On (08/04/17 19:13), Guoqing Jiang wrote:
>
> HI,
>
> With commit 0ffdaf5b41cf4435ece14d1d3e977ce69012a20d "net/sock: add
> WARN_ON(parent->sk) in sock_graft()",
> I can see the WARN_ON is triggered easily by dlm subsystem.
>
> tcp_accept_from_sock() in fs/dlm/lowcomms.c has the following snippet:
>
> 1. result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
> SOCK_STREAM, IPPROTO_TCP, &newsock);
> sk is set by the path "sock_create_kern -> __sock_creat ->
> pf->create => inet_create -> sock_init_data"
> ...
> 2. result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK, true);
> Then sock_graft is called by "con->sock->ops->accept => inet_accept
> -> sock_graft "
>
> Does it mean call accept() after the just created socket is not a acceptable
> behavior? Any comment will be appreciate, thanks.
>
It means that you have a sk leak, just like rds-tcp did. See
https://patchwork.ozlabs.org/patch/780356/
for a discussion.
You should be calling sock_create_lite, instead of sock_create_kern.
The ->sk that triggers the WARN_ON is the one that is leaking (you will
see that the ->sk befrore the ->accept (i.e., the one set up by
sock_create_kern)
is different than the one after ->accept)
--Sowmini
