Page cache could contain pages beyond end of file during write or if read races with truncate. But generic_file_buffered_read() always allocates unneeded pages beyond eof if somebody reads here and one extra page at the end if file size is page-aligned. Function generic_file_buffered_read() calls page_cache_sync_readahead() if page not found in cache and then do another lookup. Readahead checks file size in __do_page_cache_readahead() before allocating pages. After that generic_file_buffered_read() falls back to slow path and allocates page for ->readpage() without checking file size. This patch checks file size before allocating page for ->readpage(). Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> --- mm/filemap.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/filemap.c b/mm/filemap.c index 85b7d087eb45..92abf5f348a9 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2225,6 +2225,10 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, goto out; no_cached_page: + /* Do not allocate cache pages beyond end of file. */ + if (((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) + goto out; + /* * Ok, it wasn't cached, so we need to create a new * page..
