[PATCH v2 0/3] Generic multi-page exclusion

[PATCH v2 0/3] Generic multi-page exclusion

[Petr Tesarik]

Kumagai-san,

this patch was inspired by this post of yours:

http://lists.infradead.org/pipermail/kexec/2013-November/010445.html

Unfortunately, this rewrite never happened, so I took the liberty of
overtaking the job. I hope you don't mind.

This is in fact a preparatory series to add hugepage support without
having to care about the appropriate size of the cyclic buffer.

Changelog:
* v2:
  - Keep excluded regions per mem_map_data
  - Process excluded pages in chunks

Petr Tesarik (3):
  Pass mmd pointer to __exclude_unnecessary_pages
  Generic handling of multi-page exclusions
  Get rid of overrun adjustments

 makedumpfile.c | 118 +++++++++++++++++++--------------------------------------
 makedumpfile.h |   7 ++++
 2 files changed, 46 insertions(+), 79 deletions(-)

-- 
1.8.4.5


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[PATCH v2 1/3] Pass mmd pointer to __exclude_unnecessary_pages

[Petr Tesarik]

Pass the mmd pointer itself instead of the individual fields, so additional
information can be kept in mem_map_data.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
---
 makedumpfile.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 5e81cc5..81c687b 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -4658,9 +4658,11 @@ initialize_2nd_bitmap_cyclic(struct cycle *cycle)
 }
 
 int
-__exclude_unnecessary_pages(unsigned long mem_map,
-    unsigned long long pfn_start, unsigned long long pfn_end, struct cycle *cycle)
+__exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
 {
+	unsigned long mem_map = mmd->mem_map;
+	unsigned long long pfn_start = mmd->pfn_start;
+	unsigned long long pfn_end = mmd->pfn_end;
 	unsigned long long pfn, pfn_mm, maddr;
 	unsigned long long pfn_read_start, pfn_read_end, index_pg;
 	unsigned char page_cache[SIZE(page) * PGMM_CACHED];
@@ -4809,8 +4811,7 @@ exclude_unnecessary_pages(void)
 		if (mmd->mem_map == NOT_MEMMAP_ADDR)
 			continue;
 
-		if (!__exclude_unnecessary_pages(mmd->mem_map,
-						 mmd->pfn_start, mmd->pfn_end, NULL))
+		if (!__exclude_unnecessary_pages(mmd, NULL))
 			return FALSE;
 	}
 
@@ -4860,8 +4861,7 @@ exclude_unnecessary_pages_cyclic(struct cycle *cycle)
 
 			if (mmd->pfn_end >= cycle->start_pfn &&
 			    mmd->pfn_start <= cycle->end_pfn) {
-				if (!__exclude_unnecessary_pages(mmd->mem_map,
-								 mmd->pfn_start, mmd->pfn_end, cycle))
+				if (!__exclude_unnecessary_pages(mmd, cycle))
 					return FALSE;
 			}
 		}
-- 
1.8.4.5


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[PATCH v2 2/3] Generic handling of multi-page exclusions

[Petr Tesarik]

When multiple pages are excluded from the dump, store the extents in the
mem_map_data structure, and check if anything is still pending on the
next invocation of __exclude_unnecessary_pages for the same mem_map.

The start PFN of the excluded extent is set to the end of the current
cycle (which is equal to the start of the next cycle, see update_cycle),
so only the part of the excluded region which falls beyond current cycle
buffer is valid. If the excluded region is completely processed in the
current cycle, the start PFN is even bigger than the end PFN. That
causes nothing to be done at the beginning of the next cycle.

There is no check whether the adjusted pfn_start is still within the
current cycle. Nothing bad happens if it isn't, because exclude_range()
is used again to exclude the remaining part, so even if the excluded
region happens to span more than two cycles, the code will still work
correctly.

Note that clear_bit_on_2nd_bitmap_for_kernel() accepts PFNs outside the
current cyclic range. It willreturn FALSE, so such PFNs are not counted.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
---
 makedumpfile.c | 47 +++++++++++++++++++++++++++++++++--------------
 makedumpfile.h |  7 +++++++
 2 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 81c687b..9ffb901 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -2385,6 +2385,9 @@ dump_mem_map(unsigned long long pfn_start,
 	mmd->pfn_end   = pfn_end;
 	mmd->mem_map   = mem_map;
 
+	mmd->exclude_pfn_start = 0ULL;
+	mmd->exclude_pfn_end   = 0ULL;
+
 	DEBUG_MSG("mem_map (%d)\n", num_mm);
 	DEBUG_MSG("  mem_map    : %lx\n", mem_map);
 	DEBUG_MSG("  pfn_start  : %llx\n", pfn_start);
@@ -4657,6 +4660,21 @@ initialize_2nd_bitmap_cyclic(struct cycle *cycle)
 	return TRUE;
 }
 
+static void
+exclude_range(unsigned long long *counter, struct mem_map_data *mmd,
+    unsigned long long pfn, unsigned long long endpfn, struct cycle *cycle)
+{
+	while (pfn < endpfn) {
+		if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
+			(*counter)++;
+		++pfn;
+	}
+
+	mmd->exclude_pfn_start = cycle ? cycle->end_pfn : ULONGLONG_MAX;
+	mmd->exclude_pfn_end = endpfn;
+	mmd->exclude_pfn_counter = counter;
+}
+
 int
 __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
 {
@@ -4671,6 +4689,18 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
 	unsigned long flags, mapping, private = 0;
 
 	/*
+	 * If a multi-page exclusion is pending, do it first
+	 */
+	if (mmd->exclude_pfn_start < mmd->exclude_pfn_end) {
+		exclude_range(mmd->exclude_pfn_counter, mmd,
+			mmd->exclude_pfn_start, mmd->exclude_pfn_end,
+			cycle);
+
+		mem_map += (mmd->exclude_pfn_end - pfn_start) * SIZE(page);
+		pfn_start = mmd->exclude_pfn_end;
+	}
+
+	/*
 	 * Refresh the buffer of struct page, when changing mem_map.
 	 */
 	pfn_read_start = ULONGLONG_MAX;
@@ -4734,21 +4764,10 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
 		if ((info->dump_level & DL_EXCLUDE_FREE)
 		    && info->page_is_buddy
 		    && info->page_is_buddy(flags, _mapcount, private, _count)) {
-			int i, nr_pages = 1 << private;
+			int nr_pages = 1 << private;
+
+			exclude_range(&pfn_free, mmd, pfn, pfn + nr_pages, cycle);
 
