On Tue, 2012-07-03 at 15:36 -0500, Christoph Lameter wrote: > Looking through the emails it seems that there is an issue with alias > strings. To be more precise, there seems no big issue currently. I just wanted to make following usage of kmem_cache_create (SLUB) possible: name = some string kmalloced kmem_cache_create(name, ...) kfree(name); And from my understanding of the code, the saved_alias list, which is used to keep track of the alias entries during early boot (slab_state < SYSFS), is a blocker. It needs the name string to be valid until slab_sysfs_init() is finished. > That can be solved by duping the name of the slab earlier in kmem_cache_create(). > Does this patch fix the issue? I'm afraid not... With the patch below, we still need to kfree the duplicated name in slab_sysfs_init(). And I think it would be easier to understand if we duplicate the name string when creating one entry for saved_alias list, and kfree it when we remove one entry from saved_alias list. I'm not sure whether you got the patch #1 of the two I sent previously. If not, would you kindly spend some time reviewing it to see if I missed anything? Link below for your convenience: https://lkml.org/lkml/2012/6/27/83 Btw, as Ben suggested, I'm now working on duplicating the name string in SLAB to make them consistent, so we don't need the #ifdef CONFIG_SLUB any more. Will send it out for your review after it is finished. > Subject: slub: Dup name earlier in kmem_cache_create > > Dup the name earlier in kmem_cache_create so that alias > processing is done using the copy of the string and not > the string itself. > > Signed-off-by: Christoph Lameter <cl@xxxxxxxxx> > > --- > mm/slub.c | 29 ++++++++++++++--------------- > 1 file changed, 14 insertions(+), 15 deletions(-) > > Index: linux-2.6/mm/slub.c > =================================================================== > --- linux-2.6.orig/mm/slub.c 2012-06-11 08:49:56.000000000 -0500 > +++ linux-2.6/mm/slub.c 2012-07-03 15:17:37.000000000 -0500 > @@ -3933,8 +3933,12 @@ struct kmem_cache *kmem_cache_create(con > if (WARN_ON(!name)) > return NULL; > > + n = kstrdup(name, GFP_KERNEL); > + if (!n) > + goto out; > + > down_write(&slub_lock); > - s = find_mergeable(size, align, flags, name, ctor); > + s = find_mergeable(size, align, flags, n, ctor); > if (s) { > s->refcount++; > /* > @@ -3944,7 +3948,7 @@ struct kmem_cache *kmem_cache_create(con > s->objsize = max(s->objsize, (int)size); > s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *))); > > - if (sysfs_slab_alias(s, name)) { > + if (sysfs_slab_alias(s, n)) { > s->refcount--; > goto err; > } > @@ -3952,31 +3956,26 @@ struct kmem_cache *kmem_cache_create(con > return s; > } > > - n = kstrdup(name, GFP_KERNEL); > - if (!n) > - goto err; > - > s = kmalloc(kmem_size, GFP_KERNEL); > if (s) { > if (kmem_cache_open(s, n, > size, align, flags, ctor)) { > list_add(&s->list, &slab_caches); > up_write(&slub_lock); > - if (sysfs_slab_add(s)) { > - down_write(&slub_lock); > - list_del(&s->list); > - kfree(n); > - kfree(s); > - goto err; > - } > - return s; > + if (!sysfs_slab_add(s)) > + return s; > + > + down_write(&slub_lock); > + list_del(&s->list); > } > kfree(s); > } > - kfree(n); > + > err: > + kfree(n); > up_write(&slub_lock); > > +out: > if (flags & SLAB_PANIC) > panic("Cannot create slabcache %s\n", name); > else > -- 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>