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Date:   Wed, 15 Sep 2021 17:22:51 +0300
From:   Martin Zaharinov <micron10@...il.com>
To:     Wei Wang <weiwan@...gle.com>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev <netdev@...r.kernel.org>,
        Alexander Duyck <alexanderduyck@...com>,
        Paolo Abeni <pabeni@...hat.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH net v4] net: fix race between napi kthread mode and busy
 poll

Hi Wei
Please see this bug log :


Sep 15 08:04:56  [2034411.548669][ T3195] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Sep 15 08:04:56  [2034411.574642][ T3195] CR2: 00007f1e8cf58000 CR3: 0000000183cb4003 CR4: 00000000001706e0
Sep 15 08:04:56  [2034411.625156][ T3195] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Sep 15 08:04:56  [2034411.675495][ T3195] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Sep 15 08:04:56  [2034411.725536][ T3195] Call Trace:
Sep 15 08:04:56  [2034411.749948][ T3195]  netif_receive_skb_list_internal+0x25c/0x2b0
Sep 15 08:04:56  [2034411.774579][ T3195]  gro_normal_one+0x6e/0x90
Sep 15 08:04:56  [2034411.798786][ T3195]  napi_gro_flush+0xb1/0x100
Sep 15 08:04:56  [2034411.822410][ T3195]  napi_complete_done+0x107/0x180
Sep 15 08:04:56  [2034411.845614][ T3195]  ixgbe_poll+0x10e/0x240 [ixgbe]
Sep 15 08:04:56  [2034411.868480][ T3195]  __napi_poll+0x1f/0x100
Sep 15 08:04:56  [2034411.890899][ T3195]  ? __napi_poll+0x100/0x100
Sep 15 08:04:56  [2034411.912799][ T3195]  napi_threaded_poll+0x105/0x150
Sep 15 08:04:56  [2034411.934567][ T3195]  kthread+0x101/0x120
Sep 15 08:04:56  [2034411.955873][ T3195]  ? set_kthread_struct+0x30/0x30
Sep 15 08:04:56  [2034411.977157][ T3195]  ret_from_fork+0x1f/0x30
Sep 15 08:04:56  [2034411.997922][ T3195] ---[ end trace 83b8d17d2762bc73 ]---
Sep 15 08:04:56  [2034412.018439][ T3195] BUG: kernel NULL pointer dereference, address: 0000000000000000
Sep 15 08:04:56  [2034412.058658][ T3195] #PF: supervisor read access in kernel mode
Sep 15 08:04:56  [2034412.078866][ T3195] #PF: error_code(0x0000) - not-present page
Sep 15 08:04:56  [2034412.098648][ T3195] PGD 12fabb067 P4D 12fabb067 PUD 17d7fa067 PMD 0
Sep 15 08:04:56  [2034412.118230][ T3195] Oops: 0000 [#1] SMP NOPTI
Sep 15 08:04:56  [2034412.137240][ T3195] CPU: 2 PID: 3195 Comm: napi/eth0-513 Tainted: G S      W  O      5.13.12 #1
Sep 15 08:04:56  [2034412.174538][ T3195] Hardware name: Supermicro Super Server/X10SRD-F, BIOS 3.3 10/28/2020
Sep 15 08:04:56  [2034412.211613][ T3195] RIP: 0010:netif_receive_skb_list_internal+0x224/0x2b0
Sep 15 08:04:56  [2034412.230852][ T3195] Code: 20 ff ff ff 4c 89 74 24 18 4c 89 74 24 20 e9 42 ff ff ff 4c 8b 65 00 49 8b 1c 24 4d 89 e7 4c 39 e5 74 70 4c 8d 74 24 18 eb 15 <48> 8b 03 49 89 df 49 89 dc 48 39 eb 0f 84 94 fe ff ff 48 89 c3 49
Sep 15 08:04:56  [2034412.287806][ T3195] RSP: 0018:ffff9de881f47d68 EFLAGS: 00010296
Sep 15 08:04:56  [2034412.306525][ T3195] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
Sep 15 08:04:56  [2034412.343308][ T3195] RDX: ffff98b01fc626f8 RSI: 0000000000000009 RDI: 0000000000000003
Sep 15 08:04:56  [2034412.381399][ T3195] RBP: ffff98a8e29d8158 R08: 0000000000000001 R09: 00000000fffbffff
Sep 15 08:04:56  [2034412.421437][ T3195] R10: ffff98b01d600000 R11: ffff9de881f47bb0 R12: ffff98a9f1352a00
Sep 15 08:04:57  [2034412.463438][ T3195] R13: 0000000000000009 R14: ffff9de881f47d80 R15: ffff98a9f1352a00
Sep 15 08:04:57  [2034412.507493][ T3195] FS:  0000000000000000(0000) GS:ffff98b01fa80000(0000) knlGS:0000000000000000
Sep 15 08:04:57  [2034412.553528][ T3195] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Sep 15 08:04:57  [2034412.577424][ T3195] CR2: 0000000000000000 CR3: 0000000183cb4003 CR4: 00000000001706e0
