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[23.128.96.37]) by mx.google.com with ESMTPS id ix1-20020a170902f80100b001cad3a744aesi12246284plb.153.2023.11.16.09.11.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Nov 2023 09:11:59 -0800 (PST) Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=QV67bfcg; spf=pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) smtp.mailfrom=linux-nfs-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by snail.vger.email (Postfix) with ESMTP id B2A528031AF6; Thu, 16 Nov 2023 09:11:37 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229472AbjKPRL3 (ORCPT + 99 others); Thu, 16 Nov 2023 12:11:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229464AbjKPRL2 (ORCPT ); Thu, 16 Nov 2023 12:11:28 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9D541A5 for ; Thu, 16 Nov 2023 09:11:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700154684; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=ymV3s3bEKcNtX5vsiN+AkDfnW20QXlre0yO2FfbIFLY=; b=QV67bfcgd541+Lnf56JGtGwR0GA1Vv3W2ULwiLQ/ZNMdpu05cW7TSbvHFcquaMBRzAXfN+ kXGi5FV11YTC77H860sDebwcuXyeGuSC2esYs08xygI/S6fz/UdxIhrD/QSajnz15qgsc2 2ZFY5ThXO+OCIJborwW3+F9j7X/QWgw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-369-A1X2lqhKOvSSqyJE9fL4TA-1; Thu, 16 Nov 2023 12:11:22 -0500 X-MC-Unique: A1X2lqhKOvSSqyJE9fL4TA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3830685C1A1 for ; Thu, 16 Nov 2023 17:11:22 +0000 (UTC) Received: from [100.85.132.103] (unknown [10.22.48.5]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DC900C157E4 for ; Thu, 16 Nov 2023 17:11:21 +0000 (UTC) From: Benjamin Coddington To: Linux NFS Mailing List Subject: Blocklayoutdriver deadlock with knfsd Date: Thu, 16 Nov 2023 12:11:20 -0500 Message-ID: <1CC82EC5-6120-4EE4-A7F0-019CF7BC762C@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Thu, 16 Nov 2023 09:11:37 -0800 (PST) I ran into this old problem again recently, last discussed here: https://lore.kernel.org/linux-nfs/F738DB31-B527-4048-94A7-DBF00533F8C1@re= dhat.com/#t Problem is that clients can easily issue enough WRITEs that end up in __break_lease xfs_break_leased_layouts =2E.. nfsd_vfs_write =2E.. svc_process svc_recv nfsd =2E. so that all the knfsds are there, and nothing can process the LAYOUTRETURN. I'm pretty sure we can make the linux client a bit smarter about it (I sa= w one LAYOUTGET and one conflicting WRITE in the same TCP segment, in that order). But what can knfsd do to defend itself? Ben