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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 E3134C43387 for ; Tue, 8 Jan 2019 10:01:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC0D82087E for ; Tue, 8 Jan 2019 10:01:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728530AbfAHKBj (ORCPT ); Tue, 8 Jan 2019 05:01:39 -0500 Received: from mx2.suse.de ([195.135.220.15]:58378 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727001AbfAHKBi (ORCPT ); Tue, 8 Jan 2019 05:01:38 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 01C31B0DD; Tue, 8 Jan 2019 10:01:36 +0000 (UTC) From: Roman Penyaev Cc: Roman Penyaev , Davidlohr Bueso , Jason Baron , Al Viro , Andrew Morton , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/1] epoll: remove wrong assert that ep_poll_callback is always called with irqs off Date: Tue, 8 Jan 2019 11:01:21 +0100 Message-Id: <20190108100121.20247-1-rpenyaev@suse.de> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org That was wrong assumption that all drivers disable irqs before waking up a wait queue. Even assert line is removed the whole logic stays correct: epoll always locks rwlock with irqs disabled and by itself does not call from interrupts, thus it is up to driver how to call wake_up_locked(), because if driver does not handle any interrupts (like fuse in the the report) of course it is safe on its side to take a simple spin_lock. Signed-off-by: Roman Penyaev Reported-by: syzbot+aea82bf9ee6ffd9a79d9@syzkaller.appspotmail.com Cc: Davidlohr Bueso Cc: Jason Baron Cc: Al Viro Cc: Andrew Morton Cc: Linus Torvalds Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- fs/eventpoll.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index f307c8679027..f5f88250cdf2 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1217,12 +1217,6 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v __poll_t pollflags = key_to_poll(key); int ewake = 0; - /* - * Called by irq context or interrupts are disabled by the wake_up_*poll - * callers. - */ - lockdep_assert_irqs_disabled(); - read_lock(&ep->lock); ep_set_busy_poll_napi_id(epi); -- 2.19.1