On Wed, Nov 06, 2013 at 02:16:33PM -0500, Christoph Lameter wrote: > On Wed, 6 Nov 2013, Andreas Herrmann wrote: > > > When I've used slub_debug kernel option (e.g. > > "slub_debug=,skbuff_fclone_cache" or similar) on a debug session I've > > seen a panic like: > > Hmmm.. That looks like its due to some slabs not having names > during early boot. kmem_cache_flags is called with NULL as a parameter. That's because the slub_debug parameter is not evaluated before kmem_cache_flags is called. Older kernels didn't show this problem. I think the sequence of those calls has changed. Not sure what patch set has made that change. > Are you sure that this fixes the issue? Looks like the > kmem_cache_flag function should fail regardless of how early you set it. > > AFAICT the right fix would be: That would avoid the panic but I guess it won't enable slub debugging. However I'll test this. Andreas > Subject: slub: Handle NULL parameter in kmem_cache_flags > > kmem_cache_flags may be called with NULL parameter during early boot. > Skip the test in that case. > > Signed-off-by: Christoph Lameter <cl@xxxxxxxxx> > > Index: linux/mm/slub.c > =================================================================== > --- linux.orig/mm/slub.c 2013-10-15 13:55:44.000000000 -0500 > +++ linux/mm/slub.c 2013-11-06 13:09:21.810583134 -0600 > @@ -1217,7 +1217,7 @@ static unsigned long kmem_cache_flags(un > /* > * Enable debugging if selected on the kernel commandline. > */ > - if (slub_debug && (!slub_debug_slabs || > + if (slub_debug && name && (!slub_debug_slabs || > !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)))) > flags |= slub_debug; > > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>