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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 F20F4C43381 for ; Wed, 13 Mar 2019 19:10:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABC4D2184C for ; Wed, 13 Mar 2019 19:10:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552504242; bh=P4dMpDvhBPN5Wx05GPrpTJkk2VG1k+xFDs0XYWKE8pc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=188e9e4wxuF260nrANskBMN96CrtF9sgvqxda9d0d3hGZCq8MMnbrmG928iQcuePJ E4GkvIWbj92I8lFnwG07sqYtyjvscGTziUcYlQoN6TlIagjOrd+cChVWR7WHxSc18Z YEvSX3yF1+1Shjnsm8DURnyN9NEiBgRfmyPam6kc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727140AbfCMTKl (ORCPT ); Wed, 13 Mar 2019 15:10:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:41242 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727112AbfCMTKi (ORCPT ); Wed, 13 Mar 2019 15:10:38 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 874712184D; Wed, 13 Mar 2019 19:10:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552504237; bh=P4dMpDvhBPN5Wx05GPrpTJkk2VG1k+xFDs0XYWKE8pc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BqHQM1VVXeoFAgIFDgqirLcVwzk/22rrrrWuIscP2c7RGPlleNzW65Ya0nz+EYWfd v62MHMojF9crKpWotu6krwOBhfkF94D2gotze7Dy2ggRwNrXqO71MIcPq0qo4tshGz FMCJ+SI5qKJqR6jN/VpP87oHV7c1vQYMdweOBAt8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Sasha Levin Subject: [PATCH AUTOSEL 4.20 08/60] bpf: fix lockdep false positive in stackmap Date: Wed, 13 Mar 2019 15:09:29 -0400 Message-Id: <20190313191021.158171-8-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190313191021.158171-1-sashal@kernel.org> References: <20190313191021.158171-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexei Starovoitov [ Upstream commit 3defaf2f15b2bfd86c6664181ac009e91985f8ac ] Lockdep warns about false positive: [ 11.211460] ------------[ cut here ]------------ [ 11.211936] DEBUG_LOCKS_WARN_ON(depth <= 0) [ 11.211985] WARNING: CPU: 0 PID: 141 at ../kernel/locking/lockdep.c:3592 lock_release+0x1ad/0x280 [ 11.213134] Modules linked in: [ 11.214954] RIP: 0010:lock_release+0x1ad/0x280 [ 11.223508] Call Trace: [ 11.223705] [ 11.223874] ? __local_bh_enable+0x7a/0x80 [ 11.224199] up_read+0x1c/0xa0 [ 11.224446] do_up_read+0x12/0x20 [ 11.224713] irq_work_run_list+0x43/0x70 [ 11.225030] irq_work_run+0x26/0x50 [ 11.225310] smp_irq_work_interrupt+0x57/0x1f0 [ 11.225662] irq_work_interrupt+0xf/0x20 since rw_semaphore is released in a different task vs task that locked the sema. It is expected behavior. Fix the warning with up_read_non_owner() and rwsem_release() annotation. Fixes: bae77c5eb5b2 ("bpf: enable stackmap with build_id in nmi context") Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin --- kernel/bpf/stackmap.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index d43b14535827..950ab2f28922 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -44,7 +44,7 @@ static void do_up_read(struct irq_work *entry) struct stack_map_irq_work *work; work = container_of(entry, struct stack_map_irq_work, irq_work); - up_read(work->sem); + up_read_non_owner(work->sem); work->sem = NULL; } @@ -338,6 +338,12 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, } else { work->sem = ¤t->mm->mmap_sem; irq_work_queue(&work->irq_work); + /* + * The irq_work will release the mmap_sem with + * up_read_non_owner(). The rwsem_release() is called + * here to release the lock from lockdep's perspective. + */ + rwsem_release(¤t->mm->mmap_sem.dep_map, 1, _RET_IP_); } } -- 2.19.1