On 9/16/20 2:15 PM, Manjunath Patil wrote:
Hi Santosh,

inline.
On 9/16/2020 12:27 PM, santosh.shilim...@oracle.com wrote:
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.
I will add new line. checkpatch.pl didn't find it though.
+            /* 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()" ?
I think you meant, get rid of if clause and use "pr_warn_ratelimited()" instead.
That can still produce more than needed logs during low memory situation.

Try it out. It will do the same job as what you are trying to do.

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