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SubjectRe: [PATCH v5 2/7] mm, devm_memremap_pages: Kill mapping "System RAM" support
On Wed, Sep 12, 2018 at 07:22:11PM -0700, Dan Williams wrote:
> Given the fact that devm_memremap_pages() requires a percpu_ref that is
> torn down by devm_memremap_pages_release() the current support for
> mapping RAM is broken.
>
> Support for remapping "System RAM" has been broken since the beginning
> and there is no existing user of this this code path, so just kill the
> support and make it an explicit error.
>
> This cleanup also simplifies a follow-on patch to fix the error path
> when setting a devm release action for devm_memremap_pages_release()
> fails.
>
> Cc: Christoph Hellwig <hch@lst.de>

Reviewed-by: Jérôme Glisse <jglisse@redhat.com>

> Cc: Logan Gunthorpe <logang@deltatee.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> kernel/memremap.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/memremap.c b/kernel/memremap.c
> index f95c7833db6d..92e838127767 100644
> --- a/kernel/memremap.c
> +++ b/kernel/memremap.c
> @@ -202,15 +202,12 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
> is_ram = region_intersects(align_start, align_size,
> IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
>
> - if (is_ram == REGION_MIXED) {
> - WARN_ONCE(1, "%s attempted on mixed region %pr\n",
> - __func__, res);
> + if (is_ram != REGION_DISJOINT) {
> + WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__,
> + is_ram == REGION_MIXED ? "mixed" : "ram", res);
> return ERR_PTR(-ENXIO);
> }
>
> - if (is_ram == REGION_INTERSECTS)
> - return __va(res->start);
> -
> if (!pgmap->ref)
> return ERR_PTR(-EINVAL);
>
>

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