From owner-freebsd-dtrace@freebsd.org Thu May 18 20:30:03 2017 Return-Path: Delivered-To: freebsd-dtrace@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C602ED738DD for ; Thu, 18 May 2017 20:30:03 +0000 (UTC) (envelope-from longwitz@incore.de) Received: from dss.incore.de (dss.incore.de [195.145.1.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 8E234112F for ; Thu, 18 May 2017 20:30:03 +0000 (UTC) (envelope-from longwitz@incore.de) Received: from inetmail.dmz (inetmail.dmz [10.3.0.3]) by dss.incore.de (Postfix) with ESMTP id C135867A78 for ; Thu, 18 May 2017 22:20:06 +0200 (CEST) X-Virus-Scanned: amavisd-new at incore.de Received: from dss.incore.de ([10.3.0.3]) by inetmail.dmz (inetmail.dmz [10.3.0.3]) (amavisd-new, port 10024) with LMTP id s7kHStLDKJrV for ; Thu, 18 May 2017 22:20:05 +0200 (CEST) Received: from mail.local.incore (fwintern.dmz [10.0.0.253]) by dss.incore.de (Postfix) with ESMTP id B2AD067A16 for ; Thu, 18 May 2017 22:20:05 +0200 (CEST) Received: from bsdmhs.longwitz (unknown [192.168.99.6]) by mail.local.incore (Postfix) with ESMTP id 85800508A1 for ; Thu, 18 May 2017 22:20:05 +0200 (CEST) Message-ID: <591E01F5.8080208@incore.de> Date: Thu, 18 May 2017 22:20:05 +0200 From: Andreas Longwitz User-Agent: Thunderbird 2.0.0.19 (X11/20090113) MIME-Version: 1.0 To: freebsd-dtrace@freebsd.org Subject: fbt:kernel:breadn_flags:entry): invalid address (0x0) in action #7 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-dtrace@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "A discussion list for developers working on DTrace in FreeBSD." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 May 2017 20:30:03 -0000 Now running FreeBSD 10.3-STABLE #0 r317936 I try to understand the problem described in https://lists.freebsd.org/pipermail/freebsd-fs/2013-November/018610.html using DTrace. Therefore I like to use the probe fbt:kernel:breadn_flags:entry to see what is happening in ffs_vgetf() in source ffs_vfsops.c: #define bread(vp, blkno, size, cred, bpp) \ breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, 0, bpp) /* Read in the disk contents for the inode, copy into the inode. */ error = bread(ump->um_devvp, fsbtodb(fs, ino_to_fsba(fs, ino)), (int)fs->fs_bsize, NOCRED, &bp); I get the error dtrace: error on enabled probe ID 22 (ID 31371: fbt:kernel:breadn_flags:entry): invalid address (0x0) in action #6 probably because NOCRED is NULL: #define NOCRED ((struct ucred *)0) I like to know if this case can be handled in DTrace, the parameter args[6]: struct ucred * is sometimes a pointer and sometimes NOCRED. -- Dr. Andreas Longwitz