From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D502B3D81; Sun, 26 Jan 2025 12:06:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737893171; cv=none; b=ZTEX+eKC4lTSecNT/CSLwU2+iryB+SRiuQgXrkuhap/OzrZ9XH/ReISFrMLTDUgTbI74jcVAj4pIRYBA55Ow7PN5MjVeVTEMmKFvAmXZa79PIrSqdJ4lS3YxVvfyfSiyoH6is+fGpK3XOA+Yl39vGIKFt7JogZid1wk6ssqyImU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737893171; c=relaxed/simple; bh=8w9yy0qIo4JBg8oU5fWo8FhvNfpsY5b4bWhdsTY5puk=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=oPorQ0In8CgVkVn/miK57HnRMAr0dgYBRKfMdV11u7BI9SqDUt48zB/FsY/+IdmNU4ZXEzZCBj5eBlrJAYVT7UdsZ2Jd9+glaHNTBzdJiyJGI1kCZUkupP4MsIcWCQu4Ru4FD3/jvSbDjLyAFW+89OLvzIGhpoOs8U/oUvHqk1o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Xy4wZXi7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Xy4wZXi7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A022C4CEDF; Sun, 26 Jan 2025 12:06:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737893171; bh=8w9yy0qIo4JBg8oU5fWo8FhvNfpsY5b4bWhdsTY5puk=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=Xy4wZXi7JLSJHNOhEyfaPsLGPhIdz80Sbo57eCmPNx1srqF+ubbjjmArA9aVFFGim iDHwPz/8WyTjJom+rIiwDDNElsbSpCmKYfoZy6t9Gopjsp8BcAoTAj1oLVSNskRL8i iGcIQOomd1YvjsIdxDjy6KLxg4uORJZtug5PzNkhBwaTpDXqAAjZ+tilh+lD4ea7B+ o5VsirKBcaX5T3SjDRbEuU0v3DA6RkNQcvA0W3y5k5Px9lMFiIOGtjTEnni4mIT0Pf ocb/uYvPByTOHAd+11bu+wIu2jtfY5DtWIiuaATWwP7m8U0LxSjoC1PCQ3K8gBM3sQ jP3nJa62h6qjA== Message-ID: <8d8de0b77a258e1c7e7fbcde956c8eba415d4b22.camel@kernel.org> Subject: Re: kernel NULL pointer dereference: Workqueue: events_unbound nfsd_file_gc_worker, RIP: 0010:svc_wake_up+0x9/0x20 From: Jeff Layton To: Salvatore Bonaccorso Cc: Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Sun, 26 Jan 2025 07:06:09 -0500 In-Reply-To: References: <7d9f2a8aede4f7ca9935a47e1d405643220d7946.camel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Sun, 2025-01-26 at 08:57 +0100, Salvatore Bonaccorso wrote: > Hi Jeff, >=20 > On Sat, Jan 25, 2025 at 05:55:50PM -0500, Jeff Layton wrote: > > On Sat, 2025-01-25 at 21:44 +0100, Salvatore Bonaccorso wrote: > > > Hi Chuck, Jeff, NFSD maintainers, > > >=20 > > > In Debian we got a report from a user which triggered an issue during > > > package updates hwere nfs-kernel-server restart was involved, then > > > hanging and included a kernel trace of a NULL pointer dereference. > > >=20 > > > The full report is at: > > > https://bugs.debian.org/1093734 > > >=20 > > > While I was not able to trigger the issue, the provided log is as > > > follows: > > >=20 > > > 2025-01-21T12:07:01.516291+01:00 $HOST kernel: device-mapper: core: C= ONFIG_IMA_DISABLE_HTABLE is disabled. Duplicate IMA measurements will not b= e recorded in the IMA log. > > > 2025-01-21T12:07:01.516310+01:00 $HOST kernel: device-mapper: uevent:= version 1.0.3 > > > 2025-01-21T12:07:01.516312+01:00 $HOST kernel: device-mapper: ioctl: = 4.48.0-ioctl (2023-03-01) initialised: dm-devel@lists.linux.dev > > > 2025-01-21T12:07:13.528044+01:00 $HOST kernel: NFSD: Using nfsdcld cl= ient tracking operations. > > > 2025-01-21T12:07:13.528061+01:00 $HOST kernel: NFSD: no clients to re= claim, skipping NFSv4 grace period (net f0000000) > > > 2025-01-21T12:07:17.558915+01:00 $HOST blkmapd[1148]: exit on signal(= 15) > > > 2025-01-21T12:07:17.574410+01:00 $HOST blkmapd[239859]: open pipe fil= e /run/rpc_pipefs/nfs/blocklayout failed: No such file or directory > > > 2025-01-21T12:07:18.015541+01:00 $HOST kernel: BUG: kernel NULL point= er dereference, address: 0000000000000090 > >=20 > > Thanks for the bug report. It's getting late here, so I can only take a > > quick look. svc_wake_up is pretty small: > >=20 > > void svc_wake_up(struct svc_serv *serv) > > { > > struct svc_pool *pool =3D &serv->sv_pools[0]; > >=20 > > set_bit(SP_TASK_PENDING, &pool->sp_flags); > > svc_pool_wake_idle_thread(pool); > > } > >=20 > > pahole on my machine says that struct svc_serv has this at offset 0x90: > >=20 > > struct svc_pool * sv_pools; /* 0x90 0x8 */ > >=20 > > So it looks like the nn->nfsd_serv was a NULL pointer. That only > > happens when we shut down the server, so this looks like a race between > > filecache garbage collection with shutdown. > >=20 > > The filecache gets shut down in nfsd_shutdown_net, which gets called > > _after_ setting the nn->nfsd_serv pointer to NULL. We'll have to look > > at whether we can reorder the NULL pointer setting to later, or work > > around this some other way. > >=20 > > Could I trouble you to open a bug for this at bugzilla.kernel.org? >=20 > Thanks a lot for your quick response on it and the analysis. >=20 > Sure I can fill a bug in bugzilla.kernel.org, I see you submitted a > patch already, do you still want me to do it? > > If so I try to reference as well all followups so that the information > is not spread around threads. >=20 > Thanks a lot for your work! >=20 I think you can skip the BZ for now. Thanks again for the bug report! --=20 Jeff Layton