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Message-ID: <20180704072048.GA29107@outlook.office365.com>
Date: Wed, 4 Jul 2018 00:20:49 -0700
From: Andrei Vagin <avagin@...tuozzo.com>
To: Amritha Nambiar <amritha.nambiar@...el.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net,
alexander.h.duyck@...el.com, willemdebruijn.kernel@...il.com,
sridhar.samudrala@...el.com, alexander.duyck@...il.com,
edumazet@...gle.com, hannes@...essinduktion.org,
tom@...bertland.com, tom@...ntonium.net
Subject: Re: [net-next, v6, 6/7] net-sysfs: Add interface for Rx queue(s) map
per Tx queue
Hello Amritha,
I see a following warning on 4.18.0-rc3-next-20180703.
It looks like a problem is in this series.
[ 1.084722] ============================================
[ 1.084797] WARNING: possible recursive locking detected
[ 1.084872] 4.18.0-rc3-next-20180703+ #1 Not tainted
[ 1.084949] --------------------------------------------
[ 1.085024] swapper/0/1 is trying to acquire lock:
[ 1.085100] 00000000cf973d46 (cpu_hotplug_lock.rw_sem){++++}, at: static_key_slow_inc+0xe/0x20
[ 1.085189]
[ 1.085189] but task is already holding lock:
[ 1.085271] 00000000cf973d46 (cpu_hotplug_lock.rw_sem){++++}, at: init_vqs+0x513/0x5a0
[ 1.085357]
[ 1.085357] other info that might help us debug this:
[ 1.085450] Possible unsafe locking scenario:
[ 1.085450]
[ 1.085531] CPU0
[ 1.085605] ----
[ 1.085679] lock(cpu_hotplug_lock.rw_sem);
[ 1.085753] lock(cpu_hotplug_lock.rw_sem);
[ 1.085828]
[ 1.085828] *** DEADLOCK ***
[ 1.085828]
[ 1.085916] May be due to missing lock nesting notation
[ 1.085916]
[ 1.085998] 3 locks held by swapper/0/1:
[ 1.086074] #0: 00000000244bc7da (&dev->mutex){....}, at: __driver_attach+0x5a/0x110
[ 1.086164] #1: 00000000cf973d46 (cpu_hotplug_lock.rw_sem){++++}, at: init_vqs+0x513/0x5a0
[ 1.086248] #2: 000000005cd8463f (xps_map_mutex){+.+.}, at: __netif_set_xps_queue+0x8d/0xc60
[ 1.086336]
[ 1.086336] stack backtrace:
[ 1.086419] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.0-rc3-next-20180703+ #1
[ 1.086504] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 1.086587] Call Trace:
[ 1.086667] dump_stack+0x85/0xcb
[ 1.086744] __lock_acquire+0x68a/0x1330
[ 1.086821] ? lock_acquire+0x9f/0x200
[ 1.086900] ? find_held_lock+0x2d/0x90
[ 1.086976] ? lock_acquire+0x9f/0x200
[ 1.087051] lock_acquire+0x9f/0x200
[ 1.087126] ? static_key_slow_inc+0xe/0x20
[ 1.087205] cpus_read_lock+0x3e/0x80
[ 1.087280] ? static_key_slow_inc+0xe/0x20
[ 1.087355] static_key_slow_inc+0xe/0x20
[ 1.087435] __netif_set_xps_queue+0x216/0xc60
[ 1.087512] virtnet_set_affinity+0xf0/0x130
[ 1.087589] init_vqs+0x51b/0x5a0
[ 1.087665] virtnet_probe+0x39f/0x870
[ 1.087742] virtio_dev_probe+0x170/0x220
[ 1.087819] driver_probe_device+0x30b/0x480
[ 1.087897] ? set_debug_rodata+0x11/0x11
[ 1.087972] __driver_attach+0xe0/0x110
[ 1.088064] ? driver_probe_device+0x480/0x480
[ 1.088141] bus_for_each_dev+0x79/0xc0
[ 1.088221] bus_add_driver+0x164/0x260
[ 1.088302] ? veth_init+0x11/0x11
[ 1.088379] driver_register+0x5b/0xe0
[ 1.088402] ? veth_init+0x11/0x11
[ 1.088402] virtio_net_driver_init+0x6d/0x90
[ 1.088402] do_one_initcall+0x5d/0x34c
[ 1.088402] ? set_debug_rodata+0x11/0x11
[ 1.088402] ? rcu_read_lock_sched_held+0x6b/0x80
[ 1.088402] kernel_init_freeable+0x1ea/0x27b
[ 1.088402] ? rest_init+0xd0/0xd0
[ 1.088402] kernel_init+0xa/0x110
[ 1.088402] ret_from_fork+0x3a/0x50
[ 1.094190] i8042: PNP: PS/2 Controller [PNP0303:KBD,PNP0f13:MOU] at 0x60,0x64 irq 1,12
https://travis-ci.org/avagin/linux/jobs/399867744
On Fri, Jun 29, 2018 at 09:27:07PM -0700, Amritha Nambiar wrote:
> Extend transmit queue sysfs attribute to configure Rx queue(s) map
> per Tx queue. By default no receive queues are configured for the
> Tx queue.
