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J . Alumbaugh" Subject: Re: [PATCH 3/3] mm/lru_gen: Don't build multi-gen LRU page table walk code on architecture not supported Message-ID: References: <20230613120047.149573-1-aneesh.kumar@linux.ibm.com> <20230613120047.149573-3-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 9psqbed1taj3fbfhszgnb4nznwxe4kb3 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: EAB1FC0011 X-Rspam-User: X-HE-Tag: 1686663368-143930 X-HE-Meta: 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 1twaS1hC eJsQeHz3/EzF6QuOBoq/JWcletJ32bSKcXLsocEY3fR+1Sa979D/hwkhTzIUV3S7bWsgio+s7gsIzHnyB4OyWouzwSqq6Ps052CZmjI2yoEkrM+HQcafYLGQZ+hHdisL5PaCzQmCYt9xW4WJKZumdPpEIWofHqOOce3VTa/8AgeBvB4IVTjE7W1J9v3Qt36h/ZQuSviVF4c2h+0E= 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 Tue, Jun 13, 2023 at 06:58:41PM +0530, Aneesh Kumar K V wrote: > On 6/13/23 5:53 PM, Matthew Wilcox wrote: > > On Tue, Jun 13, 2023 at 05:30:47PM +0530, Aneesh Kumar K.V wrote: > >> @@ -4498,7 +4533,7 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq, > >> goto done; > >> } > >> > >> - walk = set_mm_walk(NULL, true); > >> + walk = (struct lru_gen_mm_walk *)set_mm_walk(NULL, true); > > > > This isn't C++. > > > > We have similar pattern for things like kmalloc()? No. No, we don't. Nobody does that. Perhaps some really crappy code in staging. DO NOT USE CASTS. > I understand the desire to have functions return > the correct type. But the amount of code that we are able to avoid with this patch for certain architecture is > really large. There's probably a better way to do what you're trying to do, but the simple fact remains that the cast you added is needed in C++ and not in C. Linux is not written in C++. Do not add the cast.