On Thu, May 22, 2014 at 12:22:40AM -0700, Guenter Roeck wrote: > On 05/22/2014 12:14 AM, Greg Kroah-Hartmann wrote: > > On Wed, May 21, 2014 at 03:59:58PM -0700, Guenter Roeck wrote: > >> On Wed, May 21, 2014 at 01:04:04PM -0700, Francesco Ruggeri wrote: > >>> I have been using an x86 platform. > >>> When I started working on it I got early crashes until I added the > >>> check for p not NULL in > >>> > >>> +void bus_release_device(struct device *dev) > >>> +{ > >>> + struct device_private *p = dev->p; > >>> + > >>> + if (p && klist_node_attached(&p->knode_bus)) > >>> + klist_put_last(&p->knode_bus); > >>> +} > >>> + > >>> > >>> Maybe on powerpc *p is overriden between device_del and device_release? > >>> > >>> Or maybe some of the BUG_ONs in the patch? The ones on knode_dead are > >>> treated as WARN_ONs in the current klist code. > >>> The one in BUG_ON(!klist_dec_and_del(n)); is new, and in my tests I > >>> ran into it without the second patch (but only when I ran my module > >>> and tests). > >>> > >> Hi Francesco, > >> > >> I replaced the BUG_ON with WARN_ON; still crashes. > >> > >> Anyway, the problem seems to be known. I found two related exchanges. > >> > >> [1] describes pretty much the same problem. I don't see if/where it was > >> ever fixed, though. > >> > >> [2] is a patch to fix the problem. It did not apply cleanly to 3.14, > >> so I had to make some adjustments in klist_iter_init_node. Resulting > >> patch is below. With this patch, the problem is gone. It is not perfect, > >> as it aborts the loop if it encounters a deleted kobject, but it is better > >> than nothing. Unfortunately, the patch never made it upstream; no idea why. > >> Copying the author and Greg to get additional feedback. > >> > >> Guenter > >> > >> [1] https://lkml.org/lkml/2008/10/26/79 > >> [2] https://lkml.org/lkml/2012/4/16/218 > > > > 2 years ago? I have no idea what was up with that, sorry... > > > > Ok, but do you have comments on the patch itself in its current version ?
I have no idea, and at the moment, no time to look at this at all, sorry. Feel free to work on it and verify if it is a valid fix or not for this issue and let me know. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/