-			for (i = 0; i < nr_pages; ++i) {
-				/*
-				 * According to combination of
-				 * MAX_ORDER and size of cyclic
-				 * buffer, this clearing bit operation
-				 * can overrun the cyclic buffer.
-				 *
-				 * See check_cyclic_buffer_overrun()
-				 * for the detail.
-				 */
-				if (clear_bit_on_2nd_bitmap_for_kernel((pfn + i), cycle))
-					pfn_free++;
-			}
 			pfn += nr_pages - 1;
 			mem_map += (nr_pages - 1) * SIZE(page);
 		}
diff --git a/makedumpfile.h b/makedumpfile.h
index 951ed1b..dfad569 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -816,6 +816,13 @@ struct mem_map_data {
 	unsigned long long	pfn_start;
 	unsigned long long	pfn_end;
 	unsigned long	mem_map;
+
+	/*
+	 * for excluding multi-page regions
+	 */
+	unsigned long		exclude_pfn_start;
+	unsigned long		exclude_pfn_end;
+	unsigned long long	*exclude_pfn_counter;
 };
 
 struct dump_bitmap {
-- 
1.8.4.5


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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[HATAYAMA Daisuke]

From: Petr Tesarik <ptesarik@suse.cz>
Subject: [PATCH v2 2/3] Generic handling of multi-page exclusions
Date: Fri, 4 Apr 2014 19:25:08 +0200

> When multiple pages are excluded from the dump, store the extents in the
> mem_map_data structure, and check if anything is still pending on the
> next invocation of __exclude_unnecessary_pages for the same mem_map.
> 
> The start PFN of the excluded extent is set to the end of the current
> cycle (which is equal to the start of the next cycle, see update_cycle),
> so only the part of the excluded region which falls beyond current cycle
> buffer is valid. If the excluded region is completely processed in the
> current cycle, the start PFN is even bigger than the end PFN. That
> causes nothing to be done at the beginning of the next cycle.
> 
> There is no check whether the adjusted pfn_start is still within the
> current cycle. Nothing bad happens if it isn't, because exclude_range()
> is used again to exclude the remaining part, so even if the excluded
> region happens to span more than two cycles, the code will still work
> correctly.
> 
> Note that clear_bit_on_2nd_bitmap_for_kernel() accepts PFNs outside the
> current cyclic range. It willreturn FALSE, so such PFNs are not counted.
> 
> Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
> ---
>  makedumpfile.c | 47 +++++++++++++++++++++++++++++++++--------------
>  makedumpfile.h |  7 +++++++
>  2 files changed, 40 insertions(+), 14 deletions(-)
> 
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 81c687b..9ffb901 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -2385,6 +2385,9 @@ dump_mem_map(unsigned long long pfn_start,
>  	mmd->pfn_end   = pfn_end;
>  	mmd->mem_map   = mem_map;
>  
> +	mmd->exclude_pfn_start = 0ULL;
> +	mmd->exclude_pfn_end   = 0ULL;
> +
>  	DEBUG_MSG("mem_map (%d)\n", num_mm);
>  	DEBUG_MSG("  mem_map    : %lx\n", mem_map);
>  	DEBUG_MSG("  pfn_start  : %llx\n", pfn_start);
> @@ -4657,6 +4660,21 @@ initialize_2nd_bitmap_cyclic(struct cycle *cycle)
>  	return TRUE;
>  }
>  
> +static void
> +exclude_range(unsigned long long *counter, struct mem_map_data *mmd,
> +    unsigned long long pfn, unsigned long long endpfn, struct cycle *cycle)
> +{
> +	while (pfn < endpfn) {
> +		if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
> +			(*counter)++;
> +		++pfn;
> +	}

Here endpfn is pfn + nr_pages in __exclude_unnecessary_pages(), and
the pfn could be cycle->end_pfn <= pfn < endpfn.

while (pfn < MIN(endpfn, cycle->end_pfn) {
	if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
		(*counter)++;
	++pfn;
}

> +
> +	mmd->exclude_pfn_start = cycle ? cycle->end_pfn : ULONGLONG_MAX;

When does cycle become NULL?

Along with the above point,

mmd->exclude_pfn_start = MIN(endpfn, cycle->end_pfn);

and then we can continue the processing in the next cycle.

> +	mmd->exclude_pfn_end = endpfn;
> +	mmd->exclude_pfn_counter = counter;
> +}
> +
>  int
>  __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>  {
> @@ -4671,6 +4689,18 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>  	unsigned long flags, mapping, private = 0;
>  
>  	/*
> +	 * If a multi-page exclusion is pending, do it first
> +	 */
> +	if (mmd->exclude_pfn_start < mmd->exclude_pfn_end) {
> +		exclude_range(mmd->exclude_pfn_counter, mmd,
> +			mmd->exclude_pfn_start, mmd->exclude_pfn_end,
> +			cycle);
> +
> +		mem_map += (mmd->exclude_pfn_end - pfn_start) * SIZE(page);
> +		pfn_start = mmd->exclude_pfn_end;
> +	}
> +
> +	/*
>  	 * Refresh the buffer of struct page, when changing mem_map.
>  	 */
>  	pfn_read_start = ULONGLONG_MAX;
> @@ -4734,21 +4764,10 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>  		if ((info->dump_level & DL_EXCLUDE_FREE)
>  		    && info->page_is_buddy
>  		    && info->page_is_buddy(flags, _mapcount, private, _count)) {
> -			int i, nr_pages = 1 << private;
> +			int nr_pages = 1 << private;
> +
> +			exclude_range(&pfn_free, mmd, pfn, pfn + nr_pages, cycle);
>  
> -			for (i = 0; i < nr_pages; ++i) {
> -				/*
> -				 * According to combination of
> -				 * MAX_ORDER and size of cyclic
> -				 * buffer, this clearing bit operation
> -				 * can overrun the cyclic buffer.
> -				 *
> -				 * See check_cyclic_buffer_overrun()
> -				 * for the detail.
> -				 */
> -				if (clear_bit_on_2nd_bitmap_for_kernel((pfn + i), cycle))
> -					pfn_free++;
> -			}
>  			pfn += nr_pages - 1;
>  			mem_map += (nr_pages - 1) * SIZE(page);
>  		}
> diff --git a/makedumpfile.h b/makedumpfile.h
> index 951ed1b..dfad569 100644
> --- a/makedumpfile.h
> +++ b/makedumpfile.h
> @@ -816,6 +816,13 @@ struct mem_map_data {
>  	unsigned long long	pfn_start;
>  	unsigned long long	pfn_end;
>  	unsigned long	mem_map;
> +
> +	/*
> +	 * for excluding multi-page regions
> +	 */
> +	unsigned long		exclude_pfn_start;
> +	unsigned long		exclude_pfn_end;

unsigned long long		exclude_pfn_start;
unsigned long long		exclude_pfn_end;

The integers representing page frame numbers need to be defined as
unsigned long long for architectures where physical address can have
64-bit length but unsigned long has 32-bit only, such as x86 PAE.

