On 9/16/20 12:08 PM, Manjunath Patil wrote:
RDS/IB tries to refill the recv buffer in softirq context using
GFP_NOWAIT flag. However alloc failure is handled by queueing a work to
refill the recv buffer with GFP_KERNEL flag. This means failure to
allocate with GFP_NOWAIT isn't fatal. Do not print the PAF warnings if
softirq context fails to refill the recv buffer, instead print a one
line warning once a day.

Signed-off-by: Manjunath Patil <manjunath.b.pa...@oracle.com>
Reviewed-by: Aruna Ramakrishna <aruna.ramakris...@oracle.com>
---
  net/rds/ib_recv.c | 16 +++++++++++++---
  1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 694d411dc72f..38d2894f6bb2 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -310,8 +310,8 @@ static int rds_ib_recv_refill_one(struct rds_connection 
*conn,
        struct rds_ib_connection *ic = conn->c_transport_data;
        struct ib_sge *sge;
        int ret = -ENOMEM;
-       gfp_t slab_mask = GFP_NOWAIT;
-       gfp_t page_mask = GFP_NOWAIT;
+       gfp_t slab_mask = gfp;
+       gfp_t page_mask = gfp;
if (gfp & __GFP_DIRECT_RECLAIM) {
                slab_mask = GFP_KERNEL;
@@ -406,6 +406,16 @@ void rds_ib_recv_refill(struct rds_connection *conn, int 
prefill, gfp_t gfp)
                recv = &ic->i_recvs[pos];
                ret = rds_ib_recv_refill_one(conn, recv, gfp);
                if (ret) {
+                       static unsigned long warn_time;
Comment should start on next line.
+                       /* warn max once per day. This should be enough to
+                        * warn users about low mem situation.
+                        */
+                       if (printk_timed_ratelimit(&warn_time,
+                                                  24 * 60 * 60 * 1000))
+                               pr_warn("RDS/IB: failed to refill recv buffer for 
<%pI6c,%pI6c,%d>, waking worker\n",
+                                       &conn->c_laddr, &conn->c_faddr,
+                                       conn->c_tos);
Didn't notice this before.
Why not just use "pr_warn_ratelimited()" ?
+
                        must_wake = true;
                        break;
                }
@@ -1020,7 +1030,7 @@ void rds_ib_recv_cqe_handler(struct rds_ib_connection *ic,
                rds_ib_stats_inc(s_ib_rx_ring_empty);
if (rds_ib_ring_low(&ic->i_recv_ring)) {
-               rds_ib_recv_refill(conn, 0, GFP_NOWAIT);
+               rds_ib_recv_refill(conn, 0, GFP_NOWAIT | __GFP_NOWARN);
                rds_ib_stats_inc(s_ib_rx_refill_from_cq);
        }
  }

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