* [PATCH] mm: move page_ext_init after all struct pages are initialized
@ 2016-05-19 21:29 Yang Shi
2016-05-19 22:30 ` Andrew Morton
0 siblings, 1 reply; 5+ messages in thread
From: Yang Shi @ 2016-05-19 21:29 UTC (permalink / raw)
To: akpm, iamjoonsoo.kim; +Cc: linux-kernel, linux-mm, linaro-kernel, yang.shi
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,
so move page_ext_init() after it.
CC: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
---
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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* Re: [PATCH] mm: move page_ext_init after all struct pages are initialized
2016-05-19 21:29 [PATCH] mm: move page_ext_init after all struct pages are initialized Yang Shi
@ 2016-05-19 22:30 ` Andrew Morton
2016-05-19 22:35 ` Shi, Yang
0 siblings, 1 reply; 5+ messages in thread
From: Andrew Morton @ 2016-05-19 22:30 UTC (permalink / raw)
To: Yang Shi; +Cc: iamjoonsoo.kim, linux-kernel, linux-mm, linaro-kernel
On Thu, 19 May 2016 14:29:05 -0700 Yang Shi <yang.shi@linaro.org> wrote:
> 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,
> so move page_ext_init() after it.
>
<stdreply>When fixing a bug, please fully describe the end-user impact
of that bug</>
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* Re: [PATCH] mm: move page_ext_init after all struct pages are initialized
2016-05-19 22:30 ` Andrew Morton
@ 2016-05-19 22:35 ` Shi, Yang
2016-05-19 23:21 ` Andrew Morton
0 siblings, 1 reply; 5+ messages in thread
From: Shi, Yang @ 2016-05-19 22:35 UTC (permalink / raw)
To: Andrew Morton; +Cc: iamjoonsoo.kim, linux-kernel, linux-mm, linaro-kernel
On 5/19/2016 3:30 PM, Andrew Morton wrote:
> On Thu, 19 May 2016 14:29:05 -0700 Yang Shi <yang.shi@linaro.org> wrote:
>
>> 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,
>> so move page_ext_init() after it.
>>
>
> <stdreply>When fixing a bug, please fully describe the end-user impact
> of that bug</>
The kernel ran into the below oops which is same with the oops reported
in
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_is_guard-return-false-when-page_ext-arrays-are-not-allocated-yet.patch.
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
I will add the oops info into the commit log in V2.
Thanks,
Yang
>
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* Re: [PATCH] mm: move page_ext_init after all struct pages are initialized
2016-05-19 22:35 ` Shi, Yang
@ 2016-05-19 23:21 ` Andrew Morton
2016-05-19 23:26 ` Shi, Yang
0 siblings, 1 reply; 5+ messages in thread
From: Andrew Morton @ 2016-05-19 23:21 UTC (permalink / raw)
To: Shi, Yang; +Cc: iamjoonsoo.kim, linux-kernel, linux-mm, linaro-kernel
On Thu, 19 May 2016 15:35:15 -0700 "Shi, Yang" <yang.shi@linaro.org> wrote:
> On 5/19/2016 3:30 PM, Andrew Morton wrote:
> > On Thu, 19 May 2016 14:29:05 -0700 Yang Shi <yang.shi@linaro.org> wrote:
> >
> >> 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,
> >> so move page_ext_init() after it.
> >>
> >
> > <stdreply>When fixing a bug, please fully describe the end-user impact
> > of that bug</>
>
> The kernel ran into the below oops which is same with the oops reported
> in
> http://ozlabs.org/~akpm/mmots/broken-out/mm-page_is_guard-return-false-when-page_ext-arrays-are-not-allocated-yet.patch.
So this patch makes
mm-page_is_guard-return-false-when-page_ext-arrays-are-not-allocated-yet.patch
obsolete?
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* Re: [PATCH] mm: move page_ext_init after all struct pages are initialized
2016-05-19 23:21 ` Andrew Morton
@ 2016-05-19 23:26 ` Shi, Yang
0 siblings, 0 replies; 5+ messages in thread
From: Shi, Yang @ 2016-05-19 23:26 UTC (permalink / raw)
To: Andrew Morton; +Cc: iamjoonsoo.kim, linux-kernel, linux-mm, linaro-kernel
On 5/19/2016 4:21 PM, Andrew Morton wrote:
> On Thu, 19 May 2016 15:35:15 -0700 "Shi, Yang" <yang.shi@linaro.org> wrote:
>
>> On 5/19/2016 3:30 PM, Andrew Morton wrote:
>>> On Thu, 19 May 2016 14:29:05 -0700 Yang Shi <yang.shi@linaro.org> wrote:
>>>
>>>> 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,
>>>> so move page_ext_init() after it.
>>>>
>>>
>>> <stdreply>When fixing a bug, please fully describe the end-user impact
>>> of that bug</>
>>
>> The kernel ran into the below oops which is same with the oops reported
>> in
>> http://ozlabs.org/~akpm/mmots/broken-out/mm-page_is_guard-return-false-when-page_ext-arrays-are-not-allocated-yet.patch.
>
> So this patch makes
> mm-page_is_guard-return-false-when-page_ext-arrays-are-not-allocated-yet.patch
> obsolete?
Actually, no. Checking the return value for lookup_page_ext() is still
needed. But, the commit log need to be amended since that bootup oops
won't happen anymore with this patch applied.
Thanks,
Yang
>
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2016-05-19 21:29 [PATCH] mm: move page_ext_init after all struct pages are initialized Yang Shi
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