panic: sleeping in an epoch section

[Hans Petter Selasky]

On 2019-10-09 15:56, Mark Johnston wrote:
> On Wed, Oct 09, 2019 at 10:40:04AM +0200, Hans Petter Selasky wrote:
>> On 2019-10-09 06:36, Yuri Pankov wrote:
>>> Tried updating from r353072 to r353334 and getting the following panic
>>> reproducibly on boot (starting dhclient?):
>>>
>>> panic: sleeping in an epoch section
>>> cpuid = 5
>>> time = 1570591558
>>> KDB: stack backtrace:
>>> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
>>> 0xfffffe00af780140
>>> vpanic() at vpanic+0x19d/frame 0xfffffe00af780190
>>> panic() at panic+0x43/frame 0xfffffe00af7801f0
>>> _sleep() at _sleep+0x463/frame 0xfffffe00af780290
>>> pause_sbt() at pause_sbt+0x10f/frame 0xfffffe00af7802d0
>>> e1000_write_phy_reg_mdic() at e1000_write_phy_reg_mdic+0xee/frame
>>> 0xfffffe00af780310
>>> e1000_enable_phy_wakeup_reg_access_bm() at
>>> e1000_enable_phy_wakeup_reg_access_bm+0x2b/frame 0xfffffe00af780330
>>> e1000_update_mc_addr_list_pch2lan() at
>>> e1000_update_mc_addr_list_pch2lan+0x3a/frame 0xfffffe00af780370
>>> em_if_multi_set() at em_if_multi_set+0x1d4/frame 0xfffffe00af7803c0
>>> iflib_if_ioctl() at iflib_if_ioctl+0x100/frame 0xfffffe00af780430
>>> if_addmulti() at if_addmulti+0x2af/frame 0xfffffe00af7804d0
>>> in_joingroup_locked() at in_joingroup_locked+0x235/frame 0xfffffe00af780570
>>> in_joingroup() at in_joingroup+0x5c/frame 0xfffffe00af7805d0
>>> in_control() at in_control+0xadf/frame 0xfffffe00af780680
>>> ifioctl() at ifioctl+0x40f/frame 0xfffffe00af780750
>>> kern_ioctl() at kern_ioctl+0x295/frame 0xfffffe00af7807b0
>>> sys_ioctl() at sys_ioctl+0x15d/frame 0xfffffe00af780880
>>> amd64_syscall() at amd64_syscall+0x2b9/frame 0xfffffe00af7809b0
>>> fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe00af7809b0
>>> --- syscall (54, FreeBSD ELF64, sys_ioctl), rip = 0x80048051a, rsp =
>>> 0x7fffffffe3e8, rbp = 0x7fffffffe430 ---
>>
>> The SIOCADDMULTI if_ioctl() is not allowed to sleep, because it can be
>> called from the fast-path, so this is a bug in e1000 driver. Does the
>> attached patch workaround the issue?
> 
> What fast path are you referring to?  The locking protocol used by the
> multicast code was changed specifically to allow for sleeps in driver
> ioctl handlers.

I recall a long time ago seeing that input packet processing may end up 
calling if_ioctl's . Things may have changed since then though.

--HPS