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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 66F2CC31E40 for ; Mon, 12 Aug 2019 16:06:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 476A420665 for ; Mon, 12 Aug 2019 16:06:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726693AbfHLQGu (ORCPT ); Mon, 12 Aug 2019 12:06:50 -0400 Received: from foss.arm.com ([217.140.110.172]:52304 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725923AbfHLQGs (ORCPT ); Mon, 12 Aug 2019 12:06:48 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2D24F1715; Mon, 12 Aug 2019 09:06:48 -0700 (PDT) Received: from arrakis.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 29A6B3F718; Mon, 12 Aug 2019 09:06:47 -0700 (PDT) From: Catalin Marinas To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Michal Hocko , Matthew Wilcox , Qian Cai Subject: [PATCH v3 1/3] mm: kmemleak: Make the tool tolerant to struct scan_area allocation failures Date: Mon, 12 Aug 2019 17:06:40 +0100 Message-Id: <20190812160642.52134-2-catalin.marinas@arm.com> X-Mailer: git-send-email 2.23.0.rc0 In-Reply-To: <20190812160642.52134-1-catalin.marinas@arm.com> References: <20190812160642.52134-1-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Object scan areas are an optimisation aimed to decrease the false positives and slightly improve the scanning time of large objects known to only have a few specific pointers. If a struct scan_area fails to allocate, kmemleak can still function normally by scanning the full object. Introduce an OBJECT_FULL_SCAN flag and mark objects as such when scan_area allocation fails. Signed-off-by: Catalin Marinas --- mm/kmemleak.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index f6e602918dac..5ba7fad00fda 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -168,6 +168,8 @@ struct kmemleak_object { #define OBJECT_REPORTED (1 << 1) /* flag set to not scan the object */ #define OBJECT_NO_SCAN (1 << 2) +/* flag set to fully scan the object when scan_area allocation failed */ +#define OBJECT_FULL_SCAN (1 << 3) #define HEX_PREFIX " " /* number of bytes to print per line; must be 16 or 32 */ @@ -773,12 +775,14 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp) } area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp)); - if (!area) { - pr_warn("Cannot allocate a scan area\n"); - goto out; - } spin_lock_irqsave(&object->lock, flags); + if (!area) { + pr_warn_once("Cannot allocate a scan area, scanning the full object\n"); + /* mark the object for full scan to avoid false positives */ + object->flags |= OBJECT_FULL_SCAN; + goto out_unlock; + } if (size == SIZE_MAX) { size = object->pointer + object->size - ptr; } else if (ptr + size > object->pointer + object->size) { @@ -795,7 +799,6 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp) hlist_add_head(&area->node, &object->area_list); out_unlock: spin_unlock_irqrestore(&object->lock, flags); -out: put_object(object); } @@ -1408,7 +1411,8 @@ static void scan_object(struct kmemleak_object *object) if (!(object->flags & OBJECT_ALLOCATED)) /* already freed object */ goto out; - if (hlist_empty(&object->area_list)) { + if (hlist_empty(&object->area_list) || + object->flags & OBJECT_FULL_SCAN) { void *start = (void *)object->pointer; void *end = (void *)(object->pointer + object->size); void *next;