From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id uzCQCCwlHltceAAAmS7hNA ; Mon, 11 Jun 2018 07:30:52 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 097F1607A4; Mon, 11 Jun 2018 07:30:52 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ca1X1hVw" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 8796C60791; Mon, 11 Jun 2018 07:30:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 8796C60791 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754072AbeFKHat (ORCPT + 20 others); Mon, 11 Jun 2018 03:30:49 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:54888 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753964AbeFKHas (ORCPT ); Mon, 11 Jun 2018 03:30:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=p2m7SGTa1jCUMvnQ3uC5ngNpS34viKso9DqC0IMYuY4=; b=ca1X1hVwxjfgTvdst7WZWcbsv PWLOBpBhWlp4Ytsbuvc9ESDuCycfgpQrqdy4jm8CLwmBqAeO4VQ2dSwj3C6mQOYZ8FIqrhzIp63yh TpqiZy4/J98kA9pBqXnBMKmSq34bdJtU5UfNZ4u+CQdzYs2do9HPvEnnDRMTkJ+rFpKQBB+7hlvUZ +8Fxgjaq9kWqnR4QG1I692jVHXT9fdOl+Xg12eOhHQccsmDxKxSaRLdtZscMJXQNbnF1x+Zz3sfhu UzQgrKSls7cSBK5Ii+zV0Ik1RYYGj40teou9ocVlclqNYcyW+lwN3BeYnK8S+4Z/r+t2Ty9ePIhb+ m05OiXxig==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fSHHl-0001gy-3U; Mon, 11 Jun 2018 07:30:41 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1BCA1201EA7A6; Mon, 11 Jun 2018 09:30:38 +0200 (CEST) Date: Mon, 11 Jun 2018 09:30:38 +0200 From: Peter Zijlstra To: Tetsuo Handa Cc: Ingo Molnar , Will Deacon , syzbot , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Subject: Re: INFO: task hung in __sb_start_write Message-ID: <20180611073038.GK12217@hirez.programming.kicks-ass.net> References: <000000000000283c37056b4a81a5@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 10, 2018 at 11:47:56PM +0900, Tetsuo Handa wrote: > This looks quite strange that nobody is holding percpu_rw_semaphore for > write but everybody is stuck trying to hold it for read. (Since there > is no "X locks held by ..." line without followup "#0:" line, there is > no possibility that somebody is in TASK_RUNNING state while holding > percpu_rw_semaphore for write.) > > I feel that either API has a bug or API usage is wrong. > Any idea for debugging this? Look at percpu_rwsem_release() and usage. The whole fs freezer thing is magic.