Hi Breno 30 Oct 2024 15:02:45 Breno Leitao <leitao@xxxxxxxxxx>: > The mptcp_sched_find() function must be called with the RCU read lock > held, as it accesses RCU-protected data structures. This requirement was > not properly enforced in the mptcp_init_sock() function, leading to a > RCU list traversal in a non-reader section error when > CONFIG_PROVE_RCU_LIST is enabled. > > net/mptcp/sched.c:44 RCU-list traversed in non-reader section!! > > Fix it by acquiring the RCU read lock before calling the > mptcp_sched_find() function. This ensures that the function is invoked > with the necessary RCU protection in place, as it accesses RCU-protected > data structures. Thank you for having looked at that, but there is already a fix: https://lore.kernel.org/netdev/20241021-net-mptcp-sched-lock-v1-1-637759cf061c@xxxxxxxxxx/ This fix has even been applied in the net tree already: https://git.kernel.org/netdev/net/c/3deb12c788c3 Did you not get conflicts when rebasing your branch on top of the latest version? > Additionally, the patch breaks down the mptcp_init_sched() call into > smaller parts, with the RCU read lock only covering the specific call to > mptcp_sched_find(). This helps minimize the critical section, reducing > the time during which RCU grace periods are blocked. I agree with Eric (thank you for the review!): this creates other issues. > The mptcp_sched_list_lock is not held in this case, and it is not clear > if it is necessary. It is not needed, the list is not modified, only read with RCU. Cheers, Matt
