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

2015-01-21, 16:39:12 +0100, Thierry Reding wrote: > On Wed, Jan 21, 2015 at 10:24:11AM -0500, Paul Moore wrote: >> On Wednesday, January 21, 2015 03:42:16 PM Thierry Reding wrote: >>> On Wed, Jan 21, 2015 at 12:05:39PM +0100, Sabrina Dubroca wrote: >>>> 2015-01-21, 04:36:38 +0000, Al Viro wrote: >>>>> On Tue, Jan 20, 2015 at 08:01:26PM -0800, Guenter Roeck wrote: >>>>>> With this patch: >>>>>> >>>>>> sys_mkdir .:40775 returned -17 >>>>>> sys_mkdir usr:40775 returned 0 >>>>>> sys_mkdir usr/lib:40775 returned 0 >>>>>> sys_mkdir usr/share:40755 returned 0 >>>>>> sys_mkdir usr/share/udhcpc:40755 returned 0 >>>>>> sys_mkdir usr/bin:40775 returned 0 >>>>>> sys_mkdir usr/sbin:40775 returned 0 >>>>>> sys_mkdir mnt:40775 returned 0 >>>>>> sys_mkdir proc:40775 returned 0 >>>>>> sys_mkdir root:40775 returned 0 >>>>>> sys_mkdir lib:40775 returned 0 >>>>>> sys_mkdir lib/modules:40775 returned 0 >>>>>> ... >>>>>> >>>>>> and the problem is fixed. >>>> >>>> This patch also works for me. >>>> >>>>> ... except that it simply confirms that something's fishy with >>>>> getname_kernel() of ->name of struct filename returned by getname(). >>>>> IOW, I still do not understand the mechanism of breakage there. >>>> >>>> I'm not so sure about that. I tried to copy name to a new string in >>>> do_path_lookup and that didn't help. >>>> >>>> Now, I've removed the >>>> >>>> putname(filename); >>>> >>>> line from do_path_lookup and I don't get the panic. >>> >>> That would indicate that somehow the refcount got unbalanced. Looking >>> more closely it seems like the various audit_*() function do take a >>> reference, but maybe that's not enough. >> >> I'm thinking the same thing and I think the problem may be that >> __audit_reusename() is not bumping the filename->refcnt. Can someone who is >> seeing this problem bump the refcnt in __audit_reusename()? >> >> struct filename * >> __audit_reusename(const __user char *uptr) >> { >> struct audit_context *context = current->audit_context; >> struct audit_names *n; >> >> list_for_each_entry(n, &context->names_list, list) { >> if (!n->name) >> continue; >> if (n->name->uptr == uptr) { >> + n->name->refcnt++; >> return n->name; >> } >> } >> return NULL; >> } > > That doesn't seem to help, at least in my case. Same here. Well, it's probably not an audit issue. I tried audit=0 on the commandline, and I just rebuilt a kernel with CONFIG_AUDIT=n, and it's still panicing. This should have fixed any audit-related issue, right?