Sep 15 08:04:57  [2034412.624853][ T3195] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Sep 15 08:04:57  [2034412.672633][ T3195] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Sep 15 08:04:57  [2034412.721656][ T3195] Call Trace:
Sep 15 08:04:57  [2034412.746016][ T3195]  gro_normal_one+0x6e/0x90
Sep 15 08:04:57  [2034412.770321][ T3195]  napi_gro_flush+0xb1/0x100
Sep 15 08:04:57  [2034412.794137][ T3195]  napi_complete_done+0x107/0x180
Sep 15 08:04:57  [2034412.817556][ T3195]  ixgbe_poll+0x10e/0x240 [ixgbe]
Sep 15 08:04:57  [2034412.840522][ T3195]  __napi_poll+0x1f/0x100
Sep 15 08:04:57  [2034412.862829][ T3195]  ? __napi_poll+0x100/0x100
Sep 15 08:04:57  [2034412.884804][ T3195]  napi_threaded_poll+0x105/0x150
Sep 15 08:04:57  [2034412.906305][ T3195]  kthread+0x101/0x120
Sep 15 08:04:57  [2034412.927502][ T3195]  ? set_kthread_struct+0x30/0x30
Sep 15 08:04:57  [2034412.948434][ T3195]  ret_from_fork+0x1f/0x30
Sep 15 08:04:57  [2034412.969117][ T3195] Modules linked in: xsk_diag unix_diag nf_conntrack_netlink nfnetlink vlan_mon(O) pppoe pppox ppp_generic slhc team_mode_loadbalance team xt_dtvqos(O) xt_TCPMSS xt_comment iptable_mangle xt_MASQUERADE xt_nat iptable_nat ip_tables netconsole coretemp ixgbe mdio mdio_devres libphy nf_nat_sip nf_conntrack_sip nf_nat_pptp nf_conntrack_pptp nf_nat_tftp nf_conntrack_tftp nf_nat_ftp nf_conntrack_ftp nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_xnatlog(O) acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler rtc_cmos [last unloaded: DTVIAC]
Sep 15 08:04:57  [2034413.136792][ T3195] CR2: 0000000000000000
Sep 15 08:04:57  [2034413.157289][ T3195] ---[ end trace 83b8d17d2762bc74 ]---
Sep 15 08:04:57  [2034413.177534][ T3195] RIP: 0010:netif_receive_skb_list_internal+0x224/0x2b0
Sep 15 08:04:57  [2034413.197775][ T3195] Code: 20 ff ff ff 4c 89 74 24 18 4c 89 74 24 20 e9 42 ff ff ff 4c 8b 65 00 49 8b 1c 24 4d 89 e7 4c 39 e5 74 70 4c 8d 74 24 18 eb 15 <48> 8b 03 49 89 df 49 89 dc 48 39 eb 0f 84 94 fe ff ff 48 89 c3 49
Sep 15 08:04:57  [2034413.258524][ T3195] RSP: 0018:ffff9de881f47d68 EFLAGS: 00010296
Sep 15 08:04:57  [2034413.278591][ T3195] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
Sep 15 08:04:57  [2034413.317532][ T3195] RDX: ffff98b01fc626f8 RSI: 0000000000000009 RDI: 0000000000000003
Sep 15 08:04:57  [2034413.356936][ T3195] RBP: ffff98a8e29d8158 R08: 0000000000000001 R09: 00000000fffbffff
Sep 15 08:04:57  [2034413.398408][ T3195] R10: ffff98b01d600000 R11: ffff9de881f47bb0 R12: ffff98a9f1352a00
Sep 15 08:04:58  [2034413.441949][ T3195] R13: 0000000000000009 R14: ffff9de881f47d80 R15: ffff98a9f1352a00
Sep 15 08:04:58  [2034413.487558][ T3195] FS:  0000000000000000(0000) GS:ffff98b01fa80000(0000) knlGS:0000000000000000
Sep 15 08:04:58  [2034413.535263][ T3195] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Sep 15 08:04:58  [2034413.560012][ T3195] CR2: 0000000000000000 CR3: 0000000183cb4003 CR4: 00000000001706e0
Sep 15 08:04:58  [2034413.609277][ T3195] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Sep 15 08:04:58  [2034413.658501][ T3195] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Sep 15 08:04:58  [2034413.707535][ T3195] Kernel panic - not syncing: Fatal exception in interrupt
Sep 15 08:04:58  [2034413.856962][ T3195] Kernel Offset: 0x36000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
Sep 15 08:04:58  [2034413.906445][ T3195] Rebooting in 10 seconds..
Sep 15 08:05:08  [2034423.930880][ T3195] ACPI MEMORY or I/O RESET_REG.




> On 10 Sep 2021, at 3:30, Wei Wang <weiwan@...gle.com> wrote:
> 
> Hi Martin,
> 
> Is there a reproducer for this? What kind of traffic is it running?
> What is the following config:
> cat /proc/sys/net/core/busy_poll
> cat /proc/sys/net/core/busy_read
> cat /sys/class/net/<ixgbe_dev>/threaded
> And is SO_PREFER_BUSY_POLL used?
> 
> Thanks.
