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Mon, 24 Mar 2025 09:16:47 -0700 (PDT) Date: Mon, 24 Mar 2025 09:16:47 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: Kees Cook cc: Vlastimil Babka , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, Miguel Ojeda , Nathan Chancellor , Marco Elver , Nick Desaulniers , Przemek Kitszel , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH 5/5] [DEBUG] slab: Report number of NULLings In-Reply-To: <20250321204105.1898507-5-kees@kernel.org> Message-ID: References: <20250321202620.work.175-kees@kernel.org> <20250321204105.1898507-5-kees@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5BA0180003 X-Stat-Signature: ki86m7kg3kf5tiu9gutiqwdthu8eo4fy X-HE-Tag: 1742833731-151327 X-HE-Meta: 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 yKwymWcC mkDaQXE5lmPrC4KSWPhOm6DbMZVneYFU1nlBC0X1aZu1sWA3G77FIA3iH0n27y0LpidTQZRd46ScWDOsxAz4MewFqhl5J4Rmsps3xt8Qd588LBZZXpnGpjn1n8zskKYg28j1xLkvyMX6PA/WqBl2QIz6sh0tR72cCYUwGAADUx9PBe8y11JHwBQfJlNRFuBJ1uoxr1H2pcidj+Xk2nRKjp5X3bIQeM4x9QCNr5dyU6tDtK9iGyEH1YWpk5yTqxsCk3PL9RHd8XZRCOiber3+6gr+RybDGYTJWgyYXg/EZelt9s1rb6ARTuU2X1Vbi/kfBv2+7 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, 21 Mar 2025, Kees Cook wrote: > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 2717ad238fa2..a4740c8b6ccb 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -469,6 +469,8 @@ void __kfree(const void *objp); > void __kfree_sensitive(const void *objp); > size_t __ksize(const void *objp); > > +extern atomic_t count_nulled; That is a scalability issue. Use a vmstat counter instead?