On 10/26/23 02:05, 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 ?
Thank you Zhijian for this root-cause analysis.
Hardware RDMA adapters may not support the host page size (PAGE_SIZE)
so disallowing mr.page_size != PAGE_SIZE would be wrong.
If the rxe driver only supports mr.page_size == PAGE_SIZE, does this
mean that RXE_PAGE_SIZE_CAP should be changed from
0xfffff000 into PAGE_SHIFT?
Thanks,
Bart.
