Re: [PATCH v4 2/7] mm/slab: Give bucket caches the alignment of the caches they mirror
From: Kees Cook <kees@kernel.org>
Date: 2026-09-25 01:00:45
Also in:
linux-hardening, linux-mm, lkml
On Thu, Sep 24, 2026 at 07:22:58PM +0100, Harry Yoo wrote:
On Mon, Sep 21, 2026 at 04:25:25PM -0700, Kees Cook wrote:quoted
On Mon, Sep 21, 2026 at 02:17:21PM +0100, Harry Yoo wrote:quoted
On Mon, Sep 21, 2026 at 12:58:13AM -0700, Kees Cook wrote:quoted
if (WARN_ON(!cache_name)) goto fail; (*b)[aligned_idx] = kmem_cache_create_usercopy(cache_name, size, - 0, flags, cache_useroffset, + kmalloc_caches[KMALLOC_NORMAL][idx]->align, + flags, cache_useroffset, cache_usersize, ctor); kfree(cache_name); if (WARN_ON(!(*b)[aligned_idx]))It looks "obviously correct", but I probably failed to correctly describe it. I'm happy to do whatever here.That is correct, but is there any reason why kmem_buckets users should not specify their own alignment requirement and inherit the alignment from kmalloc? For DMA yeah it might be confusing for every user to figure out that the alignment should be __kmalloc_minalign(), but otherwise there isn't really a good enough reason to inherit the alignment from kmalloc, no?
Oh, so you mean explicitly add an alignment arg to kmem_buckets_create()? And perhaps if _that_ one is "0" we can fallback to whatever kmalloc_caches uses? -- Kees Cook