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b=NbobTXkMaJCoz8B1Mrm3hCVPLVj/NtKblGSDve2mUncZusGL8g4sYRgASjGF0gVvM uCXWBjYEm5z39Dpy2JAiFmaQH9YjEoZJx/22LEC+tlKiTV3D2lngXBWtn+0l//J/Nd 47LbbMukEOiDqfEhkwK3kbyMXEX1/0Zt6eKey2ulLmMiQM8P7RTt8rpvMrnmXTvaAm S9MNZ241fc2loO7sYCqfh9pZ3K5HmYz4V9Pn0k4rJmI/QJ5KnIWoWAd1GkEwXj8lMN LepKOZmBmhsp4aKFd8NIVqnJEqpqHfqEsXEoTdu12NZmcSESILKLamATqeIiup3/Wd OpMQ38+d7Dz/Q== Date: Fri, 31 May 2024 09:48:49 -0700 From: Kees Cook To: Kent Overstreet Cc: Vlastimil Babka , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-hardening@vger.kernel.org, "GONG, Ruiqi" , Xiu Jianfeng , Suren Baghdasaryan , Jann Horn , Matteo Rizzo , Thomas Graf , Herbert Xu , julien.voisin@dustri.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/6] mm/slab: Plumb kmem_buckets into __do_kmalloc_node() Message-ID: <202405310943.D9818A4FE@keescook> References: <20240424213019.make.366-kees@kernel.org> <20240424214104.3248214-2-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 4E1E918001E X-Stat-Signature: nytckro4tuf8echa7k9oukmhty998smp X-HE-Tag: 1717174131-48913 X-HE-Meta: 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 cnSqVpma 4MQvOz0twp8W9YSFXfutQEzzBlbFKEUXk6xrtwPcGgCb6LOTkAfgYnoUiCjHFSfJ25OhbS6jJbTuKmoy2zdzsVAM+cJTZOrDiZ4ER+ryzm3HlK8J8UT/682I1sO14YgB4obHiAGk1zKy4F1tGIl3iFYfXvTwyh/i4/wv4wyr1+NiI5lwrlcoIaSajqxlw+XwdLd3PC1LHD5R6n8rKtxf5dyHV0YjaI+RndEIOWfB8cYylQKt+mHalcyfTs2bfPeuOldUrzRocT2EF7vs6+lohKycYeZA+Pp/NQKv/JdMPem1OMRUNVwumMJl3zA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, May 24, 2024 at 11:01:40AM -0400, Kent Overstreet wrote: > On Wed, Apr 24, 2024 at 02:40:59PM -0700, Kees Cook wrote: > > To be able to choose which buckets to allocate from, make the buckets > > available to the lower level kmalloc interfaces by adding them as the > > first argument. Where the bucket is not available, pass NULL, which means > > "use the default system kmalloc bucket set" (the prior existing behavior), > > as implemented in kmalloc_slab(). > > I thought the plan was to use codetags for this? That would obviate the > need for all this plumbing. > > Add fields to the alloc tag for: > - allocation size (or 0 if it's not a compile time constant) > - union of kmem_cache, kmem_buckets, depending on whether the > allocation size is constant or not I want to provide "simple" (low-hanging fruit) coverage that can live separately from the codetags-based coverage. The memory overhead for this patch series is negligible, but I suspect the codetags expansion, while not giant, will be more than some deployments will want. I want to avoid an all-or-nothing solution -- which is why I had intended this to be available "by default". But I will respin this with kmem_buckets under a Kconfig. -- Kees Cook