On 8/7/24 11:07, Pedro Falcato wrote: > Duplicate slab cache names can create havoc for userspace tooling that > expects slab cache names to be unique. This is a reasonable expectation. > > Sadly, too many duplicate name problems are out there in the wild, so > simply pr_warn instead of pr_err() + failing the sanity check. > > Link: https://lore.kernel.org/linux-fsdevel/2d1d053da1cafb3e7940c4f25952da4f0af34e38.1722293276.git.osandov@xxxxxx/ > Signed-off-by: Pedro Falcato <pedro.falcato@xxxxxxxxx> > --- > v2: > - Replace the pr_err() + failure with a simple pr_warn > > Contrary to Vlastimil's suggestion, we don't seem to require a refcount > == 0 check, because shutdown_cache already synchronously deletes the cache from the list (even reusing > the same list_head for TYPESAFE_BY_RCU). It's not deleted when leaked objects are detected and the destroy is aborted. But in this series that should no longer happen so then it will be fine: https://lore.kernel.org/all/20240807-b4-slab-kfree_rcu-destroy-v2-0-ea79102f428c@xxxxxxx/ > > mm/slab_common.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 40b582a014b..1abe6a577d5 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -88,6 +88,19 @@ unsigned int kmem_cache_size(struct kmem_cache *s) > EXPORT_SYMBOL(kmem_cache_size); > > #ifdef CONFIG_DEBUG_VM > + > +static bool kmem_cache_is_duplicate_name(const char *name) > +{ > + struct kmem_cache *s; > + > + list_for_each_entry(s, &slab_caches, list) { > + if (!strcmp(s->name, name)) > + return true; > + } > + > + return false; > +} > + > static int kmem_cache_sanity_check(const char *name, unsigned int size) > { > if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { > @@ -95,6 +108,11 @@ static int kmem_cache_sanity_check(const char *name, unsigned int size) > return -EINVAL; > } > > + if (kmem_cache_is_duplicate_name(name)) { > + /* Duplicate names will confuse slabtop, et al */ > + pr_warn("%s: name %s already exists as a cache\n", __func__, name); > + } > + > WARN_ON(strchr(name, ' ')); /* It confuses parsers */ > return 0; > }
