From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793051906; b=VqKtzFwm4smAEYWdTQuaoedoDhDR8DypHU77FVoTENY66laiGOLXxuZ3BlHjJ6ZamgJC DSvoc3SErFY8ESv6ibsrI+YDqTtDRMaCqo+xz7WK6kos8vG2SgYGEe7EZ6Agyw1RW543G TuW9qKD/4jIWYXNZ1cGrrRj5Nlracm05pqbSf9v8yQUfIVCvvrs/YY5QqUsYQwvgTuOee Sg5NnwW0pReMBTTvcwWrDphJaLqE5yJkn+WUjssx6ZKhbRKIANgYcKXjPVty3TkoWHesV a42myDuM2/o0+Eaylj/Jl8qlWVeB0NLuhaQmwMZXuKPq3sYqxYX88aXgEclevXCJ0Ow== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793051906; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=ItVTvdIep7IAfB5nagCC/njxIQmU6rUKtEVGu3hqs+U=; b=M8PHB8d8OSjukWBPyoiUe45Cz7tDYa+hdWwZNoP1tV9XL8upsnn4HAuQiecLdlwB1N5T Ku48u5R9505ozDLLDGulgRGcz089P4cazYBa+Nh28J6/Ze4BrE0a9fukM01pBUWdO3eFT jo1rF9eNolhLLA6/kanKofbOdpfC8ADd12KmNpCIv/+FLIgaSmkTiK03DC9ZJgQFBLG59 AeMv9Cc9/6dC52QYBEl4bfnQdNnrZVkv+ztekgC5qRZXb4L8RoR4OJIdK5C7NGVQ7oKLT J9w5B7mxQbXbfcoGfIxVtkSJ0L/5H5Ow08G1HHINgKSxo7I9zV+Vx2y9IC9l93FdjGQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="cnQTn/gl"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with UTF8SMTPS id 22C5E606A31A; Mon, 26 Oct 2026 21:58:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=cnQTn/gl Received: by smtp.kernel.org (Postfix) with UTF8SMTPSA id 3323D1F01825; Mon, 26 Oct 2026 21:58:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793051905; bh=ItVTvdIep7IAfB5nagCC/njxIQmU6rUKtEVGu3hqs+U=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=cnQTn/glRQOrBDUFb18cXGq16CAgeZHDi4/4jfHNSlECOK4mIg8Vjk2caWWyaYBPi N348P3WuGVkVYtm6o7JZFaXHsU59GXXAiAj/sYOSr2I5TtvcqdrrzVhmC2EEwF+BP7 7Pi8d/SWfIjY1ZeCJhUjyjMkY/BSr1n3vUxhaR/7a5CI6iEh1a0iDDhgDcWzNMREGK A9DCfiDwFFLdRJCuq960yxrYxqEUlfZo+pbrmWCA49PyLRy99vSeLxqtBAZXnDal5h nY0BlbM+4WIdQ3vs2jprGvxq0nzFjkc55UfHEz2MbJO8pZz4eKEjQLJLbhYSITgxcp rEtdji1/XnpUQ== Date: Mon, 26 Oct 2026 23:58:21 +0200 From: Jarkko Sakkinen To: David Howells Cc: keyrings@vger.kernel.org, Eric Biggers , syzbot+c15de43f1e7fffbb7b9b@syzkaller.appspotmail.com, Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , "open list:LIBRARY CODE" , "open list:SECURITY SUBSYSTEM" Subject: Re: [PATCH] KEYS: dispatch key_gc_work to system_wq. Message-ID: References: <20261026031219.2627968-1-jarkko@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261026031219.2627968-1-jarkko@kernel.org> On Mon, Oct 26, 2026 at 05:12:18AM +0200, Jarkko Sakkinen wrote: > schedule_work() dispatches key_gc_work on the per-CPU system_wq, which can > choke the queue: > > BUG: workqueue lockup - pool cpus=0 node=0 flags=0x2 nice=0 stuck for 30s! > > Queue the work on system_dfl_long_wq instead, which is an unbounded wq for > long-running tasks i.e., it has the WQ_BOUND flag set and thus cannot hog > the CPU core. > > Link: https://lore.kernel.org/keyrings/20261024042944.52493-1-hackerowskiy@gmail.com/ > Reported-by: syzbot+c15de43f1e7fffbb7b9b@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/6ad35b60.7952420f.283480.0360.GAE@google.com/T/ > Signed-off-by: Jarkko Sakkinen > --- > I sanity checked with perf that scheduler latency improved clearly as it > should, and used large keyrings that I expired, as the test payload. Based on the feedback, rather than arguing about irrelevant stuff, I'll focus on formalizing AB test for this. I have couple of additional ideas to try out but without AB test fixing this is really just shooting in the wind. Br, Jarkko