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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jul 2023 21:32:23.4828 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 56e791ca-62cd-4e04-515e-08db8fb221c2 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000044F9.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB6189 X-Rspam-User: X-Stat-Signature: n71qkiayte46j63ny3g8tnymabj8qqwn X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DC6A640019 X-HE-Tag: 1690579946-253185 X-HE-Meta: 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 /mKV+J+n B/eTKEHZ+d6W6JCdiX5x0vPY7C7lXFImM8BGJwsdgbe1hMN2z4ZjjhK3y+eQcBv/4ZcVFHPOctBf/7yM0lFuu+3F/s2pydzqbfU0jV2F1RNOb2pRlwcp9XpN/UxGmlu1X+5mxci7XnibICpnH+iWyeBYmgcH9SQ3dKlyHpDNeC5QPPWjHyCtMngbHDEaDeXNIj833OAgopusb4/igRdT6T9neKcLTYZ+Lzt6GFmfdqmww9Ecfkw153MAAdW3WL4aK8xGm/KXrK7W2uGn25dPv7aL++tfggp2wHG1bc3q6edscjUF+IEhfokMIyCta4GMtosb28WSkgTnmdtfqt42uMn7RDYmSHYjqmhBJuVq1yzChfvGyAWQ8TlxrqU6YkWmswogS 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: On 7/28/23 14:20, Peter Xu wrote: > On Fri, Jul 28, 2023 at 11:02:46PM +0200, David Hildenbrand wrote: >> Can we get a simple revert in first (without that FOLL_FORCE special casing >> and ideally with a better name) to handle stable backports, and I'll >> follow-up with more documentation and letting GUP callers pass in that flag >> instead? >> >> That would help a lot. Then we also have more time to let that "move it to >> GUP callers" mature a bit in -next, to see if we find any surprises? > > As I raised my concern over the other thread, I still worry numa users can > be affected by this change. After all, numa isn't so uncommon to me, at > least fedora / rhel as CONFIG_NUMA_BALANCING_DEFAULT_ENABLED=y. I highly > suspect that's also true to major distros. Meanwhile all kernel modules > use gup.. > > I'd say we can go ahead and try if we want, but I really don't know why > that helps in any form to move it to the callers.. with the risk of > breaking someone. It's worth the trouble, in order to clear up this historical mess. It's helping *future* callers of the API, and future maintenance efforts. Yes there is some risk, but it seems very manageable. The story of how FOLL_NUMA and FOLL_FORCE became entangled was enlightening, by the way, and now that I've read it I don't want to go back. :) thanks, -- John Hubbard NVIDIA