From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 72DA53ACA7C for ; Wed, 12 Aug 2026 08:02:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786521772; cv=none; b=fCau3SVjMuRI5ZcDlpYCqSpICxJ3MbNDh0G5xsaCXKZKwUFSs1HYQChAy2R3TXHvfAnnuv3CW555AfP/k9vZ9x/XmIIVEWdEp0ezNSsEBK8sfADkrcSHWlpFa7Yj/LokoCjMaqnrM6nU8jGZ1EwTHKUi7rhptL/tj554kQ+t7Q0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786521772; c=relaxed/simple; bh=WeclA6hpGtq/12hzZeNwLr2k3cWYGI+sBQ+Xo2Ez3ZU=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=I51KxFiIsBvlF+OON1/jpE8jcesUQp8kQldO1gJYCnU6s5xEI2nxKEl1YGzJuLYyYM+aPoLKJBL7Fjlu/1SPBqkKmz2AUYpIzrgDCVC4VcbRd5cgMMK36YRoDeklj6w1wp6du57TCQKN93W6kEGNwOrF7c3Dnm+11BvM+iRgaXE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=c4JFzCW2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="c4JFzCW2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8C0B1F000E9; Wed, 12 Aug 2026 08:02:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786521771; bh=zMKWbCFxNs+UTbvigaGnErTlMfeQCiXsHRHCVUqovps=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=c4JFzCW2EmD/DLzo/hgRkQ6ugfHyQR6JFZqipTulnx76qoKR07LaQPgAdY16xxgMl leLd/D9op4VrwCLzP4TrovhNqIIOmRX1cIUTQlGJPLbgRTqADcA52SkmsTqlMwf97j CfR6i2LLbob/F+DkrrUeavOPJ/UTbENVSsHTFrL4Com0J/iBbjByH6DLoc3vjo97D2 5vfEVNW7tPrB3P9RBjAVzTqrH5DgFaYT2lHic9QuEHzi7W7BBFIIrMLgZ/BGXs+DaB swfTNdP5kM2LKsbsQmBMOpowh/Gyv9wK1q5i6Ca8FcT3yy5+WBmptz7zIt7rxrpT1c tXsWS7Hjimyeg== From: sashiko-bot@kernel.org Subject: Re: [PATCH] s390/debug: Fix deadlock during unregister Reply-To: sashiko-reviews@lists.linux.dev To: "Peter Oberparleiter" Cc: "Alexander Gordeev" , "Christian Borntraeger" , linux-s390@vger.kernel.org, "Vasily Gorbik" , "Heiko Carstens" In-Reply-To: <20260812075319.2007940-1-oberpar@linux.ibm.com> References: <20260812075319.2007940-1-oberpar@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 12 Aug 2026 08:02:50 +0000 Message-Id: <20260812080250.A8C0B1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > Unregistering an s390dbf debug area while one of the associated debugfs > files is being written to can cause a deadlock: >=20 > $ echo >.../vmur/level $ rmmod vmur > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D > debugfs write > debugfs_file_get() > debug_unregister() > mutex_lock(debug_mutex) > debugfs_remove() > wait for debugfs_file_put() > debug_file_ops.write() > debug_input() > mutex_lock(debug_mutex) =3D=3D> DEADLOCK >=20 > Fix this by splitting debug_unregister() into an s390dbf and debugfs > part, and running only the s390dbf part with debug_mutex locked. >=20 > Signed-off-by: Peter Oberparleiter Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260812075319.2007= 940-1-oberpar@linux.ibm.com?part=3D1