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    SubjectRe: [broken-out-2007-07-20-00-22] kernel bug at kernel/params:570
    [ Considering this has sufficiently excited me, I became the second person
    to illegitimately download 2.6.22-mm1 and am presently building Michal's
    config. The strange thing is that I couldn't get 22-mm1 to even build with
    the posted .config -- so had to deselect XFS, ATA, unionfs.

    Hopefully this bug should be 100% reproducible at boot time anyway.
    Don't care much for XFS and unionfs, but hoping deselecting ATA from
    the config doesn't change the variables much in this equation. ]


    On 7/21/07, Greg KH <gregkh@suse.de> wrote:
    > On Fri, Jul 20, 2007 at 06:37:33PM -0700, Andrew Morton wrote:
    > > On Fri, 20 Jul 2007 18:02:57 -0700 Greg KH <gregkh@suse.de> wrote:
    > >
    > > > --- a/kernel/params.c
    > > > +++ b/kernel/params.c
    > > > @@ -567,7 +567,11 @@ static void __init kernel_param_sysfs_se
    > > > kobject_set_name(&mk->kobj, name);
    > > > kobject_init(&mk->kobj);
    > > > ret = kobject_add(&mk->kobj);
    > > > - BUG_ON(ret < 0);
    > > > + if (ret) {
    > > > + printk(KERN_ERR "module '%s' failed to be added to sysfs, "
    > > > + "the system will be unstable now.\n", name);
    > > > + return;
    > > > + }
    > >
    > > It would be nice to print the value of `ret' too.


    What I'm surprised about is that %eax doesn't seem to contain the
    return value `ret' of kobject_add(). It's 1, which is funny, given:

    ret = kobject_add(&mk->kobj);
    BUG_ON(ret < 0);

    One wouldn't expect BUG() -- or the corresponding exception handler --
    to clobber registers, that would be a sad day.


    > Ok, how about this version:
    >
    > ---
    > kernel/params.c | 7 ++++++-
    > 1 file changed, 6 insertions(+), 1 deletion(-)
    >
    > --- a/kernel/params.c
    > +++ b/kernel/params.c
    > @@ -567,7 +567,12 @@ static void __init kernel_param_sysfs_se
    > kobject_set_name(&mk->kobj, name);
    > kobject_init(&mk->kobj);
    > ret = kobject_add(&mk->kobj);
    > - BUG_ON(ret < 0);
    > + if (ret) {
    > + printk(KERN_ERR "Module '%s' failed to be added to sysfs, "
    > + "error number %d\n", name, ret);
    > + printk(KERN_ERR "The system will be unstable now.\n");
    > + return;
    > + }
    > param_sysfs_setup(mk, kparam, num_params, name_skip);
    > kobject_uevent(&mk->kobj, KOBJ_ADD);
    > }


    I'm building with this:

    if (ret) {
    printk("~~~~~ .%s.%d.%s. ~~~~~\n", name, ret, kparam->name);
    return;
    }

    To also print out the evil kparam->name that caused us to crash.
    When ret == EINVAL, name would be "", so not so helpful alone.

    Also enabling netconsole, though I'm sure there's zero chances
    of NET / ethXXX / netconsole being up _this_ early in the boot ...

    Will keep you guys posted :-)

    Satyam
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