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Mon, 20 Apr 2026 03:35:16 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 20 Apr 2026 12:35:14 +0200 To: Shivam Kalra Cc: Uladzislau Rezki , Alice Ryhl , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Danilo Krummrich Subject: Re: [PATCH v10 0/4] mm/vmalloc: free unused pages on vrealloc() shrink Message-ID: References: <20260404-vmalloc-shrink-v10-0-335759165dfa@zohomail.in> <7d16f260-ffd0-4e45-b66e-9e7f71332466@zohomail.in> <85a9f419-7f1e-41a0-9e8e-67aae7a1b0fe@zohomail.in> <20d2e9f5-9b4a-477d-b3a0-5a268364d70f@zohomail.in> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20d2e9f5-9b4a-477d-b3a0-5a268364d70f@zohomail.in> On Fri, Apr 17, 2026 at 11:04:21PM +0530, Shivam Kalra wrote: > On 17/04/26 22:54, Uladzislau Rezki wrote: > > I have some questions to clarify. > > > > Why should we use min()? > > Checking vm->nr_pages, can it be 0? > > > > Can we just do: > > > > if (vm) > > /* Can not use get_vm_area_size() because of realloc(). */ > > size = vm->nr_pages << PAGE_SHIFT; > > else > > size = va_size(va); > > > > or i am missing something? > > > > Thanks! > > > > -- > > Uladzislau Rezki > I honestly don't know much about the usage > of this function, so wanted to be cautious. > > 1. We can skip the usage of min though. > 2. Do need (size_t) for overflow issue > > I can include this simple version with size_t, > let me know your thoughts. > if (vm) /* * Use the actual number of mapped pages, since realloc() * may shrink the mapping and area->size may be outdated. */ size = vm->nr_pages << PAGE_SHIFT; else size = va_size(va); As for the cast to size_t, i think it is unnecessary. An overflow can occur in either case. So let's keep it simple :) -- Uladzislau Rezki