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Subject: Re: [PATCH 4.14 023/159] mm/sparsemem: Allocate mem_section at
 runtime for CONFIG_SPARSEMEM_EXTREME=y
To:     Mike Galbraith <efault@gmx.de>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
CC:     Baoquan He <bhe@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dave Young <dyoung@redhat.com>, <kexec@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <stable@vger.kernel.org>,
        Andy Lutomirski <luto@amacapital.net>, <linux-mm@kvack.org>,
        Vivek Goyal <vgoyal@redhat.com>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@suse.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
References: <20171222084623.668990192@linuxfoundation.org>
 <20171222084625.007160464@linuxfoundation.org>
 <1515302062.6507.18.camel@gmx.de> <20180108160444.2ol4fvgqbxnjmlpg@gmail.com>
 <20180108174653.7muglyihpngxp5tl@black.fi.intel.com>
 <20180109001303.dy73bpixsaegn4ol@node.shutemov.name>
 <1515469448.6766.12.camel@gmx.de>
From:   Dou Liyang <douly.fnst@cn.fujitsu.com>
Message-ID: <d71ba136-71ba-333a-f99b-b8283e2dc545@cn.fujitsu.com>
Date:   Wed, 7 Feb 2018 17:25:05 +0800
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Hi All,

I met the makedumpfile failed in the upstream kernel which contained
this patch. Did I missed something else?

In fedora27 host:

[douly@localhost code]$ ./makedumpfile -d 31 --message-level 31 -x
vmlinux_4.15+ vmcore_4.15+_from_cp_command vmcore_4.15+

sadump: does not have partition header
sadump: read dump device as unknown format
sadump: unknown format
LOAD (0)
   phys_start : 1000000
   phys_end   : 2a86000
   virt_start : ffffffff81000000
   virt_end   : ffffffff82a86000
LOAD (1)
   phys_start : 1000
   phys_end   : 9fc00
   virt_start : ffff880000001000
   virt_end   : ffff88000009fc00
LOAD (2)
   phys_start : 100000
   phys_end   : 13000000
   virt_start : ffff880000100000
   virt_end   : ffff880013000000
LOAD (3)
   phys_start : 33000000
   phys_end   : 7ffd7000
   virt_start : ffff880033000000
   virt_end   : ffff88007ffd7000
Linux kdump
page_size    : 4096

max_mapnr    : 7ffd7

Buffer size for the cyclic mode: 131061
The kernel version is not supported.
The makedumpfile operation may be incomplete.

num of NODEs : 1


Memory type  : SPARSEMEM_EX

mem_map (0)
   mem_map    : ffff88007ff26000
   pfn_start  : 0
   pfn_end    : 8000
mem_map (1)
   mem_map    : 0
   pfn_start  : 8000
   pfn_end    : 10000
mem_map (2)
   mem_map    : 0
   pfn_start  : 10000
   pfn_end    : 18000
mem_map (3)
   mem_map    : 0
   pfn_start  : 18000
   pfn_end    : 20000
mem_map (4)
   mem_map    : 0
   pfn_start  : 20000
   pfn_end    : 28000
mem_map (5)
   mem_map    : 0
   pfn_start  : 28000
   pfn_end    : 30000
mem_map (6)
   mem_map    : 0
   pfn_start  : 30000
   pfn_end    : 38000
mem_map (7)
   mem_map    : 0
   pfn_start  : 38000
   pfn_end    : 40000
mem_map (8)
   mem_map    : 0
   pfn_start  : 40000
   pfn_end    : 48000
mem_map (9)
   mem_map    : 0
   pfn_start  : 48000
   pfn_end    : 50000
mem_map (10)
   mem_map    : 0
   pfn_start  : 50000
   pfn_end    : 58000
mem_map (11)
   mem_map    : 0
   pfn_start  : 58000
   pfn_end    : 60000
mem_map (12)
   mem_map    : 0
   pfn_start  : 60000
   pfn_end    : 68000
mem_map (13)
   mem_map    : 0
   pfn_start  : 68000
   pfn_end    : 70000
mem_map (14)
   mem_map    : 0
   pfn_start  : 70000
   pfn_end    : 78000
mem_map (15)
   mem_map    : 0
   pfn_start  : 78000
   pfn_end    : 7ffd7
mmap() is available on the kernel.
Checking for memory holes                         : [100.0 %] | 
         STEP [Checking for memory holes  ] : 0.000060 seconds
__vtop4_x86_64: Can't get a valid pte.
readmem: Can't convert a virtual address(ffff88007ffd7000) to physical 
address.
readmem: type_addr: 0, addr:ffff88007ffd7000, size:32768
__exclude_unnecessary_pages: Can't read the buffer of struct page.
create_2nd_bitmap: Can't exclude unnecessary pages.
Checking for memory holes                         : [100.0 %] \ 
         STEP [Checking for memory holes  ] : 0.000010 seconds
Checking for memory holes                         : [100.0 %] - 
         STEP [Checking for memory holes  ] : 0.000004 seconds
__vtop4_x86_64: Can't get a valid pte.
readmem: Can't convert a virtual address(ffff88007ffd7000) to physical 
address.
readmem: type_addr: 0, addr:ffff88007ffd7000, size:32768
__exclude_unnecessary_pages: Can't read the buffer of struct page.
create_2nd_bitmap: Can't exclude unnecessary pages.

Thanks,
	dou
At 01/09/2018 11:44 AM, Mike Galbraith wrote:
> On Tue, 2018-01-09 at 03:13 +0300, Kirill A. Shutemov wrote:
>>
>> Mike, could you test this? (On top of the rest of the fixes.)
> 
> homer:..crash/2018-01-09-04:25 # ll
> total 1863604
> -rw------- 1 root root      66255 Jan  9 04:25 dmesg.txt
> -rw-r--r-- 1 root root        182 Jan  9 04:25 README.txt
> -rw-r--r-- 1 root root    2818240 Jan  9 04:25 System.map-4.15.0.gb2cd1df-master
> -rw------- 1 root root 1832914928 Jan  9 04:25 vmcore
> -rw-r--r-- 1 root root   72514993 Jan  9 04:25 vmlinux-4.15.0.gb2cd1df-master.gz
> 
> Yup, all better.
> 
>> Sorry for the mess.
> 
> (why, developers not installing shiny new bugs is a whole lot worse:)
> 
>>  From 100fd567754f1457be94732046aefca204c842d2 Mon Sep 17 00:00:00 2001
>> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>> Date: Tue, 9 Jan 2018 02:55:47 +0300
>> Subject: [PATCH] kdump: Write a correct address of mem_section into vmcoreinfo
>>
>> Depending on configuration mem_section can now be an array or a pointer
>> to an array allocated dynamically. In most cases, we can continue to refer
>> to it as 'mem_section' regardless of what it is.
>>
>> But there's one exception: '&mem_section' means "address of the array" if
>> mem_section is an array, but if mem_section is a pointer, it would mean
>> "address of the pointer".
>>
>> We've stepped onto this in kdump code. VMCOREINFO_SYMBOL(mem_section)
>> writes down address of pointer into vmcoreinfo, not array as we wanted.
>>
>> Let's introduce VMCOREINFO_ARRAY() that would handle the situation
>> correctly for both cases.
>>
>> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>> Fixes: 83e3c48729d9 ("mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y")
>> ---
>>   include/linux/crash_core.h | 2 ++
>>   kernel/crash_core.c        | 2 +-
>>   2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
>> index 06097ef30449..83ae04950269 100644
>> --- a/include/linux/crash_core.h
>> +++ b/include/linux/crash_core.h
>> @@ -42,6 +42,8 @@ phys_addr_t paddr_vmcoreinfo_note(void);
>>   	vmcoreinfo_append_str("PAGESIZE=%ld\n", value)
>>   #define VMCOREINFO_SYMBOL(name) \
>>   	vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)&name)
>> +#define VMCOREINFO_ARRAY(name) \
>> +	vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)name)
>>   #define VMCOREINFO_SIZE(name) \
>>   	vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
>>   			      (unsigned long)sizeof(name))
>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
>> index b3663896278e..d4122a837477 100644
>> --- a/kernel/crash_core.c
>> +++ b/kernel/crash_core.c
>> @@ -410,7 +410,7 @@ static int __init crash_save_vmcoreinfo_init(void)
>>   	VMCOREINFO_SYMBOL(contig_page_data);
>>   #endif
>>   #ifdef CONFIG_SPARSEMEM
>> -	VMCOREINFO_SYMBOL(mem_section);
>> +	VMCOREINFO_ARRAY(mem_section);
>>   	VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
>>   	VMCOREINFO_STRUCT_SIZE(mem_section);
>>   	VMCOREINFO_OFFSET(mem_section, section_mem_map);
> 
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