[RFC] io_uring: enable shmem/memfd memory registration

[RFC] io_uring: enable shmem/memfd memory registration

[Pavel Begunkov]

Relax buffer registration restictions, which filters out file backed
memory, and allow shmem/memfd as they have normal anonymous pages
underneath.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 44d1859f0dfb..e980695707ec 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8300,6 +8300,8 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
 		for (i = 0; i < nr_pages; i++) {
 			struct vm_area_struct *vma = vmas[i];
 
+			if (vma_is_shmem(vma))
+				continue;
 			if (vma->vm_file &&
 			    !is_file_hugepages(vma->vm_file)) {
 				ret = -EOPNOTSUPP;
-- 
2.31.1

Re: [RFC] io_uring: enable shmem/memfd memory registration

[Jens Axboe]

On 6/9/21 8:26 AM, Pavel Begunkov wrote:
> Relax buffer registration restictions, which filters out file backed
> memory, and allow shmem/memfd as they have normal anonymous pages
> underneath.

I think this is fine, we really only care about file backed.

-- 
Jens Axboe

Re: [RFC] io_uring: enable shmem/memfd memory registration

[Pavel Begunkov]

On 6/9/21 4:12 PM, Jens Axboe wrote:
> On 6/9/21 8:26 AM, Pavel Begunkov wrote:
>> Relax buffer registration restictions, which filters out file backed
>> memory, and allow shmem/memfd as they have normal anonymous pages
>> underneath.
> 
> I think this is fine, we really only care about file backed.

Jens, can you append a tag?

Reported-by: Mahdi Rakhshandehroo <mahdi.rakhshandehroo@gmail.com>

-- 
Pavel Begunkov

Re: [RFC] io_uring: enable shmem/memfd memory registration

[Jens Axboe]

On 6/13/21 6:45 PM, Pavel Begunkov wrote:
> On 6/9/21 4:12 PM, Jens Axboe wrote:
>> On 6/9/21 8:26 AM, Pavel Begunkov wrote:
>>> Relax buffer registration restictions, which filters out file backed
>>> memory, and allow shmem/memfd as they have normal anonymous pages
>>> underneath.
>>
>> I think this is fine, we really only care about file backed.
> 
> Jens, can you append a tag?
> 
> Reported-by: Mahdi Rakhshandehroo <mahdi.rakhshandehroo@gmail.com>

I can't, it's sitting pretty deep at this point...

-- 
Jens Axboe