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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 5779FC169C4 for ; Tue, 12 Feb 2019 02:42:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F5C22084E for ; Tue, 12 Feb 2019 02:42:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727532AbfBLCmq (ORCPT ); Mon, 11 Feb 2019 21:42:46 -0500 Received: from mga07.intel.com ([134.134.136.100]:10698 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726207AbfBLCmq (ORCPT ); Mon, 11 Feb 2019 21:42:46 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Feb 2019 18:42:45 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,361,1544515200"; d="scan'208";a="117155911" Received: from wahaih-mobl.ger.corp.intel.com (HELO [10.254.213.215]) ([10.254.213.215]) by orsmga008.jf.intel.com with ESMTP; 11 Feb 2019 18:42:40 -0800 From: "Jin, Yao" Subject: Re: [PATCH] perf/core: don't WARN for impossible rb sizes To: Mark Rutland , linux-kernel@vger.kernel.org Cc: julien.thierry@arm.com, Alexander Shishkin , Ingo Molnar , Jiri Olsa , Namhyung Kim , Peter Zijlstra , "Jin, Yao" , Arnaldo Carvalho de Melo References: <20190110142745.25495-1-mark.rutland@arm.com> Message-ID: <1f71da66-4783-0108-668c-cdffca499719@linux.intel.com> Date: Tue, 12 Feb 2019 10:42:38 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190110142745.25495-1-mark.rutland@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed 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 Hi Mark, Looks I hit a regression issue on SKL desktop. For example, root@skl:/tmp# perf record -g -a failed to mmap with 12 (Cannot allocate memory) In this case, size = 1264, order_base_2 = 11, MAX_ORDER = 11 if (order_base_2(size) >= MAX_ORDER) goto fail; It will goto fail directly. Is it really correct? Could you help to look at this? BTW, I tested with Arnaldo's perf/core branch. Thanks Jin Yao On 1/10/2019 10:27 PM, Mark Rutland wrote: > The perf tool uses /proc/sys/kernel/perf_event_mlock_kb to determine how > large its ringbuffer mmap should be. This can be configured to arbitrary > values, which can be larger than the maximum possible allocation from > kmalloc. > > When this is configured to a suitably large value (e.g. thanks to the > perf fuzzer), attempting to use perf record triggers a WARN_ON_ONCE() in > __alloc_pages_nodemask(): > > [ 337.316688] WARNING: CPU: 2 PID: 5666 at mm/page_alloc.c:4511 > __alloc_pages_nodemask+0x3f8/0xbc8 > [ 337.316694] Modules linked in: > [ 337.316704] CPU: 2 PID: 5666 Comm: perf Not tainted 5.0.0-rc1 #2669 > [ 337.316708] Hardware name: ARM Juno development board (r0) (DT) > [ 337.316714] pstate: 20000005 (nzCv daif -PAN -UAO) > [ 337.316720] pc : __alloc_pages_nodemask+0x3f8/0xbc8 > [ 337.316728] lr : alloc_pages_current+0x80/0xe8 > [ 337.316732] sp : ffff000016eeb9e0 > [ 337.316736] x29: ffff000016eeb9e0 x28: 0000000000080001 > [ 337.316744] x27: 0000000000000000 x26: ffff0000111e21f0 > [ 337.316751] x25: 0000000000000001 x24: 0000000000000000 > [ 337.316757] x23: 0000000000080001 x22: 0000000000000000 > [ 337.316762] x21: 0000000000000000 x20: 000000000000000b > [ 337.316768] x19: 000000000060c0c0 x18: 0000000000000000 > [ 337.316773] x17: 0000000000000000 x16: 0000000000000000 > [ 337.316779] x15: 0000000000000000 x14: 0000000000000000 > [ 337.316784] x13: 0000000000000000 x12: 0000000000000000 > [ 337.316789] x11: 0000000000100000 x10: 0000000000000000 > [ 337.316795] x9 : 0000000010044400 x8 : 0000000080001000 > [ 337.316800] x7 : 0000000000000000 x6 : ffff800975584700 > [ 337.316806] x5 : 0000000000000000 x4 : ffff0000111cd6c8 > [ 337.316811] x3 : 0000000000000000 x2 : 0000000000000000 > [ 337.316816] x1 : 000000000000000b x0 : 000000000060c0c0 > [ 337.316822] Call trace: > [ 337.316828] __alloc_pages_nodemask+0x3f8/0xbc8 > [ 337.316834] alloc_pages_current+0x80/0xe8 > [ 337.316841] kmalloc_order+0x14/0x30 > [ 337.316848] __kmalloc+0x1dc/0x240 > [ 337.316854] rb_alloc+0x3c/0x170 > [ 337.316860] perf_mmap+0x3bc/0x470 > [ 337.316867] mmap_region+0x374/0x4f8 > [ 337.316873] do_mmap+0x300/0x430 > [ 337.316878] vm_mmap_pgoff+0xe4/0x110 > [ 337.316884] ksys_mmap_pgoff+0xc0/0x230 > [ 337.316892] __arm64_sys_mmap+0x28/0x38 > [ 337.316899] el0_svc_common+0xb4/0x118 > [ 337.316905] el0_svc_handler+0x2c/0x80 > [ 337.316910] el0_svc+0x8/0xc > [ 337.316915] ---[ end trace fa29167e20ef0c62 ]--- > > Let's avoid this by checking that the requested allocation is possible > before calling kzalloc. > > Reported-by: Julien Thierry > Signed-off-by: Mark Rutland > Cc: Alexander Shishkin > Cc: Ingo Molnar > Cc: Jiri Olsa > Cc: Namhyung Kim > Cc: Peter Zijlstra > --- > kernel/events/ring_buffer.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c > index 4a9937076331..309ef5a64af5 100644 > --- a/kernel/events/ring_buffer.c > +++ b/kernel/events/ring_buffer.c > @@ -734,6 +734,9 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) > size = sizeof(struct ring_buffer); > size += nr_pages * sizeof(void *); > > + if (order_base_2(size) >= MAX_ORDER) > + goto fail; > + > rb = kzalloc(size, GFP_KERNEL); > if (!rb) > goto fail; >