[Makedumpfile Patch v2 0/7] Fix --mem-usage /proc/kcore

[Makedumpfile Patch v2 0/7] Fix --mem-usage /proc/kcore

[Pratyush Anand]

`makedumpfile --mem-usage /proc/kcore` has been broken after kaslr specific
modifications. A kernel patch has been ACKed by Andrew Morton and has been
sent to Linus now [0]. This kernel patch helps to fix the issue for both
the case of kaslr enabled and disabled.

[0] http://marc.info/?l=linux-mm-commits&m=148823497215968&w=2

Changes since v1:
 - One more patch..Now mem-usage with older kernel (< 4.11) will only work
   when that has been rightly patched and -f has been used in makedumpfile
   command line.

Baoquan He (2):
  makedumpfile: Correct the calculation of kvaddr in
    set_kcore_vmcoreinfo
  makedumpfile: Discard process_dump_load

Pratyush Anand (5):
  show_mem_usage(): calculate page offset after elf load
  initial(): call cach_init() a bit early
  x86_64: check physical address in PT_LOAD for none direct mapped
    regions
  elf_info: kcore: check for invalid physical address
  mem-usage: allow to work only with -f for kernel version < 4.11

 arch/x86_64.c  |  6 ++++--
 elf_info.c     | 25 +++++--------------------
 makedumpfile.c | 18 ++++++++++++------
 3 files changed, 21 insertions(+), 28 deletions(-)

-- 
2.9.3


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[Makedumpfile Patch v2 1/7] show_mem_usage(): calculate page offset after elf load

[Pratyush Anand]

x86_64 calculated page offset from PT_LOAD headers. Therefore call
get_page_offset() after get_elf_loads()

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 makedumpfile.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index e69b6df9a9ee..6942047199de 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -10944,15 +10944,15 @@ int show_mem_usage(void)
 
 	info->dump_level = MAX_DUMP_LEVEL;
 
-	if (!get_page_offset())
-		return FALSE;
-
 	if (!open_files_for_creating_dumpfile())
 		return FALSE;
 
 	if (!get_elf_loads(info->fd_memory, info->name_memory))
 		return FALSE;
 
+	if (!get_page_offset())
+		return FALSE;
+
 	if (!get_sys_kernel_vmcoreinfo(&vmcoreinfo_addr, &vmcoreinfo_len))
 		return FALSE;
 
-- 
2.9.3


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[Makedumpfile Patch v2 2/7] initial(): call cach_init() a bit early

[Pratyush Anand]

Call cach_init() before get_kcore_dump_loads(), because latter uses
cache_search().

Call path is like this :
get_kcore_dump_loads() -> process_dump_load() -> vaddr_to_paddr() ->
vtop4_x86_64() -> readmem() -> cache_search()

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 makedumpfile.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 6942047199de..3b8e9810468d 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -3878,6 +3878,9 @@ initial(void)
 	if (!get_value_for_old_linux())
 		return FALSE;
 
+	if (!is_xen_memory() && !cache_init())
+		return FALSE;
+
 	if (info->flag_mem_usage && !get_kcore_dump_loads())
 		return FALSE;
 
@@ -4000,9 +4003,6 @@ out:
 		}
 	}
 
-	if (!is_xen_memory() && !cache_init())
-		return FALSE;
-
 	if (debug_info && !get_machdep_info())
 		return FALSE;
 
-- 
2.9.3


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[Makedumpfile Patch v2 3/7] x86_64: check physical address in PT_LOAD for none direct mapped regions

[Pratyush Anand]

A kcore PT_LOAD can have a section from vmalloc region. However,
physical address in that header would be invalid (-1) after a recent
kernel changes [0]. Therefore, check for valid physical address while
calculating page_offset or phys_offset.

