net: add networking namespace refcount tracker
We have 100+ syzbot reports about netns being dismantled too soon,
still unresolved as of today.
We think a missing get_net() or an extra put_net() is the root cause.
In order to find the bug(s), and be able to spot future ones,
this patch adds CONFIG_NET_NS_REFCNT_TRACKER and new helpers
to precisely pair all put_net() with corresponding get_net().
To use these helpers, each data structure owning a refcount
should also use a "netns_tracker" to pair the get and put.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/Kconfig.debug b/net/Kconfig.debug
index fb5c70e..2f50611 100644
--- a/net/Kconfig.debug
+++ b/net/Kconfig.debug
@@ -8,3 +8,12 @@
help
Enable debugging feature to track device references.
This adds memory and cpu costs.
+
+config NET_NS_REFCNT_TRACKER
+ bool "Enable networking namespace refcount tracking"
+ depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
+ select REF_TRACKER
+ default n
+ help
+ Enable debugging feature to track netns references.
+ This adds memory and cpu costs.