Kumagai-san, I saw this sometimes in the past. How about introducing
specific abstract type for page frame number like below?

typedef unsigned long long pfn_t;

maybe with some prefix. I think this also helps code readability
because unsigned long long is too long.

> +	unsigned long long	*exclude_pfn_counter;
>  };

Also, it seems to me better to introduce a new type for this
processing rather than extending existing code. struct mem_map_data is
not specific for the excluding processing.


Thanks.
HATAYAMA, Daisuke


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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Petr Tesarik]

On Tue, 08 Apr 2014 10:49:07 +0900 (JST)
HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:

> From: Petr Tesarik <ptesarik@suse.cz>
> Subject: [PATCH v2 2/3] Generic handling of multi-page exclusions
> Date: Fri, 4 Apr 2014 19:25:08 +0200
> 
> > When multiple pages are excluded from the dump, store the extents in the
> > mem_map_data structure, and check if anything is still pending on the
> > next invocation of __exclude_unnecessary_pages for the same mem_map.
> > 
> > The start PFN of the excluded extent is set to the end of the current
> > cycle (which is equal to the start of the next cycle, see update_cycle),
> > so only the part of the excluded region which falls beyond current cycle
> > buffer is valid. If the excluded region is completely processed in the
> > current cycle, the start PFN is even bigger than the end PFN. That
> > causes nothing to be done at the beginning of the next cycle.
> > 
> > There is no check whether the adjusted pfn_start is still within the
> > current cycle. Nothing bad happens if it isn't, because exclude_range()
> > is used again to exclude the remaining part, so even if the excluded
> > region happens to span more than two cycles, the code will still work
> > correctly.
> > 
> > Note that clear_bit_on_2nd_bitmap_for_kernel() accepts PFNs outside the
> > current cyclic range. It willreturn FALSE, so such PFNs are not counted.
> > 
> > Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
> > ---
> >  makedumpfile.c | 47 +++++++++++++++++++++++++++++++++--------------
> >  makedumpfile.h |  7 +++++++
> >  2 files changed, 40 insertions(+), 14 deletions(-)
> > 
> > diff --git a/makedumpfile.c b/makedumpfile.c
> > index 81c687b..9ffb901 100644
> > --- a/makedumpfile.c
> > +++ b/makedumpfile.c
> > @@ -2385,6 +2385,9 @@ dump_mem_map(unsigned long long pfn_start,
> >  	mmd->pfn_end   = pfn_end;
> >  	mmd->mem_map   = mem_map;
> >  
> > +	mmd->exclude_pfn_start = 0ULL;
> > +	mmd->exclude_pfn_end   = 0ULL;
> > +
> >  	DEBUG_MSG("mem_map (%d)\n", num_mm);
> >  	DEBUG_MSG("  mem_map    : %lx\n", mem_map);
> >  	DEBUG_MSG("  pfn_start  : %llx\n", pfn_start);
> > @@ -4657,6 +4660,21 @@ initialize_2nd_bitmap_cyclic(struct cycle *cycle)
> >  	return TRUE;
> >  }
> >  
> > +static void
> > +exclude_range(unsigned long long *counter, struct mem_map_data *mmd,
> > +    unsigned long long pfn, unsigned long long endpfn, struct cycle *cycle)
> > +{
> > +	while (pfn < endpfn) {
> > +		if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
> > +			(*counter)++;
> > +		++pfn;
> > +	}
> 
> Here endpfn is pfn + nr_pages in __exclude_unnecessary_pages(), and
> the pfn could be cycle->end_pfn <= pfn < endpfn.
> 
> while (pfn < MIN(endpfn, cycle->end_pfn) {
> 	if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
> 		(*counter)++;
> 	++pfn;
> }

This is a non-issue: clear_bitmap_cyclic() checks the extents, and I
even mentioned it in the commit message. All right, we can save some
loop iterations by moving the check out of the loop body...

> > +
> > +	mmd->exclude_pfn_start = cycle ? cycle->end_pfn : ULONGLONG_MAX;
> 
> When does cycle become NULL?

When __exclude_unnecessary_pages() is called from
exclude_unnecessary_pages, i.e. non-cyclic.

> Along with the above point,
> 
> mmd->exclude_pfn_start = MIN(endpfn, cycle->end_pfn);
> 
> and then we can continue the processing in the next cycle.

Again, this is a non-issue. These stored extents are validated before
use in __exclude_unnecessary_pages. Why should I check them twice?
And by the way, this is also mentioned in the commit message. 

> > +	mmd->exclude_pfn_end = endpfn;
> > +	mmd->exclude_pfn_counter = counter;
> > +}
> > +
> >  int
> >  __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
> >  {
> > @@ -4671,6 +4689,18 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
> >  	unsigned long flags, mapping, private = 0;
> >  
> >  	/*
> > +	 * If a multi-page exclusion is pending, do it first
> > +	 */
> > +	if (mmd->exclude_pfn_start < mmd->exclude_pfn_end) {
> > +		exclude_range(mmd->exclude_pfn_counter, mmd,
> > +			mmd->exclude_pfn_start, mmd->exclude_pfn_end,
> > +			cycle);
> > +
> > +		mem_map += (mmd->exclude_pfn_end - pfn_start) * SIZE(page);
> > +		pfn_start = mmd->exclude_pfn_end;
> > +	}
> > +
> > +	/*
> >  	 * Refresh the buffer of struct page, when changing mem_map.
> >  	 */
> >  	pfn_read_start = ULONGLONG_MAX;
> > @@ -4734,21 +4764,10 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
> >  		if ((info->dump_level & DL_EXCLUDE_FREE)
> >  		    && info->page_is_buddy
> >  		    && info->page_is_buddy(flags, _mapcount, private, _count)) {
> > -			int i, nr_pages = 1 << private;
> > +			int nr_pages = 1 << private;
> > +
> > +			exclude_range(&pfn_free, mmd, pfn, pfn + nr_pages, cycle);
> >  
> > -			for (i = 0; i < nr_pages; ++i) {
> > -				/*
> > -				 * According to combination of
> > -				 * MAX_ORDER and size of cyclic
> > -				 * buffer, this clearing bit operation
> > -				 * can overrun the cyclic buffer.
> > -				 *
> > -				 * See check_cyclic_buffer_overrun()
> > -				 * for the detail.
> > -				 */
> > -				if (clear_bit_on_2nd_bitmap_for_kernel((pfn + i), cycle))
> > -					pfn_free++;
> > -			}
> >  			pfn += nr_pages - 1;
> >  			mem_map += (nr_pages - 1) * SIZE(page);
> >  		}
> > diff --git a/makedumpfile.h b/makedumpfile.h
> > index 951ed1b..dfad569 100644
> > --- a/makedumpfile.h
> > +++ b/makedumpfile.h
> > @@ -816,6 +816,13 @@ struct mem_map_data {
> >  	unsigned long long	pfn_start;
> >  	unsigned long long	pfn_end;
> >  	unsigned long	mem_map;
> > +
> > +	/*
> > +	 * for excluding multi-page regions
> > +	 */
> > +	unsigned long		exclude_pfn_start;
> > +	unsigned long		exclude_pfn_end;
> 
> unsigned long long		exclude_pfn_start;
> unsigned long long		exclude_pfn_end;
> 
> The integers representing page frame numbers need to be defined as
> unsigned long long for architectures where physical address can have
> 64-bit length but unsigned long has 32-bit only, such as x86 PAE.

