The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x cd7c957f936f8cb80d03e5152f4013aae65bd986 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024081248-exposable-uniformed-75e0@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

cd7c957f936f ("mptcp: pm: don't try to create sf if alloc failed") c95eb32ced82 ("mptcp: pm: reduce indentation blocks") 528cb5f2a1e8 ("mptcp: pass addr to mptcp_pm_alloc_anno_list") 77e4b94a3de6 ("mptcp: update userspace pm infos") 24430f8bf516 ("mptcp: add address into userspace pm list") fb00ee4f3343 ("mptcp: netlink: respect v4/v6-only sockets") 80638684e840 ("mptcp: get sk from msk directly") 5ccecaec5c1e ("mptcp: fix locking in mptcp_nl_cmd_sf_destroy()") 76a13b315709 ("mptcp: invoke MP_FAIL response when needed") d9fb797046c5 ("mptcp: Do not traverse the subflow connection list without lock") d42f9e4e2384 ("mptcp: Check for orphaned subflow before handling MP_FAIL timer") d7e6f5836038 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cd7c957f936f8cb80d03e5152f4013aae65bd986 Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" matttbe@kernel.org Date: Wed, 31 Jul 2024 13:05:56 +0200 Subject: [PATCH] mptcp: pm: don't try to create sf if alloc failed

It sounds better to avoid wasting cycles and / or put extreme memory pressure on the system by trying to create new subflows if it was not possible to add a new item in the announce list.

While at it, a warning is now printed if the entry was already in the list as it should not happen with the in-kernel path-manager. With this PM, mptcp_pm_alloc_anno_list() should only fail in case of memory pressure.

Fixes: b6c08380860b ("mptcp: remove addr and subflow in PM netlink") Cc: stable@vger.kernel.org Suggested-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20240731-upstream-net-20240731-mptcp-endp-subflow-s... Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 780f4cca165c..2be7af377cda 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -348,7 +348,7 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk, add_entry = mptcp_lookup_anno_list_by_saddr(msk, addr);

if (add_entry) { - if (mptcp_pm_is_kernel(msk)) + if (WARN_ON_ONCE(mptcp_pm_is_kernel(msk))) return false;

sk_reset_timer(sk, &add_entry->add_timer, @@ -555,8 +555,6 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)

/* check first for announce */ if (msk->pm.add_addr_signaled < add_addr_signal_max) { - local = select_signal_address(pernet, msk); - /* due to racing events on both ends we can reach here while * previous add address is still running: if we invoke now * mptcp_pm_announce_addr(), that will fail and the @@ -567,11 +565,15 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk) if (msk->pm.addr_signal & BIT(MPTCP_ADD_ADDR_SIGNAL)) return;

+ local = select_signal_address(pernet, msk); if (!local) goto subflow;

+ /* If the alloc fails, we are on memory pressure, not worth + * continuing, and trying to create subflows. + */ if (!mptcp_pm_alloc_anno_list(msk, &local->addr)) - goto subflow; + return;

__clear_bit(local->addr.id, msk->pm.id_avail_bitmap); msk->pm.add_addr_signaled++;