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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?vbLJBiYGI/M2wm4oyzPoF1TO+wOAwTBBA+NycfuQoHd3xvJA3LQ/G9OEm4fi?= =?us-ascii?Q?gBXs5BQm4j4LWUZ753h7w8ezk/i51QemqGbd0pXzLKFHzbswZFAs4FxRJKLm?= =?us-ascii?Q?sn3ARkMSevSlucomFeT/Y0WzV3u74E6PvsbLOk0D9YQpL5jxB2XOA4CoHLin?= =?us-ascii?Q?4/IBHiUDuyG8zzhXMdYEtHWit+rhZ6Umndy04cAjfhjapqaJ2HRCDkTNCk/n?= =?us-ascii?Q?gjVj4BHWLtFi/PvGZrP/mbe08kOj4xLEzzzg2UG2iXmcF7/VbyVTX7+eIatm?= =?us-ascii?Q?rz/iN55gb7MIVR3inmWBCuuyT5G1C/2CjCZOST27gK+U2aevLUIGW90l9oLl?= =?us-ascii?Q?F7Y5Y6U36wvZvr6TDS54XNCXjsGy/7c3diVi+q01Vs9b04KHHfPi3i1dkstU?= =?us-ascii?Q?WZcL7H78t78hykWFQDuRF0eS0yHNhAG0YBGEi3u2ykw0OpnSljbME24YRS1i?= =?us-ascii?Q?10Pm8ag1Oy9TAnnjcSXI8iP7eOjYOvAmdaQl+ske7sWO0GOWufdjlz92nsDl?= =?us-ascii?Q?ypnIGCXB2qldlwg6EvrgBemoAJCBRU3RyayFyrVOTNxjxAmdR4+9VuoFWR1/?= =?us-ascii?Q?kaW40DYZI5qhtkKb88HbLObqap6e1x/QMd7+ZCEhyO4c6XUKYVUtVJwk9Np9?= =?us-ascii?Q?eSCSdk/Nu/weKvVXk8ES6Nm1QfZFzxNMoEPabBPTq7eejuahbH5LLb4t1fwW?= =?us-ascii?Q?8ijELquUkoAwP+j/3mxRcJE1aSLPIIRSlCCFu7CAAmdVIlcU4/lBFTXuBlzK?= =?us-ascii?Q?/A09ZSgWu4ka40pFsdZNEW/E0vJlgGhlICLRKdFKXAxOWSL+jx8j9Km+JgXU?= =?us-ascii?Q?vT0G29pByrpTWU150qwbLXI6gXVWAPDQBbwATGzlz5HuuSa5cjJ6eIpAhUup?= =?us-ascii?Q?2A1tLlxiAQB5F/0hzWX1DFyy0FTGMAqBG9Yjg5vq/cKr4dmRnKmZ7l14Hknr?= =?us-ascii?Q?Xc6rx5yWyr2T/yUa22pVq1wRN1/sxvY8n6BZ77Pv/tATIt8tM2Z7tnqtyxJR?= =?us-ascii?Q?I95e7XouzZwNA8nZwnUsvMMcmf71LxD16qO4PthOG2M4KXo9cFt0mJfy1Jub?= =?us-ascii?Q?Y5bRe4pSnv/Pz2g9v+n83xQOmtST48L/oPx/ncv0qNIIRiM7FpvQlbXa6dbR?= =?us-ascii?Q?R0N9tbnRQQkUTHq9uxFUZwodbiRMWj+mYvATd1aTQg/gsUkcorVXFGGO9aRU?= =?us-ascii?Q?PZk7TU7LF3MmjHkQkoAcjoxpXIYg0ywwT89dB3lTaDupXs5f/sm5nDenBs9J?= =?us-ascii?Q?mZrRtqAEmA1hl+1eycFXUYGKmA21k8jA1r3rKZTM+kG6Gab40sOyokZKotSm?= =?us-ascii?Q?7VELY8dLtXL++kSDC6AalQwd7987lavvepY0TGLLPLhomXAYZOUW9OPCrnBY?= =?us-ascii?Q?N4X6jP7xpT94GREYNqS+hMP6ZrkXryJ8qlSM/320shFuPeZOoBY10+HeBhgE?= =?us-ascii?Q?Y1HaaX/5gDn6++br6ciBRPdrOu3UtY/Y94hHvzEVREm/v46UypVxDX/aPcED?= =?us-ascii?Q?76vi/hED79l9V9P00nWhgEzDNxp9QXYrcW8fzOcky6RBkII+K3WqGI9cbHHO?= =?us-ascii?Q?Oj2XakkitiDTIJz/u78fRzlFaJsz/dgB9qZog5munT4umWnUVLdays1G2I7I?= =?us-ascii?Q?j9XV9IKnAIQBAFpymcW7JtpYuQv956jX8MSkzBVFP1p3OMBoVJ2f7xtwwWxD?= =?us-ascii?Q?rYQiD26vDhWuY82mpsHWKzrOYmxYAdRdO0jGOShZPC8u2e0/T29TM2NvkhWT?= =?us-ascii?Q?yZEVJfmhEA=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: a7e0d8ba-7427-4846-6e02-08dea0e141e9 X-MS-Exchange-CrossTenant-AuthSource: BL4PR12MB9478.