Ouch. My mistake. I thought I covered all places, but somehow I
missed this one. I'm going to post a fixed series.

> Kumagai-san, I saw this sometimes in the past. How about introducing
> specific abstract type for page frame number like below?
> 
> typedef unsigned long long pfn_t;
> 
> maybe with some prefix. I think this also helps code readability
> because unsigned long long is too long.
> 
> > +	unsigned long long	*exclude_pfn_counter;
> >  };
> 
> Also, it seems to me better to introduce a new type for this
> processing rather than extending existing code. struct mem_map_data is
> not specific for the excluding processing.

Kind of agreed. OTOH it will most likely be embedded in struct
mem_map_data anyway, because exactly one such object per mm is needed.

Petr T

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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[HATAYAMA Daisuke]

From: Petr Tesarik <ptesarik@suse.cz>
Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
Date: Tue, 8 Apr 2014 08:54:36 +0200

> On Tue, 08 Apr 2014 10:49:07 +0900 (JST)
> HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:
> 
>> From: Petr Tesarik <ptesarik@suse.cz>
>> Subject: [PATCH v2 2/3] Generic handling of multi-page exclusions
>> Date: Fri, 4 Apr 2014 19:25:08 +0200
>> 
>> > When multiple pages are excluded from the dump, store the extents in the
>> > mem_map_data structure, and check if anything is still pending on the
>> > next invocation of __exclude_unnecessary_pages for the same mem_map.
>> > 
>> > The start PFN of the excluded extent is set to the end of the current
>> > cycle (which is equal to the start of the next cycle, see update_cycle),
>> > so only the part of the excluded region which falls beyond current cycle
>> > buffer is valid. If the excluded region is completely processed in the
>> > current cycle, the start PFN is even bigger than the end PFN. That
>> > causes nothing to be done at the beginning of the next cycle.
>> > 
>> > There is no check whether the adjusted pfn_start is still within the
>> > current cycle. Nothing bad happens if it isn't, because exclude_range()
>> > is used again to exclude the remaining part, so even if the excluded
>> > region happens to span more than two cycles, the code will still work
>> > correctly.
>> > 
>> > Note that clear_bit_on_2nd_bitmap_for_kernel() accepts PFNs outside the
>> > current cyclic range. It willreturn FALSE, so such PFNs are not counted.
>> > 
>> > Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
>> > ---
>> >  makedumpfile.c | 47 +++++++++++++++++++++++++++++++++--------------
>> >  makedumpfile.h |  7 +++++++
>> >  2 files changed, 40 insertions(+), 14 deletions(-)
>> > 
>> > diff --git a/makedumpfile.c b/makedumpfile.c
>> > index 81c687b..9ffb901 100644
>> > --- a/makedumpfile.c
>> > +++ b/makedumpfile.c
>> > @@ -2385,6 +2385,9 @@ dump_mem_map(unsigned long long pfn_start,
>> >  	mmd->pfn_end   = pfn_end;
>> >  	mmd->mem_map   = mem_map;
>> >  
>> > +	mmd->exclude_pfn_start = 0ULL;
>> > +	mmd->exclude_pfn_end   = 0ULL;
>> > +
>> >  	DEBUG_MSG("mem_map (%d)\n", num_mm);
>> >  	DEBUG_MSG("  mem_map    : %lx\n", mem_map);
>> >  	DEBUG_MSG("  pfn_start  : %llx\n", pfn_start);
>> > @@ -4657,6 +4660,21 @@ initialize_2nd_bitmap_cyclic(struct cycle *cycle)
>> >  	return TRUE;
>> >  }
>> >  
>> > +static void
>> > +exclude_range(unsigned long long *counter, struct mem_map_data *mmd,
>> > +    unsigned long long pfn, unsigned long long endpfn, struct cycle *cycle)
>> > +{
>> > +	while (pfn < endpfn) {
>> > +		if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
>> > +			(*counter)++;
>> > +		++pfn;
>> > +	}
>> 
>> Here endpfn is pfn + nr_pages in __exclude_unnecessary_pages(), and
>> the pfn could be cycle->end_pfn <= pfn < endpfn.
>> 
>> while (pfn < MIN(endpfn, cycle->end_pfn) {
>> 	if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
>> 		(*counter)++;
>> 	++pfn;
>> }
> 
> This is a non-issue: clear_bitmap_cyclic() checks the extents, and I
> even mentioned it in the commit message. All right, we can save some
> loop iterations by moving the check out of the loop body...
> 

Ah, OK, I interpreted somehow your code like:

+	mmd->exclude_pfn_start = cycle ? endpfn: ULONGLONG_MAX;

So there's no logically wrong point.

BTW, hmm, the behaviour of clear_bit_on_2nd_bitmap_for_kernel() is not
what I expect, that is, I don't expect sanity check in
set_bitmap_cyclic(), which should have been removed by clean up we did
some times ago.

int
set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val, struct cycle *cycle)
{
        int byte, bit;

        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn) <-- this
                return FALSE;

The code some time ago changes region of cycles in many places and it
was difficult to figure out. So, in the clean up, we introduced struct
cycle and for_each_cycle() to obtain invariance that cycle is not
changed under for_each_cycle().

So, could you fix also this if possible?

>> > +
>> > +	mmd->exclude_pfn_start = cycle ? cycle->end_pfn : ULONGLONG_MAX;
>> 
>> When does cycle become NULL?
> 
> When __exclude_unnecessary_pages() is called from
> exclude_unnecessary_pages, i.e. non-cyclic.
> 
>> Along with the above point,
>> 
>> mmd->exclude_pfn_start = MIN(endpfn, cycle->end_pfn);
>> 
>> and then we can continue the processing in the next cycle.
> 
> Again, this is a non-issue. These stored extents are validated before
> use in __exclude_unnecessary_pages. Why should I check them twice?
> And by the way, this is also mentioned in the commit message. 
> 
>> > +	mmd->exclude_pfn_end = endpfn;
>> > +	mmd->exclude_pfn_counter = counter;
>> > +}
>> > +
>> >  int
>> >  __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>> >  {
>> > @@ -4671,6 +4689,18 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>> >  	unsigned long flags, mapping, private = 0;
>> >  
>> >  	/*
>> > +	 * If a multi-page exclusion is pending, do it first
>> > +	 */
>> > +	if (mmd->exclude_pfn_start < mmd->exclude_pfn_end) {
>> > +		exclude_range(mmd->exclude_pfn_counter, mmd,
>> > +			mmd->exclude_pfn_start, mmd->exclude_pfn_end,
>> > +			cycle);
>> > +
>> > +		mem_map += (mmd->exclude_pfn_end - pfn_start) * SIZE(page);
>> > +		pfn_start = mmd->exclude_pfn_end;
>> > +	}
>> > +
>> > +	/*
>> >  	 * Refresh the buffer of struct page, when changing mem_map.
>> >  	 */
>> >  	pfn_read_start = ULONGLONG_MAX;
>> > @@ -4734,21 +4764,10 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>> >  		if ((info->dump_level & DL_EXCLUDE_FREE)
>> >  		    && info->page_is_buddy
>> >  		    && info->page_is_buddy(flags, _mapcount, private, _count)) {
>> > -			int i, nr_pages = 1 << private;
>> > +			int nr_pages = 1 << private;
>> > +
>> > +			exclude_range(&pfn_free, mmd, pfn, pfn + nr_pages, cycle);
>> >  
>> > -			for (i = 0; i < nr_pages; ++i) {
>> > -				/*
>> > -				 * According to combination of
>> > -				 * MAX_ORDER and size of cyclic
>> > -				 * buffer, this clearing bit operation
>> > -				 * can overrun the cyclic buffer.
>> > -				 *
>> > -				 * See check_cyclic_buffer_overrun()
>> > -				 * for the detail.
>> > -				 */
>> > -				if (clear_bit_on_2nd_bitmap_for_kernel((pfn + i), cycle))
>> > -					pfn_free++;
>> > -			}
>> >  			pfn += nr_pages - 1;
>> >  			mem_map += (nr_pages - 1) * SIZE(page);
>> >  		}
>> > diff --git a/makedumpfile.h b/makedumpfile.h
>> > index 951ed1b..dfad569 100644
>> > --- a/makedumpfile.h
>> > +++ b/makedumpfile.h
>> > @@ -816,6 +816,13 @@ struct mem_map_data {
>> >  	unsigned long long	pfn_start;
>> >  	unsigned long long	pfn_end;
>> >  	unsigned long	mem_map;
>> > +
>> > +	/*
>> > +	 * for excluding multi-page regions
>> > +	 */
>> > +	unsigned long		exclude_pfn_start;
>> > +	unsigned long		exclude_pfn_end;
>> 
>> unsigned long long		exclude_pfn_start;
>> unsigned long long		exclude_pfn_end;
>> 
>> The integers representing page frame numbers need to be defined as
>> unsigned long long for architectures where physical address can have
>> 64-bit length but unsigned long has 32-bit only, such as x86 PAE.
> 
> Ouch. My mistake. I thought I covered all places, but somehow I
> missed this one. I'm going to post a fixed series.
> 
>> Kumagai-san, I saw this sometimes in the past. How about introducing
>> specific abstract type for page frame number like below?
>> 
>> typedef unsigned long long pfn_t;
>> 
>> maybe with some prefix. I think this also helps code readability
>> because unsigned long long is too long.
>> 
>> > +	unsigned long long	*exclude_pfn_counter;
>> >  };
>> 
>> Also, it seems to me better to introduce a new type for this
>> processing rather than extending existing code. struct mem_map_data is
>> not specific for the excluding processing.
> 
> Kind of agreed. OTOH it will most likely be embedded in struct
> mem_map_data anyway, because exactly one such object per mm is needed.
> 
> Petr T

I don't understand well. It seems to me a single object is enough. Is
it possible to nr_pages cover multiple mm's?

Thanks.
HATAYAMA, Daisuke


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RE: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Atsushi Kumagai]

>From: Petr Tesarik <ptesarik@suse.cz>
>Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
>Date: Tue, 8 Apr 2014 08:54:36 +0200
>
>> On Tue, 08 Apr 2014 10:49:07 +0900 (JST)
>> HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:
>>
>>> From: Petr Tesarik <ptesarik@suse.cz>
>>> Subject: [PATCH v2 2/3] Generic handling of multi-page exclusions
>>> Date: Fri, 4 Apr 2014 19:25:08 +0200
>>>
>>> > When multiple pages are excluded from the dump, store the extents in the
>>> > mem_map_data structure, and check if anything is still pending on the
>>> > next invocation of __exclude_unnecessary_pages for the same mem_map.
>>> >
>>> > The start PFN of the excluded extent is set to the end of the current
>>> > cycle (which is equal to the start of the next cycle, see update_cycle),
>>> > so only the part of the excluded region which falls beyond current cycle
>>> > buffer is valid. If the excluded region is completely processed in the
>>> > current cycle, the start PFN is even bigger than the end PFN. That
>>> > causes nothing to be done at the beginning of the next cycle.
>>> >
>>> > There is no check whether the adjusted pfn_start is still within the
>>> > current cycle. Nothing bad happens if it isn't, because exclude_range()
>>> > is used again to exclude the remaining part, so even if the excluded
>>> > region happens to span more than two cycles, the code will still work
>>> > correctly.
>>> >
>>> > Note that clear_bit_on_2nd_bitmap_for_kernel() accepts PFNs outside the
>>> > current cyclic range. It willreturn FALSE, so such PFNs are not counted.
>>> >
>>> > Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
>>> > ---
>>> >  makedumpfile.c | 47 +++++++++++++++++++++++++++++++++--------------
>>> >  makedumpfile.h |  7 +++++++
>>> >  2 files changed, 40 insertions(+), 14 deletions(-)
>>> >
>>> > diff --git a/makedumpfile.c b/makedumpfile.c
>>> > index 81c687b..9ffb901 100644
>>> > --- a/makedumpfile.c
>>> > +++ b/makedumpfile.c
>>> > @@ -2385,6 +2385,9 @@ dump_mem_map(unsigned long long pfn_start,
>>> >  	mmd->pfn_end   = pfn_end;
>>> >  	mmd->mem_map   = mem_map;
>>> >
>>> > +	mmd->exclude_pfn_start = 0ULL;
>>> > +	mmd->exclude_pfn_end   = 0ULL;
>>> > +
>>> >  	DEBUG_MSG("mem_map (%d)\n", num_mm);
>>> >  	DEBUG_MSG("  mem_map    : %lx\n", mem_map);
>>> >  	DEBUG_MSG("  pfn_start  : %llx\n", pfn_start);
>>> > @@ -4657,6 +4660,21 @@ initialize_2nd_bitmap_cyclic(struct cycle *cycle)
>>> >  	return TRUE;
>>> >  }
>>> >
>>> > +static void
>>> > +exclude_range(unsigned long long *counter, struct mem_map_data *mmd,
>>> > +    unsigned long long pfn, unsigned long long endpfn, struct cycle *cycle)
>>> > +{
>>> > +	while (pfn < endpfn) {
>>> > +		if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
>>> > +			(*counter)++;
>>> > +		++pfn;
>>> > +	}
>>>
>>> Here endpfn is pfn + nr_pages in __exclude_unnecessary_pages(), and
>>> the pfn could be cycle->end_pfn <= pfn < endpfn.
>>>
>>> while (pfn < MIN(endpfn, cycle->end_pfn) {
>>> 	if (clear_bit_on_2nd_bitmap_for_kernel(pfn, cycle))
>>> 		(*counter)++;
>>> 	++pfn;
>>> }
>>
>> This is a non-issue: clear_bitmap_cyclic() checks the extents, and I
>> even mentioned it in the commit message. All right, we can save some
>> loop iterations by moving the check out of the loop body...
>>
>
>Ah, OK, I interpreted somehow your code like:
>
>+	mmd->exclude_pfn_start = cycle ? endpfn: ULONGLONG_MAX;
>
>So there's no logically wrong point.
>
>BTW, hmm, the behaviour of clear_bit_on_2nd_bitmap_for_kernel() is not
>what I expect, that is, I don't expect sanity check in
>set_bitmap_cyclic(), which should have been removed by clean up we did
>some times ago.

