From nobody Sun Jun 28 09:41:43 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3AFEFC433F5 for ; Wed, 9 Feb 2022 02:41:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245422AbiBIClI (ORCPT ); Tue, 8 Feb 2022 21:41:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60486 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231611AbiBIByv (ORCPT ); Tue, 8 Feb 2022 20:54:51 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2C02C06157B; Tue, 8 Feb 2022 17:54:49 -0800 (PST) Received: from dggeme754-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4JtjWb2qZczZfNF; Wed, 9 Feb 2022 09:50:35 +0800 (CST) Received: from huawei.com (10.175.104.170) by dggeme754-chm.china.huawei.com (10.3.19.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.21; Wed, 9 Feb 2022 09:54:46 +0800 From: Zhipeng Xie To: , , , , , , CC: , , , , Subject: [PATCH v2] perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled Date: Wed, 9 Feb 2022 09:54:17 -0500 Message-ID: <20220209145417.6495-1-xiezhipeng1@huawei.com> X-Mailer: git-send-email 2.18.1 MIME-Version: 1.0 X-Originating-IP: [10.175.104.170] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggeme754-chm.china.huawei.com (10.3.19.100) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This problem can be reproduced with CONFIG_PERF_USE_VMALLOC enabled on both x86_64 and aarch64 arch when using sysdig -B(using ebpf)[1]. sysdig -B works fine after rebuilding the kernel with CONFIG_PERF_USE_VMALL= OC disabled. I tracked it down to the if condition event->rb->nr_pages !=3D nr_pages in perf_mmap is true when CONFIG_PERF_USE_VMALLOC is enabled where event->rb->nr_pages =3D 1 and nr_pages =3D 2048 resulting perf_mmap to retu= rn -EINVAL.This is because when CONFIG_PERF_USE_VMALLOC is enabled, rb->nr_pag= es is always equal to 1. Arch with CONFIG_PERF_USE_VMALLOC enabled by default: arc/arm/csky/mips/sh/sparc/xtensa Arch with CONFIG_PERF_USE_VMALLOC disabled by default: x86_64/aarch64/... Fix this problem by using data_page_nr. [1] https://github.com/draios/sysdig Signed-off-by: Zhipeng Xie --- kernel/events/core.c | 2 +- kernel/events/internal.h | 5 +++++ kernel/events/ring_buffer.c | 5 ----- 3 files changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 57c7197838db..370292effd32 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6352,7 +6352,7 @@ static int perf_mmap(struct file *file, struct vm_are= a_struct *vma) again: mutex_lock(&event->mmap_mutex); if (event->rb) { - if (event->rb->nr_pages !=3D nr_pages) { + if (data_page_nr(event->rb) !=3D nr_pages) { ret =3D -EINVAL; goto unlock; } diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 082832738c8f..5816c0719dbf 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -116,6 +116,11 @@ static inline int page_order(struct perf_buffer *rb) } #endif =20 +static int data_page_nr(struct perf_buffer *rb) +{ + return rb->nr_pages << page_order(rb); +} + static inline unsigned long perf_data_size(struct perf_buffer *rb) { return rb->nr_pages << (PAGE_SHIFT + page_order(rb)); diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 52868716ec35..fb35b926024c 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -859,11 +859,6 @@ void rb_free(struct perf_buffer *rb) } =20 #else -static int data_page_nr(struct perf_buffer *rb) -{ - return rb->nr_pages << page_order(rb); -} - static struct page * __perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff) { --=20 2.18.1