From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F0C3453A59; Thu, 8 Oct 2026 21:25:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791494717; cv=none; b=f0p8yBEytPbGG6VWiEMb40c49vkaKks2RY80DrNMC4mYedNARxnucV/aW8JZhbmhA9bpcjb7cOFJ1xh2fm6wNmCzMlNqrpNA3s5YTYwevyodMGDxNw4A8eSyCiELYHWh/jPK9A0qY51kO5sZZ0jNOpwYcOnpIZji6hJtkUvHgj4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791494717; c=relaxed/simple; bh=uPub7OsJ8q3R9qEr6Szplyq7ywrqFt4oHq+xrWrCVEo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TgfNLq068SW8JvyjLBUfK4rYfe44iaR7vTgwXQl8rUTK84xlT3a56OSbg6kchHGBTkdH+R4hXs1ACQO70EW3klk7tzGSFRdGemnghhi+CA23qBSejEW116a1C9nX0ifllC2iSB620SIbZnpqm2rG5xX22llxxcL4ird0bAa+TQI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZjJl/wo1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZjJl/wo1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20B5F1F000FF; Thu, 8 Oct 2026 21:25:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791494715; bh=odDRkTcjbS423eFUVzRKgzpHhfm86iv3G3/SNcHY7is=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=ZjJl/wo18DivxZod9Ph2FuLJmJ0Pe6BmpQB57sdezehMYyARbOEVU8OGYlasU7V/S 0AT+zRfhasFu1NUWqERoTuQdlxiQP3IIeICSISEgSyXXl35VozAJVTNxB2bysN99vf JfipJu9WkWWRjdDZiddIe/cXmY43UZwTIiDZnEwIxtK2IGH0UoFZxfezn7ejJCJdq4 QGd6BQqNjD2yQzAqk9ixMc4c11z/zcWVonaLCd7MlyrrU4sbCkmiHW5YBwRkvRDG8U qZmSxy/lRaMiD4+hT2CFnuTLIH1WH3eg5IzgqjHuPhhOOpSdCVlAbQNo7AT/fvx+ph VX7EkFoGAlt2g== Date: Thu, 8 Oct 2026 23:25:13 +0200 From: Harry Yoo To: Kees Cook Cc: Vlastimil Babka , "David S. Miller" , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Pedro Falcato , Kuniyuki Iwashima , Christian Brauner , Jan Kara , Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Willem de Bruijn , Jason Xing , cgroups@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH net-next v6 0/8] net: skb: isolate skb data area allocations into a separate bucket Message-ID: References: <20261006092030.got.500-kees@kernel.org> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261006092030.got.500-kees@kernel.org> On Tue, Oct 06, 2026 at 02:20:26AM -0700, Kees Cook wrote: > Hi! Hi Kees! Was hoping to say hi to you at LPC but I missed the chance ;) Maybe next time. Safe travels! Uh, my mailbox stopped working for a few days as I forgot to renew subscription. (Kiryl told me it's bouncing, thanks!) Hopefully I didn't miss too much... > This gets the buckets able to handle memcg (GFP_KERNEL_ACCOUNT) with > isolation (since it's common due to AF_UNIX), Cool! > and GFP_DMA with fall back > (since it's rare). > It gave me an excuse to build out bucket kunit tests > too, and that (and LLM review) found a couple other issues that needed > fixing too, including msg_msg allocations going uncharged to their memcg > when CONFIG_SLAB_BUCKETS=n (fixed in 2/8). Oh. > Harry, on your v4 question[1] about bucket users giving their own > alignment: I tried that in v5, but a set's allocations don't always > come from its own caches. With CONFIG_SLAB_BUCKETS=n, after a failed > kmem_buckets_create(), and for the DMA and reclaimable fallbacks, they > come from the general kmalloc caches, which can only give kmalloc()'s > alignment. > > So v6 goes back to mirroring the kmalloc cache's alignment, I might be missing something, but why is that a problem? For kmem_buckets users, the reason* to specify alignment is because they might need less strict alignment than kmalloc. (*Perhaps it's nice to document that in the comment) However, because kmem_buckets can fall back to kmalloc on e.g. kernels w/o CONFIG_SLAB_BUCKETS, it should be fine to fall back. No? Creating kmem_buckets with more strict alignment than kmalloc doesn't make sense. > and drops the ctor and flags arguments for the same reason. Uh, for ctor and flags, yes. We can't have them in kmem_buckets. > And the whole > exploration made me realize I had a completely wrong understanding of > how memcg worked. :P > > The bulk of this is mm/slab, but the final patch is netdev, which Paolo > acked in v4, so I'm hoping this whole series can go via slab? Going thorough slab/for-next sounds reasonable to me once it gets some reviews. Vlastimil? -- Cheers, Harry / Hyeonggon