diff options
| -rw-r--r-- | mm/shmem.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 530c5033d02..ee9024483f6 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -833,6 +833,10 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s idx = 0; ptr = info->i_direct; spin_lock(&info->lock); + if (!info->swapped) { + list_del_init(&info->swaplist); + goto lost2; + } limit = info->next_index; size = limit; if (size > SHMEM_NR_DIRECT) @@ -894,8 +898,15 @@ found: inode = igrab(&info->vfs_inode); spin_unlock(&info->lock); - /* move head to start search for next from here */ - list_move_tail(&shmem_swaplist, &info->swaplist); + /* + * Move _head_ to start search for next from here. + * But be careful: shmem_delete_inode checks list_empty without taking + * mutex, and there's an instant in list_move_tail when info->swaplist + * would appear empty, if it were the only one on shmem_swaplist. We + * could avoid doing it if inode NULL; or use this minor optimization. + */ + if (shmem_swaplist.next != &info->swaplist) + list_move_tail(&shmem_swaplist, &info->swaplist); mutex_unlock(&shmem_swaplist_mutex); error = 1; @@ -955,10 +966,7 @@ int shmem_unuse(swp_entry_t entry, struct page *page) mutex_lock(&shmem_swaplist_mutex); list_for_each_safe(p, next, &shmem_swaplist) { info = list_entry(p, struct shmem_inode_info, swaplist); - if (info->swapped) - found = shmem_unuse_inode(info, entry, page); - else - list_del_init(&info->swaplist); + found = shmem_unuse_inode(info, entry, page); cond_resched(); if (found) goto out; @@ -1021,18 +1029,23 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) remove_from_page_cache(page); shmem_swp_set(info, entry, swap.val); shmem_swp_unmap(entry); + if (list_empty(&info->swaplist)) + inode = igrab(inode); + else + inode = NULL; spin_unlock(&info->lock); - if (list_empty(&info->swaplist)) { - mutex_lock(&shmem_swaplist_mutex); - /* move instead of add in case we're racing */ - list_move_tail(&info->swaplist, &shmem_swaplist); - mutex_unlock(&shmem_swaplist_mutex); - } swap_duplicate(swap); BUG_ON(page_mapped(page)); page_cache_release(page); /* pagecache ref */ set_page_dirty(page); unlock_page(page); + if (inode) { + mutex_lock(&shmem_swaplist_mutex); + /* move instead of add in case we're racing */ + list_move_tail(&info->swaplist, &shmem_swaplist); + mutex_unlock(&shmem_swaplist_mutex); + iput(inode); + } return 0; } |