From: Jason Gunthorpe jgg@nvidia.com
[ Upstream commit 10c75ccb54e4fe548cb16d7ed426d7d709e6ae76 ]
rdma_for_each_block() makes assumptions about how the SGL is constructed that don't work if the block size is below the page size used to to build the SGL.
The rules for umem SGL construction require that the SG's all be PAGE_SIZE aligned and we don't encode the actual byte offset of the VA range inside the SGL using offset and length. So rdma_for_each_block() has no idea where the actual starting/ending point is to compute the first/last block boundary if the starting address should be within a SGL.
Fixing the SGL construction turns out to be really hard, and will be the subject of other patches. For now block smaller pages.
Fixes: 4a35339958f1 ("RDMA/umem: Add API to find best driver supported page size in an MR") Link: https://lore.kernel.org/r/2-v2-270386b7e60b+28f4-umem_1_jgg@nvidia.com Reviewed-by: Leon Romanovsky leonro@nvidia.com Reviewed-by: Shiraz Saleem shiraz.saleem@intel.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/core/umem.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index 9be8f6c622db0..650f71dd4ab93 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -151,6 +151,12 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem, dma_addr_t mask; int i;
+ /* rdma_for_each_block() has a bug if the page size is smaller than the + * page size used to build the umem. For now prevent smaller page sizes + * from being returned. + */ + pgsz_bitmap &= GENMASK(BITS_PER_LONG - 1, PAGE_SHIFT); + /* At minimum, drivers must support PAGE_SIZE or smaller */ if (WARN_ON(!(pgsz_bitmap & GENMASK(PAGE_SHIFT, 0)))) return 0;