At that time, I chose the current code since it was simpler and safer.
http://www.mail-archive.com/kexec%40lists.infradead.org/msg10207.html

Don't you like this ?


Thanks
Atsushi Kumagai

>int
>set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val, struct cycle *cycle)
>{
>        int byte, bit;
>
>        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn) <-- this
>                return FALSE;
>
>The code some time ago changes region of cycles in many places and it
>was difficult to figure out. So, in the clean up, we introduced struct
>cycle and for_each_cycle() to obtain invariance that cycle is not
>changed under for_each_cycle().
>
>So, could you fix also this if possible?
>
>>> > +
>>> > +	mmd->exclude_pfn_start = cycle ? cycle->end_pfn : ULONGLONG_MAX;
>>>
>>> When does cycle become NULL?
>>
>> When __exclude_unnecessary_pages() is called from
>> exclude_unnecessary_pages, i.e. non-cyclic.
>>
>>> Along with the above point,
>>>
>>> mmd->exclude_pfn_start = MIN(endpfn, cycle->end_pfn);
>>>
>>> and then we can continue the processing in the next cycle.
>>
>> Again, this is a non-issue. These stored extents are validated before
>> use in __exclude_unnecessary_pages. Why should I check them twice?
>> And by the way, this is also mentioned in the commit message.
>>
>>> > +	mmd->exclude_pfn_end = endpfn;
>>> > +	mmd->exclude_pfn_counter = counter;
>>> > +}
>>> > +
>>> >  int
>>> >  __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>>> >  {
>>> > @@ -4671,6 +4689,18 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>>> >  	unsigned long flags, mapping, private = 0;
>>> >
>>> >  	/*
>>> > +	 * If a multi-page exclusion is pending, do it first
>>> > +	 */
>>> > +	if (mmd->exclude_pfn_start < mmd->exclude_pfn_end) {
>>> > +		exclude_range(mmd->exclude_pfn_counter, mmd,
>>> > +			mmd->exclude_pfn_start, mmd->exclude_pfn_end,
>>> > +			cycle);
>>> > +
>>> > +		mem_map += (mmd->exclude_pfn_end - pfn_start) * SIZE(page);
>>> > +		pfn_start = mmd->exclude_pfn_end;
>>> > +	}
>>> > +
>>> > +	/*
>>> >  	 * Refresh the buffer of struct page, when changing mem_map.
>>> >  	 */
>>> >  	pfn_read_start = ULONGLONG_MAX;
>>> > @@ -4734,21 +4764,10 @@ __exclude_unnecessary_pages(struct mem_map_data *mmd, struct cycle *cycle)
>>> >  		if ((info->dump_level & DL_EXCLUDE_FREE)
>>> >  		    && info->page_is_buddy
>>> >  		    && info->page_is_buddy(flags, _mapcount, private, _count)) {
>>> > -			int i, nr_pages = 1 << private;
>>> > +			int nr_pages = 1 << private;
>>> > +
>>> > +			exclude_range(&pfn_free, mmd, pfn, pfn + nr_pages, cycle);
>>> >
>>> > -			for (i = 0; i < nr_pages; ++i) {
>>> > -				/*
>>> > -				 * According to combination of
>>> > -				 * MAX_ORDER and size of cyclic
>>> > -				 * buffer, this clearing bit operation
>>> > -				 * can overrun the cyclic buffer.
>>> > -				 *
>>> > -				 * See check_cyclic_buffer_overrun()
>>> > -				 * for the detail.
>>> > -				 */
>>> > -				if (clear_bit_on_2nd_bitmap_for_kernel((pfn + i), cycle))
>>> > -					pfn_free++;
>>> > -			}
>>> >  			pfn += nr_pages - 1;
>>> >  			mem_map += (nr_pages - 1) * SIZE(page);
>>> >  		}
>>> > diff --git a/makedumpfile.h b/makedumpfile.h
>>> > index 951ed1b..dfad569 100644
>>> > --- a/makedumpfile.h
>>> > +++ b/makedumpfile.h
>>> > @@ -816,6 +816,13 @@ struct mem_map_data {
>>> >  	unsigned long long	pfn_start;
>>> >  	unsigned long long	pfn_end;
>>> >  	unsigned long	mem_map;
>>> > +
>>> > +	/*
>>> > +	 * for excluding multi-page regions
>>> > +	 */
>>> > +	unsigned long		exclude_pfn_start;
>>> > +	unsigned long		exclude_pfn_end;
>>>
>>> unsigned long long		exclude_pfn_start;
>>> unsigned long long		exclude_pfn_end;
>>>
>>> The integers representing page frame numbers need to be defined as
>>> unsigned long long for architectures where physical address can have
>>> 64-bit length but unsigned long has 32-bit only, such as x86 PAE.
>>
>> Ouch. My mistake. I thought I covered all places, but somehow I
>> missed this one. I'm going to post a fixed series.
>>
>>> Kumagai-san, I saw this sometimes in the past. How about introducing
>>> specific abstract type for page frame number like below?
>>>
>>> typedef unsigned long long pfn_t;
>>>
>>> maybe with some prefix. I think this also helps code readability
>>> because unsigned long long is too long.
>>>
>>> > +	unsigned long long	*exclude_pfn_counter;
>>> >  };
>>>
>>> Also, it seems to me better to introduce a new type for this
>>> processing rather than extending existing code. struct mem_map_data is
>>> not specific for the excluding processing.
>>
>> Kind of agreed. OTOH it will most likely be embedded in struct
>> mem_map_data anyway, because exactly one such object per mm is needed.
>>
>> Petr T
>
>I don't understand well. It seems to me a single object is enough. Is
>it possible to nr_pages cover multiple mm's?
>
>Thanks.
>HATAYAMA, Daisuke


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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[HATAYAMA Daisuke]

From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Subject: RE: [PATCH v2 2/3] Generic handling of multi-page exclusions
Date: Tue, 8 Apr 2014 09:00:19 +0000

> 
> At that time, I chose the current code since it was simpler and safer.
> http://www.mail-archive.com/kexec%40lists.infradead.org/msg10207.html
> 
> Don't you like this ?
> 

Sorry. I had forgotten this. We should keep the sanity check
there. But in our policy, we should not pass to set_bitmap_cyclic(),
pfn and cycle where pfn is not in the cycle. We should chceck that in
the caller side and pass pfn in the cycle only.

Also, on the current implementation, even if pfn outside a current
cycle is passed to set_bitmap_cyclic(), we don't have any means to
know that.

So, how about warning that only once at runtime?

Thanks.
HATAYAMA, Daisuke


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RE: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Atsushi Kumagai]

>> At that time, I chose the current code since it was simpler and safer.
>> http://www.mail-archive.com/kexec%40lists.infradead.org/msg10207.html
>>
>> Don't you like this ?
>>
>
>Sorry. I had forgotten this. We should keep the sanity check
>there. But in our policy, we should not pass to set_bitmap_cyclic(),
>pfn and cycle where pfn is not in the cycle. We should chceck that in
>the caller side and pass pfn in the cycle only.
>
>Also, on the current implementation, even if pfn outside a current
>cycle is passed to set_bitmap_cyclic(), we don't have any means to
>know that.
>
>So, how about warning that only once at runtime?

Sounds good, it will be helpful to detect bugs in caller side.
Like this?

diff --git a/makedumpfile.c b/makedumpfile.c
index 75092a8..da960ad 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -3361,9 +3361,16 @@ int
 set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val, struct cycle *cycle)
 {
 	int byte, bit;
+	static int warning = 0;
 
-        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn)
+        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn) {
+		if (!warning) {
+			MSG("WARNING: PFN out of cycle range. (pfn:%llx, ", pfn);
+			MSG("cycle:[%llx-%llx])\n", cycle->start_pfn, cycle->end_pfn);
+			warning = 1;
+		}
                 return FALSE;
+	}
 
 	/*
 	 * If val is 0, clear bit on the bitmap.


Thanks
Atsushi Kumagai

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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[HATAYAMA Daisuke]

From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Subject: RE: [PATCH v2 2/3] Generic handling of multi-page exclusions
Date: Tue, 15 Apr 2014 04:18:31 +0000

>>> At that time, I chose the current code since it was simpler and safer.
>>> http://www.mail-archive.com/kexec%40lists.infradead.org/msg10207.html
>>>
>>> Don't you like this ?
>>>
>>
>>Sorry. I had forgotten this. We should keep the sanity check
>>there. But in our policy, we should not pass to set_bitmap_cyclic(),
>>pfn and cycle where pfn is not in the cycle. We should chceck that in
>>the caller side and pass pfn in the cycle only.
>>
>>Also, on the current implementation, even if pfn outside a current
>>cycle is passed to set_bitmap_cyclic(), we don't have any means to
>>know that.
>>
>>So, how about warning that only once at runtime?
> 
> Sounds good, it will be helpful to detect bugs in caller side.
> Like this?
> 
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 75092a8..da960ad 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -3361,9 +3361,16 @@ int
>  set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val, struct cycle *cycle)
>  {
>  	int byte, bit;
> +	static int warning = 0;
>  
> -        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn)
> +        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn) {
> +		if (!warning) {
> +			MSG("WARNING: PFN out of cycle range. (pfn:%llx, ", pfn);
> +			MSG("cycle:[%llx-%llx])\n", cycle->start_pfn, cycle->end_pfn);
> +			warning = 1;
> +		}
>                  return FALSE;
> +	}
>  
>  	/*
>  	 * If val is 0, clear bit on the bitmap.
> 

Yes, I thought this logic.

--
Thanks.
HATAYAMA, Daisuke


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RE: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Atsushi Kumagai]

>From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
>Subject: RE: [PATCH v2 2/3] Generic handling of multi-page exclusions
>Date: Tue, 15 Apr 2014 04:18:31 +0000
>
>>>> At that time, I chose the current code since it was simpler and safer.
>>>> http://www.mail-archive.com/kexec%40lists.infradead.org/msg10207.html
>>>>
>>>> Don't you like this ?
>>>>
>>>
>>>Sorry. I had forgotten this. We should keep the sanity check
>>>there. But in our policy, we should not pass to set_bitmap_cyclic(),
>>>pfn and cycle where pfn is not in the cycle. We should chceck that in
>>>the caller side and pass pfn in the cycle only.
>>>
>>>Also, on the current implementation, even if pfn outside a current
>>>cycle is passed to set_bitmap_cyclic(), we don't have any means to
>>>know that.
>>>
>>>So, how about warning that only once at runtime?
>>
>> Sounds good, it will be helpful to detect bugs in caller side.
>> Like this?
>>
>> diff --git a/makedumpfile.c b/makedumpfile.c
>> index 75092a8..da960ad 100644
>> --- a/makedumpfile.c
>> +++ b/makedumpfile.c
>> @@ -3361,9 +3361,16 @@ int
>>  set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val, struct cycle *cycle)
>>  {
>>  	int byte, bit;
>> +	static int warning = 0;
>>
>> -        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn)
>> +        if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn) {
>> +		if (!warning) {
>> +			MSG("WARNING: PFN out of cycle range. (pfn:%llx, ", pfn);
>> +			MSG("cycle:[%llx-%llx])\n", cycle->start_pfn, cycle->end_pfn);
>> +			warning = 1;
>> +		}
>>                  return FALSE;
>> +	}
>>
>>  	/*
>>  	 * If val is 0, clear bit on the bitmap.
>>
>
>Yes, I thought this logic.

Thanks, I've pushed this into devel branch.

Atsushi Kumagai

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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Petr Tesarik]

On Tue, 08 Apr 2014 17:19:03 +0900 (JST)
HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:

> From: Petr Tesarik <ptesarik@suse.cz>
> Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
> Date: Tue, 8 Apr 2014 08:54:36 +0200
> 
> > On Tue, 08 Apr 2014 10:49:07 +0900 (JST)
> > HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:
> >> 
> >> Also, it seems to me better to introduce a new type for this
> >> processing rather than extending existing code. struct mem_map_data is
> >> not specific for the excluding processing.
> > 
> > Kind of agreed. OTOH it will most likely be embedded in struct
> > mem_map_data anyway, because exactly one such object per mm is needed.
> > 
> > Petr T
> 
> I don't understand well. It seems to me a single object is enough. Is
> it possible to nr_pages cover multiple mm's?

