From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C8AEC11F68 for ; Wed, 30 Jun 2021 15:02:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 21AE0611CC for ; Wed, 30 Jun 2021 15:02:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235789AbhF3PFK (ORCPT ); Wed, 30 Jun 2021 11:05:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235352AbhF3PFI (ORCPT ); Wed, 30 Jun 2021 11:05:08 -0400 Received: from mail-wm1-x34a.google.com (mail-wm1-x34a.google.com [IPv6:2a00:1450:4864:20::34a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A4E74C061756 for ; Wed, 30 Jun 2021 08:02:39 -0700 (PDT) Received: by mail-wm1-x34a.google.com with SMTP id f9-20020a7bcd090000b02901eca9a0d67cso1438971wmj.0 for ; Wed, 30 Jun 2021 08:02:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=lvrIaQ6ThTaENrGFdNSy44zlHv6vzHwWs8O331HJaOs=; b=UedDNaHadRhM1ur9CcmhNsbBrMJzHEB1U+0r2AOapItU7e7vsnxt3c9g0LnyNpCox3 oY1ub/Vq0GNFDP4URYTbHrG8G5qqLvTSMvekpZ4F39GE+u/bot8Kanw4LCwn+j36aEhj i47cryF1FdWFZi8blrc9xRb9zSV5lPP5aTPFNlpA3Y2di1UfAV6KrCZKzGTJqnsnSEQU sgUjRWtus0jBIR8XPgwE9r6tldW5PgFmHRGZm3jmRejMWv/x/2NmjRQGf/uWQZsvRxvE ymtFZELBVHFsnM8UZ/4gj3dTCBECQeH/udKlGBdrzTQKS3VQ5J61/+i+aKSV6UlzGt7g 5ARQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=lvrIaQ6ThTaENrGFdNSy44zlHv6vzHwWs8O331HJaOs=; b=UbYIAiGfPkO6GiLOBpjew1MdzNAjYifKq3fOJue48YuNc+uI4haOl53qAaNJ40EBnb +ktyhXKEbKQkQI1FnuUZgpPcXOh+J+lQr+WKFiZnHYcvj/3FbCIYd7WbSKTrunAnna84 Nd8jALnlQP1WxkgCs5Io7KjnDDkjoxRAcQs1M54U6QfOTKUmYnR+F6LtCVOBRTfH51ej igzc5gkU4w3LFeNjb48TcZ1BvwtKcId8JVznAxb29mSR/dyYBP197OJplk5Yxteukj9y iBBJMxNXL0JRDizrVxsBJGGYgSiYo4fSc2sIM2saO8O85o/Xv/6kVTpTkpgaEr+otlQU QuUw== X-Gm-Message-State: AOAM532984wC2lo6CUbwqPpwEOIchVRhr8pYtZ/YF7+zo3siOYmuCxoT PZtdZZ5cm0rnWoX9uttslxSAGS5Slj0= X-Google-Smtp-Source: ABdhPJw3Yb4pAIycwjH7H7zCVelcp5Z4pYuZ2OS90TFwioUrU+wqzGQYm+MMsUvB66LM+CC6SclAOogXvy4= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:a3fc:e8:8089:1013]) (user=glider job=sendgmr) by 2002:a05:600c:1552:: with SMTP id f18mr39350083wmg.184.1625065358251; Wed, 30 Jun 2021 08:02:38 -0700 (PDT) Date: Wed, 30 Jun 2021 17:02:33 +0200 Message-Id: <20210630150234.1109496-1-glider@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.93.g670b81a890-goog Subject: [PATCH v4 1/2] kfence: move the size check to the beginning of __kfence_alloc() From: Alexander Potapenko To: akpm@linux-foundation.org Cc: dvyukov@google.com, elver@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, gregkh@linuxfoundation.org, jrdr.linux@gmail.com, Alexander Potapenko Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Check the allocation size before toggling kfence_allocation_gate. This way allocations that can't be served by KFENCE will not result in waiting for another CONFIG_KFENCE_SAMPLE_INTERVAL without allocating anything. Suggested-by: Marco Elver Cc: Andrew Morton Cc: Dmitry Vyukov Cc: Marco Elver Cc: Greg Kroah-Hartman Cc: stable@vger.kernel.org # 5.12+ Signed-off-by: Alexander Potapenko Reviewed-by: Marco Elver --- mm/kfence/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 4d21ac44d5d35..33bb20d91bf6a 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -733,6 +733,13 @@ void kfence_shutdown_cache(struct kmem_cache *s) void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) { + /* + * Perform size check before switching kfence_allocation_gate, so that + * we don't disable KFENCE without making an allocation. + */ + if (size > PAGE_SIZE) + return NULL; + /* * allocation_gate only needs to become non-zero, so it doesn't make * sense to continue writing to it and pay the associated contention @@ -757,9 +764,6 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) if (!READ_ONCE(kfence_enabled)) return NULL; - if (size > PAGE_SIZE) - return NULL; - return kfence_guarded_alloc(s, size, flags); } -- 2.32.0.93.g670b81a890-goog