On Tue, Oct 06, 2015 at 01:44:25PM -0400, Doug Ledford wrote:
> On 09/28/2015 05:46 PM, Steve Wise wrote:
> > The server rdma_read_chunk_lcl() and rdma_read_chunk_frmr() functions
> > were not taking into account the initial page_offset when determining
> > the rdma read length. This resulted in a read who's starting address
> > and length exceeded the base/bounds of the frmr.
> >
> > Most work loads don't tickle this bug apparently, but one test hit it
> > every time: building the linux kernel on a 16 core node with 'make -j
> > 16 O=/mnt/0' where /mnt/0 is a ramdisk mounted via NFSRDMA.
> >
> > This bug seems to only be tripped with devices having small fastreg page
> > list depths. I didn't see it with mlx4, for instance.
>
> Bruce, what's you're take on this? Do you want to push this through or
> would you care if I push it through my tree?
Whoops, sorry, I meant to send a pull request for that last week. Uh, I
think I'll go ahead and do that now if it's OK with you.
--b.
>
> > Fixes: 0bf4828983df ('svcrdma: refactor marshalling logic')
> > Signed-off-by: Steve Wise <[email protected]>
> > Tested-by: Chuck Lever <[email protected]>
> > ---
> >
> > net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 6 ++++--
> > 1 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> > b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> > index cb51742..5f6ca47 100644
> > --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> > +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> > @@ -136,7 +136,8 @@ int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
> > ctxt->direction = DMA_FROM_DEVICE;
> > ctxt->read_hdr = head;
> > pages_needed = min_t(int, pages_needed, xprt->sc_max_sge_rd);
> > - read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
> > + read = min_t(int, (pages_needed << PAGE_SHIFT) - *page_offset,
> > + rs_length);
> >
> > for (pno = 0; pno < pages_needed; pno++) {
> > int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
> > @@ -235,7 +236,8 @@ int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
> > ctxt->direction = DMA_FROM_DEVICE;
> > ctxt->frmr = frmr;
> > pages_needed = min_t(int, pages_needed, xprt->sc_frmr_pg_list_len);
> > - read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
> > + read = min_t(int, (pages_needed << PAGE_SHIFT) - *page_offset,
> > + rs_length);
> >
> > frmr->kva = page_address(rqstp->rq_arg.pages[pg_no]);
> > frmr->direction = DMA_FROM_DEVICE;
> >
> > --
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> >
>
>
> --
> Doug Ledford <[email protected]>
> GPG KeyID: 0E572FDD
>
>
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