On 10/07/2015 01:01 PM, J. Bruce Fields wrote:
> 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.
Fine with me. I was just trying to make sure it didn't get forgotten ;-)
> --b.
>
>>
>>> Fixes: 0bf4828983df ('svcrdma: refactor marshalling logic')
>>> Signed-off-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>
>>> Tested-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>>> ---
>>>
>>> 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 <dledford@xxxxxxxxxx>
>> GPG KeyID: 0E572FDD
>>
>>
>
>
--
Doug Ledford <dledford@xxxxxxxxxx>
GPG KeyID: 0E572FDD
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