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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?1BIRC8ebNzJojU9IWpb03BXCuSKv8UA2gI7DftJ69fJ/VtnhPXVKZZKfTHWw?= =?us-ascii?Q?Z0zcJDItw6Ok2y6AYEXlJ2ZC1WsCI8dbsGEarIbRERqoe2VYFQWliRL5NTay?= =?us-ascii?Q?rwza12NyjHMm4TbqbT3uPJ6dSs5yg8Lb+34jDLa965Luu3BGYjjW3nuz1uLQ?= =?us-ascii?Q?H1B3X99t9f5p/C38wYbNgZCXNHtne8TkPwEQ+P6Mtr/nxdWkRrwr3Pzezua2?= =?us-ascii?Q?g+NZopsCZ4JYcl7hkeLrN6aJMSeitCmFzbBpKE0u5VXTUKVvLir2quLI5ejN?= =?us-ascii?Q?K/A0jq6R2HjGXYScnHMvUTzICXWVxp1ntUZMF8tS0SdrQBz8NAcZaUHrMSx1?= =?us-ascii?Q?33ZahucBpbd+AG9vv8eeAMNVYN/SigsXYD/K447MRuH+AkHp4kivWQMwtBQl?= =?us-ascii?Q?3+ce19nyGC3S4vIrzkfHt7h0ortyQWWG+sIsjZAdScN8I1Hh4OAKN4AjGM5s?= =?us-ascii?Q?ijECRJilm3qcI/5DS7oHLXmuGqCpD4uVxJj0COWS71AT7tSRsJ86DZTBaeeD?= =?us-ascii?Q?sh827a2MAfOUvKxHlVfrBZrjQ25Bh1n1oSo1L36x9/S7UGbH2tcD7lKg0Pzr?= =?us-ascii?Q?T1dEfkckwEUbMMiTyl/U/zbJ2wR8KPvSRKyHpdbww1ZeY6Jh62VwKsk3oLkA?= =?us-ascii?Q?tb1+JEg+zdD4qvgzWvEUcI3i9bnEhZXhd1q20AcrNRhJqRNlUqmSz7SC1/rw?= =?us-ascii?Q?e5A/aFSaRVeEeqhkvc0S8snb8+6VRKcgHBs6Ia9pjpwEacqFh27Qc/QHv8A0?= =?us-ascii?Q?RAflAALH7AdV7xMdJy946+yy4dynBvmAVD6rNKC2EfTfmGPXsJp95Eb8NMR6?= =?us-ascii?Q?ThSi96xLWEkq3CYarQ5VgCpcBsR15Gt9mIUNYxZh9+TKaqNJpSAQKF4MaGCd?= =?us-ascii?Q?AjY2laZAOvGAK2Tu9pJoQ5zD2b7Qc4sKE1jBV4IYC2NuerOJuUD1JtHQXbMu?= =?us-ascii?Q?gW+1RTmHq9KR34O3SYq2nzlV+gwfkBn+cBiqlqi3WM1fCF0USNG1FjOcRXJf?= =?us-ascii?Q?GXso3LpZGXzPfkchYzrsARTLVfdCvYI8Iedptz3x7zgJv0KuwgGOpXZ5N7OP?= =?us-ascii?Q?qMw2BM4dRXXnNTlUtYU/aXyreF1gra94sGw2JrfZWwE+YFPKlR5RxONGcfUU?= =?us-ascii?Q?Zy5MDd6kO8XEDINk3fHt9EGH3wKQ5uuizhu2d6XffqHILyPQrkgIu8D8OWJ6?= =?us-ascii?Q?N/9nLXWCEBa8Buo8I8O1lX8iMZ4X9rkt0wWxt3rA+NMDxLIOktEbo86kkcic?= =?us-ascii?Q?5mQjjFVd7IzQasxPi2GeE4Zx9+3fkhqxHBp8jqwsQYnJIZsp1pO5HgifGFbw?= =?us-ascii?Q?Pexq7nDzp8UHyB0EwxJzgnLgyb7ub6kBUWGB4uCWsG0tWTWjTzNaWs9roP2N?= =?us-ascii?Q?5zm8yp3CyIY+F2FUAF1on0zMuD//g0A6KbTgcwGy62qdaGi1ZKAd4D6iX7ne?= =?us-ascii?Q?EXJUxRrj4uzGh2ZbEyNA0xNot6gSca/URZkzFonGQKDu4DUFj5fz+MSZMjRT?= =?us-ascii?Q?9ySAnedzQzifFJH7tP2gw1nVxuefjEr9fEFX2uJ1o+MAii9g1dCp+jJiLWRF?= =?us-ascii?Q?zVbskoc7mV+SEryG98d0TMCksYifpqwZYHFDoJs6?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 26384549-292d-4295-de44-08ddaf0cf1aa X-MS-Exchange-CrossTenant-AuthSource: CY8PR12MB7705.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Jun 2025 08:40:28.9434 (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: EY1NgozUq4ApkAmyh0mocnA6g5ioPWsM3lX+4YedOAZTByj5xGGvAeU/XijncjGlOj3Catu+bYM0PK9rrIj9nA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY5PR12MB6274 On Tue, Jun 17, 2025 at 11:19:34AM +0200, David Hildenbrand wrote: > On 16.06.25 13:58, Alistair Popple wrote: > > Currently dax is the only user of pmd and pud mapped ZONE_DEVICE > > pages. Therefore page walkers that want to exclude DAX pages can check > > pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV, > > meaning dax pages are mapped as normal pages. > > > > Ensure page walkers that currently use pXd_devmap to skip DAX pages > > continue to do so by adding explicit checks of the VMA instead. > > > Signed-off-by: Alistair Popple > > Reviewed-by: Jason Gunthorpe > > Reviewed-by: Dan Williams > > > > --- > > > > Changes from v1: > > > > - Remove vma_is_dax() check from mm/userfaultfd.c as > > validate_move_areas() will already skip DAX VMA's on account of them > > not being anonymous. > > This should be documented in the patch description above. Ok. > > --- > > fs/userfaultfd.c | 2 +- > > mm/hmm.c | 2 +- > > mm/userfaultfd.c | 6 ------ > > 3 files changed, 2 insertions(+), 8 deletions(-) > > > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > > index ef054b3..a886750 100644 > > --- a/fs/userfaultfd.c > > +++ b/fs/userfaultfd.c > > @@ -304,7 +304,7 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, > > goto out; > > ret = false; > > - if (!pmd_present(_pmd) || pmd_devmap(_pmd)) > > + if (!pmd_present(_pmd) || vma_is_dax(vmf->vma)) > > goto out; > > VMA checks should be done before doing any page table walk. Actually upon review I think this check was always redundant as well - vma_can_userfault() checks limit userfaultfd to anon/hugetlb/shmem vma's. Boy we sure have a lot of these "normal vma" checks around the place ... at least for certain definitions of normal. Anyway will remove this and add a note to the commit (and apologies for not catching this last time as I think you may have ready mentioned this or at least the general concept). > > if (pmd_trans_huge(_pmd)) { > > diff --git a/mm/hmm.c b/mm/hmm.c > > index feac861..5311753 100644 > > --- a/mm/hmm.c > > +++ b/mm/hmm.c > > @@ -441,7 +441,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > > return hmm_vma_walk_hole(start, end, -1, walk); > > } > > - if (pud_leaf(pud) && pud_devmap(pud)) { > > + if (pud_leaf(pud) && vma_is_dax(walk->vma)) { > > unsigned long i, npages, pfn; > > unsigned int required_fault; > > unsigned long *hmm_pfns; > > Dito. Actually I see little reason to restrict this only to DAX for HMM ... we don't end up doing that for the equivalent PMD path so will drop this as well. Thanks! > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > > index 58b3ad6..8395db2 100644 > > --- a/mm/userfaultfd.c > > +++ b/mm/userfaultfd.c > > @@ -1818,12 +1818,6 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start, > > ptl = pmd_trans_huge_lock(src_pmd, src_vma); > > if (ptl) { > > - if (pmd_devmap(*src_pmd)) { > > - spin_unlock(ptl); > > - err = -ENOENT; > > - break; > > - } > > - > > /* Check if we can move the pmd without splitting it. */ > > if (move_splits_huge_pmd(dst_addr, src_addr, src_start + len) || > > !pmd_none(dst_pmdval)) { > > > -- > Cheers, > > David / dhildenb > >