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    SubjectRe: [PATCH v2 1/5] mm: vmalloc must set pte via arch code
    On Thu, May 18, 2023 at 12:07:23PM +0100, Ryan Roberts wrote:
    > It is bad practice to directly set pte entries within a pte table.
    > Instead all modifications must go through arch-provided helpers such as
    > set_pte_at() to give the arch code visibility and allow it to check
    > (and potentially modify) the operation.
    >
    > Fixes: 3e9a9e256b1e ("mm: add a vmap_pfn function")
    > Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
    > Reviewed-by: Zi Yan <ziy@nvidia.com>
    > Acked-by: Lorenzo Stoakes <lstoakes@gmail.com>
    > Reviewed-by: Christoph Hellwig <hch@lst.de>

    Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>

    > ---
    > mm/vmalloc.c | 10 ++++++++--
    > 1 file changed, 8 insertions(+), 2 deletions(-)
    >
    > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
    > index 9683573f1225..48202ec5f79a 100644
    > --- a/mm/vmalloc.c
    > +++ b/mm/vmalloc.c
    > @@ -2899,10 +2899,16 @@ struct vmap_pfn_data {
    > static int vmap_pfn_apply(pte_t *pte, unsigned long addr, void *private)
    > {
    > struct vmap_pfn_data *data = private;
    > + unsigned long pfn = data->pfns[data->idx];
    > + pte_t ptent;
    >
    > - if (WARN_ON_ONCE(pfn_valid(data->pfns[data->idx])))
    > + if (WARN_ON_ONCE(pfn_valid(pfn)))
    > return -EINVAL;
    > - *pte = pte_mkspecial(pfn_pte(data->pfns[data->idx++], data->prot));
    > +
    > + ptent = pte_mkspecial(pfn_pte(pfn, data->prot));
    > + set_pte_at(&init_mm, addr, pte, ptent);
    > +
    > + data->idx++;
    > return 0;
    > }
    >
    > --
    > 2.25.1
    >
    >

    --
    Sincerely yours,
    Mike.

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