Re: linux-next: Tree for Jan 20 -- Kernel panic - Unable to mount root fs

On Tue, Jan 20, 2015 at 06:51:35PM +0100, Sabrina Dubroca wrote: > 2015-01-20, 12:39:08 -0500, Paul Moore wrote: > > On Tuesday, January 20, 2015 05:56:55 PM Sabrina Dubroca wrote: > > > Hello, > > > > > > Today's linux-next doesn't boot on my qemu VM: > > > > ... > > > > > I bisected it down to: > > > > > > 5dc5218840e1 fs: create proper filename objects using getname_kernel() > > > > > > I reverted then reapplied each part of that patch. It works if I > > > leave out the hunk for do_path_lookup: > > > > > > diff --git a/fs/namei.c b/fs/namei.c > > > index eeb3b83661f8..c3d21b79090e 100644 > > > --- a/fs/namei.c > > > +++ b/fs/namei.c > > > @@ -2001,9 +2001,15 @@ static int filename_lookup(int dfd, struct filename > > > *name, static int do_path_lookup(int dfd, const char *name, > > > unsigned int flags, struct nameidata *nd) > > > { > > > - struct filename filename = { .name = name }; > > > + int retval; > > > + struct filename *filename; > > > > > > - return filename_lookup(dfd, &filename, flags, nd); > > > + filename = getname_kernel(name); > > > + if (unlikely(IS_ERR(filename))) > > > + return PTR_ERR(filename); > > > + retval = filename_lookup(dfd, filename, flags, nd); > > > + putname(filename); > > > + return retval; > > > } > > > > > > I don't know what other info you may need. > > > Full dmesg for the failed boot included below. > > > > Thanks for testing this and reporting the problem, especially such a small > > bisection. Unfortunately nothing is immediately obvious to me, would you mind > > sharing your kernel config so I can try to reproduce and debug the problem? > > Sure. > > I run qemu with: > > qemu-system-x86_64 -enable-kvm -cpu host -m 512 -kernel bzImage -append 'root=/dev/sda1' $IMG > > and the image contains a single ext4 partition with a basic ArchLinux install. Could you turn that return PTR_ERR(filename); into { printk(KERN_ERR "failed(%p -> %d)", name, PTR_ERR(filename)); return PTR_ERR(filename); } reproduce the panic and see what has it produced?