From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 639F0C77B7C for ; Thu, 11 May 2023 12:17:50 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4QH9rr6R93z3fWG for ; Thu, 11 May 2023 22:17:48 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=Dnnz4ZrI; dkim-atps=neutral Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4QH9qv4ZmHz3bjY for ; Thu, 11 May 2023 22:16:59 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=Dnnz4ZrI; dkim-atps=neutral Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4QH9qv3KDKz4x4V; Thu, 11 May 2023 22:16:59 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1683807419; bh=KQWCV9FmJH5CqzWvqzks5FSok5ibmu2vlrQSNtsRn/c=; h=From:To:Subject:In-Reply-To:References:Date:From; b=Dnnz4ZrICZyFD2i+dGe19uBY2xMo+ASbmj7O0G7XbCdxspqP7O4KixfnTZ3bvRvcn HJoDq3+wJrmxr79EgEKIbrJw1t+GEfrF8FxY8pvoWWljfAez8hFDTbqpEuaHwoeAFr wMpIg2RppfCNDgNz/U0iKQElNoD7+t7OVuHIIPfEn02/t2zd3ch7bdrm7oEs//vIpd N3oaOT49e0ODkzY+UF8fzd3O/p9ZImkUzJEryAiMkme8kqC/syGuBuQBvVTC0iFwBt xi5G8kZT4ufZmYX8pDe4kNGKp0eT63gqli4pQwQ/Ul3aMddBP5bVQPDPcyjkMKKuVU XW4cn+1DuOyrA== From: Michael Ellerman To: Dan =?utf-8?Q?Hor=C3=A1k?= , linuxppc-dev@lists.ozlabs.org Subject: Re: a possible issue with radix MMU on P9 In-Reply-To: <20230511095558.56663a50f86bdc4cd97700b7@danny.cz> References: <20230511095558.56663a50f86bdc4cd97700b7@danny.cz> Date: Thu, 11 May 2023 22:16:51 +1000 Message-ID: <87bkirkqq4.fsf@mail.lhotse> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Dan Hor=C3=A1k writes: > Hi all, > > we have been struggling with an issue in the bdwgc project (garbage > collector) on P9 systems for a while [1]. There were some test failing > on P9, but not on P8 or other platforms (x86, s390x, aarch64). Recently > the upstream developer has found out there is likely a problem in the > kernel memory mgmt [2], there is a reproduction scenario included. I > have rechecked the original code on P9 with hash MMU and it worked. Thus > I believe there is a problem in the radix MMU code on Power, where it > behaves differently. My testing was using Fedora, which means recent > kernels up to 6.4-rc1. > > [1] https://github.com/ivmai/bdwgc/issues/479 > [2] https://github.com/ivmai/bdwgc/issues/479#issuecomment-1535274481 Thanks Dan. Fix patch here: https://lore.kernel.org/linuxppc-dev/20230511114224.977423-= 1-mpe@ellerman.id.au/ I tested that it fixes the bdwgc failures (with their workaround reverted). cheers