Messages in this thread | | | Subject | Re: [PATCH v3 08/23] vfio, mm: fix get_user_pages_remote() and FOLL_LONGTERM | From | John Hubbard <> | Date | Tue, 12 Nov 2019 17:08:07 -0800 |
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On 11/12/19 4:58 PM, Dan Williams wrote: ... >>> It's not redundant relative to upstream which does not do anything the >>> FOLL_LONGTERM in the gup-slow path... but I have not looked at patches >>> 1-7 to see if something there made it redundant. >> >> Oh, the hunk John had below for get_user_pages_remote() also needs to >> call __gup_longterm_locked() when FOLL_LONGTERM is specified, then >> that calls check_dax_vmas() which duplicates the vma_is_fsdax() check >> above. > > Oh true, good eye. It is redundant if it does additionally call > __gup_longterm_locked(), and it needs to do that otherwises it undoes > the CMA migration magic that Aneesh added. >
OK. So just to be clear, I'll be removing this from the patch:
/* * The lifetime of a vaddr_get_pfn() page pin is * userspace-controlled. In the fs-dax case this could * lead to indefinite stalls in filesystem operations. * Disallow attempts to pin fs-dax pages via this * interface. */ if (ret > 0 && vma_is_fsdax(vmas[0])) { ret = -EOPNOTSUPP; put_page(page[0]); }
(and the declaration of "vmas", as well).
thanks, -- John Hubbard NVIDIA
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