From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: linux-next: Tree for Jan 20 -- Kernel panic - Unable to mount root fs Date: Tue, 20 Jan 2015 23:17:25 +0000 Message-ID: <20150120231725.GL29656@ZenIV.linux.org.uk> References: <20150120185308.53f4af4e@canb.auug.org.au> <20150120165655.GA10904@kria> <4237741.ePaG0Gba6D@sifl> <20150120175135.GA25973@kria> <20150120195432.GH29656@ZenIV.linux.org.uk> <20150120204504.GA309@kria> <20150120210202.GI29656@ZenIV.linux.org.uk> <20150120220823.GB18129@kria> <20150120221309.GA18589@roeck-us.net> <20150120225041.GK29656@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sabrina Dubroca , Paul Moore , Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-audit@redhat.com, Richard Guy Briggs To: Guenter Roeck Return-path: Content-Disposition: inline In-Reply-To: <20150120225041.GK29656@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Jan 20, 2015 at 10:50:41PM +0000, Al Viro wrote: > doesn't look at _anything_ other than name->name other than for audit_inode(). > And name->name is apparently the same. > > It looks like something ends up buggering name->name in process, but then > the damn thing appears to be normal after return from filename_lookup()... If my reconstruction of what's going on is correct, the call chain here is do_path_lookup() <- kern_path() <- lookup_bdev() <- blkdev_get_by_path() <- mount_bdev() <- some_type.mount() <- mount_fs() <- vfs_kern_mount() <- do_new_mount() <- do_mount() <- sys_mount() <- do_mount_root() <- mount_block_root() <- mount_root(). Which is obscenely long, BTW, but that's a separate story... Could you slap struct stat buf; int n = sys_newstat(name, &buf); printk(KERN_ERR "stat(\"%s\") -> %d\n", name, n); n = sys_newstat("/dev", &buf); printk(KERN_ERR "stat(\"dev\") -> %d\n", n); in the beginning of mount_block_root() (init/do_mounts.c) and see what it prints?