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[v2 PATCH] mm: move page_ext_init after all struct pages are initialized

Started byYang Shi <yang.shi@linaro.org>
First post2016-05-20 00:50 +0200
Last post2016-05-23 20:10 +0200
Articles 6 — 3 participants

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  [v2 PATCH] mm: move page_ext_init after all struct pages are initialized Yang Shi <yang.shi@linaro.org> - 2016-05-20 00:50 +0200
    Re: [v2 PATCH] mm: move page_ext_init after all struct pages are  initialized Michal Hocko <mhocko@kernel.org> - 2016-05-20 15:20 +0200
      Re: [v2 PATCH] mm: move page_ext_init after all struct pages are  initialized "Shi, Yang" <yang.shi@linaro.org> - 2016-05-20 17:50 +0200
        Re: [v2 PATCH] mm: move page_ext_init after all struct pages are  initialized Michal Hocko <mhocko@kernel.org> - 2016-05-23 09:40 +0200
          Re: [v2 PATCH] mm: move page_ext_init after all struct pages are  initialized "Shi, Yang" <yang.shi@linaro.org> - 2016-05-23 18:50 +0200
            Re: [v2 PATCH] mm: move page_ext_init after all struct pages are  initialized Michal Hocko <mhocko@kernel.org> - 2016-05-23 20:10 +0200

#1404006 — [v2 PATCH] mm: move page_ext_init after all struct pages are initialized

FromYang Shi <yang.shi@linaro.org>
Date2016-05-20 00:50 +0200
Subject[v2 PATCH] mm: move page_ext_init after all struct pages are initialized
Message-ID<rAEVs-5Qz-13@gated-at.bofh.it>
When DEFERRED_STRUCT_PAGE_INIT is enabled, just a subset of memmap at boot
are initialized, then the rest are initialized in parallel by starting one-off
"pgdatinitX" kernel thread for each node X.

If page_ext_init is called before it, some pages will not have valid extension,
this may lead the below kernel oops when booting up kernel:

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff8118d982>] free_pcppages_bulk+0x2d2/0x8d0
PGD 0
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in:
CPU: 11 PID: 106 Comm: pgdatinit1 Not tainted 4.6.0-rc5-next-20160427 #26
Hardware name: Intel Corporation S5520HC/S5520HC, BIOS S5500.86B.01.10.0025.030220091519 03/02/2009
task: ffff88017c080040 ti: ffff88017c084000 task.ti: ffff88017c084000
RIP: 0010:[<ffffffff8118d982>]  [<ffffffff8118d982>] free_pcppages_bulk+0x2d2/0x8d0
RSP: 0000:ffff88017c087c48  EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000980 RSI: 0000000000000080 RDI: 0000000000660401
RBP: ffff88017c087cd0 R08: 0000000000000401 R09: 0000000000000009
R10: ffff88017c080040 R11: 000000000000000a R12: 0000000000000400
R13: ffffea0019810000 R14: ffffea0019810040 R15: ffff88066cfe6080
FS:  0000000000000000(0000) GS:ffff88066cd40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000002406000 CR4: 00000000000006e0
Stack:
 ffff88066cd5bbd8 ffff88066cfe6640 0000000000000000 0000000000000000
 0000001f0000001f ffff88066cd5bbe8 ffffea0019810000 000000008118f53e
 0000000000000009 0000000000000401 ffffffff0000000a 0000000000000001
Call Trace:
 [<ffffffff8118f602>] free_hot_cold_page+0x192/0x1d0
 [<ffffffff8118f69c>] __free_pages+0x5c/0x90
 [<ffffffff8262a676>] __free_pages_boot_core+0x11a/0x14e
 [<ffffffff8262a6fa>] deferred_free_range+0x50/0x62
 [<ffffffff8262aa46>] deferred_init_memmap+0x220/0x3c3
 [<ffffffff8262a826>] ? setup_per_cpu_pageset+0x35/0x35
 [<ffffffff8108b1f8>] kthread+0xf8/0x110
 [<ffffffff81c1b732>] ret_from_fork+0x22/0x40
 [<ffffffff8108b100>] ? kthread_create_on_node+0x200/0x200
Code: 49 89 d4 48 c1 e0 06 49 01 c5 e9 de fe ff ff 4c 89 f7 44 89 4d b8 4c 89 45 c0 44 89 5d c8 48 89 4d d0 e8 62 c7 07 00 48 8b 4d d0 <48> 8b 00 44 8b 5d c8 4c 8b 45 c0 44 8b 4d b8 a8 02 0f 84 05 ff
RIP  [<ffffffff8118d982>] free_pcppages_bulk+0x2d2/0x8d0
 RSP <ffff88017c087c48>
CR2: 0000000000000000

Move page_ext_init() after page_alloc_init_late() to make sure page extension
is setup for all pages.

CC: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
---
Changelog v1 --> v2:
 Added bug description in the commit log per Andrew's comment

 init/main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index b3c6e36..2075faf 100644
--- a/init/main.c
+++ b/init/main.c
@@ -606,7 +606,6 @@ asmlinkage __visible void __init start_kernel(void)
 		initrd_start = 0;
 	}
 #endif
-	page_ext_init();
 	debug_objects_mem_init();
 	kmemleak_init();
 	setup_per_cpu_pageset();
@@ -1004,6 +1003,8 @@ static noinline void __init kernel_init_freeable(void)
 	sched_init_smp();
 
 	page_alloc_init_late();
+	/* Initialize page ext after all struct pages are initializaed */
+	page_ext_init();
 
 	do_basic_setup();
 
-- 
2.0.2

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#1404422 — Re: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized

FromMichal Hocko <mhocko@kernel.org>
Date2016-05-20 15:20 +0200
SubjectRe: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized
Message-ID<rASvn-5Wx-5@gated-at.bofh.it>
In reply to#1404006
On Thu 19-05-16 15:13:26, Yang Shi wrote:
[...]
> diff --git a/init/main.c b/init/main.c
> index b3c6e36..2075faf 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -606,7 +606,6 @@ asmlinkage __visible void __init start_kernel(void)
>  		initrd_start = 0;
>  	}
>  #endif
> -	page_ext_init();
>  	debug_objects_mem_init();
>  	kmemleak_init();
>  	setup_per_cpu_pageset();
> @@ -1004,6 +1003,8 @@ static noinline void __init kernel_init_freeable(void)
>  	sched_init_smp();
>  
>  	page_alloc_init_late();
> +	/* Initialize page ext after all struct pages are initializaed */
> +	page_ext_init();
>  
>  	do_basic_setup();

I might be missing something but don't we have the same problem with
CONFIG_FLATMEM? page_ext_init_flatmem is called way earlier. Or
CONFIG_DEFERRED_STRUCT_PAGE_INIT is never enabled for CONFIG_FLATMEM?
-- 
Michal Hocko
SUSE Labs

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#1404562 — Re: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized

From"Shi, Yang" <yang.shi@linaro.org>
Date2016-05-20 17:50 +0200
SubjectRe: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized
Message-ID<rAUQy-7ji-23@gated-at.bofh.it>
In reply to#1404422
On 5/20/2016 6:16 AM, Michal Hocko wrote:
> On Thu 19-05-16 15:13:26, Yang Shi wrote:
> [...]
>> diff --git a/init/main.c b/init/main.c
>> index b3c6e36..2075faf 100644
>> --- a/init/main.c
>> +++ b/init/main.c
>> @@ -606,7 +606,6 @@ asmlinkage __visible void __init start_kernel(void)
>>  		initrd_start = 0;
>>  	}
>>  #endif
>> -	page_ext_init();
>>  	debug_objects_mem_init();
>>  	kmemleak_init();
>>  	setup_per_cpu_pageset();
>> @@ -1004,6 +1003,8 @@ static noinline void __init kernel_init_freeable(void)
>>  	sched_init_smp();
>>
>>  	page_alloc_init_late();
>> +	/* Initialize page ext after all struct pages are initializaed */
>> +	page_ext_init();
>>
>>  	do_basic_setup();
>
> I might be missing something but don't we have the same problem with
> CONFIG_FLATMEM? page_ext_init_flatmem is called way earlier. Or
> CONFIG_DEFERRED_STRUCT_PAGE_INIT is never enabled for CONFIG_FLATMEM?

Yes, CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which 
depends on SPARSEMEM. So, this config is not valid for FLATMEM at all.

Thanks,
Yang

>

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#1405138 — Re: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized

FromMichal Hocko <mhocko@kernel.org>
Date2016-05-23 09:40 +0200
SubjectRe: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized
Message-ID<rBSD0-2Y6-21@gated-at.bofh.it>
In reply to#1404562
On Fri 20-05-16 08:41:09, Shi, Yang wrote:
> On 5/20/2016 6:16 AM, Michal Hocko wrote:
> > On Thu 19-05-16 15:13:26, Yang Shi wrote:
> > [...]
> > > diff --git a/init/main.c b/init/main.c
> > > index b3c6e36..2075faf 100644
> > > --- a/init/main.c
> > > +++ b/init/main.c
> > > @@ -606,7 +606,6 @@ asmlinkage __visible void __init start_kernel(void)
> > >  		initrd_start = 0;
> > >  	}
> > >  #endif
> > > -	page_ext_init();
> > >  	debug_objects_mem_init();
> > >  	kmemleak_init();
> > >  	setup_per_cpu_pageset();
> > > @@ -1004,6 +1003,8 @@ static noinline void __init kernel_init_freeable(void)
> > >  	sched_init_smp();
> > > 
> > >  	page_alloc_init_late();
> > > +	/* Initialize page ext after all struct pages are initializaed */
> > > +	page_ext_init();
> > > 
> > >  	do_basic_setup();
> > 
> > I might be missing something but don't we have the same problem with
> > CONFIG_FLATMEM? page_ext_init_flatmem is called way earlier. Or
> > CONFIG_DEFERRED_STRUCT_PAGE_INIT is never enabled for CONFIG_FLATMEM?
> 
> Yes, CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which
> depends on SPARSEMEM. So, this config is not valid for FLATMEM at all.

Well
config MEMORY_HOTPLUG
        bool "Allow for memory hot-add"
	depends on SPARSEMEM || X86_64_ACPI_NUMA
	depends on ARCH_ENABLE_MEMORY_HOTPLUG

I wasn't really sure about X86_64_ACPI_NUMA dependency branch which
depends on X86_64 && NUMA && ACPI && PCI and that didn't sound like
SPARSEMEM only. If the FLATMEM shouldn't exist with
CONFIG_DEFERRED_STRUCT_PAGE_INIT can we make that explicit please?
-- 
Michal Hocko
SUSE Labs

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#1405508 — Re: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized

From"Shi, Yang" <yang.shi@linaro.org>
Date2016-05-23 18:50 +0200
SubjectRe: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized
Message-ID<rC1df-8iS-11@gated-at.bofh.it>
In reply to#1405138
On 5/23/2016 12:31 AM, Michal Hocko wrote:
> On Fri 20-05-16 08:41:09, Shi, Yang wrote:
>> On 5/20/2016 6:16 AM, Michal Hocko wrote:
>>> On Thu 19-05-16 15:13:26, Yang Shi wrote:
>>> [...]
>>>> diff --git a/init/main.c b/init/main.c
>>>> index b3c6e36..2075faf 100644
>>>> --- a/init/main.c
>>>> +++ b/init/main.c
>>>> @@ -606,7 +606,6 @@ asmlinkage __visible void __init start_kernel(void)
>>>>  		initrd_start = 0;
>>>>  	}
>>>>  #endif
>>>> -	page_ext_init();
>>>>  	debug_objects_mem_init();
>>>>  	kmemleak_init();
>>>>  	setup_per_cpu_pageset();
>>>> @@ -1004,6 +1003,8 @@ static noinline void __init kernel_init_freeable(void)
>>>>  	sched_init_smp();
>>>>
>>>>  	page_alloc_init_late();
>>>> +	/* Initialize page ext after all struct pages are initializaed */
>>>> +	page_ext_init();
>>>>
>>>>  	do_basic_setup();
>>>
>>> I might be missing something but don't we have the same problem with
>>> CONFIG_FLATMEM? page_ext_init_flatmem is called way earlier. Or
>>> CONFIG_DEFERRED_STRUCT_PAGE_INIT is never enabled for CONFIG_FLATMEM?
>>
>> Yes, CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which
>> depends on SPARSEMEM. So, this config is not valid for FLATMEM at all.
>
> Well
> config MEMORY_HOTPLUG
>         bool "Allow for memory hot-add"
> 	depends on SPARSEMEM || X86_64_ACPI_NUMA
> 	depends on ARCH_ENABLE_MEMORY_HOTPLUG
>
> I wasn't really sure about X86_64_ACPI_NUMA dependency branch which
> depends on X86_64 && NUMA && ACPI && PCI and that didn't sound like
> SPARSEMEM only. If the FLATMEM shouldn't exist with

Actually, FLATMEMT depends on !NUMA.

> CONFIG_DEFERRED_STRUCT_PAGE_INIT can we make that explicit please?

Sure, it makes the condition clearer and more readable.

Thanks,
Yang

>

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#1405552 — Re: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized

FromMichal Hocko <mhocko@kernel.org>
Date2016-05-23 20:10 +0200
SubjectRe: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized
Message-ID<rC2sF-Qg-11@gated-at.bofh.it>
In reply to#1405508
On Mon 23-05-16 09:42:00, Shi, Yang wrote:
> On 5/23/2016 12:31 AM, Michal Hocko wrote:
> > On Fri 20-05-16 08:41:09, Shi, Yang wrote:
> > > On 5/20/2016 6:16 AM, Michal Hocko wrote:
> > > > On Thu 19-05-16 15:13:26, Yang Shi wrote:
> > > > [...]
> > > > > diff --git a/init/main.c b/init/main.c
> > > > > index b3c6e36..2075faf 100644
> > > > > --- a/init/main.c
> > > > > +++ b/init/main.c
> > > > > @@ -606,7 +606,6 @@ asmlinkage __visible void __init start_kernel(void)
> > > > >  		initrd_start = 0;
> > > > >  	}
> > > > >  #endif
> > > > > -	page_ext_init();
> > > > >  	debug_objects_mem_init();
> > > > >  	kmemleak_init();
> > > > >  	setup_per_cpu_pageset();
> > > > > @@ -1004,6 +1003,8 @@ static noinline void __init kernel_init_freeable(void)
> > > > >  	sched_init_smp();
> > > > > 
> > > > >  	page_alloc_init_late();
> > > > > +	/* Initialize page ext after all struct pages are initializaed */
> > > > > +	page_ext_init();
> > > > > 
> > > > >  	do_basic_setup();
> > > > 
> > > > I might be missing something but don't we have the same problem with
> > > > CONFIG_FLATMEM? page_ext_init_flatmem is called way earlier. Or
> > > > CONFIG_DEFERRED_STRUCT_PAGE_INIT is never enabled for CONFIG_FLATMEM?
> > > 
> > > Yes, CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which
> > > depends on SPARSEMEM. So, this config is not valid for FLATMEM at all.
> > 
> > Well
> > config MEMORY_HOTPLUG
> >         bool "Allow for memory hot-add"
> > 	depends on SPARSEMEM || X86_64_ACPI_NUMA
> > 	depends on ARCH_ENABLE_MEMORY_HOTPLUG
> > 
> > I wasn't really sure about X86_64_ACPI_NUMA dependency branch which
> > depends on X86_64 && NUMA && ACPI && PCI and that didn't sound like
> > SPARSEMEM only. If the FLATMEM shouldn't exist with
> 
> Actually, FLATMEMT depends on !NUMA.

Ahh, OK, you are right! Thanks for the clarification.
-- 
Michal Hocko
SUSE Labs

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