[FS#9] Kernel panic with SQM scripts

[LEDE Bugs]

The following task has a new comment added:

FS#9 - Kernel panic with SQM scripts
User who did this - Hannu Nyman (hnyman)

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One more me-too report of HFSC crashes. I tested new R7800 with different qdiscs and HFSC seems to cause problems.

Netgear R7800, IPQ8065 SoC (ipq806x platform in LEDE).
LEDE Reboot r2154, kernel 4.4.30

A few slightly different variations of the crash, but are at net/sched/sch_hfsc.c:1426 hfsc_dequeue+0x188/0x568

Example below:

[67086.803277] ------------[ cut here ]------------
[67086.806968] WARNING: CPU: 0 PID: 3 at net/sched/sch_hfsc.c:1426 hfsc_dequeue+0x188/0x568 [sch_hfsc]()
[67086.811517] Modules linked in: pppoe ppp_async iptable_nat ip6table_nat pptp pppox ppp_mppe ppp_generic nf_nat_ipv6 nf_nat_ipv4 nf_conntrack_ipv6 nf_conntrack_ipv4 ipt_REJECT ipt_MASQUERADE xt_time xt_tcpudp xt_tcpmss xt_statistic xt_state xt_recent xt_nat xt_multiport xt_mark xt_mac xt_limit xt_length xt_id xt_hl xt_helper xt_esp xt_ecn xt_dscp xt_conntrack xt_connmark xt_connlimit xt_connbytes xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_HL xt_DSCP xt_CT xt_CLASSIFY usbserial slhc nf_reject_ipv4 nf_nat_rtsp nf_nat_redirect nf_nat_masquerade_ipv4 nf_log_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack_rtsp nf_conntrack_rtcache iptable_raw iptable_mangle iptable_filter ipt_ah ipt_ECN ip_tables crc_ccitt sch_cake em_cmp sch_teql em_nbyte sch_htb sch_tbf sch_dsmark sch_pie sch_gred em_meta cls_basic act_ipt sch_prio em_text sch_codel sch_sfq act_police sch_fq sch_red act_skbedit act_mirred em_u32 cls_u32 cls_tcindex cls_flow cls_route cls_fw sch_hfsc sch_ingress ath10k_pci ath10k_core ath mac80211 cfg80211 compat ledtrig_usbport xt_set ip_set_list_set ip_set_hash_netiface ip_set_hash_netport ip_set_hash_netnet ip_set_hash_net ip_set_hash_netportnet ip_set_hash_mac ip_set_hash_ipportnet ip_set_hash_ipportip ip_set_hash_ipport ip_set_hash_ipmark ip_set_hash_ip ip_set_bitmap_port ip_set_bitmap_ipmac ip_set_bitmap_ip ip_set nfnetlink ip6t_NPT ip6t_MASQUERADE nf_nat_masquerade_ipv6 nf_nat nf_conntrack ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 nf_log_common ip6table_raw ip6table_mangle ip6table_filter ip6_tables x_tables msdos ip_gre gre ifb sit tunnel4 ip_tunnel tun vfat fat ntfs hfsplus cifs nls_utf8 nls_iso8859_15 nls_iso8859_1 nls_cp850 nls_cp437 nls_cp1250 sha256_generic sha1_generic md5 md4 hmac ecb des_generic usb_storage leds_gpio xhci_plat_hcd xhci_pci xhci_hcd dwc3 dwc3_qcom dwc3_of_simple ohci_platform ohci_hcd phy_qcom_dwc3 ahci ehci_platform ehci_hcd sd_mod ahci_platform libahci_platform libahci libata scsi_mod gpio_button_hotplug ext4 jbd2 mbcache usbcore nls_base usb_common cryptomgr aead crypto_null crc32c_generic crypto_hash
[67086.999791] CPU: 0 PID: 3 Comm: ksoftirqd/0 Tainted: G        W       4.4.30 #0
[67087.000143] Hardware name: Qualcomm (Flattened Device Tree)
[67087.007284] [] (unwind_backtrace) from [] (show_stack+0x14/0x20)
[67087.012830] [] (show_stack) from [] (dump_stack+0x8c/0xa0)
[67087.020816] [] (dump_stack) from [] (warn_slowpath_common+0xa4/0xd0)
[67087.027845] [] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24)
[67087.036121] [] (warn_slowpath_null) from [] (hfsc_dequeue+0x188/0x568 [sch_hfsc])
[67087.044895] [] (hfsc_dequeue [sch_hfsc]) from [] (__qdisc_run+0xcc/0x1b4)
[67087.053983] [] (__qdisc_run) from [] (net_tx_action+0xf4/0x180)
[67087.062488] [] (net_tx_action) from [] (__do_softirq+0xdc/0x230)
[67087.069948] [] (__do_softirq) from [] (run_ksoftirqd+0x34/0x64)
[67087.077937] [] (run_ksoftirqd) from [] (smpboot_thread_fn+0x190/0x1b8)
[67087.085321] [] (smpboot_thread_fn) from [] (kthread+0xf8/0x100)
[67087.093648] [] (kthread) from [] (ret_from_fork+0x14/0x3c)
[67087.101259] ---[ end trace 829b74d04ace8079 ]---



Ps. Somebody with edit rights might add "HFSC qdisc" to be visible in the bug title.

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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=9#comment838