Re: [PATCH 1/1] RDMA/rxe: Fix blktests srp lead kernel panic with 64k page size

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Oct 26, 2023 at 09:05:52AM +0000, Zhijian Li (Fujitsu) wrote:
> The root cause is that
> 
> rxe:rxe_set_page() gets wrong when mr.page_size != PAGE_SIZE where it only stores the *page to xarray.
> So the offset will get lost.
> 
> For example,
> store process:
> page_size = 0x1000;
> PAGE_SIZE = 0x10000;
> va0 = 0xffff000020651000;
> page_offset = 0 = va & (page_size - 1);
> page = va_to_page(va);
> xa_store(&mr->page_list, mr->nbuf, page, GFP_KERNEL);
> 
> load_process:
> page = xa_load(&mr->page_list, index);
> page_va = kmap_local_page(page) --> it must be a PAGE_SIZE align value, assume it as 0xffff000020650000
> va1 = page_va + page_offset = 0xffff000020650000 + 0 = 0xffff000020650000;
> 
> Obviously, *va0 != va1*, page_offset get lost.
> 
> 
> How to fix:
> - revert 325a7eb85199 ("RDMA/rxe: Cleanup page variables in rxe_mr.c")
> - don't allow ulp registering mr.page_size != PAGE_SIZE ?

Lets do the second one please. Most devices only support PAGE_SIZE anyhow.

Jason