>
> - /sys/class/net/eth0/queues/tx-*/xps_rxqs
>
> Signed-off-by: Amritha Nambiar <amritha.nambiar@...el.com>
> ---
> net/core/net-sysfs.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 83 insertions(+)
>
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index b39987c..f25ac5f 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -1283,6 +1283,88 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue,
>
> static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init
> = __ATTR_RW(xps_cpus);
> +
> +static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf)
> +{
> + struct net_device *dev = queue->dev;
> + struct xps_dev_maps *dev_maps;
> + unsigned long *mask, index;
> + int j, len, num_tc = 1, tc = 0;
> +
> + index = get_netdev_queue_index(queue);
> +
> + if (dev->num_tc) {
> + num_tc = dev->num_tc;
> + tc = netdev_txq_to_tc(dev, index);
> + if (tc < 0)
> + return -EINVAL;
> + }
> + mask = kcalloc(BITS_TO_LONGS(dev->num_rx_queues), sizeof(long),
> + GFP_KERNEL);
> + if (!mask)
> + return -ENOMEM;
> +
> + rcu_read_lock();
> + dev_maps = rcu_dereference(dev->xps_rxqs_map);
> + if (!dev_maps)
> + goto out_no_maps;
> +
> + for (j = -1; j = netif_attrmask_next(j, NULL, dev->num_rx_queues),
> + j < dev->num_rx_queues;) {
> + int i, tci = j * num_tc + tc;
> + struct xps_map *map;
> +
> + map = rcu_dereference(dev_maps->attr_map[tci]);
> + if (!map)
> + continue;
> +
> + for (i = map->len; i--;) {
> + if (map->queues[i] == index) {
> + set_bit(j, mask);
> + break;
> + }
> + }
> + }
> +out_no_maps:
> + rcu_read_unlock();
> +
> + len = bitmap_print_to_pagebuf(false, buf, mask, dev->num_rx_queues);
> + kfree(mask);
> +
> + return len < PAGE_SIZE ? len : -EINVAL;
> +}
> +
> +static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
> + size_t len)
> +{
> + struct net_device *dev = queue->dev;
> + struct net *net = dev_net(dev);
> + unsigned long *mask, index;
> + int err;
> +
> + if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
> + return -EPERM;
> +
> + mask = kcalloc(BITS_TO_LONGS(dev->num_rx_queues), sizeof(long),
> + GFP_KERNEL);
> + if (!mask)
> + return -ENOMEM;
> +
> + index = get_netdev_queue_index(queue);
> +
> + err = bitmap_parse(buf, len, mask, dev->num_rx_queues);
> + if (err) {
> + kfree(mask);
> + return err;
> + }
> +
> + err = __netif_set_xps_queue(dev, mask, index, true);
> + kfree(mask);
> + return err ? : len;
> +}
> +
> +static struct netdev_queue_attribute xps_rxqs_attribute __ro_after_init
> + = __ATTR_RW(xps_rxqs);
> #endif /* CONFIG_XPS */
>
> static struct attribute *netdev_queue_default_attrs[] __ro_after_init = {
> @@ -1290,6 +1372,7 @@ static struct attribute *netdev_queue_default_attrs[] __ro_after_init = {
> &queue_traffic_class.attr,
> #ifdef CONFIG_XPS
> &xps_cpus_attribute.attr,
> + &xps_rxqs_attribute.attr,
> &queue_tx_maxrate.attr,
> #endif
> NULL
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