Re: netpoll_send_skb_on_dev warning with bnx2

[Neil Horman]

On Wed, Oct 07, 2015 at 10:46:21AM -0700, Vinson Lee wrote:
> On Wed, Oct 7, 2015 at 7:38 AM, Neil Horman <nhorman@xxxxxxxxxx> wrote:
> > On Tue, Oct 06, 2015 at 10:12:56PM -0700, Vinson Lee wrote:
> >> On Fri, Oct 2, 2015 at 6:10 AM, Neil Horman <nhorman@xxxxxxxxxx> wrote:
> >> > On Thu, Oct 01, 2015 at 08:25:46PM -0700, Vinson Lee wrote:
> >> >> Hi.
> >> >>
> >> >> I am seeing a netpoll_send_skb_on_dev warning with bnx2. It happens on
> >> >> Linux 4.1 and I am able to reproduce the warning with Linux 4.3-rc3.
> >> >>
> >> >> ------------[ cut here ]------------
> >> >> WARNING: CPU: 11 PID: 3110 at net/core/netpoll.c:368
> >> >> netpoll_send_skb_on_dev+0x183/0x201()
> >> >> netpoll_send_skb_on_dev(): eth0 enabled interrupts in poll
> >> >> (bnx2_start_xmit+0x0/0x5d4 [bnx2])
> >> >> Modules linked in: netconsole(+) configfs ipv6 ppdev parport_pc lp
> >> >> parport tcp_diag inet_diag ipmi_devintf serio_raw iTCO_wdt
> >> >> iTCO_vendor_support ipmi_si ipmi_msghandler hpilo hpwdt bnx2 coretemp
> >> >> kvm_intel kvm crc32c_intel ghash_clmulni_intel microcode lpc_ich
> >> >> mfd_core i7core_edac edac_core pcc_cpufreq acpi_cpufreq shpchp
> >> >> sch_fq_codel hpsa radeon ttm drm_kms_helper drm fb_sys_fops sysimgblt
> >> >> sysfillrect syscopyarea i2c_algo_bit i2c_core
> >> >> CPU: 11 PID: 3110 Comm: modprobe Not tainted 4.3.0-rc3 #1
> >> >>  0000000000000170 ffff88060be17a18 ffffffff812bc84c ffffffff818b1a78
> >> >>  ffff88060be17a68 ffff88060be17a58 ffffffff81064712 000000000be17a68
> >> >>  ffffffff814ec12e ffff88060bc10900 0000000000000000 ffff8800d941c000
> >> >> Call Trace:
> >> >>  [<ffffffff812bc84c>] dump_stack+0x48/0x5c
> >> >>  [<ffffffff81064712>] warn_slowpath_common+0xa1/0xbb
> >> >>  [<ffffffff814ec12e>] ? netpoll_send_skb_on_dev+0x183/0x201
> >> >>  [<ffffffff810647cf>] warn_slowpath_fmt+0x46/0x48
> >> >>  [<ffffffffa039a6b9>] ? bnx2_run_loopback+0x391/0x391 [bnx2]
> >> >>  [<ffffffff814ec12e>] netpoll_send_skb_on_dev+0x183/0x201
> >> >>  [<ffffffff814ec58b>] netpoll_send_udp+0x3df/0x3f1
> >> >>  [<ffffffffa049324a>] write_msg+0xaf/0xe9 [netconsole]
> >> >>  [<ffffffff810a6daa>] call_console_drivers.clone.2+0xd1/0xe9
> >> >>  [<ffffffff810a70d0>] console_unlock+0x30e/0x3a5
> >> >>  [<ffffffff810a757d>] register_console+0x2af/0x322
> >> >>  [<ffffffffa04971b4>] init_netconsole+0x1b4/0x224 [netconsole]
> >> >>  [<ffffffffa0497000>] ? 0xffffffffa0497000
> >> >>  [<ffffffff810002bf>] do_one_initcall+0xf7/0x182
> >> >>  [<ffffffff811764fe>] ? kmem_cache_alloc_trace+0xb6/0xf0
> >> >>  [<ffffffff810cb8d8>] ? do_init_module+0x31/0x1e4
> >> >>  [<ffffffff810cb910>] do_init_module+0x69/0x1e4
> >> >>  [<ffffffff810ccedc>] load_module+0x1451/0x160b
> >> >>  [<ffffffff810ca1a3>] ? mod_kobject_put+0x4d/0x4d
> >> >>  [<ffffffff811606f3>] ? __vmalloc_node+0x3e/0x40
> >> >>  [<ffffffff810cd2aa>] SyS_init_module+0x14f/0x155
> >> >>  [<ffffffff815833d7>] entry_SYSCALL_64_fastpath+0x12/0x6a
> >> >> ---[ end trace 878215466e581776 ]---
> >> >>
> >> >> Cheers,
> >> >> Vinson
> >> >
> >> > Hmm, that would suggest that someone called local_irq_enable in either the xmit,
> >> > poll_controller or napi poll paths (or one of its always-disable, bretheren),
> >> > but I dont see where that might be happening.  Are you able to instrument the
> >> > kernel (either by cloning that WARN_ON_ONCE call or via stap script), so we can
> >> > further isolate which call path the problem is happening in?
> >> >
> >> > Neil
> >> >
> >>
> >> I bisected the regression and it is introduced with this Linux 3.19-rc1 commit.
> >>
> >> e22b886a8a43b147e1994a9f970f678fc0df2033 is the first bad commit
> >> commit e22b886a8a43b147e1994a9f970f678fc0df2033
> >> Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> >> Date:   Wed Sep 24 10:18:48 2014 +0200
> >>
> >>     sched/wait: Add might_sleep() checks
> >>
> >>     Add more might_sleep() checks, suppose someone put a wait_event() like
> >>     thing in a wait loop..
> >>
> >>     Can't put might_sleep() in ___wait_event() because there's the locked
> >>     primitives which call ___wait_event() with locks held.
> >>
> >>     Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> >>     Cc: tglx@xxxxxxxxxxxxx
> >>     Cc: ilya.dryomov@xxxxxxxxxxx
> >>     Cc: umgwanakikbuti@xxxxxxxxx
> >>     Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> >>     Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> >>     Link: http://lkml.kernel.org/r/20140924082242.119255706@xxxxxxxxxxxxx
> >>     Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> >>
> >> :040000 040000 1536c4cc3c706b4129452ce023c69733b46a23e4
> >> 22c894c6ae02be75e5f772d39fde178f036e906f M    include
> >>
> >> Vinson
> >
> > That doesn't make any sense.  That commitis just adding some warning messages,
> > it doesn't change any locking or irq enablement states.  That in turn suggests
> > that you are seeing something is transient and sensitive to timing.  What driver
> > is eth0 using?  Is it bnx2 or something else?
> >
> > Neil
> >
> 
> eth0 is using bnx2.
> 
> $ ethtool -i eth0
> driver: bnx2
> version: 2.2.6
> firmware-version: bc 5.2.3 NCSI 2.0.12
> bus-info: 0000:03:00.0
> supports-statistics: yes
> supports-test: yes
> supports-eeprom-access: yes
> supports-register-dump: yes
> supports-priv-flags: no
> 
> I can add some WARN_ON_ONCE calls elsewhere in the kernel. Do you have
> suggestions where or can provide me an example patch?
> 
I would suggest peppering bnx2_poll with this:
WARN_ON(test_bit(NAPI_STATE_NPSVC, &napi->state) && !irqs_disabled())

That should trigger anytime irqs are enabled and we're polling from the netpoll
path

Neil

> Vinson
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