> Wei
> 
> 
> 
> On Thu, Sep 9, 2021 at 4:18 AM Martin Zaharinov <micron10@...il.com> wrote:
>> 
>> Hi Eric and Wei
>> 
>> Please see this bug report from last hour ,
>> Kernel 5.13.13, Traffic is 7Gb/s down/ 7Gb/s up
>> Uptime before crash : 10day
>> 
>> 
>> 
>> 
>> Sep  9 12:49:31  [829553.899833][ T2925] ------------[ cut here ]------------
>> Sep  9 12:49:31  [829553.927316][ T2925] list_del corruption. next->prev should be ffff9651016c0b00, but was ffff96511a87c158
>> Sep  9 12:49:31  [829553.981630][ T2925] WARNING: CPU: 3 PID: 2925 at lib/list_debug.c:54 __list_del_entry_valid+0x8a/0x90
>> Sep  9 12:49:31  [829554.035795][ T2925] Modules linked in: xsk_diag unix_diag nf_conntrack_netlink nfnetlink vlan_mon(O) pppoe pppox ppp_generic slhc team_mode_loadbalance team xt_MASQUERADE xt_nat iptable_nat xt_TCPMSS xt_comment iptable_mangle ip_tables netconsole coretemp ixgbe mdio mdio_devres libphy nf_nat_sip nf_conntrack_sip nf_nat_pptp nf_conntrack_pptp nf_nat_tftp nf_conntrack_tftp nf_nat_ftp nf_conntrack_ftp nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_xnatlog(O) acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler rtc_cmos [last unloaded: iptable_raw]
>> Sep  9 12:49:31  [829554.254022][ T2925] CPU: 3 PID: 2925 Comm: kresd Tainted: G           O      5.13.13 #1
>> Sep  9 12:49:31  [829554.307304][ T2925] Hardware name: Supermicro Super Server/X10SRD-F, BIOS 3.3 10/28/2020
>> Sep  9 12:49:31  [829554.360188][ T2925] RIP: 0010:__list_del_entry_valid+0x8a/0x90
>> Sep  9 12:49:31  [829554.386671][ T2925] Code: 46 00 0f 0b 31 c0 c3 48 89 f2 48 89 fe 48 c7 c7 40 33 16 9a e8 0b 69 46 00 0f 0b 31 c0 c3 48 c7 c7 80 33 16 9a e8 fa 68 46 00 <0f> 0b 31 c0 c3 cc 89 f8 48 85 d2 74 1f 48 01 f2 0f b6 0e 48 ff c6
>> Sep  9 12:49:31  [829554.465378][ T2925] RSP: 0018:ffffa90ec1affd00 EFLAGS: 00010286
>> Sep  9 12:49:31  [829554.491219][ T2925] RAX: 0000000000000054 RBX: ffff9651016c0a00 RCX: 0000000000000001
>> Sep  9 12:49:32  [829554.541672][ T2925] RDX: 00000000ffffffea RSI: 00000000fffbffff RDI: 00000000fffbffff
>> Sep  9 12:49:32  [829554.592016][ T2925] RBP: ffff96511a87c158 R08: 0000000000000001 R09: 00000000fffbffff
>> Sep  9 12:49:32  [829554.642131][ T2925] R10: ffff96546d600000 R11: ffffa90ec1affb50 R12: ffff9651016c0b00
>> Sep  9 12:49:32  [829554.692890][ T2925] R13: 0000000000000008 R14: ffffa90ec1affd20 R15: ffff9651016c0b00
>> Sep  9 12:49:32  [829554.744221][ T2925] FS:  00007f38717a5900(0000) GS:ffff96546fac0000(0000) knlGS:0000000000000000
>> Sep  9 12:49:32  [829554.795701][ T2925] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> Sep  9 12:49:32  [829554.821598][ T2925] CR2: 00007f3854c0a000 CR3: 0000000115a7c001 CR4: 00000000001706e0
>> Sep  9 12:49:32  [829554.872045][ T2925] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> Sep  9 12:49:32  [829554.922284][ T2925] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Sep  9 12:49:32  [829554.972250][ T2925] Call Trace:
>> Sep  9 12:49:32  [829554.996597][ T2925]  netif_receive_skb_list_internal+0x25c/0x2b0
>> Sep  9 12:49:32  [829555.021270][ T2925]  busy_poll_stop+0x113/0x140
>> Sep  9 12:49:32  [829555.045679][ T2925]  ? ep_destroy_wakeup_source+0x20/0x20
>> Sep  9 12:49:32  [829555.069833][ T2925]  ? ixgbe_clean_rx_irq+0x790/0x790 [ixgbe]
>> Sep  9 12:49:32  [829555.093659][ T2925]  napi_busy_loop+0x212/0x280
>> Sep  9 12:49:32  [829555.117046][ T2925]  ep_poll+0xba/0x380
>> Sep  9 12:49:32  [829555.140048][ T2925]  ? __napi_poll+0x1f/0x100
>> Sep  9 12:49:32  [829555.162477][ T2925]  do_epoll_wait+0xa6/0xc0
>> Sep  9 12:49:32  [829555.184504][ T2925]  do_epoll_pwait.part.0+0x9/0x70
>> Sep  9 12:49:32  [829555.206138][ T2925]  __x64_sys_epoll_pwait+0x6a/0x100
>> Sep  9 12:49:32  [829555.227619][ T2925]  ? do_syscall_64+0x3a/0x70
>> Sep  9 12:49:32  [829555.248592][ T2925]  ? entry_SYSCALL_64_after_hwframe+0x44/0xae
>> Sep  9 12:49:32  [829555.269414][ T2925] ---[ end trace 7792cf332872df55 ]---
>> Sep  9 12:49:32  [829555.317238][ T2925] BUG: unable to handle page fault for address: 00000000000496c9
>> Sep  9 12:49:32  [829555.357231][ T2925] #PF: supervisor read access in kernel mode
>> Sep  9 12:49:32  [829555.377314][ T2925] #PF: error_code(0x0000) - not-present page
>> Sep  9 12:49:32  [829555.396972][ T2925] PGD 12ad0f067 P4D 12ad0f067 PUD 12ad11067 PMD 0
>> Sep  9 12:49:32  [829555.416441][ T2925] Oops: 0000 [#1] SMP NOPTI
>> Sep  9 12:49:32  [829555.435328][ T2925] CPU: 3 PID: 2925 Comm: kresd Tainted: G        W  O      5.13.13 #1
>> Sep  9 12:49:32  [829555.472060][ T2925] Hardware name: Supermicro Super Server/X10SRD-F, BIOS 3.3 10/28/2020
>> Sep  9 12:49:32  [829555.508998][ T2925] RIP: 0010:get_rps_cpu+0x1b/0x2f0
>> Sep  9 12:49:33  [829555.527449][ T2925] Code: 0f 0b e8 28 e7 1b 00 0f 1f 84 00 00 00 00 00 41 57 41 56 49 89 d6 41 55 49 89 fd 41 54 55 48 89 f5 53 48 83 ec 20 0f b7 56 7c <48> 8b 87 e8 02 00 00 66 85 d2 74 1f ff ca 0f b7 ca 44 8b 87 f4 02
