Message-ID: <20251009153049.OC9WFY8_@linutronix.de>
Date: Thu, 9 Oct 2025 17:30:49 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Thomas Gleixner <tglx@...utronix.de>, linux-rt-devel@...ts.linux.dev
Cc: LKML <linux-kernel@...r.kernel.org>, linux-rt-users@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>
Subject: [ANNOUNCE] v6.17.1-rt5

Dear RT folks!

I'm pleased to announce the v6.17.1-rt5 patch set. 

Changes since v6.17.1-rt4:

  - Update the workqueue patch for BH-worker to the version which
    merged.

  - Backport two patches for nft_set_pipapo from upstream which were
    marked for stable nd clash somehow with already made backport of
    nft_set_pipapo in order to drop the BH-lock.

  - syzbot report a failure in networking with GRO offloading caused by
    the removal of the BH-lock.

Known issues
    - Yoann Congal reported a bit spinlock in dm_exception_table_lock().
        https://lore.kernel.org/all/Z8GTjqgDe_5EkE3t@P-ASN-ECS-830T8C3.local

The delta patch against v6.17.1-rt4 is appended below and can be found here:
 
     https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.17/incr/patch-6.17.1-rt4-rt5.patch.xz

You can get this release via the git tree at:

    https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v6.17.1-rt5

The RT patch against v6.17.1 can be found here:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.17/older/patch-6.17.1-rt5.patch.xz

The split quilt queue is available at:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.17/older/patches-6.17.1-rt5.tar.xz

Sebastian

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 94e226f637992..d6c94ee8edfc5 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4258,11 +4258,10 @@ static bool __flush_work(struct work_struct *work, bool from_cancel)
 				if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
 					struct worker_pool *pool;
 
-					mutex_lock(&wq_pool_mutex);
+					guard(rcu)();
 					pool = get_work_pool(work);
 					if (pool)
 						workqueue_callback_cancel_wait_running(pool);
-					mutex_unlock(&wq_pool_mutex);
 				} else {
 					cpu_relax();
 				}
diff --git a/localversion-rt b/localversion-rt
index ad3da1bcab7e8..0efe7ba1930e1 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt4
+-rt5
diff --git a/net/core/gro_cells.c b/net/core/gro_cells.c
index ff8e5b64bf6b7..b43911562f4d1 100644
--- a/net/core/gro_cells.c
+++ b/net/core/gro_cells.c
@@ -8,11 +8,13 @@
 struct gro_cell {
 	struct sk_buff_head	napi_skbs;
 	struct napi_struct	napi;
+	local_lock_t		bh_lock;
 };
 
 int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
+	bool have_bh_lock = false;
 	struct gro_cell *cell;
 	int res;
 
@@ -25,6 +27,8 @@ int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 		goto unlock;
 	}
 
+	local_lock_nested_bh(&gcells->cells->bh_lock);
+	have_bh_lock = true;
 	cell = this_cpu_ptr(gcells->cells);
 
 	if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) {
@@ -39,6 +43,9 @@ int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 	if (skb_queue_len(&cell->napi_skbs) == 1)
 		napi_schedule(&cell->napi);
 
+	if (have_bh_lock)
+		local_unlock_nested_bh(&gcells->cells->bh_lock);
+
 	res = NET_RX_SUCCESS;
 
 unlock:
@@ -54,6 +61,7 @@ static int gro_cell_poll(struct napi_struct *napi, int budget)
 	struct sk_buff *skb;
 	int work_done = 0;
 
+	__local_lock_nested_bh(&cell->bh_lock);
 	while (work_done < budget) {
 		skb = __skb_dequeue(&cell->napi_skbs);
 		if (!skb)
@@ -64,6 +72,7 @@ static int gro_cell_poll(struct napi_struct *napi, int budget)
 
 	if (work_done < budget)
 		napi_complete_done(napi, work_done);
+	__local_unlock_nested_bh(&cell->bh_lock);
 	return work_done;
 }
 
@@ -79,6 +88,7 @@ int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
 		struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
 
 		__skb_queue_head_init(&cell->napi_skbs);
+		local_lock_init(&cell->bh_lock);
 
 		set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state);
 
diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index 96aefa504f57a..337daa777c353 100644
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -550,8 +550,7 @@ static struct nft_pipapo_elem *pipapo_get(const struct nft_pipapo_match *m,
  *
  * This function is called from the data path.  It will search for
  * an element matching the given key in the current active copy.
- * Unlike other set types, this uses NFT_GENMASK_ANY instead of
- * nft_genmask_cur().
+ * Unlike other set types, this uses 0 instead of nft_genmask_cur().
  *
  * This is because new (future) elements are not reachable from
  * priv->match, they get added to priv->clone instead.
@@ -561,8 +560,8 @@ static struct nft_pipapo_elem *pipapo_get(const struct nft_pipapo_match *m,
  * inconsistent state: matching old entries get skipped but thew
  * newly matching entries are unreachable.
  *
- * GENMASK will still find the 'now old' entries which ensures consistent
- * priv->match view.
+ * GENMASK_ANY doesn't work for the same reason: old-gen entries get
+ * skipped, new-gen entries are only reachable from priv->clone.
  *
  * nft_pipapo_commit swaps ->clone and ->match shortly after the
  * genbit flip.  As ->clone doesn't contain the old entries in the first
@@ -579,7 +578,7 @@ nft_pipapo_lookup(const struct net *net, const struct nft_set *set,
 	const struct nft_pipapo_elem *e;
 
 	m = rcu_dereference(priv->match);
-	e = pipapo_get_slow(m, (const u8 *)key, NFT_GENMASK_ANY, get_jiffies_64());
+	e = pipapo_get_slow(m, (const u8 *)key, 0, get_jiffies_64());
 
 	return e ? &e->ext : NULL;
 }
diff --git a/net/netfilter/nft_set_pipapo_avx2.c b/net/netfilter/nft_set_pipapo_avx2.c
index 3e584dc4ad20e..9235efb10dd52 100644
--- a/net/netfilter/nft_set_pipapo_avx2.c
+++ b/net/netfilter/nft_set_pipapo_avx2.c
@@ -1179,7 +1179,6 @@ struct nft_pipapo_elem *pipapo_get_avx2(const struct nft_pipapo_match *m,
 
 	nft_pipapo_avx2_prepare();
 
-next_match:
 	nft_pipapo_for_each_field(f, i, m) {
 		bool last = i == m->field_count - 1, first = !i;
 		int ret = 0;
@@ -1226,6 +1225,7 @@ struct nft_pipapo_elem *pipapo_get_avx2(const struct nft_pipapo_match *m,
 
 #undef NFT_SET_PIPAPO_AVX2_LOOKUP
 
+next_match:
 		if (ret < 0) {
 			scratch->map_index = map_index;
 			kernel_fpu_end();
@@ -1238,8 +1238,11 @@ struct nft_pipapo_elem *pipapo_get_avx2(const struct nft_pipapo_match *m,
 
 			e = f->mt[ret].e;
 			if (unlikely(__nft_set_elem_expired(&e->ext, tstamp) ||
-				     !nft_set_elem_active(&e->ext, genmask)))
+				     !nft_set_elem_active(&e->ext, genmask))) {
+				ret = pipapo_refill(res, f->bsize, f->rules,
+						    fill, f->mt, last);
 				goto next_match;
+			}
 
 			scratch->map_index = map_index;
 			kernel_fpu_end();

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