From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) (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 5519C2F38 for ; Thu, 17 Mar 2022 11:22:43 +0000 (UTC) Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id C41DF1C0B7F; Thu, 17 Mar 2022 12:13:06 +0100 (CET) Date: Thu, 17 Mar 2022 12:13:05 +0100 From: Pavel Machek To: Tony Luck Cc: Thomas Gleixner , Fenghua Yu , x86@kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev Subject: Re: [PATCH v2 1/2] x86/split_lock: Make life miserable for split lockers Message-ID: <20220317111305.GB2237@amd> References: <20220217012721.9694-1-tony.luck@intel.com> <20220310204854.31752-1-tony.luck@intel.com> <20220310204854.31752-2-tony.luck@intel.com> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="6sX45UoQRIJXqkqR" Content-Disposition: inline In-Reply-To: <20220310204854.31752-2-tony.luck@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) --6sX45UoQRIJXqkqR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > In https://lore.kernel.org/all/87y22uujkm.ffs@tglx/ Thomas > said: >=20 > Its's simply wishful thinking that stuff gets fixed because of a > WARN_ONCE(). This has never worked. The only thing which works is to > make stuff fail hard or slow it down in a way which makes it annoying > enough to users to complain. >=20 > He was talking about WBINVD. But it made me think about how we > use the split lock detection feature in Linux. >=20 > Existing code has three options for applications: > 1) Don't enable split lock detection (allow arbitrary split locks) > 2) Warn once when a process uses split lock, but let the process > keep running with split lock detection disabled > 3) Kill process that use split locks I'm not sure what split locks are, and if you want applications to stop doing that maybe documentation would help. Anyway, you can't really introduce regressions to userspace to "get stuff fixed" in applications. Pavel --=20 DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany --6sX45UoQRIJXqkqR Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAmIzF8EACgkQMOfwapXb+vLXtgCgu8hgn9uzvyozj3rvbJXWngQE huUAn2kdrz3cZJ4I3rLkm+d3qORv5dd+ =nuYL -----END PGP SIGNATURE----- --6sX45UoQRIJXqkqR--