On Mon, Sep 21, 2026 at 12:58:17AM -0700, Kees Cook wrote: > A bucket set holds one row of caches, cloned from KMALLOC_NORMAL, and an > allocation of any other kmalloc type falls back to the general caches. > Extend this to handle __GFP_ACCOUNT, so that a single bucket user can > isolate either GFP_KERNEL or GFP_KERNEL_ACCOUNT allocations, as is > needed for skb data, where AF_UNIX uses: > > sk->sk_allocation = GFP_KERNEL_ACCOUNT; > > The coverage is selected at bucket creation time: > > b = kmem_buckets_create_types(name, flags, 0, INT_MAX, NULL, > BIT(KMEM_BUCKET_NORMAL) | > BIT(KMEM_BUCKET_CGROUP)); > > The prior kmem_buckets_create() function keeps its name and defaults > to only KMEM_BUCKET_NORMAL, leaving existing users as-is. > > Only the accounted type is offered. Nothing wants a reclaimable or > no-obj-ext row, and of the twelve places passing GFP_DMA to an skb > allocator, all rare hardware: b44, b43legacy, prestera and s390 ctcm.
Well, yes, BUT I don't think silently falling back is a great option. I would rather things be done Properly(tm) and kmem_buckets allowing instantiation of most/all kmalloc cache types. Given it's security stuff, I would prefer being quite explicit over silent. Perhaps, to save on memory, users could choose to fall back to the default caches. But at kmem_buckets_create time. -- Pedro