>> Sep  9 12:49:33  [829555.582511][ T2925] RSP: 0018:ffffa90ec1affcb0 EFLAGS: 00010282
>> Sep  9 12:49:33  [829555.600509][ T2925] RAX: ffff9651847be000 RBX: ffff9651847be000 RCX: 0000000000200015
>> Sep  9 12:49:33  [829555.636779][ T2925] RDX: 0000000000009654 RSI: ffff96546fae26f8 RDI: 00000000000493e1
>> Sep  9 12:49:33  [829555.674280][ T2925] RBP: ffff96546fae26f8 R08: 0000000000000001 R09: ffff96519f7f1900
>> Sep  9 12:49:33  [829555.713363][ T2925] R10: 0000000000000000 R11: 00000000000262c8 R12: ffff96546fae26f8
>> Sep  9 12:49:33  [829555.754362][ T2925] R13: 00000000000493e1 R14: ffffa90ec1affd08 R15: ffff96546fae26f8
>> Sep  9 12:49:33  [829555.797754][ T2925] FS:  00007f38717a5900(0000) GS:ffff96546fac0000(0000) knlGS:0000000000000000
>> Sep  9 12:49:33  [829555.843229][ T2925] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> Sep  9 12:49:33  [829555.866726][ T2925] CR2: 00000000000496c9 CR3: 0000000115a7c001 CR4: 00000000001706e0
>> Sep  9 12:49:33  [829555.913285][ T2925] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> Sep  9 12:49:33  [829555.960278][ T2925] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Sep  9 12:49:33  [829556.008563][ T2925] Call Trace:
>> Sep  9 12:49:33  [829556.032547][ T2925]  ? enqueue_to_backlog+0x81/0x250
>> Sep  9 12:49:33  [829556.056686][ T2925]  netif_receive_skb_list_internal+0x24d/0x2b0
>> Sep  9 12:49:33  [829556.080870][ T2925]  busy_poll_stop+0x113/0x140
>> Sep  9 12:49:33  [829556.104559][ T2925]  ? ep_destroy_wakeup_source+0x20/0x20
>> Sep  9 12:49:33  [829556.128028][ T2925]  ? ixgbe_clean_rx_irq+0x790/0x790 [ixgbe]
>> Sep  9 12:49:33  [829556.151405][ T2925]  napi_busy_loop+0x212/0x280
>> Sep  9 12:49:33  [829556.174478][ T2925]  ep_poll+0xba/0x380
>> Sep  9 12:49:33  [829556.196887][ T2925]  ? __napi_poll+0x1f/0x100
>> Sep  9 12:49:33  [829556.219070][ T2925]  do_epoll_wait+0xa6/0xc0
>> Sep  9 12:49:33  [829556.240778][ T2925]  do_epoll_pwait.part.0+0x9/0x70
>> Sep  9 12:49:33  [829556.262203][ T2925]  __x64_sys_epoll_pwait+0x6a/0x100
>> Sep  9 12:49:33  [829556.283188][ T2925]  ? do_syscall_64+0x3a/0x70
>> Sep  9 12:49:33  [829556.303666][ T2925]  ? entry_SYSCALL_64_after_hwframe+0x44/0xae
>> Sep  9 12:49:33  [829556.323995][ T2925] Modules linked in: xsk_diag unix_diag nf_conntrack_netlink nfnetlink vlan_mon(O) pppoe pppox ppp_generic slhc team_mode_loadbalance team xt_MASQUERADE xt_nat iptable_nat xt_TCPMSS xt_comment iptable_mangle ip_tables netconsole coretemp ixgbe mdio mdio_devres libphy nf_nat_sip nf_conntrack_sip nf_nat_pptp nf_conntrack_pptp nf_nat_tftp nf_conntrack_tftp nf_nat_ftp nf_conntrack_ftp nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_xnatlog(O) acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler rtc_cmos [last unloaded: iptable_raw]
>> Sep  9 12:49:33  [829556.487037][ T2925] CR2: 00000000000496c9
>> Sep  9 12:49:33  [829556.507006][ T2925] ---[ end trace 7792cf332872df56 ]---
>> Sep  9 12:49:33  [829556.526984][ T2925] RIP: 0010:get_rps_cpu+0x1b/0x2f0
>> Sep  9 12:49:34  [829556.546524][ T2925] Code: 0f 0b e8 28 e7 1b 00 0f 1f 84 00 00 00 00 00 41 57 41 56 49 89 d6 41 55 49 89 fd 41 54 55 48 89 f5 53 48 83 ec 20 0f b7 56 7c <48> 8b 87 e8 02 00 00 66 85 d2 74 1f ff ca 0f b7 ca 44 8b 87 f4 02
>> Sep  9 12:49:34  [829556.604787][ T2925] RSP: 0018:ffffa90ec1affcb0 EFLAGS: 00010282
>> Sep  9 12:49:34  [829556.623841][ T2925] RAX: ffff9651847be000 RBX: ffff9651847be000 RCX: 0000000000200015
>> Sep  9 12:49:34  [829556.662385][ T2925] RDX: 0000000000009654 RSI: ffff96546fae26f8 RDI: 00000000000493e1
>> Sep  9 12:49:34  [829556.702267][ T2925] RBP: ffff96546fae26f8 R08: 0000000000000001 R09: ffff96519f7f1900
>> Sep  9 12:49:34  [829556.743605][ T2925] R10: 0000000000000000 R11: 00000000000262c8 R12: ffff96546fae26f8
>> Sep  9 12:49:34  [829556.786604][ T2925] R13: 00000000000493e1 R14: ffffa90ec1affd08 R15: ffff96546fae26f8
>> Sep  9 12:49:34  [829556.831749][ T2925] FS:  00007f38717a5900(0000) GS:ffff96546fac0000(0000) knlGS:0000000000000000
>> Sep  9 12:49:34  [829556.879295][ T2925] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> Sep  9 12:49:34  [829556.903908][ T2925] CR2: 00000000000496c9 CR3: 0000000115a7c001 CR4: 00000000001706e0
>> Sep  9 12:49:34  [829556.952783][ T2925] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> Sep  9 12:49:34  [829557.001612][ T2925] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Sep  9 12:49:34  [829557.050193][ T2925] Kernel panic - not syncing: Fatal exception in interrupt
>> Sep  9 12:49:34  [829557.182948][ T2925] Kernel Offset: 0x18000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
>> Sep  9 12:49:34  [829557.231174][ T2925] Rebooting in 10 seconds..
