On 20/01/2020 16:10, Gal Pressman wrote:
> The cited commit leads to register MR failures and random hangs when
> running different MPI applications. The exact root cause for the issue
> is still not clear, this revert brings us back to a stable state.
>
> This reverts commit 40ddb3f020834f9afb7aab31385994811f4db259.
>
> Fixes: 40ddb3f02083 ("RDMA/efa: Use API to get contiguous memory blocks aligned to device supported page size")
> Cc: Shiraz Saleem <shiraz.saleem@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 5.3
> Signed-off-by: Gal Pressman <galpress@xxxxxxxxxx>
Shiraz, I think I found the root cause here.
I'm noticing a register MR of size 32k, which is constructed from two sges, the
first sge of size 12k and the second of 20k.
ib_umem_find_best_pgsz returns page shift 13 in the following way:
0x103dcb2000 0x103dcb5000 0x103dd5d000 0x103dd62000
+----------+ +------------------+
| | | |
| 12k | | 20k |
+----------+ +------------------+
+------+------+ +------+------+------+
| | | | | | |
| 8k | 8k | | 8k | 8k | 8k |
+------+------+ +------+------+------+
0x103dcb2000 0x103dcb6000 0x103dd5c000 0x103dd62000
The top row is the original umem sgl, and the bottom is the sgl constructed by
rdma_for_each_block with page size of 8k.
Is this the expected output? The 8k pages cover addresses which aren't part of
the MR. This breaks some of the assumptions in the driver (for example, the way
we calculate the number of pages in the MR) and I'm not sure our device can
handle such sgl.