[0] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?h=next-20170206&id=c9d4e5d7b7fd6c74e134ca44df8a5386efbc561c

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 arch/x86_64.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86_64.c b/arch/x86_64.c
index 893cd516fc8b..e978a36f8878 100644
--- a/arch/x86_64.c
+++ b/arch/x86_64.c
@@ -41,7 +41,8 @@ get_page_offset_x86_64(void)
 	unsigned long long virt_start;
 
 	for (i = 0; get_pt_load(i, &phys_start, NULL, &virt_start, NULL); i++) {
-		if (virt_start < __START_KERNEL_map) {
+		if (virt_start < __START_KERNEL_map
+				&& phys_start != NOT_PADDR) {
 			info->page_offset = virt_start - phys_start;
 			return TRUE;
 		}
@@ -76,7 +77,8 @@ get_phys_base_x86_64(void)
 	}
 
 	for (i = 0; get_pt_load(i, &phys_start, NULL, &virt_start, NULL); i++) {
-		if (virt_start >= __START_KERNEL_map) {
+		if (virt_start >= __START_KERNEL_map
+				&& phys_start != NOT_PADDR) {
 
 			info->phys_base = phys_start -
 			    (virt_start & ~(__START_KERNEL_map));
-- 
2.9.3


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[Makedumpfile Patch v2 4/7] elf_info: kcore: check for invalid physical address

[Pratyush Anand]

After a recent kernel changes [0], kcore passes correct phys_start for
direct mapped region and an invalid value (-1) for all other regions.
arch specific function is_phys_addr() accepts only virt_start.
Therefore, check for valid phys_start in get_kcore_dump_loads().

[0] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?h=next-20170206&id=c9d4e5d7b7fd6c74e134ca44df8a5386efbc561c

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 elf_info.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/elf_info.c b/elf_info.c
index 65ff333cf33a..c5743b3cab28 100644
--- a/elf_info.c
+++ b/elf_info.c
@@ -881,7 +881,8 @@ int get_kcore_dump_loads(void)
 
 	for (i = 0; i < num_pt_loads; ++i) {
 		struct pt_load_segment *p = &pt_loads[i];
-		if (!is_phys_addr(p->virt_start))
+		if (p->phys_start == NOT_PADDR
+				|| !is_phys_addr(p->virt_start))
 			continue;
 		loads++;
 	}
@@ -901,7 +902,8 @@ int get_kcore_dump_loads(void)
 
 	for (i = 0, j = 0; i < num_pt_loads; ++i) {
 		struct pt_load_segment *p = &pt_loads[i];
-		if (!is_phys_addr(p->virt_start))
+		if (p->phys_start == NOT_PADDR
+				|| !is_phys_addr(p->virt_start))
 			continue;
 		if (j >= loads)
 			return FALSE;
-- 
2.9.3


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[Makedumpfile Patch v2 5/7] makedumpfile: Correct the calculation of kvaddr in set_kcore_vmcoreinfo

[Pratyush Anand]

From: Baoquan He <bhe@redhat.com>

In set_kcore_vmcoreinfo, we calculate the virtual address of vmcoreinfo
by OR operation as below:

	kvaddr = (ulong)vmcoreinfo_addr | PAGE_OFFSET;

When mm sections kaslr is not enabled, this is correct since the starting
address of direct mapping section is 0xffff880000000000 which 1T aligned.
Usually system with memory below 1T won't cause problem.

However with mm section kaslr enabled, the starting address of direct
mapping is 1G aligned. The above code makes kvaddr unsure.

So change it to adding operation:
	kvaddr = (ulong)vmcoreinfo_addr + PAGE_OFFSET;

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 elf_info.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/elf_info.c b/elf_info.c
index c5743b3cab28..100272f83c48 100644
--- a/elf_info.c
+++ b/elf_info.c
@@ -372,7 +372,7 @@ int set_kcore_vmcoreinfo(uint64_t vmcoreinfo_addr, uint64_t vmcoreinfo_len)
 	off_t offset_desc;
 
 	offset = UNINITIALIZED;
-	kvaddr = (ulong)vmcoreinfo_addr | PAGE_OFFSET;
+	kvaddr = (ulong)vmcoreinfo_addr + PAGE_OFFSET;
 
 	for (i = 0; i < num_pt_loads; ++i) {
 		struct pt_load_segment *p = &pt_loads[i];
-- 
2.9.3


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[Makedumpfile Patch v2 6/7] makedumpfile: Discard process_dump_load

[Pratyush Anand]

From: Baoquan He <bhe@redhat.com>

Pratyush has made a kernel patch [0] to add the physical address of
direct mapping kcore program segments. So no need to calculate it
specifically now. And the old code is not correct since it calls
vaddr_to_paddr() which has been not ready at that time.

