From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751265Ab3KQGTQ (ORCPT ); Sun, 17 Nov 2013 01:19:16 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:59382 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750721Ab3KQGTK (ORCPT ); Sun, 17 Nov 2013 01:19:10 -0500 Date: Sun, 17 Nov 2013 06:19:07 +0000 From: Al Viro To: Peter Wu Cc: linux-kernel@vger.kernel.org Subject: Re: [REGRESSION] coredumps truncated after "new helper: dump_align()" Message-ID: <20131117061907.GL13318@ZenIV.linux.org.uk> References: <11835033.kIc1RH0rS1@al> <20131115203838.GJ13318@ZenIV.linux.org.uk> <8708646.IsEyNQP0iB@al> <20131116000408.GK13318@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131116000408.GK13318@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Nov 16, 2013 at 12:04:08AM +0000, Al Viro wrote: > On Fri, Nov 15, 2013 at 10:34:43PM +0100, Peter Wu wrote: > > > Unfortunately, this patch still does not fix the issue. I rm'd the output > > directory just to be sure, but the bug is still there. What does this commit > > do anyway? The commit message is quite vague. > > Introduces a helper that used to be open-coded in a bunch of places - > pads the coredump to given alignment. And switches those places > to that new helper... > > FWIW, I haven't tried that on your config yet, but here (with the patch > in my previous mail) I'm seeing a sane-looking coredump - > -rw------- 1 root root 315392 Nov 15 17:48 core > Different userland, presumably, since that static binary is 684349 > bytes long. > > I'll try to reproduce with your config... ... and on your config I'm seeing Inited Segmentation fault (core dumped) [ 0.123351] Core size: 315392 in the log. Same size, same apparently sane coredump. Can you check what you get on mainline + diff below (combination of dump_align() and locking fix)? diff --git a/fs/coredump.c b/fs/coredump.c index 62406b6..bc3fbcd 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -695,7 +695,7 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr) while (nr) { if (dump_interrupted()) return 0; - n = vfs_write(file, addr, nr, &pos); + n = __kernel_write(file, addr, nr, &pos); if (n <= 0) return 0; file->f_pos = pos; @@ -733,7 +733,7 @@ int dump_align(struct coredump_params *cprm, int align) { unsigned mod = cprm->written & (align - 1); if (align & (align - 1)) - return -EINVAL; - return mod ? dump_skip(cprm, align - mod) : 0; + return 0; + return mod ? dump_skip(cprm, align - mod) : 1; } EXPORT_SYMBOL(dump_align);