From nobody Sun May 10 20:32:08 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DE42C433F5 for ; Sun, 24 Apr 2022 10:48:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239145AbiDXKva (ORCPT ); Sun, 24 Apr 2022 06:51:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239046AbiDXKvN (ORCPT ); Sun, 24 Apr 2022 06:51:13 -0400 Received: from mail-ej1-x633.google.com (mail-ej1-x633.google.com [IPv6:2a00:1450:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C71E17D496 for ; Sun, 24 Apr 2022 03:48:12 -0700 (PDT) Received: by mail-ej1-x633.google.com with SMTP id dk23so1099006ejb.8 for ; Sun, 24 Apr 2022 03:48:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=ifhTT6RWFXDH8HUEGtKLOt2yTklDAIxczpprS6iV9sg=; b=n55X0jCN3rd+35JSwnUSgh9WdYBxyYC0C/eVbUYHLd6G/I6dl3R66sgt7bEARIfGPa U92qMQviohsxEm8dzT6VPNZAOWPWPkmkagUDnTXNEahjzw0aG1oXAZvj+PL5VLH+k6W7 Raogl5ajpBl4qazS8tw3BSG+K91ZsMchhewqdP2+R4NlVa+C3SEM1/7YXBrVsbW1cDpw G7ofklYP3B9U9CJKYXyNZXllYXfe1t7SSugAFpFbyF9PtSXVrOmlCArrgfsDbksCPs6p Q5G1HXk+YyEETVU2m7kWdTuzlcU4En35jAd5km5GeX1MOwcdWcCKqQuS7eCU+xYpnE04 hlUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=ifhTT6RWFXDH8HUEGtKLOt2yTklDAIxczpprS6iV9sg=; b=iXpMTJuPU1zVhx+C/Zewr8KaC5hafUw8BBiLoZx7jpgGU6/o76bETiQCSJV1+PZXxP xehlA7ec49MkxPAVXPOUmg8wkSPiEWzMbBbj15B/lSb/kKZ1QjCbRi8OGa7JZCFxp2Qv cZjTYC+99ufeKMcjPTKA5ZXGfAMKE4WLWcYp3Ml00NXjoKLIP1r8EhNdoOuzG4zOaiyV /eqelOYS5YGwFdsKWj9fN2+AbIZvkfl5d2yR1J+2GQCNU9QTZPNK3oGyJcCvXzCYhjUl E/rvOExd7meGMXd66aB/KqLUD137WHN0JAd6vHxSlMOC6vQplkrj65m1k7enJCubHpWg 3Cew== X-Gm-Message-State: AOAM533ZOkl0rBLBsLKI7b8Q4glvuM5msuTpWm1OOKRwD18GyevLD7ul 18cqvJhquVY3/rtlkEZH4f8= X-Google-Smtp-Source: ABdhPJyLnX5s8GUwwVixgNEumHfZfhOyeKA+Mb3i/nZlf3WAx/M2bsxGm8F1BOaIVNiAJKwj/PVt9A== X-Received: by 2002:a17:906:c116:b0:6f3:832f:3c8 with SMTP id do22-20020a170906c11600b006f3832f03c8mr3765451ejc.235.1650797291042; Sun, 24 Apr 2022 03:48:11 -0700 (PDT) Received: from localhost.localdomain (host-79-50-86-254.retail.telecomitalia.it. [79.50.86.254]) by smtp.gmail.com with ESMTPSA id h8-20020a1709066d8800b006e09a49a713sm2488133ejt.159.2022.04.24.03.48.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 24 Apr 2022 03:48:09 -0700 (PDT) From: "Fabio M. De Francesco" To: Ira Weiny , Andrew Morton , "Matthew Wilcox (Oracle)" , Catalin Marinas , Will Deacon , Peter Collingbourne , linux-kernel@vger.kernel.org Cc: "Fabio M. De Francesco" Subject: [RFC PATCH] mm/highmem: VM_BUG_ON() if offset + len > PAGE_SIZE Date: Sun, 24 Apr 2022 12:48:06 +0200 Message-Id: <20220424104806.25396-1-fmdefrancesco@gmail.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Call VM_BUG_ON() if offset + len > PAGE_SIZE. This is an RFC patch because I'm not sure if we actually need to BUG_ON(), so I'd like to know what Maintainers and other developers think about this proposal. Please note that memset_page() uses VM_BUG_ON() to prevent the same issue. Furthermore, I also cannot understand why memset_page() does not call flush_dcache_page() after memset() but I suppose that the different implementations of these two functions should be addressed in another RFC. Signed-off-by: Fabio M. De Francesco --- include/linux/highmem.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index c3d562b5f0c1..bdb16d5f8148 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -349,6 +349,8 @@ static inline void memcpy_to_page(struct page *page, si= ze_t offset, static inline void memzero_page(struct page *page, size_t offset, size_t l= en) { char *addr =3D kmap_local_page(page); + + VM_BUG_ON(offset + len > PAGE_SIZE); memset(addr + offset, 0, len); flush_dcache_page(page); kunmap_local(addr); --=20 2.34.1