be storing a swap entry - * here as an exceptional entry: so stop looking for - * contiguous pages. + * A shadow entry of a recently evicted page, + * or a swap entry from shmem/tmpfs. Stop + * looking for contiguous pages. */ break; } @@ -1341,10 +1341,17 @@ repeat: goto restart; } /* - * This function is never used on a shmem/tmpfs - * mapping, so a swap entry won't be found here. + * A shadow entry of a recently evicted page. + * + * Those entries should never be tagged, but + * this tree walk is lockless and the tags are + * looked up in bulk, one radix tree node at a + * time, so there is a sizable window for page + * reclaim to evict a page we saw tagged. + * + * Skip over it. */ - BUG(); + continue; } if (!page_cache_get_speculative(page)) |
