From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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