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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id k25-20020aa792d9000000b0068c0fcb40d3sm3306512pfa.211.2023.09.15.13.59.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Sep 2023 13:59:22 -0700 (PDT) Date: Fri, 15 Sep 2023 13:59:22 -0700 From: Kees Cook To: Matteo Rizzo Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, corbet@lwn.net, luto@kernel.org, peterz@infradead.org, jannh@google.com, evn@google.com, poprdi@google.com, jordyzomer@google.com Subject: Re: [RFC PATCH 04/14] mm: use virt_to_slab instead of folio_slab Message-ID: <202309151359.D608396BF@keescook> References: <20230915105933.495735-1-matteorizzo@google.com> <20230915105933.495735-5-matteorizzo@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230915105933.495735-5-matteorizzo@google.com> X-Rspamd-Queue-Id: 764F2140006 X-Rspam-User: X-Stat-Signature: mmwtdoqa5hteumbyazj9pz8r6ngpc875 X-Rspamd-Server: rspam01 X-HE-Tag: 1694811564-156345 X-HE-Meta: U2FsdGVkX19+m1i9kBuNJgrcwSEWjUJlV2gZDf4euf+PyxjzXVaamFwCNGerYHsLGa8HrSwYCuKj1dXkYp/lg+pNAMAguxrFouS+NGR/+MDXDID9h/3ALbXDL1ZsjGUsO+91CUFcTJLiWSvx8Rb/RHDc4zJOK6kCf7VrRfqQjmxzehoaa7fZvebsIg0Rt4vZlesah1nu4EluxiseQapH5HYEliZ34aqrdMMqTUC/nnFNOkUN2OuZO8qrbORo3y40KS7NtPyIaEifd/85kq4k6Ujp7Eb5rmbQG39JPdFTlMYSFT8yrk17m/qeR34wYqhMkHCm285MxgxSJfK2m0j8a/88EpsG5mpWyvZvUvBuPQRLlFhizEUb4HFVNdWAAkM8SNqQMuFay+l/TvEB2BW4+JXtHxtBfsFNX9gpymkJ64zh4qy5KuwT0fae6+PE5VEUlJHNKO+lHJXGNEtpBayal29cZMSK1Dej1VT8zrn56OqnjdPxim2C3+hLd/6c+ya/iY+nTJh5L4gZJWX41EJhp2s9ibkDeobKGhHcPpOCXwKSCixq89JO7x2A+QtI79kd75N9Fl9g68VWVkgTxhCO5GwCeP4uOLW9UMlsn4ojTFls1QfnpEy/GvflG43/s413Oi3qhhpBqN4W1Ciz45VqLJ8ZBHaQ/NQV2/JHyZLXRZ8hTcsuUj7aw3sfNR2IIqQZ4lWf5ccbzxt53I46D0BNOOfHYS8asQ2pHBv0Z9cBRrmd24XwiSOR3a0KSdZTsXWR6zooyXvx9WKhKTSp6TgP7dLaNbQMXDJbxprSnhTCehziI3l08XRr5nQN/h758ASakZVL0dS1ZHpjyowkGC0JM44D/A4ZGU4VC98houswU8fWjBpbT+FEfzQUoI3ZoWFWjyM+fF0ASTLRU47ZQd6kjL0mc3WlPjljADV3ea17WoptSL00UjsIqnFYQ6vJGaEsGtLV7vb9M5RjSpPGKBV hZhFu5CF 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 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: On Fri, Sep 15, 2023 at 10:59:23AM +0000, Matteo Rizzo wrote: > From: Jann Horn > > This is refactoring in preparation for the introduction of SLAB_VIRTUAL > which does not implement folio_slab. > > With SLAB_VIRTUAL there is no longer a 1:1 correspondence between slabs > and pages of physical memory used by the slab allocator. There is no way > to look up the slab which corresponds to a specific page of physical > memory without iterating over all slabs or over the page tables. Instead > of doing that, we can look up the slab starting from its virtual address > which can still be performed cheaply with both SLAB_VIRTUAL enabled and > disabled. > > Signed-off-by: Jann Horn Refactoring continues to track. Reviewed-by: Kees Cook -- Kees Cook