linux-kernel - Re: [PATCH V3] ia64/mm: fix a bad_page bug when crash kernel booting

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Date:	Sat, 16 Feb 2013 09:55:44 +0800
From:	Xishi Qiu <qiuxishi@...wei.com>
To:	Matt Fleming <matt.fleming@...el.com>,
	"Luck, Tony" <tony.luck@...el.com>, <fenghua.yu@...el.com>,
	Liujiang <jiang.liu@...wei.com>,
	Andrew Morton <akpm@...ux-foundation.org>
CC:	<linux-ia64@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-efi@...r.kernel.org>, <linux-mm@...ck.org>,
	Hanjun Guo <guohanjun@...wei.com>,
	WuJianguo <wujianguo@...wei.com>
Subject: Re: [PATCH V3] ia64/mm: fix a bad_page bug when crash kernel booting

On 2013/2/13 18:07, Matt Fleming wrote:

>> In efi_init() memory aligns in IA64_GRANULE_SIZE(16M). If set "crashkernel=1024M-:600M"
>> and use sparse memory model, when crash kernel booting it changes [128M-728M] to [128M-720M].
>> But initrd memory is in [709M-727M], and virt_addr_valid() *can not* check the invalid pages
>> when freeing initrd memory. There are some pages missed at the end of the seciton.
>>
>> ChangeLog V3:
>> 	fixed vaddr mistake
>> ChangeLog V2:
>> 	add invalid pages check when freeing initrd memory
>>
>> Signed-off-by: Xishi Qiu <qiuxishi@...wei.com>
>> ---
>>  arch/ia64/mm/init.c |    4 ++++
>>  1 files changed, 4 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
>> index 082e383..8a269f8 100644
>> --- a/arch/ia64/mm/init.c
>> +++ b/arch/ia64/mm/init.c
>> @@ -173,6 +173,7 @@ void __init
>>  free_initrd_mem (unsigned long start, unsigned long end)
>>  {
>>  	struct page *page;
>> +	unsigned long pfn;
>>  	/*
>>  	 * EFI uses 4KB pages while the kernel can use 4KB or bigger.
>>  	 * Thus EFI and the kernel may have different page sizes. It is
>> @@ -213,6 +214,9 @@ free_initrd_mem (unsigned long start, unsigned long end)
>>  	for (; start < end; start += PAGE_SIZE) {
>>  		if (!virt_addr_valid(start))
>>  			continue;
>> +		pfn = __pa(start) >> PAGE_SHIFT;
>> +		if (pfn >= max_low_pfn)
>> +			continue;
>>  		page = virt_to_page(start);
>>  		ClearPageReserved(page);
>>  		init_page_count(page);
> 
> I would have presumed that fixing this bug would involve modifying the
> ia64-specific kexec code?
> 
> Tony, Fenghua? Any thoughts?


Hi, I had the Spring Festival a few days ago. Please ignore the earlier
patch and consider the V3 one above.

Thanks,
Xishi Qiu


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