In all versions from 2.5.62 to 3.15, on each iteration through the loop by iovec array in do_blockdev_direct_IO() we used to do this: sdio.head = 0; sdio.tail = 0; ... retval = do_direct_IO(dio, &sdio, &map_bh); if (retval) { dio_cleanup(dio, &sdio); break; } with another dio_cleanup() done after the loop, catching the situation when retval had been 0. Consider the situation when e.g. the 3rd iovec in 4-iovec array passed to readv() has crossed the EOF. do_direct_IO() returns 0 and buggers off *without* exhausting the page array. The loop proceeds to the next iovec without calling dio_cleanup() and resets sdio.head and sdio.tail. That reset of sdio.{head,tail} has prevented the eventual dio_cleanup() from seeing anything and the page reference end up leaking. Commit 7b2c99d15559 (new helper: iov_iter_get_pages()) in 3.16 had eliminated the loop by iovec array, along with sdio.head and sdio.tail resets. Backporting that is too much work - the minimal fix is simply to make sure that the only case when do_direct_IO() buggers off early without returning non-zero will not skip dio_cleanup(). The fix applies to all versions from 2.5.62 to 3.15. Reported-and-tested-by: Venki Pallipadi <venki@xxxxxxxxxxxx> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> --- diff --git a/fs/direct-io.c b/fs/direct-io.c index 387d919..d0288b8 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -997,6 +997,7 @@ do_holes: i_size_aligned >> blkbits) { /* We hit eof */ page_cache_release(page); + dio_cleanup(dio, sdio); goto out; } zero_user(page, block_in_page << blkbits,