>> Sep  9 12:49:44  [829567.255206][ T2925] ACPI MEMORY or I/O RESET_REG.
>> 
>>> On 30 Mar 2021, at 16:39, Eric Dumazet <edumazet@...gle.com> wrote:
>>> 
>>> On Tue, Mar 30, 2021 at 11:25 AM Martin Zaharinov <micron10@...il.com> wrote:
>>>> 
>>>> Hi Eric and Wei
>>>> 
>>>> Please check this log :
>>>> 
>>> 
>>> Please send a normal report to netdev.
>>> 
>>> This has nothing to to with us (Eric & Wei)
>>> 
>>> Thanks.
>>> 
>>>> 
>>>> 1584288.951272] napi/eth0-523: page allocation failure: order:0, mode:0x40a20(GFP_ATOMIC|__GFP_COMP), nodemask=(null)
>>>> [1584289.003674] CPU: 4 PID: 3179 Comm: napi/eth0-523 Tainted: G           O      5.11.4 #1
>>>> [1584289.055545] Hardware name: Supermicro SYS-5038MR-H8TRF/X10SRD-F, BIOS 3.2 11/22/2019
>>>> [1584289.107263] Call Trace:
>>>> [1584289.107266]  dump_stack+0x58/0x6b
>>>> [1584289.209562]  warn_alloc.cold+0x70/0xd4
>>>> [1584289.209569]  __alloc_pages_slowpath.constprop.0+0xd57/0xfb0
>>>> [1584289.209574]  __alloc_pages_nodemask+0x15a/0x180
>>>> [1584289.474009]  allocate_slab+0x272/0x450
>>>> [1584289.496731]  ___slab_alloc.constprop.0+0x41e/0x4d0
>>>> [1584289.519147]  kmem_cache_alloc+0x110/0x120
>>>> [1584289.541416]  build_skb+0x1a/0x200
>>>> [1584289.563121]  ixgbe_clean_rx_irq+0x5fc/0xa10 [ixgbe]
>>>> [1584289.584618]  ixgbe_poll+0xeb/0x2a0 [ixgbe]
>>>> [1584289.605528]  __napi_poll+0x1f/0x130
>>>> [1584289.625842]  napi_threaded_poll+0x110/0x160
>>>> [1584289.646110]  ? __napi_poll+0x130/0x130
>>>> [1584289.665810]  kthread+0xea/0x120
>>>> [1584289.684836]  ? kthread_park+0x80/0x80
>>>> [1584289.703440]  ret_from_fork+0x1f/0x30
>>>> [1584289.721616] Mem-Info:
>>>> [1584289.739066] active_anon:8157 inactive_anon:2100191 isolated_anon:0
>>>>                 active_file:17408 inactive_file:149 isolated_file:32
>>>>                 unevictable:1440359 dirty:17500 writeback:0
>>>>                 slab_reclaimable:43368 slab_unreclaimable:155124
>>>>                 mapped:817431 shmem:7650 pagetables:32093 bounce:0
>>>>                 free:17832 free_pcp:113 free_cma:0
>>>> [1584289.842614] Node 0 active_anon:32628kB inactive_anon:8400764kB active_file:69312kB inactive_file:880kB unevictable:5761436kB isolated(anon):0kB isolated(file):128kB mapped:3269724kB dirty:69740kB writeback:0kB shmem:30600kB writeback_tmp:0kB kernel_stack:5376kB pagetables:128372kB all_unreclaimable? no
>>>> [1584289.913793] Node 0 DMA free:13836kB min:12kB low:24kB high:36kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15968kB managed:15884kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
>>>> [1584289.986882] lowmem_reserve[]: 0 1741 15726 15726
>>>> [1584290.005519] Node 0 DMA32 free:54448kB min:9780kB low:11560kB high:13340kB reserved_highatomic:24576KB active_anon:5104kB inactive_anon:760844kB active_file:51532kB inactive_file:388kB unevictable:885428kB writepending:51744kB present:1965124kB managed:1899588kB mlocked:0kB bounce:0kB free_pcp:684kB local_pcp:0kB free_cma:0kB
>>>> [1584290.104980] lowmem_reserve[]: 0 0 13985 13985
>>>> [1584290.125807] Node 0 Normal free:2288kB min:78608kB low:92928kB high:107248kB reserved_highatomic:32768KB active_anon:27524kB inactive_anon:7639920kB active_file:17776kB inactive_file:1304kB unevictable:4876016kB writepending:17736kB present:14680064kB managed:14326620kB mlocked:0kB bounce:0kB free_pcp:288kB local_pcp:28kB free_cma:0kB
>>>> [1584290.237051] lowmem_reserve[]: 0 0 0 0
>>>> [1584290.260423] Node 0 DMA: 1*4kB (U) 1*8kB (U) 0*16kB 0*32kB 2*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 0*2048kB 3*4096kB (M) = 13836kB
>>>> [1584290.308847] Node 0 DMA32: 12500*4kB (UMEH) 553*8kB (MH) 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 54424kB
>>>> [1584290.358363] Node 0 Normal: 0*4kB 25*8kB (H) 0*16kB 5*32kB (H) 1*64kB (H) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 424kB
>>>> [1584290.409087] 1465768 total pagecache pages
>>>> [1584290.434531] 4165289 pages RAM
>>>> [1584290.459616] 0 pages HighMem/MovableOnly
>>>> [1584290.484480] 104766 pages reserved
>>>> [1584290.508709] 0 pages hwpoisoned
>>>> [1584301.710231] team0: Failed to send options change via netlink (err -105)
>>>> [1584302.635731] telegraf invoked oom-killer: gfp_mask=0x400dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO), order=1, oom_score_adj=0
>>>> [1584302.682874] CPU: 0 PID: 3494492 Comm: telegraf Tainted: G           O      5.11.4 #1
