linux-kernel - Re: [PATCH v3] RDMA/cm: add timeout to cm_destroy

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Message-ID: <293eb402-73c9-441a-97ec-a5939ed44256@oracle.com>
Date: Sun, 10 Mar 2024 21:13:18 -0700
From: Manjunath Patil <manjunath.b.patil@...cle.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: dledford@...hat.com, jgg@...pe.ca, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org, rama.nichanamatlu@...cle.com
Subject: Re: [PATCH v3] RDMA/cm: add timeout to cm_destroy_id wait



On 3/10/24 4:17 AM, Leon Romanovsky wrote:
> On Fri, Mar 08, 2024 at 10:33:23PM -0800, Manjunath Patil wrote:
>> Add timeout to cm_destroy_id, so that userspace can trigger any data
>> collection that would help in analyzing the cause of delay in destroying
>> the cm_id.
>>
>> New noinline function helps dtrace/ebpf programs to hook on to it.
>> Existing functionality isn't changed except triggering a probe-able new
>> function at every timeout interval.
>>
>> We have seen cases where CM messages stuck with MAD layer (either due to
>> software bug or faulty HCA), leading to cm_id getting stuck in the
>> following call stack. This patch helps in resolving such issues faster.
>>
>> kernel: ... INFO: task XXXX:56778 blocked for more than 120 seconds.
>> ...
>> 	Call Trace:
>> 	__schedule+0x2bc/0x895
>> 	schedule+0x36/0x7c
>> 	schedule_timeout+0x1f6/0x31f
>>   	? __slab_free+0x19c/0x2ba
>> 	wait_for_completion+0x12b/0x18a
>> 	? wake_up_q+0x80/0x73
>> 	cm_destroy_id+0x345/0x610 [ib_cm]
>> 	ib_destroy_cm_id+0x10/0x20 [ib_cm]
>> 	rdma_destroy_id+0xa8/0x300 [rdma_cm]
>> 	ucma_destroy_id+0x13e/0x190 [rdma_ucm]
>> 	ucma_write+0xe0/0x160 [rdma_ucm]
>> 	__vfs_write+0x3a/0x16d
>> 	vfs_write+0xb2/0x1a1
>> 	? syscall_trace_enter+0x1ce/0x2b8
>> 	SyS_write+0x5c/0xd3
>> 	do_syscall_64+0x79/0x1b9
>> 	entry_SYSCALL_64_after_hwframe+0x16d/0x0
>>
>> Orabug: 36280065
> 
> Not related to the upstream.
> 
>>
>> Signed-off-by: Manjunath Patil <manjunath.b.patil@...cle.com>
>> ---
>> v3:
>>   - added #define
>>
>> v2:
>>   - removed sysctl related code
>>
>>   drivers/infiniband/core/cm.c | 20 +++++++++++++++++++-
>>   1 file changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
>> index ff58058aeadc..793103cf8152 100644
>> --- a/drivers/infiniband/core/cm.c
>> +++ b/drivers/infiniband/core/cm.c
>> @@ -34,6 +34,7 @@ MODULE_AUTHOR("Sean Hefty");
>>   MODULE_DESCRIPTION("InfiniBand CM");
>>   MODULE_LICENSE("Dual BSD/GPL");
>>   
>> +#define CM_DESTORY_ID_WAIT_TIMEOUT 10000 /* msecs */
> 
> CM_DESTORY_ID_WAIT_TIMEOUT -> CM_DESTROY_ID_WAIT_TIMEOUT
> 
> Fixed and applied.
Thank you fixing and applying. Sorry for Orabug and not being careful about the typo.

-Manjunath
> 
> Thanks