linux-kernel - Re: [PATCH 00/22] Openrisc patchees from backlog for 4.11

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Date:   Mon, 16 Jan 2017 20:58:48 +0900
From:   Stafford Horne <shorne@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>, vbabka@...e.cz
Cc:     Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        openrisc@...ts.librecores.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 00/22] Openrisc patchees from backlog for 4.11

(+Vlastimil Babka)

Hello,

On Sat, Jan 14, 2017 at 09:17:01PM -0800, Guenter Roeck wrote:
> On 01/14/2017 03:07 PM, Stafford Horne wrote:
> > Hi All,
> > 
> > This is another set of patches which I have been pulling out of the
> > openrisc backlogs. Its a bit of a process since I need to cleanup commit
> > messages, review and test the patches.
> > 
> > The interesting things here are:
> >  - optimized memset and memcpy routines, ~20% boot time saving
> >  - support for cpu idling
> >  - adding support for l.swa and l.lwa atomic operations (in spec from 2014)
> >  - use atomics to implement: bitops, cmpxchg, futex, spinlocks
> >  - the atomics are in preparation for SMP support
> > 
> > Testing:
> > I have used the kselftests to validate the changes especially the futex
> > operations with the futex test. Other atomic operations are common so no
> > explicit testing.
> > 
> > Note for testers:
> > The l.swa and l.lwa emulation is broken in qemu openrisc port. I have sent
> > patches [1] to qemu-devel to fix the qemu issues.
> > 
> 
> Thanks a lot for the note. Cherry-picked and applied ...
> 
> Are you going to add the series to -next ? That would give it some automatic
> test exposure (including the various auto-builders).
> 
> Anyway, today's -next gets a warning traceback as attached. That happens even
> with the above mentioned patch applied to qemu.
> 
> Guenter
> 
> ---
> 
> OpenRISC Linux -- http://openrisc.io
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 0 at ./include/linux/jump_label.h:198 0xc02d758c
> static_key_slow_inc used before call to jump_label_init
> Modules linked in:
> CPU: 0 PID: 0 Comm: swapper Not tainted 4.10.0-rc3-next-20170113 #1
> Stack dump [0xc0385f3c]:
> sp + 00: 0xc0385f3c
> sp + 04: 0xc0385f60
> sp + 08: 0xc047a0b4
> sp + 12: 0xc0303662
> sp + 16: 0x00000000
> sp + 20: 0xc02d758c
> sp + 24: 0x00000009
> sp + 28: 0x000000c6
> sp + 32: 0xc0167bc0
> sp + 36: 0xc0385f68
> sp + 40: 0xc000b5d8
> sp + 44: 0x00000000
> sp + 48: 0x00000000
> sp + 52: 0xc0303662
> sp + 56: 0x000000c6
> sp + 60: 0xc02d758c
> sp + 64: 0xc0385f9c
> sp + 68: 0xc0385fb0
> sp + 72: 0xc0483954
> sp + 76: 0xc04839b0
> sp + 80: 0xc1fff1e0
> sp + 84: 0xc047a00c
> sp + 88: 0x00000000
> sp + 92: 0xc000b620
> sp + 96: 0xc030367f
> sp + 100: 0xc0385fb0
> sp + 104: 0xc0385fb0
> sp + 108: 0xc0483930
> sp + 112: 0xc02d758c
> sp + 116: 0xc02e1cc4
> sp + 120: 0x00000000
> sp + 124: 0x00000000
> sp + 128: 0xc03a6798
> sp + 132: 0xc0385fd8
> sp + 136: 0xc047a014
> sp + 140: 0xc047a02c
> sp + 144: 0xc03beb14
> sp + 148: 0xc1fff1e0
> sp + 152: 0xc03a68e0
> sp + 156: 0xc02e0070
> sp + 160: 0xc03b9e74
> sp + 164: 0xc03beb14
> sp + 168: 0xc0386000
> sp + 172: 0x00000000
> sp + 176: 0x00000000
> sp + 180: 0x00000000
> sp + 184: 0x00000000
> sp + 188: 0x00000000
> sp + 192: 0x00000000
> 
>  [<c02d758c>]
> 
>  [<c0167bc0>]
> 
>  [<c000b5d8>]
> 
>  [<c02d758c>]
> 
>  [<c000b620>]
> 
>  [<c02d758c>]
> 
>  [<c03a6798>]
> 
>  [<c03a68e0>]
> 
>  [<c03b9e74>]
> 
>  =======================
> ---[ end trace 0000000000000000 ]---

Annotated stack:
 [<c01612cc>]   dump_stack()+36
 [<c000b830>]   __warn()+300
 [<c02c4dc8>]   build_all_zonelists()+560
 [<c02c4dc8>]   build_all_zonelists()+560
 [<c000b878>]   warn_slowpath_fmt()+48
 [<c02c4dc8>]   build_all_zonelists()+560
 [<c0396d98>]   setup_per_cpu_areas()+176
 [<c038e8fc>]   start_kernel()+328
 [<c039eb40>]   early_init_dt_scan()+36

I bisected this to:

  commit f5adbdff6a1c40e19a9e700bd92e8121411b1475
  Author: Vlastimil Babka <vbabka@...e.cz>
  Date:   Thu Jan 12 12:19:03 2017 +1100

    mm, page_alloc: convert page_group_by_mobility_disable to static key


This change uses static keys in build_all_zonelists, but this is before
jump_label_init. The below patch fixes this, but I am suprized the issue
is not showing up in other targets.


diff --git a/init/main.c b/init/main.c
index b0c9d6f..758753a 100644
--- a/init/main.c
+++ b/init/main.c
@@ -513,6 +513,7 @@ asmlinkage __visible void __init start_kernel(void)
 	boot_cpu_state_init();
 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
 
+	jump_label_init();
 	build_all_zonelists(NULL, NULL);
 	page_alloc_init();
 
@@ -526,7 +527,6 @@ asmlinkage __visible void __init start_kernel(void)
 		parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
 			   NULL, set_init_arg);
 
-	jump_label_init();
 
 	/*
 	 * These use large bootmem allocations and must precede

-Stafford