FAILED: patch "[PATCH] mptcp: pm: don't try to create sf if alloc failed" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] mptcp: pm: don't try to create sf if alloc failed" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-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-5.15.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 '2024081246-rinse-rockslide-346f@gregkh' --subject-prefix 'PATCH 5.15.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-signal-v1-4-c8a9b036493b@kernel.org
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++;

Re: FAILED: patch "[PATCH] mptcp: pm: don't try to create sf if alloc failed" failed to apply to 5.15-stable tree

[Matthieu Baerts]

Hi Greg,

On 12/08/2024 14:39, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 5.15-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-5.15.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 '2024081246-rinse-rockslide-346f@gregkh' --subject-prefix 'PATCH 5.15.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.

I think it is better not to backport this patch to v5.15: the
dependencies list is quite big, and the fix is probably not worth it: in
case of memory pressure, we don't try to do more actions (because they
will fail as well).

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.