On 8/24/20 11:36 AM, John Hubbard wrote:
This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.
There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.
[1] Documentation/core-api/pin_user_pages.rst
[2] "Explicit pinning of user-space pages":
https://lwn.net/Articles/807108/
Cc: Jens Wiklander jens.wiklander@linaro.org
Cc: Sumit Semwal sumit.semwal@linaro.org
Cc: tee-dev@lists.linaro.org
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: John Hubbard jhubbard@nvidia.com
OK, this should be indentical to v1 [1], but now rebased against
Linux 5.9-rc2.
...ohhh, wait, I should have read the earlier message from Jens more
carefully:
"The conflict isn't trivial, I guess we need to handle the different
types of pages differently when releasing them."
So it's not good to have a logically identical patch. argghhh. Let me see
how hard it is to track these memory types separately and handle the release
accordingly, just a sec.
Sorry about the false move here.
thanks,
--
John Hubbard
NVIDIA
> As before, I've compile-tested it again with a cross compiler, but that's
> the only testing I'm set up for with CONFIG_TEE.
>
> [1]
https://lore.kernel.org/r/20200519051850.2845561-1-jhubbard@nvidia.com
>
> thanks,
> John Hubbard
> NVIDIA
>
> drivers/tee/tee_shm.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 827ac3d0fea9..3c29e6c3ebe8 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -32,16 +32,13 @@ static void tee_shm_release(struct tee_shm *shm)
>
> poolm->ops->free(poolm, shm);
> } else if (shm->flags & TEE_SHM_REGISTER) {
> - size_t n;
> int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
>
> if (rc)
> dev_err(teedev->dev.parent,
> "unregister shm %p failed: %d", shm, rc);
>
> - for (n = 0; n < shm->num_pages; n++)
> - put_page(shm->pages[n]);
> -
> + unpin_user_pages(shm->pages, shm->num_pages);
> kfree(shm->pages);
> }
>
> @@ -228,7 +225,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> }
>
> if (flags & TEE_SHM_USER_MAPPED) {
> - rc = get_user_pages_fast(start, num_pages, FOLL_WRITE,
> + rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
> shm->pages);
> } else {
> struct kvec *kiov;
> @@ -292,16 +289,13 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> return shm;
> err:
> if (shm) {
> - size_t n;
> -
> if (shm->id >= 0) {
> mutex_lock(&teedev->mutex);
> idr_remove(&teedev->idr, shm->id);
> mutex_unlock(&teedev->mutex);
> }
> if (shm->pages) {
> - for (n = 0; n < shm->num_pages; n++)
> - put_page(shm->pages[n]);
> + unpin_user_pages(shm->pages, shm->num_pages);
> kfree(shm->pages);
> }
> }
>
v
