Re: [PATCH rdma-next] RDMA/rxe: Break endless pagefault loop for RO pages

[Leon Romanovsky <leon@kernel.org>]

On Thu, May 22, 2025 at 05:40:38PM +0200, Zhu Yanjun wrote:
> 在 2025/5/22 13:36, Leon Romanovsky 写道:
> > From: Leon Romanovsky <leonro@nvidia.com>
> > 
> > RO pages has "perm" equal to 0, that caused to the situation
> > where such pages were marked as needed to have fault and caused
> > to infinite loop.
> > 
> > Fixes: eedd5b1276e7 ("RDMA/umem: Store ODP access mask information in PFN")
> > Reported-by: Daisuke Matsuda <dskmtsd@gmail.com>
> > Closes: https://lore.kernel.org/all/3e8f343f-7d66-4f7a-9f08-3910623e322f@gmail.com
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> > ---
> >   drivers/infiniband/sw/rxe/rxe_odp.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c
> > index a1416626f61a5..0f67167ddddd1 100644
> > --- a/drivers/infiniband/sw/rxe/rxe_odp.c
> > +++ b/drivers/infiniband/sw/rxe/rxe_odp.c
> > @@ -137,7 +137,7 @@ static inline bool rxe_check_pagefault(struct ib_umem_odp *umem_odp,
> >   	while (addr < iova + length) {
> >   		idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
> > -		if (!(umem_odp->map.pfn_list[idx] & perm)) {
> > +		if (!(umem_odp->map.pfn_list[idx] & HMM_PFN_VALID)) {
> 
> Because perm is not used, it is not necessary to calculate and pass perm to
> rxe_check_pagefault. The cleanup is as below:

Thanks a lot, I folded this cleanup to the fix.