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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pm4tX-005HBj-Uy; Tue, 11 Apr 2023 03:42:12 +0000 Date: Tue, 11 Apr 2023 04:42:11 +0100 From: Matthew Wilcox To: Andrew Morton Cc: Peng Zhang , Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org, David Binderman , stable@vger.kernel.org Subject: Re: [PATCH v2] maple_tree: Use correct variable type in sizeof Message-ID: References: <20230411023513.15227-1-zhangpeng.00@bytedance.com> <20230410202935.d1abf62f386eefb1efa36ce4@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230410202935.d1abf62f386eefb1efa36ce4@linux-foundation.org> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 180BAC000A X-Stat-Signature: qdcwzgs58khhhus4jgxc9jmarompmrww X-HE-Tag: 1681184540-970218 X-HE-Meta: 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 gED2Dbvd ueoXhrmlgemUn3cpAj+sC6ljdprCSzWjvLjI6Ci37AQt4bVjf84Mk+D46JAi0BMlbZBIwtP9yVZvnaqzQH8Odhi54vrxzNOe0Bt8wwpuMddMWoMDSaVjHkBwHmdEtN/eYA5IxkePZ/6YmDu/1RJIW3HRh59SbimV/PGFYJpZ/vqBGxVLGGrCaFjx+hjZfJIQH7C0IDM/C7azDXULW0z3OprT3F+BnTCp5EAbO197xOAXBK/3i4gRmTY3RUiLhCIs14O/x 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 Mon, Apr 10, 2023 at 08:29:35PM -0700, Andrew Morton wrote: > On Tue, 11 Apr 2023 10:35:13 +0800 Peng Zhang wrote: > > > The type of variable pointed to by pivs is unsigned long, but the type > > used in sizeof is a pointer type. Change it to unsigned long. > > Thanks, but there's nothing in this changelog which explains why a > -stable backport is being proposed. When fixing a bug, please always > describe the user-visible effects of that bug. There is no user-visible effect of this bug as the assembly code generated will be identical. > > --- a/lib/maple_tree.c > > +++ b/lib/maple_tree.c > > @@ -3255,7 +3255,7 @@ static inline void mas_destroy_rebalance(struct ma_state *mas, unsigned char end > > > > if (tmp < max_p) > > memset(pivs + tmp, 0, > > - sizeof(unsigned long *) * (max_p - tmp)); > > + sizeof(unsigned long) * (max_p - tmp)); > > > > if (tmp < mt_slots[mt]) > > memset(slots + tmp, 0, sizeof(void *) * (max_s - tmp)); > > Is there any situation in which > sizeof(unsigned long *) != sizeof(unsigned long)? Windows 64-bit (pointer 64-bit, unsigned long is 32 bit) is the only one I know. Linux is all ILP32 or LP64. There may be some embedded environments which are different, but I have no idea what they might be.