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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 7FC99C10F14 for ; Thu, 18 Apr 2019 10:39:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50B0E20656 for ; Thu, 18 Apr 2019 10:39:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388665AbfDRKji (ORCPT ); Thu, 18 Apr 2019 06:39:38 -0400 Received: from relay.sw.ru ([185.231.240.75]:53410 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388369AbfDRKji (ORCPT ); Thu, 18 Apr 2019 06:39:38 -0400 Received: from [172.16.25.12] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1hH4Rp-0002dq-HX; Thu, 18 Apr 2019 13:39:17 +0300 Subject: Re: [patch V2 09/29] mm/kasan: Simplify stacktrace handling To: Thomas Gleixner , LKML Cc: Josh Poimboeuf , x86@kernel.org, Andy Lutomirski , Steven Rostedt , Alexander Potapenko , Dmitry Vyukov , kasan-dev@googlegroups.com, linux-mm@kvack.org, Alexey Dobriyan , Andrew Morton , Pekka Enberg , David Rientjes , Christoph Lameter , Catalin Marinas , Mike Rapoport , Akinobu Mita , iommu@lists.linux-foundation.org, Robin Murphy , Christoph Hellwig , Marek Szyprowski , Johannes Thumshirn , David Sterba , Chris Mason , Josef Bacik , linux-btrfs@vger.kernel.org, dm-devel@redhat.com, Mike Snitzer , Alasdair Kergon , intel-gfx@lists.freedesktop.org, Joonas Lahtinen , Maarten Lankhorst , dri-devel@lists.freedesktop.org, David Airlie , Jani Nikula , Daniel Vetter , Rodrigo Vivi , linux-arch@vger.kernel.org References: <20190418084119.056416939@linutronix.de> <20190418084253.903603121@linutronix.de> From: Andrey Ryabinin Message-ID: <5b77992a-52b6-807e-f77d-9cf3e648c71f@virtuozzo.com> Date: Thu, 18 Apr 2019 13:39:45 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190418084253.903603121@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/18/19 11:41 AM, Thomas Gleixner wrote: > Replace the indirection through struct stack_trace by using the storage > array based interfaces. > > Signed-off-by: Thomas Gleixner > Acked-by: Dmitry Vyukov > Cc: Andrey Ryabinin > Cc: Alexander Potapenko > Cc: kasan-dev@googlegroups.com > Cc: linux-mm@kvack.org Acked-by: Andrey Ryabinin > > static inline depot_stack_handle_t save_stack(gfp_t flags) > { > unsigned long entries[KASAN_STACK_DEPTH]; > - struct stack_trace trace = { > - .nr_entries = 0, > - .entries = entries, > - .max_entries = KASAN_STACK_DEPTH, > - .skip = 0 > - }; > + unsigned int nr_entries; > > - save_stack_trace(&trace); > - filter_irq_stacks(&trace); > - > - return depot_save_stack(&trace, flags); > + nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0); > + nr_entries = filter_irq_stacks(entries, nr_entries); > + return stack_depot_save(entries, nr_entries, flags); Suggestion for further improvement: stack_trace_save() shouldn't unwind beyond irq entry point so we wouldn't need filter_irq_stacks(). Probably all call sites doesn't care about random stack above irq entry point, so it doesn't make sense to spend resources on unwinding non-irq stack from interrupt first an filtering out it later. It would improve performance of stack_trace_save() called from interrupt and fix page_owner which feed unfiltered stack to stack_depot_save(). Random non-irq part kills the benefit of using the stack_deopt_save().