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 1BFAFC11F65 for ; Wed, 30 Jun 2021 14:02:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F40DC61446 for ; Wed, 30 Jun 2021 14:02:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236483AbhF3OEu (ORCPT ); Wed, 30 Jun 2021 10:04:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236413AbhF3OEb (ORCPT ); Wed, 30 Jun 2021 10:04:31 -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 A728AC09B094 for ; Wed, 30 Jun 2021 06:53:22 -0700 (PDT) Received: by mail-wm1-x34a.google.com with SMTP id n11-20020a05600c3b8bb02901ec5ef98aa0so548052wms.0 for ; Wed, 30 Jun 2021 06:53:22 -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=dtH0IQ32mjHBoYzYQxUVAIZ8CYFo4XITSUGYSoSmvuA=; b=n8OrDYvB4lu0VQjvPLvwRPRKVdXxpGavb6OmQT8FlcNgMfasGdem5Xe1GYKcQwQLjF eqsZ/j6Bbhjo4RwvKBjlIA3938u9XJL5kaLuPE+AemK9oldlEH9n/O7jYcK/nQm3nGC/ Nodeu3rbuP4Y585s02N0WHsbJ2x4Ya5xzJ+LCr23nVTYRDU3lUUHASCch1pHLLVWRqzx qK2MpDY+sFqPLYhBmtHXEGpiDV69xYuYF+iyRSt6NjSv0Iz7u/pnaDM80+VLCjkUWrmC MpK9GM8HVUwec7+08q8yLbjtgq8yh5ljCYRIegMIXTR9+YZw73NAB/ZVV8kyVtmNYwC6 MRIQ== 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=dtH0IQ32mjHBoYzYQxUVAIZ8CYFo4XITSUGYSoSmvuA=; b=Be6xiCglaHdZgQMbhOJg/bmspIN+LzXgaaVGPrmOqERMdpv/TB/XYVQBm4ElaAQ4cV mXGLQ/aH6Bik79gw0AdgtRHW/9ho4aqjKr+p8k9xt7I2LOrkOIkjtztkiQEZd5XoUi1y kxyzkIBGkuFMz84mfb+Bo+51f96PK42JLXDb3r7eea+p0pSx3EwM9s/r7RZlf0YFXtMd WcgSiUF2VBqizB/X84odAOV7fPj8I1okh8zGhIhG+l3vt61zjRSLXoGMeKaMV5D1znZ+ EPWwNbr/P5+lnhYd7Sp0rzkjn0yOMjnPvHYBytgHonbRGwY/d4cX2HOsnO4BofuXa5zf D+9w== X-Gm-Message-State: AOAM5304+BpswndDKrujBKUUgpcRJZaDfJ+ieJjmS4c3mcWrFFYnmxPp aXNN2MYWzAiPN1BoRqnmFM9+MydyIuM= X-Google-Smtp-Source: ABdhPJxEOOWrV1qY5ZQLKAMR0q+wxV55Lm0/JLt5nQqznaRHf1ul1AN8gIWXEvsyC132NIT7onyLV9XuHP4= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:a3fc:e8:8089:1013]) (user=glider job=sendgmr) by 2002:a1c:638a:: with SMTP id x132mr4681717wmb.90.1625061200569; Wed, 30 Jun 2021 06:53:20 -0700 (PDT) Date: Wed, 30 Jun 2021 15:53:12 +0200 Message-Id: <20210630135313.1072577-1-glider@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.93.g670b81a890-goog Subject: [PATCH v3 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 --- 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