From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thayne Harbaugh Date: Mon, 25 Oct 2004 18:30:08 +0000 Subject: chicken/egg between pipefs and initramfs/hotplug Message-Id: <1098729008.19348.80.camel@tubarao> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: klibc@zytor.com Cc: linux-kernel@vger.kernel.org, linux-hotplug-devel@lists.sourceforge.net I have a hotplug setup in initramfs. Everytime that modprobe is called I get a kernel oops: NULL pointer dereference: Unable to handle kernel NULL pointer dereference<1>Unable to handle kernel = NULL pointer dereference at virtual address 00000014 printing eip: c015db49 *pde =3D 00000000 Oops: 0000 [#1] PREEMPT SMP Modules linked in: CPU: 3 EIP: 0060:[] Not tainted EFLAGS: 00010296 (2.6.8) EIP is at get_pipe_inode+0x9/0xb2 eax: 00000000 ebx: f74f4780 ecx: 00000000 edx: 00000000 esi: f7575580 edi: 0805cbdc ebp: f767a000 esp: f767bf3c ds: 007b es: 007b ss: 0068 Process default.hotplug (pid: 184, threadinfo=F767a000 task=F74d9110) Stack: f74f4780 f74f4780 c015dc24 f74d9110 c0168225 f7963ef0 c0392e80 f74f4= 780 ffffffe9 f74f4080 f767bfac 00000ff8 c014ff5f f7963cb0 00000001 00000= ff8 f767bfac c0162d17 00000000 f74f4080 fffffff7 bfffdeec f767bfb0 0805c= bdc Call Trace: [] do_pipe+0x32/0x20e [] dput+0x9e/0x2b0 [] vfs_read+0x94/0x103 [] do_fcntl+0x18c/0x21f [] sys_pipe+0x11/0x49 [] syscall_call+0x7/0xb Code: 8b 40 14 89 04 24 e8 4e d5 00 00 85 c0 89 c3 0f 84 8d 00 00 It appears that linux/init/main.c:init() has a chicken/egg problem. Apparently modprobe and other programs need a pipe and pipefs isn't mounted until later on in do_basic_setup()/do_initcalls(). That means that linux/fs/pipe.c:static struct vfsmount *pipe_mnt; isn't initialized and blows up when it's derefernced in linux/fs/pipe.c:get_pipe_inode(). Has this been discussed before? Is there something that userspace can wait on until pipefs is mounted or more of the kernel is initialized? I did some searching and I just can't turn up a previous discussion about this - my apologies if it's already been covered. --=20 Thayne Harbaugh Linux Networx ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel