Re: [PATCH] mm/ia64: fix a memory block size bug

[wujianguo]

Hi Michal,
	Thanks for your comments and review.

On 2012-8-23 23:48, Michal Hocko wrote:
> [Fixed gregkh email address]
> 
> On Tue 21-08-12 11:46:10, wujianguo wrote:
>> From: Jianguo Wu <wujianguo@xxxxxxxxxx>
>>
>> Hi all,
>> 	I found following definition in include/linux/memory.h, in my IA64
>> platform, SECTION_SIZE_BITS is equal to 32, and MIN_MEMORY_BLOCK_SIZE will be 0.
>> 	#define MIN_MEMORY_BLOCK_SIZE     (1 << SECTION_SIZE_BITS)
> 
> OK, so I assume you have CONFIG_FORCE_MAX_ZONEORDER 17 and PAGE_SHIFT
> 16, right? But even CONFIG_FORCE_MAX_ZONEORDER 16 would be a problem.
> 

Yes, you are right, CONFIG_FORCE_MAX_ZONEORDER 16 would be a problem too.

>> 	Because MIN_MEMORY_BLOCK_SIZE is 32bits, so MIN_MEMORY_BLOCK_SIZE(1 << 32)
>> will equal to 0. This will cause wrong system memory infomation in sysfs. I think
>> it should be:
>> 	#define MIN_MEMORY_BLOCK_SIZE     (1UL << SECTION_SIZE_BITS)
>>
> 
> I guess the part below is not necessary for the changelog
> 

Thanks for your suggestion, I will delete them in version 2.

>> linux-drf:/sys/devices/system/memory # ll
>> total 0
>> -r--r--r-- 1 root root 65536 Aug 20 02:35 block_size_bytes
>> drwxr-xr-x 3 root root     0 Aug 20 02:19 memory0
>> drwxr-xr-x 2 root root     0 Aug 20 02:35 power
>> -rw-r--r-- 1 root root 65536 Aug 20 02:35 uevent
>>
>> linux-drf:/sys/devices/system/memory # cat block_size_bytes
>> 0
>>
>> linux-drf:/sys/devices/system/memory/memory0 # cat *
>> 8000000000000000
>> cat: node0: Is a directory
>> cat: node1: Is a directory
>> cat: node2: Is a directory
>> cat: node3: Is a directory
>> 0
>> 8000000000000000
>> cat: power: Is a directory
>> 1
>> online
>> cat: subsystem: Is a directory
>>
> 
> Up to here.
> 
>> 	And "echo offline > memory0/state" will cause following call trace:
>>
>> kernel BUG at mm/memory_hotplug.c:885!
>> sh[6455]: bugcheck! 0 [1]
>>
>> Pid: 6455, CPU 0, comm:                   sh
>> psr : 0000101008526030 ifs : 8000000000000fa4 ip  : [<a0000001008c40f0>]    Not tainted (3.6.0-rc1)
>> ip is at offline_pages+0x210/0xee0
>> unat: 0000000000000000 pfs : 0000000000000fa4 rsc : 0000000000000003
>> rnat: a0000001008f2d50 bsps: 0000000000000000 pr  : 65519a96659a9565
>> ldrs: 0000000000000000 ccv : 0000010b9263f310 fpsr: 0009804c0270033f
>> csd : 0000000000000000 ssd : 0000000000000000
>> b0  : a0000001008c40f0 b6  : a000000100473980 b7  : a0000001000106d0
>> f6  : 000000000000000000000 f7  : 1003e0000000085c9354c
>> f8  : 1003e0044b82fa09b5a53 f9  : 1003e000000d65cd62abf
>> f10 : 1003efd02efdec682803d f11 : 1003e0000000000000042
>> r1  : a00000010152c2e0 r2  : 0000000000006ada r3  : 000000000000fffe
>> r8  : 0000000000000026 r9  : a00000010121cc18 r10 : a0000001013309f0
>> r11 : 65519a96659a19e9 r12 : e00000070a91fdf0 r13 : e00000070a910000
>> r14 : 0000000000006ada r15 : 0000000000004000 r16 : 000000006ad8356c
>> r17 : a0000001019a525e r18 : 0000000000007fff r19 : 0000000000000000
>> r20 : 0000000000006ad6 r21 : 0000000000006ad6 r22 : a00000010133bec8
>> r23 : 0000000000006ad4 r24 : 0000000000000002 r25 : 8200000000260038
>> r26 : 00000000000004f9 r27 : 00000000000004f8 r28 : 000000000001cf98
>> r29 : 0000000000000038 r30 : a0000001019a5ae0 r31 : 000000000001cf60
>>
>> Call Trace:
>>  [<a0000001000163e0>] show_stack+0x80/0xa0
>>                                 sp=e00000070a91f9b0 bsp=e00000070a9115e0
>>  [<a000000100016a40>] show_regs+0x640/0x920
>>                                 sp=e00000070a91fb80 bsp=e00000070a911588
>>  [<a000000100040590>] die+0x190/0x2c0
>>                                 sp=e00000070a91fb90 bsp=e00000070a911548
>>  [<a000000100040710>] die_if_kernel+0x50/0x80
>>                                 sp=e00000070a91fb90 bsp=e00000070a911518
>>  [<a0000001008f8030>] ia64_bad_break+0x3d0/0x6e0
>>                                 sp=e00000070a91fb90 bsp=e00000070a9114f0
>>  [<a00000010000c0c0>] ia64_native_leave_kernel+0x0/0x270
>>                                 sp=e00000070a91fc20 bsp=e00000070a9114f0
>>  [<a0000001008c40f0>] offline_pages+0x210/0xee0
>>                                 sp=e00000070a91fdf0 bsp=e00000070a9113c8
>>  [<a00000010022d580>] alloc_pages_current+0x180/0x2a0
>>                                 sp=e00000070a91fe20 bsp=e00000070a9113a
>>
>> This patch is trying to fix the bug.
> 
> not just trying ;)
> 
>>
>> Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxx>
> 
> Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
> 
>> ---
>>  include/linux/memory.h |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/include/linux/memory.h b/include/linux/memory.h
>> index 1ac7f6e..ff9a9f8 100644
>> --- a/include/linux/memory.h
>> +++ b/include/linux/memory.h
>> @@ -19,7 +19,7 @@
>>  #include <linux/compiler.h>
>>  #include <linux/mutex.h>
>>
>> -#define MIN_MEMORY_BLOCK_SIZE     (1 << SECTION_SIZE_BITS)
>> +#define MIN_MEMORY_BLOCK_SIZE     (1UL << SECTION_SIZE_BITS)
>>
>>  struct memory_block {
>>  	unsigned long start_section_nr;
> 

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