John Ernberg d68a867d74 net: usbnet: Avoid potential RCU stall on LINK_CHANGE event ... commit 0d9cfc9b8c upstream. The Gemalto Cinterion PLS83-W modem (cdc_ether) is emitting confusing link up and down events when the WWAN interface is activated on the modem-side. Interrupt URBs will in consecutive polls grab: * Link Connected * Link Disconnected * Link Connected Where the last Connected is then a stable link state. When the system is under load this may cause the unlink_urbs() work in __handle_link_change() to not complete before the next usbnet_link_change() call turns the carrier on again, allowing rx_submit() to queue new SKBs. In that event the URB queue is filled faster than it can drain, ending up in a RCU stall: rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-.... } 33108 jiffies s: 201 root: 0x1/. rcu: blocking rcu_node structures (internal RCU debug): Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 Call trace: arch_local_irq_enable+0x4/0x8 local_bh_enable+0x18/0x20 __netdev_alloc_skb+0x18c/0x1cc rx_submit+0x68/0x1f8 [usbnet] rx_alloc_submit+0x4c/0x74 [usbnet] usbnet_bh+0x1d8/0x218 [usbnet] usbnet_bh_tasklet+0x10/0x18 [usbnet] tasklet_action_common+0xa8/0x110 tasklet_action+0x2c/0x34 handle_softirqs+0x2cc/0x3a0 __do_softirq+0x10/0x18 ____do_softirq+0xc/0x14 call_on_irq_stack+0x24/0x34 do_softirq_own_stack+0x18/0x20 __irq_exit_rcu+0xa8/0xb8 irq_exit_rcu+0xc/0x30 el1_interrupt+0x34/0x48 el1h_64_irq_handler+0x14/0x1c el1h_64_irq+0x68/0x6c _raw_spin_unlock_irqrestore+0x38/0x48 xhci_urb_dequeue+0x1ac/0x45c [xhci_hcd] unlink1+0xd4/0xdc [usbcore] usb_hcd_unlink_urb+0x70/0xb0 [usbcore] usb_unlink_urb+0x24/0x44 [usbcore] unlink_urbs.constprop.0.isra.0+0x64/0xa8 [usbnet] __handle_link_change+0x34/0x70 [usbnet] usbnet_deferred_kevent+0x1c0/0x320 [usbnet] process_scheduled_works+0x2d0/0x48c worker_thread+0x150/0x1dc kthread+0xd8/0xe8 ret_from_fork+0x10/0x20 Get around the problem by delaying the carrier on to the scheduled work. This needs a new flag to keep track of the necessary action. The carrier ok check cannot be removed as it remains required for the LINK_RESET event flow. Fixes: 4b49f58fff ("usbnet: handle link change") Cc: stable@vger.kernel.org Signed-off-by: John Ernberg <john.ernberg@actia.se> Link: https://patch.msgid.link/20250723102526.1305339-1-john.ernberg@actia.se Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2025-08-15 12:14:12 +02:00
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acpi	ACPICA: Avoid sequence overread in call to strncmp()	2025-06-27 11:11:26 +01:00
asm-generic
clocksource
crypto	crypto: ahash - Set default reqsize from ahash_alg	2025-05-29 11:02:40 +02:00
cxl
drm	drm/amdgpu: Reset the clear flag in buddy during resume	2025-08-01 09:48:42 +01:00
dt-bindings
keys
kunit
kvm
linux	net: usbnet: Avoid potential RCU stall on LINK_CHANGE event	2025-08-15 12:14:12 +02:00
math-emu
media	media: v4l: Memset argument to 0 before calling get_mbus_config pad op	2025-05-29 11:02:49 +02:00
memory
misc
net	net: drop UFO packets in udp_rcv_segment()	2025-08-15 12:14:06 +02:00
pcmcia
ras
rdma	RDMA/uverbs: Propagate errors from rdma_lookup_get_uobject()	2025-05-29 11:02:19 +02:00
rv
scsi
soc	soc: qcom: ice: introduce devm_of_qcom_ice_get	2025-05-02 07:58:52 +02:00
sound	ASoC: tas2781: Fix the wrong step for TLV on tas2781	2025-08-15 12:14:06 +02:00
target
trace	rxrpc: Fix recv-recv race of completed call	2025-07-24 08:56:35 +02:00
uapi	vhost: Reintroduce kthread API and add mode selection	2025-08-15 12:13:58 +02:00
ufs	scsi: ufs: Introduce quirk to extend PA_HIBERN8TIME for UFS devices	2025-05-29 11:01:58 +02:00
vdso
video
xen