>>>> [1584302.729535] Hardware name: Supermicro SYS-5038MR-H8TRF/X10SRD-F, BIOS 3.2 11/22/2019
>>>> [1584302.776532] Call Trace:
>>>> [1584302.799361]  dump_stack+0x58/0x6b
>>>> [1584302.821791]  dump_header+0x4c/0x2e6
>>>> [1584302.843580]  oom_kill_process.cold+0xb/0x10
>>>> [1584302.865223]  out_of_memory.part.0+0x125/0x5f0
>>>> [1584302.886641]  out_of_memory+0x54/0xa0
>>>> [1584302.907302]  __alloc_pages_slowpath.constprop.0+0xb03/0xfb0
>>>> [1584302.927913]  __alloc_pages_nodemask+0x15a/0x180
>>>> [1584302.947874]  __get_free_pages+0x8/0x30
>>>> [1584302.967246]  pgd_alloc+0x21/0x180
>>>> [1584302.986355]  mm_alloc+0x1af/0x250
>>>> [1584303.005085]  alloc_bprm+0x80/0x2a0
>>>> [1584303.023328]  do_execveat_common+0x8b/0x330
>>>> [1584303.041181]  __x64_sys_execve+0x2b/0x40
>>>> [1584303.058513]  do_syscall_64+0x2d/0x40
>>>> [1584303.075281]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>>> [1584303.091891] RIP: 0033:0x488376
>>>> [1584303.108045] Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 48 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 1b 48 c7 44 24 28 ff ff ff ff 48 c7 44 24 30
>>>> [1584303.159632] RSP: 002b:000000c001108528 EFLAGS: 00000206 ORIG_RAX: 000000000000003b
>>>> [1584303.195446] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000488376
>>>> [1584303.231451] RDX: 000000c002b1a080 RSI: 000000c0028432e0 RDI: 000000c000cae660
>>>> [1584303.267407] RBP: 000000c0011086c8 R08: 0000000000000018 R09: 0000000000000000
>>>> [1584303.303594] R10: 0000000000000008 R11: 0000000000000206 R12: 000000000047f258
>>>> [1584303.340218] R13: 000000000000000e R14: 000000000000000d R15: 0000000000000100
>>>> [1584303.379094] Mem-Info:
>>>> [1584303.398713] active_anon:8159 inactive_anon:2138194 isolated_anon:0
>>>>                 active_file:12975 inactive_file:168 isolated_file:32
>>>>                 unevictable:909709 dirty:12864 writeback:10
>>>>                 slab_reclaimable:42415 slab_unreclaimable:154783
>>>>                 mapped:39825 shmem:14744 pagetables:26041 bounce:0
>>>>                 free:537002 free_pcp:1813 free_cma:0
>>>> [1584303.547011] Node 0 active_anon:32636kB inactive_anon:8552776kB active_file:51476kB inactive_file:1112kB unevictable:3638836kB isolated(anon):0kB isolated(file):128kB mapped:159480kB dirty:51024kB writeback:28kB shmem:58976kB writeback_tmp:0kB kernel_stack:5392kB pagetables:104164kB all_unreclaimable? no
>>>> [1584303.640025] Node 0 DMA free:13428kB min:12kB low:24kB high:36kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15968kB managed:15884kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
>>>> [1584303.739414] lowmem_reserve[]: 0 1741 15726 15726
>>>> [1584303.764535] Node 0 DMA32 free:121320kB min:5872kB low:7652kB high:9432kB reserved_highatomic:24576KB active_anon:5104kB inactive_anon:761140kB active_file:37160kB inactive_file:772kB unevictable:885428kB writepending:37672kB present:1965124kB managed:1899588kB mlocked:0kB bounce:0kB free_pcp:1448kB local_pcp:0kB free_cma:0kB
>>>> [1584303.888935] lowmem_reserve[]: 0 0 13985 13985
>>>> [1584303.913532] Node 0 Normal free:1970692kB min:78608kB low:92928kB high:107248kB reserved_highatomic:126976KB active_anon:27524kB inactive_anon:7812248kB active_file:13664kB inactive_file:1528kB unevictable:2753408kB writepending:12888kB present:14680064kB managed:14326620kB mlocked:0kB bounce:0kB free_pcp:4076kB local_pcp:0kB free_cma:0kB
>>>> [1584304.036531] lowmem_reserve[]: 0 0 0 0
>>>> [1584304.060733] Node 0 DMA: 1*4kB (U) 40*8kB (U) 37*16kB (U) 32*32kB (U) 24*64kB (U) 14*128kB (U) 8*256kB (U) 2*512kB (U) 1*1024kB (U) 0*2048kB 1*4096kB (M) = 13460kB
>>>> [1584304.134551] Node 0 DMA32: 15098*4kB (UMEH) 6204*8kB (UMEH) 662*16kB (UMEH) 20*32kB (UMEH) 1*64kB (U) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 121320kB
>>>> [1584304.209349] Node 0 Normal: 1038*4kB (UEH) 392*8kB (EH) 56*16kB (UEH) 28*32kB (UEH) 14*64kB (MEH) 25*128kB (MEH) 6*256kB (MH) 3*512kB (UMH) 3*1024kB (MH) 5*2048kB (UMH) 472*4096kB (U) = 1962872kB
>>>> [1584304.287094] 933871 total pagecache pages
>>>> [1584304.312815] 4165289 pages RAM
>>>> [1584304.337915] 0 pages HighMem/MovableOnly
>>>> [1584304.362522] 104766 pages reserved
>>>> [1584304.386516] 0 pages hwpoisoned
>>>> 
>>>>> On 20 Mar 2021, at 11:55, Eric Dumazet <edumazet@...gle.com> wrote:
>>>>> 
