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Thu, 13 May 2021 05:38:29 -0700 (PDT) Received: from hyeyoo ([121.135.181.35]) by smtp.gmail.com with ESMTPSA id t19sm2148448pgv.75.2021.05.13.05.38.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 May 2021 05:38:28 -0700 (PDT) Date: Thu, 13 May 2021 21:38:22 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Marco Elver Cc: Vlastimil Babka , Andrew Morton , Joonsoo Kim , David Rientjes , Pekka Enberg , Christoph Lameter , Linux Memory Management List , LKML Subject: Re: [PATCH v3] mm, slub: change run-time assertion in kmalloc_index() to compile-time Message-ID: <20210513123822.GA776220@hyeyoo> References: <20210511173448.GA54466@hyeyoo> <20210512195227.245000695c9014242e9a00e5@linux-foundation.org> <20210513031220.GA133011@hyeyoo> <20210512204024.401ff3de38649d7d0f5a45e8@linux-foundation.org> <20210513062809.GA319973@hyeyoo> <20210513120339.GA772931@hyeyoo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 3434580192E1 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=hA41ma5H; spf=pass (imf08.hostedemail.com: domain of 42hyeyoo@gmail.com designates 209.85.210.173 as permitted sender) smtp.mailfrom=42hyeyoo@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam04 X-Stat-Signature: 14warbmbfa8iexnc3a7psknhi5bfraa6 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from="<42.hyeyoo@gmail.com>"; helo=mail-pf1-f173.google.com; client-ip=209.85.210.173 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620909482-951631 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 Thu, May 13, 2021 at 02:29:13PM +0200, Marco Elver wrote: > On Thu, 13 May 2021 at 14:03, Hyeonggon Yoo <42.hyeyoo@gmail.com> wrote: > > On Thu, May 13, 2021 at 12:31:38PM +0200, Marco Elver wrote: > [...] > > what about checking size it on top of kmalloc_index? because by definition of > > KMALLOC_SHIFT_HIGH, it's not always 25. it can be less than 25. for some > > situations. > > > > below is what I suggested beofre. for just reference: > > This doesn't solve the problem. We want the compiler to complain > whenever kmalloc_index() is used with non-constant in normal code. in the beginning, I thought kmalloc_index is called only from kmalloc. but if kmalloc_index is called from other place, I think it should correctly check its size. that's what kmalloc_index should do. or... should it be solved as another patch?