Thread (10 messages) flat view 10 messages, 3 authors, 2024-09-24

Re: Namespaced network devices not cleaned up properly after execution of pmtu.sh kernel selftest

From: Mitchell Augustin <hidden>
Date: 2024-09-24 16:21:20
Also in: lkml

As I said before, we were aware of this issue, well before your report.
Yes, sorry - to clarify, I wasn't commenting on the state of the bug
itself, just asking whether my reproducer is helpful in exposing it
more easily/reliably and on more systems than other known methods, per
Jakub's original request.

In any case, thank you for the additional context on the bug itself though.

-Mitchell Augustin

On Mon, Sep 23, 2024 at 3:14 PM Eric Dumazet [off-list ref] wrote:
quoted hunk ↗ jump to hunk
On Mon, Sep 23, 2024 at 10:01 PM Mitchell Augustin
[off-list ref] wrote:
quoted
Hi!

I'm wondering if anyone has taken a look at my reproducer yet. I'd
love to know if it has helped any of you reproduce the bug more
easily.

Patch w/ reproducer:
https://lore.kernel.org/all/20240916191857.1082092-1-mitchell.augustin@canonical.com/ (local)
As I said before, we were aware of this issue, well before your report.

We have no efficient fix yet.
https://lore.kernel.org/netdev/202405311808.vqBTwxEf-lkp@intel.com/T/ (local)

You can disable dst_cache, this should remove the issue.
diff --git a/net/core/dst_cache.c b/net/core/dst_cache.c
index 70c634b9e7b02300188582a1634d5977838db132..53351ff58b35dbee37ff587f7ef8f72580d9e116
100644
--- a/net/core/dst_cache.c
+++ b/net/core/dst_cache.c
@@ -142,12 +142,7 @@ EXPORT_SYMBOL_GPL(dst_cache_get_ip6);

 int dst_cache_init(struct dst_cache *dst_cache, gfp_t gfp)
 {
-       dst_cache->cache = alloc_percpu_gfp(struct dst_cache_pcpu,
-                                           gfp | __GFP_ZERO);
-       if (!dst_cache->cache)
-               return -ENOMEM;
-
-       dst_cache_reset(dst_cache);
+       dst_cache->cache = NULL;
        return 0;
 }
 EXPORT_SYMBOL_GPL(dst_cache_init);


-- 
Mitchell Augustin
Software Engineer - Ubuntu Partner Engineering
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