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Thu, 27 Apr 2023 00:51:00 -0400 X-MC-Unique: 07epsV5EOGqN665UvC9buQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 237DF2812940; Thu, 27 Apr 2023 04:51:00 +0000 (UTC) Received: from ovpn-8-24.pek2.redhat.com (ovpn-8-24.pek2.redhat.com [10.72.8.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 569C1C15BA0; Thu, 27 Apr 2023 04:50:52 +0000 (UTC) Date: Thu, 27 Apr 2023 12:50:48 +0800 From: Ming Lei To: Matthew Wilcox Cc: Theodore Ts'o , linux-ext4@vger.kernel.org, Andreas Dilger , linux-block@vger.kernel.org, Andrew Morton , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Eric Sandeen , Christoph Hellwig , Zhang Yi , ming.lei@redhat.com Subject: Re: [ext4 io hang] buffered write io hang in balance_dirty_pages Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Rspam-User: X-Rspamd-Queue-Id: DD8471C0010 X-Rspamd-Server: rspam09 X-Stat-Signature: 6h9qa8nji1f3so6zsmaf4ut3fkbaixtg X-HE-Tag: 1682571064-423053 X-HE-Meta: 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 2XGqn6IO s63zm0xwZJZt+I0iNc7p/PJokZ1YAgdxOsCBvpIjXrVNG/szmWMCWx+5W3795xAFReCHudN/NcpV9ZE1CtISbg4QYD9we1VrkKIfnIu5NeOrtwlPBSkBLSLB9XVhhjc9EPrBTpMjLIQlgiia7PqNJjncpYLZJpfG9TqwfYDeAOc9lkgoPmPGePpOSdPf6BbsuxGv6+cRli+2arKHEu9MIsGuHrQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hello Matthew, On Thu, Apr 27, 2023 at 04:58:36AM +0100, Matthew Wilcox wrote: > On Thu, Apr 27, 2023 at 10:20:28AM +0800, Ming Lei wrote: > > Hello Guys, > > > > I got one report in which buffered write IO hangs in balance_dirty_pages, > > after one nvme block device is unplugged physically, then umount can't > > succeed. > > That's a feature, not a bug ... the dd should continue indefinitely? Can you explain what the feature is? And not see such 'issue' or 'feature' on xfs. The device has been gone, so IMO it is reasonable to see FS buffered write IO failed. Actually dmesg has shown that 'EXT4-fs (nvme0n1): Remounting filesystem read-only'. Seems these things may confuse user. > > balance_dirty_pages() is sleeping in KILLABLE state, so kill -9 of > the dd process should succeed. Yeah, dd can be killed, however it may be any application(s), :-) Fortunately it won't cause trouble during reboot/power off, given userspace will be killed at that time. Thanks, Ming