[0] http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?h=next-20170206&id=c9d4e5d7b7fd6c74e134ca44df8a5386efbc561c

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 elf_info.c | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/elf_info.c b/elf_info.c
index 100272f83c48..8e2437622141 100644
--- a/elf_info.c
+++ b/elf_info.c
@@ -857,22 +857,6 @@ static int exclude_segment(struct pt_load_segment **pt_loads,
 	return 0;
 }
 
-static int
-process_dump_load(struct pt_load_segment	*pls)
-{
-	unsigned long long paddr;
-
-	paddr = vaddr_to_paddr(pls->virt_start);
-	pls->phys_start  = paddr;
-	pls->phys_end    = paddr + (pls->virt_end - pls->virt_start);
-	DEBUG_MSG("process_dump_load\n");
-	DEBUG_MSG("  phys_start : %llx\n", pls->phys_start);
-	DEBUG_MSG("  phys_end   : %llx\n", pls->phys_end);
-	DEBUG_MSG("  virt_start : %llx\n", pls->virt_start);
-	DEBUG_MSG("  virt_end   : %llx\n", pls->virt_end);
-
-	return TRUE;
-}
 
 int get_kcore_dump_loads(void)
 {
@@ -917,7 +901,6 @@ int get_kcore_dump_loads(void)
 		}
 
 		pls[j] = *p;
-		process_dump_load(&pls[j]);
 		j++;
 	}
 
-- 
2.9.3


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[Makedumpfile Patch v2 7/7] mem-usage: allow to work only with -f for kernel version < 4.11

[Pratyush Anand]

PT_LOAD of kcore does not have valid p_paddr values for kernel version
less that v4.11. Therefore, older kernel will no long work for mem-usage
with current makedumpfile code. They can only work when they are patched
with fix to "update physical address for kcore ram and text".

This patch fixes the makedumpfile so that it does not allow to work
older kernel for --mem-usage until someone is sure that kernel is
rightly patched and so uses -f in command line.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 makedumpfile.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/makedumpfile.c b/makedumpfile.c
index 3b8e9810468d..bf006ea5dd5f 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
 			MSG("Try `makedumpfile --help' for more information.\n");
 			goto out;
 		}
+		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&
+				!info->flag_force) {
+			MSG("mem-usage not supported for this kernel.\n");
+			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
+			return COMPLETED;
+		}
 
 		if (!show_mem_usage())
 			goto out;
-- 
2.9.3


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Re: [Makedumpfile Patch v2 0/7] Fix --mem-usage /proc/kcore

[Pratyush Anand]

On Tuesday 28 February 2017 11:22 AM, Pratyush Anand wrote:
> `makedumpfile --mem-usage /proc/kcore` has been broken after kaslr specific
> modifications. A kernel patch has been ACKed by Andrew Morton and has been
> sent to Linus now [0]. This kernel patch helps to fix the issue for both
> the case of kaslr enabled and disabled.
>
> [0] http://marc.info/?l=linux-mm-commits&m=148823497215968&w=2

Just FYI,patch is in upstream now.

commit 464920104bf7adac12722035bfefb3d772eb04d8
Author: Pratyush Anand <panand@redhat.com>
Date:   Mon Feb 27 14:27:31 2017 -0800

     /proc/kcore: update physical address for kcore ram and text


>
> Changes since v1:
>  - One more patch..Now mem-usage with older kernel (< 4.11) will only work
>    when that has been rightly patched and -f has been used in makedumpfile
>    command line.
>
> Baoquan He (2):
>   makedumpfile: Correct the calculation of kvaddr in
>     set_kcore_vmcoreinfo
>   makedumpfile: Discard process_dump_load
>
> Pratyush Anand (5):
>   show_mem_usage(): calculate page offset after elf load
>   initial(): call cach_init() a bit early
>   x86_64: check physical address in PT_LOAD for none direct mapped
>     regions
>   elf_info: kcore: check for invalid physical address
>   mem-usage: allow to work only with -f for kernel version < 4.11
>
>  arch/x86_64.c  |  6 ++++--
>  elf_info.c     | 25 +++++--------------------
>  makedumpfile.c | 18 ++++++++++++------
>  3 files changed, 21 insertions(+), 28 deletions(-)
>

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RE: [Makedumpfile Patch v2 7/7] mem-usage: allow to work only with -f for kernel version < 4.11

[Atsushi Kumagai]

Hello Pratyush,

>PT_LOAD of kcore does not have valid p_paddr values for kernel version
>less that v4.11. Therefore, older kernel will no long work for mem-usage
>with current makedumpfile code. They can only work when they are patched
>with fix to "update physical address for kcore ram and text".
>
>This patch fixes the makedumpfile so that it does not allow to work
>older kernel for --mem-usage until someone is sure that kernel is
>rightly patched and so uses -f in command line.
>
>Signed-off-by: Pratyush Anand <panand@redhat.com>
>---
> makedumpfile.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/makedumpfile.c b/makedumpfile.c
>index 3b8e9810468d..bf006ea5dd5f 100644
>--- a/makedumpfile.c
>+++ b/makedumpfile.c
>@@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
> 			MSG("Try `makedumpfile --help' for more information.\n");
> 			goto out;
> 		}
>+		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&
>+				!info->flag_force) {
>+			MSG("mem-usage not supported for this kernel.\n");
>+			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
>+			return COMPLETED;
>+		}

Should use "goto out" to prevent memory leaks since some heap blocks are
allocated at the head of main().

BTW, the descriptions of -f option in man and print_usage() don't mention this usage:

       -f     Force existing DUMPFILE to be overwritten.
              Example:
              # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
              This command overwrites DUMPFILE even if it already exists.

so they should be updated.


Thanks,
Atsushi Kumagai


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Re: [Makedumpfile Patch v2 7/7] mem-usage: allow to work only with -f for kernel version < 4.11

[Pratyush Anand]

Hi Atsushi,

On Thursday 02 March 2017 10:19 AM, Atsushi Kumagai wrote:
> Hello Pratyush,
>
>> PT_LOAD of kcore does not have valid p_paddr values for kernel version
>> less that v4.11. Therefore, older kernel will no long work for mem-usage
>> with current makedumpfile code. They can only work when they are patched
>> with fix to "update physical address for kcore ram and text".
>>
>> This patch fixes the makedumpfile so that it does not allow to work
>> older kernel for --mem-usage until someone is sure that kernel is
>> rightly patched and so uses -f in command line.
>>
>> Signed-off-by: Pratyush Anand <panand@redhat.com>
>> ---
>> makedumpfile.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/makedumpfile.c b/makedumpfile.c
>> index 3b8e9810468d..bf006ea5dd5f 100644
>> --- a/makedumpfile.c
>> +++ b/makedumpfile.c
>> @@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
>> 			MSG("Try `makedumpfile --help' for more information.\n");
>> 			goto out;
>> 		}
>> +		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&
>> +				!info->flag_force) {
>> +			MSG("mem-usage not supported for this kernel.\n");
>> +			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
>> +			return COMPLETED;
>> +		}
>
> Should use "goto out" to prevent memory leaks since some heap blocks are
> allocated at the head of main().

OK

>
> BTW, the descriptions of -f option in man and print_usage() don't mention this usage:
>
>        -f     Force existing DUMPFILE to be overwritten.
>               Example:
>               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
>               This command overwrites DUMPFILE even if it already exists.
>
> so they should be updated.

Does following looks fine to you?

$ makedumpfile --help | grep -A3 "\-f"
   [-f]:
       Overwrite DUMPFILE even if it already exists
       Force mem-usage to work with older kernel as well.


$ man makedumpfile | grep -w "\-f  " -A6
        -f     Force existing DUMPFILE to be overwritten and mem-usage 
to work with older kernel as well.
               Example:
               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
               This command overwrites DUMPFILE even if it already exists.
               # makedumpfile -f --mem-usage /proc/kcore
               Kernel version lesser than v4.11 will not work with 
--mem-usage functionality until it has been  patched  with  upstream  commit
               464920104bf7.  Therefore if you have patched your older 
kernel then use -f.

Thanks for the review.

~Pratyush

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Re: [Makedumpfile Patch v2 7/7] mem-usage: allow to work only with -f for kernel version < 4.11

[Pratyush Anand]

Hi Atsushi,

On Thursday 02 March 2017 10:19 AM, Atsushi Kumagai wrote:
> Hello Pratyush,
>
>> PT_LOAD of kcore does not have valid p_paddr values for kernel version
>> less that v4.11. Therefore, older kernel will no long work for mem-usage
>> with current makedumpfile code. They can only work when they are patched
>> with fix to "update physical address for kcore ram and text".
>>
>> This patch fixes the makedumpfile so that it does not allow to work
>> older kernel for --mem-usage until someone is sure that kernel is
>> rightly patched and so uses -f in command line.
>>
>> Signed-off-by: Pratyush Anand <panand@redhat.com>
>> ---
>> makedumpfile.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/makedumpfile.c b/makedumpfile.c
>> index 3b8e9810468d..bf006ea5dd5f 100644
>> --- a/makedumpfile.c
>> +++ b/makedumpfile.c
>> @@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
>> 			MSG("Try `makedumpfile --help' for more information.\n");
>> 			goto out;
>> 		}
>> +		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&
>> +				!info->flag_force) {
>> +			MSG("mem-usage not supported for this kernel.\n");
>> +			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
>> +			return COMPLETED;
>> +		}
>
> Should use "goto out" to prevent memory leaks since some heap blocks are
> allocated at the head of main().

