Runtime warnings in powerpc code

[Guenter Roeck]

Hi Scott,

On Thu, Dec 27, 2018 at 07:31:33PM -0600, Scott Wood wrote:
> On Thu, 2018-12-27 at 11:05 -0800, Guenter Roeck wrote:
> > ---
> > CONFIG_DEBUG_ATOMIC_SLEEP
> > 
> > ------------[ cut here ]------------
> > do not call blocking ops when !TASK_RUNNING; state=2 set at [<(ptrval)>]
> > prepare_to_wait+0x54/0xe4
> > WARNING: CPU: 0 PID: 1 at kernel/sched/core.c:6099 __might_sleep+0x94/0x9c
> > Modules linked in:
> > CPU: 0 PID: 1 Comm: init Not tainted 4.20.0-yocto-standard+ #1
> > NIP:  c00667a0 LR: c00667a0 CTR: 00000000
> > REGS: cf8df8c0 TRAP: 0700   Not tainted  (4.20.0-yocto-standard+)
> > MSR:  00029032 <EE,ME,IR,DR,RI>  CR: 28888822  XER: 20000000
> > 
> > GPR00: c00667a0 cf8df970 cf8e0000 00000062 c0af15c8 00000007 fa1ae97e
> > 757148e2 
> > GPR08: cf8de000 00000000 00000000 00000000 1f386000 00000000 00000000
> > cfd83c8c 
> > GPR16: 00000004 00000004 00000004 00000000 0000060c 0000000a cf8dfdb8
> > cf267804 
> > GPR24: cf8dfd78 cf8dfd68 cfa88a20 cec70830 00000001 00000000 000001d3
> > c0b444cc 
> > NIP [c00667a0] __might_sleep+0x94/0x9c
> > LR [c00667a0] __might_sleep+0x94/0x9c
> > Call Trace:
> > [cf8df970] [c00667a0] __might_sleep+0x94/0x9c (unreliable)
> > [cf8df990] [c05beddc] do_ide_request+0x48/0x6bc
> > [cf8dfa10] [c0492bcc] __blk_run_queue+0x80/0x10c
> > [cf8dfa20] [c049a938] blk_flush_plug_list+0x23c/0x258
> > [cf8dfa60] [c006b888] io_schedule_prepare+0x44/0x5c
> > [cf8dfa70] [c006b8c0] io_schedule+0x20/0x48
> > [cf8dfa80] [c095e1ac] bit_wait_io+0x24/0x74
> > [cf8dfa90] [c095dd94] __wait_on_bit+0xac/0x104
> > [cf8dfab0] [c095de74] out_of_line_wait_on_bit+0x88/0x98
> > [cf8dfae0] [c0229094] bh_submit_read+0xf8/0x104
> > [cf8dfaf0] [c028b9a8] ext4_get_branch+0xdc/0x168
> > [cf8dfb20] [c028c7fc] ext4_ind_map_blocks+0x2b0/0xc08
> > [cf8dfc30] [c029551c] ext4_map_blocks+0x2e0/0x65c
> > [cf8dfc80] [c02b8c84] ext4_mpage_readpages+0x5e8/0x97c
> > [cf8dfd60] [c016c3cc] read_pages+0x60/0x1a0
> > [cf8dfdb0] [c016c6e8] __do_page_cache_readahead+0x1dc/0x208
> > [cf8dfe10] [c0159768] filemap_fault+0x418/0x834
> > [cf8dfe50] [c02a00fc] ext4_filemap_fault+0x40/0x64
> > [cf8dfe60] [c0198d0c] __do_fault+0x34/0xb8
> > [cf8dfe70] [c019e264] handle_mm_fault+0xc44/0xf88
> > [cf8dfef0] [c001a218] __do_page_fault+0x158/0x7b4
> > [cf8dff40] [c00143b4] handle_page_fault+0x14/0x40
> > --- interrupt: 301 at 0xb7904a70
> >     LR = 0xb78ef0c8
> > Instruction dump:
> > 7fe3fb78 bba10014 7c0803a6 38210020 4bfffd20 808a0000 3c60c0b0 39400001 
> > 7cc53378 3863a558 99490001 4bfd03bd <0fe00000> 4bffffc0 7c0802a6 90010004 
> > irq event stamp: 126702
> > hardirqs last  enabled at (126701): [<c0091a74>] console_unlock+0x434/0x5d0
> > hardirqs last disabled at (126702): [<c00140b4>] reenable_mmu+0x30/0x88
> > softirqs last  enabled at (126552): [<c0964614>] __do_softirq+0x42c/0x4a0
> > softirqs last disabled at (126529): [<c003cda4>] irq_exit+0x104/0x108
> > ---[ end trace 4f6c84b7815474d9 ]---
> 
> This doesn't look PPC-specific, but rather IDE-specific.  Here's a similar one
> on x86:
> https://lkml.org/lkml/2016/12/12/596
> 
I wasn't sure, since I don't see the problem anywhere else.

Anyway, I'll disable the debug option in my tests if CONFIG_IDE is enabled.

> > ---
> > #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
> >     defined(CONFIG_TRACE_IRQFLAGS)
> > 
> > ------------[ cut here ]------------
> > DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)
> > WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3762
> 
> http://patchwork.ozlabs.org/patch/1016541/ should fix this.  It should also
> only be showing up on 32-bit, not all platforms.
> 
Looks like it. Unfortunately the patch does not apply to mainline.
I'll monitor its progress. And, yes, I should have been more
specific - both problem are only seen with ppc32 tests.

Thanks,
Guenter