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Mon, 2 Nov 2020 18:23:15 +0000 (UTC) Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-221-3eybHYmXNVuuSrMONPCpiQ-1; Mon, 02 Nov 2020 18:23:12 +0000 X-MC-Unique: 3eybHYmXNVuuSrMONPCpiQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 2 Nov 2020 18:23:11 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Mon, 2 Nov 2020 18:23:11 +0000 From: David Laight To: 'Greg KH' CC: 'David Hildenbrand' , Al Viro , Nick Desaulniers , Christoph Hellwig , "kernel-team@android.com" , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mips@vger.kernel.org" , "linux-parisc@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-s390@vger.kernel.org" , "sparclinux@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-aio@kvack.org" , "io-uring@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-mm@kvack.org" , "netdev@vger.kernel.org" , "keyrings@vger.kernel.org" , "linux-security-module@vger.kernel.org" Subject: RE: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Thread-Topic: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Thread-Index: AQHWqE5GNDfnH4y9nkGWtfqJueR1KKmjTCJQgAAN4UiAAAD2IIAASOeCgAF+12CAAB+UKYAAAQNg///yIQCAD2i/YIAAT+MAgABLYlA= Date: Mon, 2 Nov 2020 18:23:11 +0000 Message-ID: References: <20201022121849.GA1664412@kroah.com> <98d9df88-b7ef-fdfb-7d90-2fa7a9d7bab5@redhat.com> <20201022125759.GA1685526@kroah.com> <20201022135036.GA1787470@kroah.com> <134f162d711d466ebbd88906fae35b33@AcuMS.aculab.com> <935f7168-c2f5-dd14-7124-412b284693a2@redhat.com> <999e2926-9a75-72fd-007a-1de0af341292@redhat.com> <35d0ec90ef4f4a35a75b9df7d791f719@AcuMS.aculab.com> <20201023144718.GA2525489@kroah.com> <0ab5ac71f28d459db2f350c2e07b88ca@AcuMS.aculab.com> <20201102135202.GA1016272@kroah.com> In-Reply-To: <20201102135202.GA1016272@kroah.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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: 'Greg KH' > Sent: 02 November 2020 13:52 >=20 > On Mon, Nov 02, 2020 at 09:06:38AM +0000, David Laight wrote: > > From: 'Greg KH' > > > Sent: 23 October 2020 15:47 > > > > > > On Fri, Oct 23, 2020 at 02:39:24PM +0000, David Laight wrote: > > > > From: David Hildenbrand > > > > > Sent: 23 October 2020 15:33 > > > > ... > > > > > I just checked against upstream code generated by clang 10 and it > > > > > properly discards the upper 32bit via a mov w23 w2. > > > > > > > > > > So at least clang 10 indeed properly assumes we could have garbag= e and > > > > > masks it off. > > > > > > > > > > Maybe the issue is somewhere else, unrelated to nr_pages ... or c= lang 11 > > > > > behaves differently. > > > > > > > > We'll need the disassembly from a failing kernel image. > > > > It isn't that big to hand annotate. > > > > > > I've worked around the merge at the moment in the android tree, but i= t > > > is still quite reproducable, and will try to get a .o file to > > > disassemble on Monday or so... > > > > Did this get properly resolved? >=20 > For some reason, 5.10-rc2 fixed all of this up. I backed out all of the > patches I had to revert to get 5.10-rc1 to work properly, and then did > the merge and all is well. >=20 > It must have been something to do with the compat changes in this same > area that went in after 5.10-rc1, and something got reorganized in the > files somehow. I really do not know, and at the moment, don't have the > time to track it down anymore. So for now, I'd say it's all good, sorry > for the noise. Hopefully it won't appear again. Saved me spending a day off reading arm64 assembler. =09David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales)