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From: Michael Ellerman <mpe@ellerman.id.au>
To: Michal Hocko <mhocko@kernel.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>
Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>,
	Pekka Enberg <penberg@kernel.org>,
	Linux-Next Mailing List <linux-next@vger.kernel.org>,
	David Rientjes <rientjes@google.com>,
	Christopher Lameter <cl@linux.com>,
	linuxppc-dev@lists.ozlabs.org,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [5.6.0-rc2-next-20200218/powerpc] Boot failure on POWER9
Date: Thu, 12 Mar 2020 23:18:42 +1100	[thread overview]
Message-ID: <87a74lix5p.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200310150114.GO8447@dhcp22.suse.cz>

Michal Hocko <mhocko@kernel.org> writes:
> On Thu 27-02-20 19:26:54, Michal Hocko wrote:
>> [Cc ppc maintainers]
> [...]
>> Please have a look at http://lkml.kernel.org/r/52EF4673-7292-4C4C-B459-AF583951BA48@linux.vnet.ibm.com
>> for the boot log with the debugging patch which tracks set_numa_mem.
>> This seems to lead to a crash in the slab allocator bebcause
>> node_to_mem_node(0) for memory less node resolves to the memory less
>> node http://lkml.kernel.org/r/dd450314-d428-6776-af07-f92c04c7b967@suse.cz.
>> The original report is http://lkml.kernel.org/r/3381CD91-AB3D-4773-BA04-E7A072A63968@linux.vnet.ibm.com
>
> ping 

The obvious fix is:

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 37c12e3bab9e..33b1fca0b258 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -892,6 +892,7 @@ void smp_prepare_boot_cpu(void)
 	paca_ptrs[boot_cpuid]->__current = current;
 #endif
 	set_numa_node(numa_cpu_lookup_table[boot_cpuid]);
+	set_numa_mem(local_memory_node(numa_cpu_lookup_table[boot_cpuid]));
 	current_set[boot_cpuid] = current;
 }


But that doesn't work because smp_prepare_boot_cpu() is called too
early:

asmlinkage __visible void __init start_kernel(void)
{
	...
	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
	boot_cpu_hotplug_init();

	build_all_zonelists(NULL);


And local_memory_node() uses first_zones_zonelist() which doesn't work
prior to build_all_zonelists() being called.


The patch below might work. Sachin can you test this? I tried faking up
a system with a memoryless node zero but couldn't get it to even start
booting.

cheers


diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9b4f5fb719e0..d1f11437f6c4 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -282,6 +282,9 @@ void __init mem_init(void)
 	 */
 	BUILD_BUG_ON(MMU_PAGE_COUNT > 16);
 
+	BUG_ON(smp_processor_id() != boot_cpuid);
+	set_numa_mem(local_memory_node(numa_cpu_lookup_table[boot_cpuid]));
+
 #ifdef CONFIG_SWIOTLB
 	/*
 	 * Some platforms (e.g. 85xx) limit DMA-able memory way below

  reply	other threads:[~2020-03-12 12:18 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 10:45 [5.6.0-rc2-next-20200218/powerpc] Boot failure on POWER9 Sachin Sant
2020-02-18 10:50 ` Kirill Tkhai
2020-02-18 11:01   ` Kirill Tkhai
2020-02-18 11:35     ` Kirill Tkhai
2020-02-18 11:40     ` Sachin Sant
2020-02-18 11:55       ` Michal Hocko
2020-02-18 14:00         ` Sachin Sant
2020-02-18 14:26           ` Michal Hocko
2020-02-18 15:11             ` Sachin Sant
2020-02-18 15:24               ` Michal Hocko
2020-02-22  3:38                 ` Christopher Lameter
2020-02-24  8:58                   ` Michal Hocko
2020-02-26 18:25                     ` Christopher Lameter
2020-02-26 18:41                       ` Michal Hocko
2020-02-26 18:44                         ` Christopher Lameter
2020-02-26 19:01                           ` Michal Hocko
2020-02-26 20:31                             ` David Rientjes
2020-02-26 20:52                               ` Michal Hocko
2020-02-26 21:45                         ` Vlastimil Babka
2020-02-26 22:29                           ` Vlastimil Babka
2020-02-27 12:12                             ` Michal Hocko
2020-02-27 16:00                               ` Sachin Sant
2020-02-27 16:16                                 ` Vlastimil Babka
2020-02-27 18:26                                   ` Michal Hocko
2020-03-10 15:01                                     ` Michal Hocko
2020-03-12 12:18                                       ` Michael Ellerman [this message]
2020-03-12 16:51                                         ` Sachin Sant
2020-03-13 10:48                                           ` Michael Ellerman
2020-03-13 11:12                                             ` Srikar Dronamraju
2020-03-13 11:35                                               ` Vlastimil Babka
2020-03-14  8:10                                                 ` Sachin Sant
2020-02-27 12:02                           ` Michal Hocko
2020-02-18 11:38   ` Sachin Sant
2020-02-18 11:53     ` Kirill Tkhai

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