On Mon, 2018-05-07 at 09:39 +0200, Sebastian Andrzej Siewior wrote:
> On 2018-05-06 12:59:19 [+0200], Mike Galbraith wrote:
> > On Sun, 2018-05-06 at 12:26 +0200, Thomas Gleixner wrote:
> > > On Fri, 4 May 2018, Sebastian Andrzej Siewior wrote:
> > >
> > > > From: Mike Galbraith <umgwanakikb...@gmail.com>
> > > >
> > > > Shrug. Lots of hobbyists have a beast in their basement, right?
> > >
> > > This hardly qualifies as a proper changelog ...
> >
> > Hm, that wasn't intended to be a changelog.
> >
> > This patch may not be current either, I haven't tested RT on a UV box
> > in quite some time.
>
> That last hunk looks like something that would be required even for !RT.
> Would you mind to check that patch and write a changelog? If it doesn't
> work for RT there is no need to carry this in -RT.
None of that patch is needed for a UV3000, but the below is. It's
likely still valid for now ancient UV boxen, but the UV100 the patch
was originally written for (2011/2.6.33-rt) has apparently wandered off
to become a beer keg or something meanwhile, so I can't test.
UV: Fix uv_bau_init() check_preemption_disabled() gripeage
[ 2.851947] BUG: using smp_processor_id() in preemptible [00000000] code:
swapper/0/1
[ 2.851951] caller is uv_bau_init+0x28/0xb62
[ 2.851954] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
4.17.0-rc5-0.g3e3e37b-rt_debug
[ 2.851956] Hardware name: SGI UV3000/UV3000, BIOS SGI UV 3000 series BIOS
01/15/2015
[ 2.851957] Call Trace:
[ 2.851964] dump_stack+0x85/0xcb
[ 2.851969] check_preemption_disabled+0x10c/0x120
[ 2.851972] ? init_per_cpu+0x88c/0x88c
[ 2.851974] uv_bau_init+0x28/0xb62
[ 2.851979] ? lapic_cal_handler+0xbb/0xbb
[ 2.851982] ? rt_mutex_unlock+0x35/0x50
[ 2.851985] ? init_per_cpu+0x88c/0x88c
[ 2.851988] ? set_debug_rodata+0x11/0x11
[ 2.851991] do_one_initcall+0x46/0x249
[ 2.851995] kernel_init_freeable+0x207/0x29c
[ 2.851999] ? rest_init+0xd0/0xd0
[ 2.852000] kernel_init+0xa/0x110
[ 2.852000] ret_from_fork+0x3a/0x50
(gdb) list *uv_bau_init+0x28
0xffffffff824a4d96 is in uv_bau_init (./arch/x86/include/asm/uv/uv_hub.h:212).
207 return (struct uv_hub_info_s *)__uv_hub_info_list[node];
208 }
209
210 static inline struct uv_hub_info_s *_uv_hub_info(void)
211 {
212 return (struct uv_hub_info_s *)uv_cpu_info->p_uv_hub_info;
213 }
214 #define uv_hub_info _uv_hub_info()
215
216 static inline struct uv_hub_info_s *uv_cpu_hub_info(int cpu)
(gdb)
arch/x86/include/asm/uv/uv_hub.h:
197 #define uv_cpu_info this_cpu_ptr(&__uv_cpu_info)
This and other substitutions make uv_bau_init() annoying for a PREEMPT
kernel, but PREEMPT_RT can silence the lot with one migrate_disable().
Signed-off-by: Mike Galbraith <efa...@gmx.de>
---
arch/x86/platform/uv/tlb_uv.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -2213,6 +2213,8 @@ static int __init uv_bau_init(void)
if (!is_uv_system())
return 0;
+ migrate_disable();
+
if (is_uv4_hub())
ops = uv4_bau_ops;
else if (is_uv3_hub())
@@ -2269,6 +2271,8 @@ static int __init uv_bau_init(void)
}
}
+ migrate_enable();
+
return 0;
err_bau_disable:
@@ -2276,6 +2280,7 @@ static int __init uv_bau_init(void)
for_each_possible_cpu(cur_cpu)
free_cpumask_var(per_cpu(uv_flush_tlb_mask, cur_cpu));
+ migrate_enable();
set_bau_off();
nobau_perm = 1;
