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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F118C433EF for ; Tue, 24 May 2022 16:45:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235090AbiEXQp2 (ORCPT ); Tue, 24 May 2022 12:45:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49034 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233170AbiEXQp1 (ORCPT ); Tue, 24 May 2022 12:45:27 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF427427FF; Tue, 24 May 2022 09:45:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1653410713; bh=gLTqESgkAFXqK+taUv6Ift55c8iBixK6EHmM6tkr+gs=; h=X-UI-Sender-Class:Date:Subject:To:Cc:References:From:In-Reply-To; b=Ntf5/GKPt7waxQaMaK91YXanz0KAshFY6MJ595uEIAJGjwVkzYt11D2x5AiYA0b4L twFxRySc+irwcXFnXYMcXCcV6bmOiofaZRn0+Bbib8yOkx5N2cAqRkOjefbe7J6YES Iqi2teVjOTaqqmn8FakI/Zq7URGni2+MtNEz2W84= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [192.168.20.60] ([92.116.137.3]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MPokN-1oFtl42BsZ-00MrQe; Tue, 24 May 2022 18:45:13 +0200 Message-ID: <786f58e8-aa61-d439-c9bb-4a27599d2aa5@gmx.de> Date: Tue, 24 May 2022 18:44:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH AUTOSEL 5.10 2/8] parisc: Disable debug code regarding cache flushes in handle_nadtlb_fault() Content-Language: en-US To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: John David Anglin , James.Bottomley@HansenPartnership.com, akpm@linux-foundation.org, zhengqi.arch@bytedance.com, linux-parisc@vger.kernel.org References: <20220524160035.827109-1-sashal@kernel.org> <20220524160035.827109-2-sashal@kernel.org> From: Helge Deller In-Reply-To: <20220524160035.827109-2-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:lxjHMfxahx2TQbAWs57lPcq/4pfkYB1LueL12A81ItzRKOHqtC5 prI0PdUpPX+ZV+ug1dWE1Y7yDjLaTULuj+7l6JO6U9GOmUDrP2LKSXlcuH3eLy//2gEzQJx rQCRNoz3YEBjeuiS/K6R5a2HK3vGW1GKMQmpK4W1srU3zXvyUyiW4IZYwoOKVlxdMIpOc/T mQX/e4mgmonfqX73Lu0+w== X-UI-Out-Filterresults: notjunk:1;V03:K0:rWhv9GBFGZM=:xV29K9fWzhmf773KfTlsUz Ikf52/0aHB5vOQIBKFABHzm6X5oWLcXySsabm19UtEQZXtfdAhJIo1vNjaZ2W2fLBRBZCqrTT /lio+1p84hJdwbNA6rDXzYkDwcGyt7dpTX3k5eBgN0YRen/FOoQ9OsdqUmBSJF7SEuTAceSwd ZnVy3lbLOt3tdB5YjpAYX7Gpu6p+X0dABKH/e7rh9Y1wxch1RxkldREvqIhjv/iYb9fnMDZi5 8DNLr9WK6wPTSxVrvs7wypDhJV4ogp+aQajIg3KpSVJ7lgxnFKgxUEeHDmATxfmsiUZkSMKmY vSZtgDu+IGyus8QN6NNepGsyfz8vCXS+a+2odmFsdHXwRekxQtwsoJKaGsotS1uCaD6Zi/lcU BuysxZIVSy1nAe5pFiWc+P/nSSffq+4LhQohcJKATQvJXMK2mo3Z0+U5BtWGa0ORy/2rmRyAO CPL+rAkPRsqRtlogQ5XUg7ExSQn2H7mfB09FC+5vPhgxQE3/bGM6VCz5TosHQzuDpzUZtegC6 Pby5VvYreBkcsOvDoplsz9u9e+f3Wc7bFsmoVaJO9QNBBGp010y0PStDWONLb0laMRhIb/98V jsS8+cc6xXSwjilMZ3aKdxhekaqpyNa/dw+yKk4sN91HBuagQzXYF6YSlr+dmrKRYkf8OiAqw uSM3itKcDJyy0N5elr+W/c2++Q312XgmoRP1QAOzC7QDTx2RSqRWMM5udX42bJ2LwY7ewAlH2 3riI5TlvuyK6EqKQ2Ko7DkmxnSeiwzUsJtclqZmgKlC+7271iIWIBBeE8Dihi85PcSbsNsbxD 0InxplVOTwNoOS6VKdfNKB3cyKnb9PON3L2hkDHvldS0jkgXOdSQImaYeYZMzLabpePOFpUBV hIOQw5g684ZgL9eB5H2fhKntcSGZYHcn7SUYeR6fO6Cy44U/ZPu+eJ0VtUyA31yEXIhYC+a5r xiI8Co0QpY8gGE467YLTdE/58i4VESW5xHTPMLcROGTbNaxAwYtzzgavX3Z0AWj9iaWdWMxnO pQLncz4W/54Ax76szGC7XTjtcvBv1CbBYFmj7IutA/Nb4Ey7G5qkz3OXAP1liorvUcgkdtLzL 2ICqcEcttdAj1H1mW5MYdSxcZAbvMXw07qN Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org Hello Sascha, On 5/24/22 18:00, Sasha Levin wrote: > From: John David Anglin > > [ Upstream commit 67c35a3b646cc68598ff0bb28de5f8bd7b2e81b3 ] > > Change the "BUG" to "WARNING" and disable the message because it trigger= s > occasionally in spite of the check in flush_cache_page_if_present. Please drop this patch from the backporting-queue (v5.10, v5.15 and v5.17)= . It's not necessary since the warning will only trigger on v5.18 on machine= s with PA8800/PA8900 processors. Thanks. Helge > The pte value extracted for the "from" page in copy_user_highpage is rac= y and > occasionally the pte is cleared before the flush is complete. I assume = that > the page is simultaneously flushed by flush_cache_mm before the pte is c= leared > as nullifying the fdc doesn't seem to cause problems. > > I investigated various locking scenarios but I wasn't able to find a way= to > sequence the flushes. This code is called for every COW break and locks= impact > performance. > > This patch is related to the bigger cache flush patch because we need th= e pte > on PA8800/PA8900 to flush using the vma context. > I have also seen this from copy_to_user_page and copy_from_user_page. > > The messages appear infrequently when enabled. > > Signed-off-by: John David Anglin > Signed-off-by: Helge Deller > Signed-off-by: Sasha Levin > --- > arch/parisc/mm/fault.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c > index 5faa3cff4738..2472780d4039 100644 > --- a/arch/parisc/mm/fault.c > +++ b/arch/parisc/mm/fault.c > @@ -22,6 +22,8 @@ > > #include > > +#define DEBUG_NATLB 0 > + > /* Various important other fields */ > #define bit22set(x) (x & 0x00000200) > #define bits23_25set(x) (x & 0x000001c0) > @@ -449,8 +451,8 @@ handle_nadtlb_fault(struct pt_regs *regs) > fallthrough; > case 0x380: > /* PDC and FIC instructions */ > - if (printk_ratelimit()) { > - pr_warn("BUG: nullifying cache flush/purge instruction\n"); > + if (DEBUG_NATLB && printk_ratelimit()) { > + pr_warn("WARNING: nullifying cache flush/purge instruction\n"); > show_regs(regs); > } > if (insn & 0x20) {