6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Suren Baghdasaryan surenb@google.com
commit 4038016397da5c1cebb10e7c85a36d06123724a8 upstream.
When object extension vector allocation fails, we set slab->obj_exts to OBJEXTS_ALLOC_FAIL to indicate the failure. Later, once the vector is successfully allocated, we will use this flag to mark codetag references stored in that vector as empty to avoid codetag warnings.
slab_obj_exts() used to retrieve the slab->obj_exts vector pointer checks slab->obj_exts for being either NULL or a pointer with MEMCG_DATA_OBJEXTS bit set. However it does not handle the case when slab->obj_exts equals OBJEXTS_ALLOC_FAIL. Add the missing condition to avoid extra warning.
Fixes: 09c46563ff6d ("codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations") Reported-by: Shakeel Butt shakeel.butt@linux.dev Closes: https://lore.kernel.org/all/jftidhymri2af5u3xtcqry3cfu6aqzte3uzlznhlaylgrdzt... Signed-off-by: Suren Baghdasaryan surenb@google.com Cc: stable@vger.kernel.org # v6.10+ Acked-by: Shakeel Butt shakeel.butt@linux.dev Signed-off-by: Vlastimil Babka vbabka@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/slab.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/mm/slab.h +++ b/mm/slab.h @@ -572,8 +572,12 @@ static inline struct slabobj_ext *slab_o unsigned long obj_exts = READ_ONCE(slab->obj_exts);
#ifdef CONFIG_MEMCG - VM_BUG_ON_PAGE(obj_exts && !(obj_exts & MEMCG_DATA_OBJEXTS), - slab_page(slab)); + /* + * obj_exts should be either NULL, a valid pointer with + * MEMCG_DATA_OBJEXTS bit set or be equal to OBJEXTS_ALLOC_FAIL. + */ + VM_BUG_ON_PAGE(obj_exts && !(obj_exts & MEMCG_DATA_OBJEXTS) && + obj_exts != OBJEXTS_ALLOC_FAIL, slab_page(slab)); VM_BUG_ON_PAGE(obj_exts & MEMCG_DATA_KMEM, slab_page(slab)); #endif return (struct slabobj_ext *)(obj_exts & ~OBJEXTS_FLAGS_MASK);