On Mon, 28 Jun 2010, Benjamin Herrenschmidt wrote: > Hi folks ! > > Internally, I'm hitting a little "nit"... > > sysfs_slab_add() has this check: > > if (slab_state < SYSFS) > /* Defer until later */ > return 0; > > But sysfs_slab_remove() doesn't. > > So if the slab is created -and- destroyed at, for example, arch_initcall > time, then we hit a WARN in the kobject code, trying to dispose of a > non-existing kobject. > Indeed, but shouldn't we be appropriately handling the return value of sysfs_slab_add() so that it fails cache creation? We wouldn't be calling sysfs_slab_remove() on a cache that was never created. > Now, at first sight, just adding the same test to sysfs_slab_remove() > would do the job... but it all seems very racy to me. > > I don't understand in fact how this slab_state deals with races at all. > All modifiers of slab_state are intended to be run only on the boot cpu so the only concern is the ordering. We need slab_state to indicate how far slab has been initialized since we can't otherwise enforce how code uses slab in between things like kmem_cache_init(), kmem_cache_init_late(), and initcalls on the boot cpu. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>