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 49B332E7F22 for ; Thu, 6 Nov 2025 17:14:23 +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=1762449263; cv=none; b=foU4itMCCHZN60nTf0nnAqyFQwv6JYpdsEKNMTsgd8W7Qy9uJgXgAHlpQO+5QVzjEBFK4BX0UrmduG+vRwD9IsLoSVcGcJK++7UpgZJ1gEsCf3ptpLHdE7Hs5GIBmnQKIDRSdlqBFq3rTZTsr+MimrynS/KVU+mpy6l23bJtam4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762449263; c=relaxed/simple; bh=QSqaI083gbYKPADI3jQ9Ln9LqUt3nNjqoeyJ0QfsdXs=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Ni6bGKB4RVEhocaQfbvbALnvWoQ2NGGUDXyomKGMkd4hAxJidWfN3Ll5Rpl5U9WDtQD2UUVI0KURXRHwwX6M5drMfah8BFhSLwwg1USHuKkPYeBKLAI79I5PLmC3+aQxIoZ94FsPNOHis7h2qpXNFQko+FiXe7raYob4o2TbzhA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rGq4woPy; 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="rGq4woPy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A120C4CEFB; Thu, 6 Nov 2025 17:14:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762449263; bh=QSqaI083gbYKPADI3jQ9Ln9LqUt3nNjqoeyJ0QfsdXs=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=rGq4woPyPXOfje9Q9uruWAnx19AxJQ1QDYPKiCFWUmEZs0etEtZQDo3iXi3277ZoG 7pVeQUWUKKNlG32Jycp95UIdCnZ1ne0v+L5QzS+z1HlGm3gMSbyF7v9VPcoobdQH6C 4loZF834IYRAOuzlnOQDbtvzruP3S7jtNx2x02050vwCaGIvHmjY546scJVb49sf+G F8fEsG7gDyrD2PwllV7S33Ah5zESg6i2/O/4vXHsCRJORQQeBzs1gXTkQnI2oiBHQ/ l8DXCc/j3usFpnZf13FOniEXU+L18ohAnvNC5EjpqCLpILKAkR5xFS3emMWAOHjjOA 1gU6rKsdDEWZA== Message-ID: Subject: Re: [PATCH 2/2] NFSD: Fix server hang when there are multiple layout conflicts From: Jeff Layton To: Dai Ngo , chuck.lever@oracle.com, neilb@ownmail.net, okorniev@redhat.com, tom@talpey.com, hch@lst.de Cc: linux-nfs@vger.kernel.org Date: Thu, 06 Nov 2025 12:14:21 -0500 In-Reply-To: <20251106164821.300872-3-dai.ngo@oracle.com> References: <20251106164821.300872-1-dai.ngo@oracle.com> <20251106164821.300872-3-dai.ngo@oracle.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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a call to __break_lease, the function > nfsd4_layout_lm_break clears the fl_break_time timeout before sending > the CB_LAYOUTRECALL. As a result, __break_lease repeatedly restarts > its loop, waiting indefinitely for the conflicting file lease to be > released. >=20 > If the number of lease conflicts matches the number of NFSD threads > (which defaults to 8), all available NFSD threads become occupied. > Consequently, there are no threads left to handle incoming requests > or callback replies, leading to a total hang of the NFS server. >=20 > This issue is reliably reproducible by running the Git test suite > on a configuration using SCSI layout. >=20 > This patch addresses the problem by using the break lease timeout > and ensures that the unresponsive client is fenced, preventing it from > accessing the data server directly. >=20 > Fixes: f99d4fbdae67 ("nfsd: add SCSI layout support") > Signed-off-by: Dai Ngo > --- > fs/nfsd/nfs4layouts.c | 25 +++++++++++++++++++++---- > 1 file changed, 21 insertions(+), 4 deletions(-) >=20 > diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c > index 683bd1130afe..b9b1eb32624c 100644 > --- a/fs/nfsd/nfs4layouts.c > +++ b/fs/nfsd/nfs4layouts.c > @@ -747,11 +747,10 @@ static bool > nfsd4_layout_lm_break(struct file_lease *fl) > { > /* > - * We don't want the locks code to timeout the lease for us; > - * we'll remove it ourself if a layout isn't returned > - * in time: > + * Enforce break lease timeout to prevent starvation of > + * NFSD threads in __break_lease that causes server to > + * hang. > */ > - fl->fl_break_time =3D 0; I guess this ends up with whatever the default fl_break_time is which is: jiffies + lease_break_time * HZ; I wonder if this should be based around some multiple of the grace period instead? > nfsd4_recall_file_layout(fl->c.flc_owner); > return false; > } > @@ -764,9 +763,27 @@ nfsd4_layout_lm_change(struct file_lease *onlist, in= t arg, > return lease_modify(onlist, arg, dispose); > } > =20 > +static void nfsd_layout_breaker_timedout(struct file_lease *fl) > +{ > + struct nfs4_layout_stateid *ls =3D fl->c.flc_owner; > + struct nfsd_file *nf; > + > + rcu_read_lock(); > + nf =3D nfsd_file_get(ls->ls_file); > + rcu_read_unlock(); > + if (nf) { > + int type =3D ls->ls_layout_type; > + > + if (nfsd4_layout_ops[type]->fence_client) > + nfsd4_layout_ops[type]->fence_client(ls, nf); > + nfsd_file_put(nf); > + } > +} > + > static const struct lease_manager_operations nfsd4_layouts_lm_ops =3D { > .lm_break =3D nfsd4_layout_lm_break, > .lm_change =3D nfsd4_layout_lm_change, > + .lm_breaker_timedout =3D nfsd_layout_breaker_timedout, > }; > =20 > int --=20 Jeff Layton