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[2620:137:e000::1:9]) by mx.google.com with ESMTPS id x34si11075edm.138.2019.07.18.14.14.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Jul 2019 14:14:08 -0700 (PDT) Received-SPF: neutral (google.com: 2620:137:e000::1:9 is neither permitted nor denied by best guess record for domain of davem@davemloft.net) client-ip=2620:137:e000::1:9; Authentication-Results: mx.google.com; spf=neutral (google.com: 2620:137:e000::1:9 is neither permitted nor denied by best guess record for domain of davem@davemloft.net) smtp.mailfrom=davem@davemloft.net Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::d71]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 29B831528342B; Thu, 18 Jul 2019 14:14:06 -0700 (PDT) Date: Thu, 18 Jul 2019 14:14:05 -0700 (PDT) Message-Id: <20190718.141405.1070121094691581998.davem@davemloft.net> To: ldv@altlinux.org Cc: hch@lst.de, khalid.aziz@oracle.com, torvalds@linux-foundation.org, akpm@linux-foundation.org, matorola@gmail.com, sparclinux@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 09/16] sparc64: use the generic get_user_pages_fast code From: David Miller In-Reply-To: <20190717215956.GA30369@altlinux.org> References: <20190625143715.1689-1-hch@lst.de> <20190625143715.1689-10-hch@lst.de> <20190717215956.GA30369@altlinux.org> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 18 Jul 2019 14:14:06 -0700 (PDT) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: "Dmitry V. Levin" Date: Thu, 18 Jul 2019 00:59:56 +0300 > So this ended up as commit 7b9afb86b6328f10dc2cad9223d7def12d60e505 > (thanks to Anatoly for bisecting) and introduced a regression: > futex.test from the strace test suite now causes an Oops on sparc64 > in futex syscall. > > Here is a heavily stripped down reproducer: Does not reproduce for me on a T4-2 machine. So this problem might depend on the type of system you are on, I suspect it's one of those "pre-Niagara vs. Niagara and later" situations because that's the dividing line between two set of wildly different TLB and cache management methods. What kind of machine are you on?