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SubjectRe: [PATCH v9 20/25] powerpc: book3s64: convert to pin_user_pages() and put_user_page()
On Tue 10-12-19 18:53:13, John Hubbard wrote:
> 1. Convert from get_user_pages() to pin_user_pages().
>
> 2. As required by pin_user_pages(), release these pages via
> put_user_page().
>
> Cc: Jan Kara <jack@suse.cz>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

I'd just note that mm_iommu_do_alloc() has a pre-existing bug that the last
jump to 'free_exit' (at line 157) happens already after converting page
pointers to physical addresses so put_page() calls there will just crash.
But that's completely unrelated to your change. I'll send a fix separately.

Honza

> ---
> arch/powerpc/mm/book3s64/iommu_api.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/mm/book3s64/iommu_api.c b/arch/powerpc/mm/book3s64/iommu_api.c
> index 56cc84520577..a86547822034 100644
> --- a/arch/powerpc/mm/book3s64/iommu_api.c
> +++ b/arch/powerpc/mm/book3s64/iommu_api.c
> @@ -103,7 +103,7 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
> for (entry = 0; entry < entries; entry += chunk) {
> unsigned long n = min(entries - entry, chunk);
>
> - ret = get_user_pages(ua + (entry << PAGE_SHIFT), n,
> + ret = pin_user_pages(ua + (entry << PAGE_SHIFT), n,
> FOLL_WRITE | FOLL_LONGTERM,
> mem->hpages + entry, NULL);
> if (ret == n) {
> @@ -167,9 +167,8 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
> return 0;
>
> free_exit:
> - /* free the reference taken */
> - for (i = 0; i < pinned; i++)
> - put_page(mem->hpages[i]);
> + /* free the references taken */
> + put_user_pages(mem->hpages, pinned);
>
> vfree(mem->hpas);
> kfree(mem);
> @@ -215,7 +214,8 @@ static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
> if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
> SetPageDirty(page);
>
> - put_page(page);
> + put_user_page(page);
> +
> mem->hpas[i] = 0;
> }
> }
> --
> 2.24.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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