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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 782FCC83F3F for ; Mon, 4 Sep 2023 06:57:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350419AbjIDG5Z (ORCPT ); Mon, 4 Sep 2023 02:57:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37278 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345038AbjIDG5Y (ORCPT ); Mon, 4 Sep 2023 02:57:24 -0400 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:242:246e::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA64E11A; Sun, 3 Sep 2023 23:57:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:To:From:Subject:Message-ID:Sender: Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=ML3nN0Bovw/HBwQG6YVdv3gL++y5/3rFGx6GGczGCis=; t=1693810640; x=1695020240; b=P1ZLi6DGpReD2zSdvNT7Q/UeDBrHqldsWHtVX4tGtN4n5z5 xDI5U3AOwTKGZ8MbdJ1cduLYBTiOZQXpdVskQIZU6VoCB6HDmJe2b/YPjWXwKG6IH+pwraa9ywl7N 2cx/wfVw+pN4fLFpzvBNCukokACNy7Z9/Y7rci4fAz/EPa+REWJRVsdPYWgNICRoiCL+lFbeUNwAa CDfI5YXCIE3A1wSg/HZhqus3pmuaLvZobldb0qzPltexpDYnenLlsBQtbQRPLtH0pF8a5L3lZu6T+ LipEn74Sp/nbC3bcd0IV+N+5lhzwFtmVYqOkbGUSbk0d1zND+Sgye/25IX/KzN0A==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1qd3WL-00ChVX-20; Mon, 04 Sep 2023 08:57:13 +0200 Message-ID: Subject: Re: [syzbot] [wireless?] WARNING in ieee80211_link_release_channel From: Johannes Berg To: syzbot , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Date: Mon, 04 Sep 2023 08:57:11 +0200 In-Reply-To: <000000000000bcd80b06046a98ac@google.com> References: <000000000000bcd80b06046a98ac@google.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.48.4 (3.48.4-1.fc38) MIME-Version: 1.0 X-malware-bazaar: not-scanned Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2023-09-02 at 18:48 -0700, syzbot wrote: >=20 > WARNING: CPU: 0 PID: 7597 at net/mac80211/chan.c:2021 ieee80211_link_rele= ase_channel+0x19f/0x200 net/mac80211/chan.c:2021 >=20 That's a lockdep warning, so it's kind of a known issue. I don't know if I've yet encountered this specific way to get the locking checks screaming, but generally we knew for a while that the locking was a bit messy and possibly to some extent broken (*). Anyway, point is - this is basically the reason I did this series: https://lore.kernel.org/linux-wireless/20230828115927.116700-41-johannes@si= psolutions.net/ so this should go away - though sadly only in -next. Per the footnote, I believe that the issue in the current kernel is mostly not an issue, and it should only happen with multi-link in the first place. There may be an issue in what syzbot found, processing a multi-link response or something though. johannes (*) in many cases it's not _actually_ broken because we hold some common outer lock anyway, so no data races are possible