Re: netpoll_send_skb_on_dev warning with bnx2

On Fri, Oct 2, 2015 at 6:10 AM, Neil Horman [off-list ref] wrote:

On Thu, Oct 01, 2015 at 08:25:46PM -0700, Vinson Lee wrote:

quoted

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 [off-list ref]
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) [off-list ref]
    Cc: tglx@linutronix.de
    Cc: ilya.dryomov@inktank.com
    Cc: umgwanakikbuti@gmail.com
    Cc: Oleg Nesterov [off-list ref]
    Cc: Linus Torvalds [off-list ref]
    Link: http://lkml.kernel.org/r/20140924082242.119255706@infradead.org
    Signed-off-by: Ingo Molnar [off-list ref]

:040000 040000 1536c4cc3c706b4129452ce023c69733b46a23e4
22c894c6ae02be75e5f772d39fde178f036e906f M    include

Vinson