On Thu, Apr 24, 2025 at 02:44:13PM +0200, David Rheinsberg wrote: > Hi > > On Thu, Apr 24, 2025, at 2:24 PM, Christian Brauner wrote: > [...] > > Link: > > https://lore.kernel.org/lkml/20230807085203.819772-1-david@xxxxxxxxxxxx > > [1] > > Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> > > Very nice! Highly appreciated! > > > --- > > net/unix/af_unix.c | 90 > > +++++++++++++++++++++++++++++++++++++++++++++++------- > > 1 file changed, 79 insertions(+), 11 deletions(-) > > > > diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c > > index f78a2492826f..83b5aebf499e 100644 > > --- a/net/unix/af_unix.c > > +++ b/net/unix/af_unix.c > > @@ -100,6 +100,7 @@ > > #include <linux/splice.h> > > #include <linux/string.h> > > #include <linux/uaccess.h> > > +#include <linux/pidfs.h> > > #include <net/af_unix.h> > > #include <net/net_namespace.h> > > #include <net/scm.h> > > @@ -643,6 +644,14 @@ static void unix_sock_destructor(struct sock *sk) > > return; > > } > > > > + if (sock_flag(sk, SOCK_RCU_FREE)) { > > + pr_info("Attempting to release RCU protected socket with sleeping > > locks: %p\n", sk); > > + return; > > + } > > unix-sockets do not use `SOCK_RCU_FREE`, but even if they did, doesn't > this flag imply that the destructor is delayed via `call_rcu`, and > thus *IS* allowed to sleep? And then, sleeping in the destructor is > always safe, isn't it? `SOCK_RCU_FREE` just guarantees that it is > delayed for at least an RCU grace period, right? Not sure, what you > are getting at here, but I might be missing something obvious as well. Callbacks run from call_rcu() can be called from softirq context and in general are not allowed to block. That's what queue_rcu_work() is for which uses system_unbound_wq. > > Regardless, wouldn't you want WARN_ON_ONCE() rather than pr_info? Sure.
