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[2620:137:e000::1:20]) by mx.google.com with ESMTP id gt39-20020a1709072da700b00787e1d77943si12702087ejc.49.2022.10.18.02.51.20; Tue, 18 Oct 2022 02:51:46 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=H3KfKVWf; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229928AbiJRJX6 (ORCPT + 99 others); Tue, 18 Oct 2022 05:23:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54796 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229722AbiJRJXq (ORCPT ); Tue, 18 Oct 2022 05:23:46 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93010A99CB for ; Tue, 18 Oct 2022 02:23:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666085010; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=yBOtDHeeIVLfwUhAyBSCeK/RWi8e6lg4gpPb3l/BEu4=; b=H3KfKVWfLobBiNh5an9JoxUvic9t0cnyJ7Dj8jDP+0VRu+Upq2gIqAFyENtXncWehIcL0n yXtbHCuFt3cthYUKthWhAczyPIcZfkbOTKSrJ1Tt4HjcTCTudxrvskV0+2KzyjvVwqV87F Y782hW5TWdczAVUoKzfUQ/5qRr4YuM8= Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-220-rqbdr_D4PcieJMW8vUY5sw-1; Tue, 18 Oct 2022 05:23:29 -0400 X-MC-Unique: rqbdr_D4PcieJMW8vUY5sw-1 Received: by mail-pg1-f200.google.com with SMTP id p24-20020a63f458000000b0043cd718c49dso7869249pgk.15 for ; Tue, 18 Oct 2022 02:23:29 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=yBOtDHeeIVLfwUhAyBSCeK/RWi8e6lg4gpPb3l/BEu4=; b=DScUM8bUJxdEQnQI8A+IiR7Gl4o5+K6UJeeFCIaam1WbB3sMd/ZTFykmecAoMLiJbX 951LHN71JTyBi2ZMGtx0B7SrTT98BdyQlkGq7B4Xw6UHGCZ8Jw5Gwux6lhIPTtLp17ei cMa0uewNb9VLBtgRyW4l+1EQhtEligOYttA2/oKdOpFAoWedUFMgsGtKDrPlyzEvpL32 ZQ3KFFQYhGRnFrrxF5LG18O9az+4HNABfY1VzL94I6N08dRG2BY53YbgEIEzb5B/EYNU +aCgNQkSA7KPI8tNE3/Ae/eoQ4FZytYKB+Epzbq3GSjEGeIQYPuAxAe/4m5PRDYDZk5V gDtw== X-Gm-Message-State: ACrzQf1DOJvs3FzTuR58m9EFijhzKr43LFCjsc2p2CHFhgyr8ite2h07 G5mwc5aUXu9qhTCoQXRO7cioDacCyGt/+LT8UjRxbRxazsZpL9VHX8TP69IJ0SxqEechvbE+FZv UhxBr8kYO5u2SEVgcK1O3PbyVi4MF98AQYUrQBDYX X-Received: by 2002:a17:90b:3c02:b0:20d:2af9:821c with SMTP id pb2-20020a17090b3c0200b0020d2af9821cmr2468185pjb.181.1666085008521; Tue, 18 Oct 2022 02:23:28 -0700 (PDT) X-Received: by 2002:a17:90b:3c02:b0:20d:2af9:821c with SMTP id pb2-20020a17090b3c0200b0020d2af9821cmr2468172pjb.181.1666085008314; Tue, 18 Oct 2022 02:23:28 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Miklos Szeredi Date: Tue, 18 Oct 2022 11:23:17 +0200 Message-ID: Subject: Re: [Syzkaller] INFO: task hung in fuse_lookup with v6.0 kernel in guest To: Pengfei Xu Cc: linux-kernel@vger.kernel.org, heng.su@intel.com Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-2.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE 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-kernel@vger.kernel.org On Mon, Oct 17, 2022 at 11:17 AM Pengfei Xu wrote: > > Hi Miklos, > > Greeting! > > Platform: Tiger lake CPU platform. > > We found 1 "task hung in fuse_lookup" issue by syzkaller with v6.0 mainline > kernel in guest. > > Bisected and found the bad commit: > " > commit: 62dd1fc8cc6b22e3e568be46ebdb817e66f5d6a5 > fuse: move fget() to fuse_get_tree() > " > > Reproduced code generated by syzkaller, binary, bisect log and all the dmesg > info are in attached package. Thanks for the report. I tried out the reproducer, and the deadlock can be triggered. Unfortunately killing the deadlocked processes is not enough, but it still should be possible to recover with "echo 1 > /sys/fs/fuse/connections/$FUSE_DEV/abort". In my tests this works, so I'm not sure there's anything to fix here. Is there a real life situation where this occurs, or is this just triggered with fuzzing? I'm wondering why syzbot didn't try aborting using the "abort" file in sysfs, AFAICS it does know this trick. Thanks, Miklos