From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755007Ab0EZPtz (ORCPT ); Wed, 26 May 2010 11:49:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53030 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754900Ab0EZPtw (ORCPT ); Wed, 26 May 2010 11:49:52 -0400 Date: Wed, 26 May 2010 11:49:40 -0400 From: Rik van Riel To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, lwoodman@redhat.com, jmoyer@redhat.com, torvalds@linux-foundation.org Subject: [PATCH] do_generic_file_read: clear page errors when issuing a fresh read of the page Message-ID: <20100526114940.49f51028@annuminas.surriel.com> Organization: Red Hat, Inc. Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jeff Moyer I/O errors can happen due to temporary failures, like multipath errors or losing network contact with the iSCSI server. Because of that, the VM will retry readpage on the page. However, do_generic_file_read does not clear PG_error. This causes the system to be unable to actually use the data in the page cache page, even if the subsequent readpage completes successfully! The function filemap_fault has had a ClearPageError before readpage forever. This patch simply adds the same to do_generic_file_read. Signed-off-by: Rik van Riel Signed-off-by: Jeff Moyer --- mm/filemap.c | 6 ++++++ 1 file changed, 6 insertions(+) Index: linux-2.6.34/mm/filemap.c =================================================================== --- linux-2.6.34.orig/mm/filemap.c +++ linux-2.6.34/mm/filemap.c @@ -1106,6 +1106,12 @@ page_not_up_to_date_locked: } readpage: + /* + * A previous I/O error may have been due to temporary + * failures, eg. multipath errors. + * PG_error will be set again if readpage fails. + */ + ClearPageError(page); /* Start the actual read. The read will unlock the page. */ error = mapping->a_ops->readpage(filp, page);