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Message-ID: <392801e0-cebd-d0dd-fc65-666161c6599b@oracle.com>
Date: Wed, 16 Sep 2020 14:15:08 -0700
From: Manjunath Patil <manjunath.b.patil@...cle.com>
To: santosh.shilimkar@...cle.com
Cc: netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
aruna.ramakrishna@...cle.com, rama.nichanamatlu@...cle.com
Subject: Re: [PATCH 1/1] net/rds: suppress page allocation failure error in
recv buffer refill
Hi Santosh,
inline.
On 9/16/2020 12:27 PM, santosh.shilimkar@...cle.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.patil@...cle.com>
>> Reviewed-by: Aruna Ramakrishna <aruna.ramakrishna@...cle.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.
-Thanks,
Manjunath
>> +
>> 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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