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Sat, 24 Jan 2026 02:49:01 -0800 (PST) Received: from pc636 ([2001:9b1:d5a0:a500::800]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-385da1ab6acsm11193501fa.40.2026.01.24.02.49.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 24 Jan 2026 02:49:00 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Sat, 24 Jan 2026 11:48:59 +0100 To: "D. Wythe" Cc: Uladzislau Rezki , "David S. Miller" , Andrew Morton , Dust Li , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Sidraya Jayagond , Wenjia Zhang , Mahanta Jambigi , Simon Horman , Tony Lu , Wen Gu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org, oliver.yang@linux.alibaba.com Subject: Re: [PATCH net-next 2/3] mm: vmalloc: export find_vm_area() Message-ID: References: <20260123082349.42663-1-alibuda@linux.alibaba.com> <20260123082349.42663-3-alibuda@linux.alibaba.com> <20260124093505.GA98529@j66a10360.sqa.eu95> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260124093505.GA98529@j66a10360.sqa.eu95> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D8E2F1A0005 X-Stat-Signature: 5zi86eoskfymkyk4rze9gcer68fj6y8y X-Rspam-User: X-HE-Tag: 1769251743-518627 X-HE-Meta: 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 ZWN/hpC4 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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: List-Subscribe: List-Unsubscribe: Hello, D. Wythe! > On Fri, Jan 23, 2026 at 07:55:17PM +0100, Uladzislau Rezki wrote: > > On Fri, Jan 23, 2026 at 04:23:48PM +0800, D. Wythe wrote: > > > find_vm_area() provides a way to find the vm_struct associated with a > > > virtual address. Export this symbol to modules so that modularized > > > subsystems can perform lookups on vmalloc addresses. > > > > > > Signed-off-by: D. Wythe > > > --- > > > mm/vmalloc.c | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > index ecbac900c35f..3eb9fe761c34 100644 > > > --- a/mm/vmalloc.c > > > +++ b/mm/vmalloc.c > > > @@ -3292,6 +3292,7 @@ struct vm_struct *find_vm_area(const void *addr) > > > > > > return va->vm; > > > } > > > +EXPORT_SYMBOL_GPL(find_vm_area); > > > > > This is internal. We can not just export it. > > > > -- > > Uladzislau Rezki > > Hi Uladzislau, > > Thank you for the feedback. I agree that we should avoid exposing > internal implementation details like struct vm_struct to external > subsystems. > > Following Christoph's suggestion, I'm planning to encapsulate the page > order lookup into a minimal helper instead: > > unsigned int vmalloc_page_order(const void *addr){ > struct vm_struct *vm; > vm = find_vm_area(addr); > return vm ? vm->page_order : 0; > } > EXPORT_SYMBOL_GPL(vmalloc_page_order); > > Does this approach look reasonable to you? It would keep the vm_struct > layout private while satisfying the optimization needs of SMC. > Could you please clarify why you need info about page_order? I have not looked at your second patch. Thanks! -- Uladzislau Rezki