Hi,
Regarding to the SEGFAULT question I asked yesterday, while I was
searching on the internet I stumbled upon an email sent on DPDK user
list which explained the solution to a similar problem. (Link to the
email:
https://inbox.dpdk.org/users/[email protected]/t/#m3f14d7e92c0a0b3c530717632ca5047420083112
)
As Andrew Rybchenko mentioned in the email, the way two applications
are built can result in issues with mempool operations. I do not
understand how the mempool handlers work and how the order of shared
libraries affect the DPDK system but I can confirm that by changing one
of the applications' Makefile I could get through this problem and thing
are working properly now.
It looks like there is a note on DPDK guide about this subject. (Link to
DPDK guide: https://doc.dpdk.org/guides/prog_guide/mempool_lib.html )
excerpt from DPDK guide:
```
When running a multi-process application with shared libraries, the -d
arguments for mempool handlers /must be specified in the same order for
all processes/ to ensure correct operation.
```
I am not using `-d` while I am running my applications maybe I should. I
just wanted to share my findings with you and thank you all for creating
such a community.
Thank you
~ Farbod
On 10/23/20 6:08 PM, Farbod wrote:
Hi,
I am using DPDK multi-processor mode for sending packets from one
application (secondary) to another application (primary) using rings.
The primary applications role is to just free the packet with
`rte_pktmbuf_free()`.
I encounter a SEGFAULT error in the line of `rte_pktmbuf_free()`.
My DPDK version is 19.11.1.
```
Signal: 11 (Segmentation fault), si_code: 1 (SEGV_MAPERR: address not
mapped to object)
Backtrace (recent calls first) ---
(0): (+0x81a1ee) [0x562d35df51ee]
bucket_enqueue_single at
---/dpdk-19.11.1/drivers/mempool/bucket/rte_mempool_bucket.c:111
(discriminator 3)
108: addr &= bd->bucket_page_mask;
109: hdr = (struct bucket_header *)addr;
110:
-> 111: if (likely(hdr->lcore_id == lcore_id)) {
112: if (hdr->fill_cnt < bd->obj_per_bucket - 1) {
113: hdr->fill_cnt++;
114: } else {
(inlined by) bucket_enqueue at
---/dpdk-19.11.1/drivers/mempool/bucket/rte_mempool_bucket.c:148
(discriminator 3)
145: int rc = 0;
146:
147: for (i = 0; i < n; i++) {
-> 148: rc = bucket_enqueue_single(bd, obj_table[i]);
149: RTE_ASSERT(rc == 0);
150: }
[0x562d35cd2f8c]
rte_mempool_ops_enqueue_bulk at
---/dpdk-19.11.1/build/include/rte_mempool.h:786
-> 786: return ops->enqueue(mp, obj_table, n);
(inlined by) __mempool_generic_put at
---/dpdk-19.11.1/build/include/rte_mempool.h:1329
-> 1329: rte_mempool_ops_enqueue_bulk(mp,
&cache->objs[cache->size],
(inlined by) rte_mempool_generic_put at
---/dpdk-19.11.1/build/include/rte_mempool.h:1365
-> 1365: __mempool_generic_put(mp, obj_table, n, cache);
(inlined by) rte_mempool_put_bulk at
---/dpdk-19.11.1/build/include/rte_mempool.h:1388
-> 1388: rte_mempool_generic_put(mp, obj_table, n, cache);
(inlined by) rte_mempool_put at
---/dpdk-19.11.1/build/include/rte_mempool.h:1406
-> 1406: rte_mempool_put_bulk(mp, &obj, 1);
(inlined by) rte_mbuf_raw_free at
---/dpdk-19.11.1/build/include/rte_mbuf.h:579
-> 579: rte_mempool_put(m->pool, m);
(inlined by) rte_pktmbuf_free_seg at
---/dpdk-19.11.1/build/include/rte_mbuf.h:1223
-> 1223: rte_mbuf_raw_free(m); 151: if
(local_stack->top > bd->bucket_stack_thresh) {
(inlined by) rte_pktmbuf_free at ---/rte_mbuf.h:1244
-> 1244: rte_pktmbuf_free_seg(m);
(inlined by) ?? at --- /packet.h:199
-> 199: rte_pktmbuf_free(reinterpret_cast<struct rte_mbuf
*>(pkt));
```
I have made sure that primary and secondary process does not share any
cpu in common. The packets received in the primary application are
valid and the information inside them is readable. It only runs in to
SEGFAULT when I am trying to free the mubf structures.
I would like to mention that the applications are in two different
projects and are built separately.
Thank you
