From 2b70b32aef9e8e1ff275872d551c610368079911 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Fri, 3 Jan 2025 20:22:13 +0100 Subject: [PATCH] kernel: add workaround for page_pool_release warnings defer_list skbs held by NAPI can block releasing page pools. Work around this by scheduling rx softirq on all CPUs while trying to release a page pool. Signed-off-by: Felix Fietkau --- ...y-to-free-deferred-skbs-while-waitin.patch | 43 +++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 target/linux/generic/hack-6.6/610-net-page_pool-try-to-free-deferred-skbs-while-waitin.patch diff --git a/target/linux/generic/hack-6.6/610-net-page_pool-try-to-free-deferred-skbs-while-waitin.patch b/target/linux/generic/hack-6.6/610-net-page_pool-try-to-free-deferred-skbs-while-waitin.patch new file mode 100644 index 000000000000..36c28b94f60e --- /dev/null +++ b/target/linux/generic/hack-6.6/610-net-page_pool-try-to-free-deferred-skbs-while-waitin.patch @@ -0,0 +1,43 @@ +From: Felix Fietkau +Date: Fri, 3 Jan 2025 19:29:00 +0100 +Subject: [PATCH] net: page_pool: try to free deferred skbs while waiting for + pool release + +The NAPI defer list can accumulate no longer used skbs, which can be reused +during alloc. If this happens on a CPU that otherwise does not do any +rx softirq processing, skbs can be held indefinitely, causing warnings +on releasing page pools. +Deal with this by scheduling rx softirq on all CPUs. + +Patch by Lorenzo Bianconi + +Signed-off-by: Felix Fietkau +--- + +--- a/net/core/page_pool.c ++++ b/net/core/page_pool.c +@@ -862,12 +862,23 @@ static void page_pool_release_retry(stru + { + struct delayed_work *dwq = to_delayed_work(wq); + struct page_pool *pool = container_of(dwq, typeof(*pool), release_dw); +- int inflight; ++ int cpu, inflight; + + inflight = page_pool_release(pool); + if (!inflight) + return; + ++ /* Run NET_RX_SOFTIRQ in order to free pending skbs in softnet_data ++ * defer_list that can stay in the list until we have enough queued ++ * traffic. ++ */ ++ for_each_online_cpu(cpu) { ++ struct softnet_data *sd = &per_cpu(softnet_data, cpu); ++ ++ if (!cmpxchg(&sd->defer_ipi_scheduled, 0, 1)) ++ smp_call_function_single_async(cpu, &sd->defer_csd); ++ } ++ + /* Periodic warning */ + if (time_after_eq(jiffies, pool->defer_warn)) { + int sec = (s32)((u32)jiffies - (u32)pool->defer_start) / HZ;