>>>>> On Sat, Mar 20, 2021 at 9:45 AM Martin Zaharinov <micron10@...il.com> wrote:
>>>>>> 
>>>>>> Hi Wei
>>>>>> Check this:
>>>>>> 
>>>>>> [   39.706567] ------------[ cut here ]------------
>>>>>> [   39.706568] RTNL: assertion failed at net/ipv4/udp_tunnel_nic.c (557)
>>>>>> [   39.706585] WARNING: CPU: 0 PID: 429 at net/ipv4/udp_tunnel_nic.c:557 __udp_tunnel_nic_reset_ntf+0xea/0x100
>>>>> 
>>>>> Probably more relevant to Intel maintainers than Wei :/
>>>>> 
>>>>>> [   39.706594] Modules linked in: i40e(+) nf_nat_sip nf_conntrack_sip nf_nat_pptp nf_conntrack_pptp nf_nat_tftp nf_conntrack_tftp nf_nat_ftp nf_conntrack_ftp nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler rtc_cmos megaraid_sas
>>>>>> [   39.706614] CPU: 0 PID: 429 Comm: kworker/0:2 Tainted: G           O      5.11.7 #1
>>>>>> [   39.706618] Hardware name: Supermicro X11DPi-N(T)/X11DPi-NT, BIOS 3.4 11/23/2020
>>>>>> [   39.706619] Workqueue: events work_for_cpu_fn
>>>>>> [   39.706627] RIP: 0010:__udp_tunnel_nic_reset_ntf+0xea/0x100
>>>>>> [   39.706631] Code: c0 79 f1 00 00 0f 85 4e ff ff ff ba 2d 02 00 00 48 c7 c6 45 3c 3a 93 48 c7 c7 40 de 39 93 c6 05 a0 79 f1 00 01 e8 f5 ad 0c 00 <0f> 0b e9 28 ff ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00
>>>>>> [   39.706634] RSP: 0018:ffffa8390d9b3b38 EFLAGS: 00010292
>>>>>> [   39.706637] RAX: 0000000000000039 RBX: ffff8e02630b2768 RCX: 00000000ffdfffff
>>>>>> [   39.706639] RDX: 00000000ffdfffff RSI: ffff8e80ad400000 RDI: 0000000000000001
>>>>>> [   39.706641] RBP: ffff8e025df72000 R08: ffff8e80bb3fffe8 R09: 00000000ffffffea
>>>>>> [   39.706643] R10: 00000000ffdfffff R11: 80000000ffe00000 R12: ffff8e02630b2008
>>>>>> [   39.706645] R13: 0000000000000000 R14: ffff8e024a88ba00 R15: 0000000000000000
>>>>>> [   39.706646] FS:  0000000000000000(0000) GS:ffff8e40bf800000(0000) knlGS:0000000000000000
>>>>>> [   39.706649] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>>> [   39.706651] CR2: 00000000004d8f40 CR3: 0000002ca140a002 CR4: 00000000001706f0
>>>>>> [   39.706652] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>>>>> [   39.706654] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>>>>> [   39.706656] Call Trace:
>>>>>> [   39.706658]  i40e_setup_pf_switch+0x617/0xf80 [i40e]
>>>>>> [   39.706683]  i40e_probe.part.0.cold+0x8dc/0x109e [i40e]
>>>>>> [   39.706708]  ? acpi_ns_check_object_type+0xd4/0x193
>>>>>> [   39.706713]  ? acpi_ns_check_package_list+0xfd/0x205
>>>>>> [   39.706716]  ? __kmalloc+0x37/0x160
>>>>>> [   39.706720]  ? kmem_cache_alloc+0xcb/0x120
>>>>>> [   39.706723]  ? irq_get_irq_data+0x5/0x20
>>>>>> [   39.706726]  ? mp_check_pin_attr+0xe/0xf0
>>>>>> [   39.706729]  ? irq_get_irq_data+0x5/0x20
>>>>>> [   39.706731]  ? mp_map_pin_to_irq+0xb7/0x2c0
>>>>>> [   39.706735]  ? acpi_register_gsi_ioapic+0x86/0x150
>>>>>> [   39.706739]  ? pci_conf1_read+0x9f/0xf0
>>>>>> [   39.706743]  ? pci_bus_read_config_word+0x2e/0x40
>>>>>> [   39.706746]  local_pci_probe+0x1b/0x40
>>>>>> [   39.706750]  work_for_cpu_fn+0xb/0x20
>>>>>> [   39.706754]  process_one_work+0x1ec/0x350
>>>>>> [   39.706758]  worker_thread+0x24b/0x4d0
>>>>>> [   39.706760]  ? process_one_work+0x350/0x350
>>>>>> [   39.706762]  kthread+0xea/0x120
>>>>>> [   39.706766]  ? kthread_park+0x80/0x80
>>>>>> [   39.706770]  ret_from_fork+0x1f/0x30
>>>>>> [   39.706774] ---[ end trace 7a203f3ec972a377 ]---
>>>>>> 
>>>>>> Martin
>>>>>> 
>>>>>> 
>>>>>>> On 17 Mar 2021, at 0:36, Wei Wang <weiwan@...gle.com> wrote:
>>>>>>> 
>>>>>>> Currently, napi_thread_wait() checks for NAPI_STATE_SCHED bit to
>>>>>>> determine if the kthread owns this napi and could call napi->poll() on
>>>>>>> it. However, if socket busy poll is enabled, it is possible that the
>>>>>>> busy poll thread grabs this SCHED bit (after the previous napi->poll()
>>>>>>> invokes napi_complete_done() and clears SCHED bit) and tries to poll
>>>>>>> on the same napi. napi_disable() could grab the SCHED bit as well.
>>>>>>> This patch tries to fix this race by adding a new bit
>>>>>>> NAPI_STATE_SCHED_THREADED in napi->state. This bit gets set in
>>>>>>> ____napi_schedule() if the threaded mode is enabled, and gets cleared
>>>>>>> in napi_complete_done(), and we only poll the napi in kthread if this
>>>>>>> bit is set. This helps distinguish the ownership of the napi between
>>>>>>> kthread and other scenarios and fixes the race issue.
