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Mon, 20 Apr 2026 03:35:16 -0700 (PDT) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5a4185bc672sm2933276e87.34.2026.04.20.03.35.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20d2e9f5-9b4a-477d-b3a0-5a268364d70f@zohomail.in> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E0102180009 X-Stat-Signature: qjbexufoikz8wbi8dkwfzsiaadbfxtcd X-Rspam-User: X-HE-Tag: 1776681318-751833 X-HE-Meta: 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 dSJSy+Q5 6gPJFA2dCpXzYTrysmNXwhu1M8h0ZGF1wYBdr4v3wTZjAjtzp7Wfw4CltX66MtCvK9x+FXIdLERciBrMzGqktCK4E3vYGY2QQxj9rsZgdwg4dYZU5ky3xYHONjiCwrya/4TWjLl1IPEg2xI9TNhcix/pVxE9dahybr3q5Gu+B6w4ElYFunW/Z9Tt2VhZKzqZ/G484dRV+E1bv98iBH0EdOADMdjucFXSgk7BDeqX7Dq7op3aeEUYQcPJsJuWCwP66b80WL/20A8qvprHEJ/xqkhldiYRuiT+5OVHsNDzG4lwGGfBk84g3AB7LjcV87wDmWEPYGfYZAzfju1mKrHHs6Sxu2/dhl67res64NQDRQzn/zikYJh1SfuNhPp+P9LKfwdH4u5f6CIqXisndoIFGeorEkYFhvptL/4CBMfo/PcJdKgD/WiXApSEQuVRUKhi4d8aBbmCgFG2K7yq09w48mcWfuwtCLzYoIpMd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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