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SubjectRe: [PATCH v2] nfs-rdma: Fix for FMR leaks
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On Apr 15, 2014, at 4:34 PM, Allen Andrews <allen.andrews@emulex.com> wrote:

> Two memory region leaks were found during testing:
>
> 1. rpcrdma_buffer_create: While allocating RPCRDMA_FRMR's
> ib_alloc_fast_reg_mr is called and then ib_alloc_fast_reg_page_list is
> called. If ib_alloc_fast_reg_page_list returns an error it bails out of
> the routine dropping the last ib_alloc_fast_reg_mr frmr region creating a
> memory leak. Added code to dereg the last frmr if
> ib_alloc_fast_reg_page_list fails.
>
> 2. rpcrdma_buffer_destroy: While cleaning up, the routine will only free
> the MR's on the rb_mws list if there are rb_send_bufs present. However, in
> rpcrdma_buffer_create while the rb_mws list is being built if one of the MR
> allocation requests fail after some MR's have been allocated on the rb_mws
> list the routine never gets to create any rb_send_bufs but instead jumps to
> the rpcrdma_buffer_destroy routine which will never free the MR's on rb_mws
> list because the rb_send_bufs were never created. This leaks all the MR's
> on the rb_mws list that were created prior to one of the MR allocations
> failing.
>
> Issue(2) was seen during testing. Our adapter had a finite number of MR's
> available and we created enough connections to where we saw an MR
> allocation failure on our Nth NFS connection request. After the kernel
> cleaned up the resources it had allocated for the Nth connection we noticed
> that FMR's had been leaked due to the coding error described above.
>
> Issue(1) was seen during a code review while debugging issue(2).
>
> Signed-off-by: Allen Andrews <allen.andrews@emulex.com>

Reviewed-by: Chuck Lever <chuck.lever@oracle.com>

> ---
>
> net/sunrpc/xprtrdma/verbs.c | 73 ++++++++++++++++++++++---------------------
> 1 files changed, 38 insertions(+), 35 deletions(-)
>
> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
> index 9372656..1683e05 100644
> --- a/net/sunrpc/xprtrdma/verbs.c
> +++ b/net/sunrpc/xprtrdma/verbs.c
> @@ -1058,6 +1058,8 @@ rpcrdma_buffer_create(struct rpcrdma_buffer *buf, struct rpcrdma_ep *ep,
> dprintk("RPC: %s: "
> "ib_alloc_fast_reg_page_list "
> "failed %i\n", __func__, rc);
> +
> + ib_dereg_mr(r->r.frmr.fr_mr);
> goto out;
> }
> list_add(&r->mw_list, &buf->rb_mws);
> @@ -1194,41 +1196,6 @@ rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
> kfree(buf->rb_recv_bufs[i]);
> }
> if (buf->rb_send_bufs && buf->rb_send_bufs[i]) {
> - while (!list_empty(&buf->rb_mws)) {
> - r = list_entry(buf->rb_mws.next,
> - struct rpcrdma_mw, mw_list);
> - list_del(&r->mw_list);
> - switch (ia->ri_memreg_strategy) {
> - case RPCRDMA_FRMR:
> - rc = ib_dereg_mr(r->r.frmr.fr_mr);
> - if (rc)
> - dprintk("RPC: %s:"
> - " ib_dereg_mr"
> - " failed %i\n",
> - __func__, rc);
> - ib_free_fast_reg_page_list(r->r.frmr.fr_pgl);
> - break;
> - case RPCRDMA_MTHCAFMR:
> - rc = ib_dealloc_fmr(r->r.fmr);
> - if (rc)
> - dprintk("RPC: %s:"
> - " ib_dealloc_fmr"
> - " failed %i\n",
> - __func__, rc);
> - break;
> - case RPCRDMA_MEMWINDOWS_ASYNC:
> - case RPCRDMA_MEMWINDOWS:
> - rc = ib_dealloc_mw(r->r.mw);
> - if (rc)
> - dprintk("RPC: %s:"
> - " ib_dealloc_mw"
> - " failed %i\n",
> - __func__, rc);
> - break;
> - default:
> - break;
> - }
> - }
> rpcrdma_deregister_internal(ia,
> buf->rb_send_bufs[i]->rl_handle,
> &buf->rb_send_bufs[i]->rl_iov);
> @@ -1236,6 +1203,42 @@ rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
> }
> }
>
> + while (!list_empty(&buf->rb_mws)) {
> + r = list_entry(buf->rb_mws.next,
> + struct rpcrdma_mw, mw_list);
> + list_del(&r->mw_list);
> + switch (ia->ri_memreg_strategy) {
> + case RPCRDMA_FRMR:
> + rc = ib_dereg_mr(r->r.frmr.fr_mr);
> + if (rc)
> + dprintk("RPC: %s:"
> + " ib_dereg_mr"
> + " failed %i\n",
> + __func__, rc);
> + ib_free_fast_reg_page_list(r->r.frmr.fr_pgl);
> + break;
> + case RPCRDMA_MTHCAFMR:
> + rc = ib_dealloc_fmr(r->r.fmr);
> + if (rc)
> + dprintk("RPC: %s:"
> + " ib_dealloc_fmr"
> + " failed %i\n",
> + __func__, rc);
> + break;
> + case RPCRDMA_MEMWINDOWS_ASYNC:
> + case RPCRDMA_MEMWINDOWS:
> + rc = ib_dealloc_mw(r->r.mw);
> + if (rc)
> + dprintk("RPC: %s:"
> + " ib_dealloc_mw"
> + " failed %i\n",
> + __func__, rc);
> + break;
> + default:
> + break;
> + }
> + }
> +
> kfree(buf->rb_pool);
> }
>
>
> --
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--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com





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