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Apr 2026 02:37:26.7863 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ycx8p+Tlq/dUp+9Ym1a03I4vSS5Fr16Vr05YgY3aYva/Ozoj6G3M9epYXhFt410J X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB7494 On 22 Apr 2026, at 21:41, Baolin Wang wrote: > This reverts commit 5a90c155defa684f3a21f68c3f8e40c056e6114c. > > Currently, when shmem mounts are initialized, they only use 'sbinfo->hu= ge' to > determine whether the shmem mount supports large folios. However, for a= nonymous > shmem, whether it supports large folios can be dynamically configured v= ia sysfs > interfaces, so setting or not setting mapping_set_large_folios() during= initialization > cannot accurately reflect whether anonymous shmem actually supports lar= ge folios, > which has already caused some confusion[1]. > > Moreover, for tmpfs mounts, relying on 'sbinfo->huge' cannot keep the m= apping_set_large_folios() > setting consistent across all mappings in the entire tmpfs mount. In ot= her words, > under the same tmpfs mount, after remount, we might end up with some ma= ppings > supporting large folios (calling mapping_set_large_folios()) while othe= rs don't. > > After some investigation, I found that the write performance regression= addressed > by commit 5a90c155defa has already been fixed by the following commit 6= 65575cff098b > ("filemap: move prefaulting out of hot write path"). See the following = test data: > > Base: > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D400K count=3D10485 (3.2 GB/= s) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D800K count=3D5242 (3.2 GB/s= ) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D1600K count=3D2621 (3.1 GB/= s) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D2200K count=3D1906 (3.0 GB/= s ) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D3000K count=3D1398 (3.0 GB/= s) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D4500K count=3D932 (3.1 GB/s= ) > > Base + revert 5a90c155defa: > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D400K count=3D10485 (3.3 GB/= s) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D800K count=3D5242 (3.3 GB/s= ) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D1600K count=3D2621 (3.2 GB/= s) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D2200K count=3D1906 (3.1 GB/= s) > dd if=3D/dev/zero of=3D/mnt/tmpfs/testbs=3D3000K count=3D1398 (3.0 GB/s= ) > dd if=3D/dev/zero of=3D/mnt/tmpfs/test bs=3D4500K count=3D932 (3.1 GB/s= ) > > The data is basically consistent with minor fluctuation noise. So we ca= n now > safely revert commit 5a90c155defa to set mapping_set_large_folios() for= all > shmem mounts unconditionally. > > [1] https://lore.kernel.org/all/ec927492-4577-4192-8fad-85eb1bb43121@li= nux.alibaba.com/ > Signed-off-by: Baolin Wang > --- > Note: for more investigation and test data, see: > https://lore.kernel.org/all/116df9f9-4db7-40d4-a4a4-30a87c0feffa@linux.= alibaba.com/ > Thanks Kefeng for confirming the performance issue. > --- > mm/shmem.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > Thank you for the investigation and explanation. Acked-by: Zi Yan Best Regards, Yan, Zi