>>>>>>> 
>>>>>>> Fixes: 29863d41bb6e ("net: implement threaded-able napi poll loop support")
>>>>>>> Reported-by: Martin Zaharinov <micron10@...il.com>
>>>>>>> Suggested-by: Jakub Kicinski <kuba@...nel.org>
>>>>>>> Signed-off-by: Wei Wang <weiwan@...gle.com>
>>>>>>> Cc: Alexander Duyck <alexanderduyck@...com>
>>>>>>> Cc: Eric Dumazet <edumazet@...gle.com>
>>>>>>> Cc: Paolo Abeni <pabeni@...hat.com>
>>>>>>> Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>
>>>>>>> ---
>>>>>>> Change since v3:
>>>>>>> - Add READ_ONCE() for thread->state and add comments in
>>>>>>> ____napi_schedule().
>>>>>>> 
>>>>>>> include/linux/netdevice.h |  2 ++
>>>>>>> net/core/dev.c            | 19 ++++++++++++++++++-
>>>>>>> 2 files changed, 20 insertions(+), 1 deletion(-)
>>>>>>> 
>>>>>>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>>>>>>> index 5b67ea89d5f2..87a5d186faff 100644
>>>>>>> --- a/include/linux/netdevice.h
>>>>>>> +++ b/include/linux/netdevice.h
>>>>>>> @@ -360,6 +360,7 @@ enum {
>>>>>>>    NAPI_STATE_IN_BUSY_POLL,        /* sk_busy_loop() owns this NAPI */
>>>>>>>    NAPI_STATE_PREFER_BUSY_POLL,    /* prefer busy-polling over softirq processing*/
>>>>>>>    NAPI_STATE_THREADED,            /* The poll is performed inside its own thread*/
>>>>>>> +     NAPI_STATE_SCHED_THREADED,      /* Napi is currently scheduled in threaded mode */
>>>>>>> };
>>>>>>> 
>>>>>>> enum {
>>>>>>> @@ -372,6 +373,7 @@ enum {
>>>>>>>    NAPIF_STATE_IN_BUSY_POLL        = BIT(NAPI_STATE_IN_BUSY_POLL),
>>>>>>>    NAPIF_STATE_PREFER_BUSY_POLL    = BIT(NAPI_STATE_PREFER_BUSY_POLL),
>>>>>>>    NAPIF_STATE_THREADED            = BIT(NAPI_STATE_THREADED),
>>>>>>> +     NAPIF_STATE_SCHED_THREADED      = BIT(NAPI_STATE_SCHED_THREADED),
>>>>>>> };
>>>>>>> 
>>>>>>> enum gro_result {
>>>>>>> diff --git a/net/core/dev.c b/net/core/dev.c
>>>>>>> index 6c5967e80132..d3195a95f30e 100644
>>>>>>> --- a/net/core/dev.c
>>>>>>> +++ b/net/core/dev.c
>>>>>>> @@ -4294,6 +4294,13 @@ static inline void ____napi_schedule(struct softnet_data *sd,
>>>>>>>             */
>>>>>>>            thread = READ_ONCE(napi->thread);
>>>>>>>            if (thread) {
>>>>>>> +                     /* Avoid doing set_bit() if the thread is in
>>>>>>> +                      * INTERRUPTIBLE state, cause napi_thread_wait()
>>>>>>> +                      * makes sure to proceed with napi polling
>>>>>>> +                      * if the thread is explicitly woken from here.
>>>>>>> +                      */
>>>>>>> +                     if (READ_ONCE(thread->state) != TASK_INTERRUPTIBLE)
>>>>>>> +                             set_bit(NAPI_STATE_SCHED_THREADED, &napi->state);
>>>>>>>                    wake_up_process(thread);
>>>>>>>                    return;
>>>>>>>            }
>>>>>>> @@ -6486,6 +6493,7 @@ bool napi_complete_done(struct napi_struct *n, int work_done)
>>>>>>>            WARN_ON_ONCE(!(val & NAPIF_STATE_SCHED));
>>>>>>> 
>>>>>>>            new = val & ~(NAPIF_STATE_MISSED | NAPIF_STATE_SCHED |
>>>>>>> +                           NAPIF_STATE_SCHED_THREADED |
>>>>>>>                          NAPIF_STATE_PREFER_BUSY_POLL);
>>>>>>> 
>>>>>>>            /* If STATE_MISSED was set, leave STATE_SCHED set,
>>>>>>> @@ -6968,16 +6976,25 @@ static int napi_poll(struct napi_struct *n, struct list_head *repoll)
>>>>>>> 
>>>>>>> static int napi_thread_wait(struct napi_struct *napi)
>>>>>>> {
>>>>>>> +     bool woken = false;
>>>>>>> +
>>>>>>>    set_current_state(TASK_INTERRUPTIBLE);
>>>>>>> 
>>>>>>>    while (!kthread_should_stop() && !napi_disable_pending(napi)) {
>>>>>>> -             if (test_bit(NAPI_STATE_SCHED, &napi->state)) {
>>>>>>> +             /* Testing SCHED_THREADED bit here to make sure the current
>>>>>>> +              * kthread owns this napi and could poll on this napi.
>>>>>>> +              * Testing SCHED bit is not enough because SCHED bit might be
>>>>>>> +              * set by some other busy poll thread or by napi_disable().
>>>>>>> +              */
>>>>>>> +             if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state) || woken) {
>>>>>>>                    WARN_ON(!list_empty(&napi->poll_list));
>>>>>>>                    __set_current_state(TASK_RUNNING);
>>>>>>>                    return 0;
>>>>>>>            }
>>>>>>> 
>>>>>>>            schedule();
>>>>>>> +             /* woken being true indicates this thread owns this napi. */
>>>>>>> +             woken = true;
>>>>>>>            set_current_state(TASK_INTERRUPTIBLE);
>>>>>>>    }
>>>>>>>    __set_current_state(TASK_RUNNING);
>>>>>>> --
>>>>>>> 2.31.0.rc2.261.g7f71774620-goog
>>>>>>> 
>>>>>> 
>>>> 
>> 

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