OK

>
> BTW, the descriptions of -f option in man and print_usage() don't mention this usage:
>
>        -f     Force existing DUMPFILE to be overwritten.
>               Example:
>               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
>               This command overwrites DUMPFILE even if it already exists.
>
> so they should be updated.

Does following looks fine to you?

$ makedumpfile --help | grep -A3 "\-f"
   [-f]:
       Overwrite DUMPFILE even if it already exists
       Force mem-usage to work with older kernel as well.


$ man makedumpfile | grep -w "\-f  " -A6
        -f     Force existing DUMPFILE to be overwritten and mem-usage 
to work with older kernel as well.
               Example:
               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
               This command overwrites DUMPFILE even if it already exists.
               # makedumpfile -f --mem-usage /proc/kcore
               Kernel version lesser than v4.11 will not work with 
--mem-usage functionality until it has been  patched  with  upstream  commit
               464920104bf7.  Therefore if you have patched your older 
kernel then use -f.

Thanks for the review.

~Pratyush

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RE: [Makedumpfile Patch v2 7/7] mem-usage: allow to work only with -f for kernel version < 4.11

[Atsushi Kumagai]

>Hi Atsushi,
>
>On Thursday 02 March 2017 10:19 AM, Atsushi Kumagai wrote:
>> Hello Pratyush,
>>
>>> PT_LOAD of kcore does not have valid p_paddr values for kernel version
>>> less that v4.11. Therefore, older kernel will no long work for mem-usage
>>> with current makedumpfile code. They can only work when they are patched
>>> with fix to "update physical address for kcore ram and text".
>>>
>>> This patch fixes the makedumpfile so that it does not allow to work
>>> older kernel for --mem-usage until someone is sure that kernel is
>>> rightly patched and so uses -f in command line.
>>>
>>> Signed-off-by: Pratyush Anand <panand@redhat.com>
>>> ---
>>> makedumpfile.c | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/makedumpfile.c b/makedumpfile.c
>>> index 3b8e9810468d..bf006ea5dd5f 100644
>>> --- a/makedumpfile.c
>>> +++ b/makedumpfile.c
>>> @@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
>>> 			MSG("Try `makedumpfile --help' for more information.\n");
>>> 			goto out;
>>> 		}
>>> +		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&
>>> +				!info->flag_force) {
>>> +			MSG("mem-usage not supported for this kernel.\n");
>>> +			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
>>> +			return COMPLETED;
>>> +		}
>>
>> Should use "goto out" to prevent memory leaks since some heap blocks are
>> allocated at the head of main().
>
>OK
>
>>
>> BTW, the descriptions of -f option in man and print_usage() don't mention this usage:
>>
>>        -f     Force existing DUMPFILE to be overwritten.
>>               Example:
>>               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
>>               This command overwrites DUMPFILE even if it already exists.
>>
>> so they should be updated.
>
>Does following looks fine to you?

looks good to me.
I'll wait for the next version.

Thanks,
Atsushi Kumagai

>$ makedumpfile --help | grep -A3 "\-f"
>   [-f]:
>       Overwrite DUMPFILE even if it already exists
>       Force mem-usage to work with older kernel as well.
>
>
>$ man makedumpfile | grep -w "\-f  " -A6
>        -f     Force existing DUMPFILE to be overwritten and mem-usage
>to work with older kernel as well.
>               Example:
>               # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
>               This command overwrites DUMPFILE even if it already exists.
>               # makedumpfile -f --mem-usage /proc/kcore
>               Kernel version lesser than v4.11 will not work with
>--mem-usage functionality until it has been  patched  with  upstream  commit
>               464920104bf7.  Therefore if you have patched your older
>kernel then use -f.
>
>Thanks for the review.
>
>~Pratyush


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