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AJvYcCWS3ar1TX6QYCO0CCvkRGq9L9cWqvAzjtSobX4dDIeh/SZ9QCsp7KCoJpTGxj+LOsqFH9Ze8jAx0g==@kvack.org X-Gm-Message-State: AOJu0YwZtc8gdKj9oevVGbOAwxlTvAzq0nXy4oto77iJzG+Vm0GPDdy3 9kcrlrc4O4j9AmzL09Nioh+sQSXYV2M2M48hMpf6T4tfEQt9iJVGVp9C7El6LHLRYFy+pU5qB5e 7yZVWXrD24sFBwBiZkA== X-Received: from wmsk23-n2.prod.google.com ([2002:a05:600d:8497:20b0:487:f69:2be4]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:4705:b0:46e:4e6d:79f4 with SMTP id 5b1f17b1804b1-486fee0e2ecmr212740435e9.15.1774350114065; Tue, 24 Mar 2026 04:01:54 -0700 (PDT) Date: Tue, 24 Mar 2026 11:01:53 +0000 In-Reply-To: <20260324-vmalloc-shrink-v7-2-c0e62b8e5d83@zohomail.in> Mime-Version: 1.0 References: <20260324-vmalloc-shrink-v7-0-c0e62b8e5d83@zohomail.in> <20260324-vmalloc-shrink-v7-2-c0e62b8e5d83@zohomail.in> Message-ID: Subject: Re: [PATCH v7 2/6] mm/vmalloc: fix vrealloc() grow-in-place check From: Alice Ryhl To: shivamkalra98@zohomail.in Cc: Andrew Morton , Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Danilo Krummrich Content-Type: text/plain; charset="utf-8" X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: F1696140002 X-Stat-Signature: i4s3szj7qeoyb15s6iuqsemgwmj9uq96 X-HE-Tag: 1774350115-408795 X-HE-Meta: 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 YD0X3rs4 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 24, 2026 at 03:30:27PM +0530, Shivam Kalra via B4 Relay wrote: > From: Shivam Kalra > > Fix the grow-in-place check in vrealloc() to compare the requested size > against the actual physical page count (vm->nr_pages) rather than the > virtual area size (alloced_size, derived from get_vm_area_size()). > > The virtual reservation size (get_vm_area_size()) does not decrease when > pages are freed during a shrink operation. Consequently, without this fix, > a subsequent grow-in-place operation after a shrink would incorrectly > succeed and attempt to access freed pages. Correcting this check is a > prerequisite for the upcoming vrealloc() shrink functionality. > > Signed-off-by: Shivam Kalra This commit is titled 'fix', but is it actually a fix for a bug that exists today? Or is it just a refactor to support the follow-up shrinking logic? Alice