In fact, I believe it may be sufficient, but the loop nesting is like
this (pseudo-code):

  for each cycle:
    for each mm:
       call __exclude_unnecessary_pages

I'm not 100% sure that the region cannot change back and forth between
two consecutive calls to __exclude_unnecessary_pages.

Thinking about it some more, this can be harmful only if there are
overlapping memory maps... Can it happen, or can I safely ignore this
possibility?

Petr T

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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[HATAYAMA Daisuke]

From: Petr Tesarik <ptesarik@suse.cz>
Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
Date: Tue, 8 Apr 2014 12:07:28 +0200

> On Tue, 08 Apr 2014 17:19:03 +0900 (JST)
> HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:
> 
>> From: Petr Tesarik <ptesarik@suse.cz>
>> Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
>> Date: Tue, 8 Apr 2014 08:54:36 +0200
>> 
>> > On Tue, 08 Apr 2014 10:49:07 +0900 (JST)
>> > HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> wrote:
>> >> 
>> >> Also, it seems to me better to introduce a new type for this
>> >> processing rather than extending existing code. struct mem_map_data is
>> >> not specific for the excluding processing.
>> > 
>> > Kind of agreed. OTOH it will most likely be embedded in struct
>> > mem_map_data anyway, because exactly one such object per mm is needed.
>> > 
>> > Petr T
>> 
>> I don't understand well. It seems to me a single object is enough. Is
>> it possible to nr_pages cover multiple mm's?
> 
> In fact, I believe it may be sufficient, but the loop nesting is like
> this (pseudo-code):
> 
>   for each cycle:
>     for each mm:
>        call __exclude_unnecessary_pages
> 
> I'm not 100% sure that the region cannot change back and forth between
> two consecutive calls to __exclude_unnecessary_pages.
> 
> Thinking about it some more, this can be harmful only if there are
> overlapping memory maps... Can it happen, or can I safely ignore this
> possibility?
> 
> Petr T

The list of mm is sorted and not overlapping. See get_mm_sparsemem(),
get_mm_sparsemem(), get_mm_discontigmem() and get_mm_flatmem() from
get_mem_map(). In particular, in get_mm_discontigmem(), sorting and
removing overlapping portions are done explicitly.

Thanks.
HATAYAMA, Daisuke


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RE: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Atsushi Kumagai]

[...]
> diff --git a/makedumpfile.h b/makedumpfile.h
>> index 951ed1b..dfad569 100644
>> --- a/makedumpfile.h
>> +++ b/makedumpfile.h
>> @@ -816,6 +816,13 @@ struct mem_map_data {
>>  	unsigned long long	pfn_start;
>>  	unsigned long long	pfn_end;
>>  	unsigned long	mem_map;
>> +
>> +	/*
>> +	 * for excluding multi-page regions
>> +	 */
>> +	unsigned long		exclude_pfn_start;
>> +	unsigned long		exclude_pfn_end;
>
>unsigned long long		exclude_pfn_start;
>unsigned long long		exclude_pfn_end;
>
>The integers representing page frame numbers need to be defined as
>unsigned long long for architectures where physical address can have
>64-bit length but unsigned long has 32-bit only, such as x86 PAE.
>
>Kumagai-san, I saw this sometimes in the past. How about introducing
>specific abstract type for page frame number like below?
>
>typedef unsigned long long pfn_t;

Good idea! We should do it.

>maybe with some prefix. I think this also helps code readability
>because unsigned long long is too long.
>
>> +	unsigned long long	*exclude_pfn_counter;
>>  };
>
>Also, it seems to me better to introduce a new type for this
>processing rather than extending existing code. struct mem_map_data is
>not specific for the excluding processing.

I agree, too.


Thanks
Atsushi Kumagai

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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Petr Tesarik]

On Tue, 8 Apr 2014 07:06:34 +0000
Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> wrote:

> [...]
> > diff --git a/makedumpfile.h b/makedumpfile.h
> >> index 951ed1b..dfad569 100644
> >> --- a/makedumpfile.h
> >> +++ b/makedumpfile.h
> >> @@ -816,6 +816,13 @@ struct mem_map_data {
> >>  	unsigned long long	pfn_start;
> >>  	unsigned long long	pfn_end;
> >>  	unsigned long	mem_map;
> >> +
> >> +	/*
> >> +	 * for excluding multi-page regions
> >> +	 */
> >> +	unsigned long		exclude_pfn_start;
> >> +	unsigned long		exclude_pfn_end;
> >
> >unsigned long long		exclude_pfn_start;
> >unsigned long long		exclude_pfn_end;
> >
> >The integers representing page frame numbers need to be defined as
> >unsigned long long for architectures where physical address can have
> >64-bit length but unsigned long has 32-bit only, such as x86 PAE.
> >
> >Kumagai-san, I saw this sometimes in the past. How about introducing
> >specific abstract type for page frame number like below?
> >
> >typedef unsigned long long pfn_t;
> 
> Good idea! We should do it.

Like the following patch?

From 9f3f6876bf1e8c93690097c510dff9982651bfa5 Mon Sep 17 00:00:00 2001
From: Petr Tesarik <ptesarik@suse.cz>
Date: Thu, 10 Apr 2014 12:40:31 +0200
Subject: [PATCH] Introduce the pfn_t type

Replace unsigned long long with pfn_t where:

  a. the variable denotes a PFN
  b. the variable is a number of pages

The number of pages is converted to a pfn_t, because it is a result of
subtracting two PFNs or incremented in a loop over a range of PFNs, so
it can get as large as a PFN.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
---
 makedumpfile.c | 151 +++++++++++++++++++++++++++++----------------------------
 makedumpfile.h |  46 +++++++++---------
 sadump_info.c  |  15 +++---
 sadump_info.h  |   4 +-
 4 files changed, 113 insertions(+), 103 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 75092a8..c4a6a96 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -37,7 +37,7 @@ struct DumpInfo		*info = NULL;
 
 char filename_stdout[] = FILENAME_STDOUT;
 
-static void first_cycle(unsigned long long start, unsigned long long max, struct cycle *cycle)
+static void first_cycle(pfn_t start, pfn_t max, struct cycle *cycle)
 {
 	cycle->start_pfn = round(start, info->pfn_cyclic);
 	cycle->end_pfn = cycle->start_pfn + info->pfn_cyclic;
@@ -46,7 +46,7 @@ static void first_cycle(unsigned long long start, unsigned long long max, struct
 		cycle->end_pfn = max;
 }
 
-static void update_cycle(unsigned long long max, struct cycle *cycle)
+static void update_cycle(pfn_t max, struct cycle *cycle)
 {
 	cycle->start_pfn= cycle->end_pfn;
 	cycle->end_pfn=  cycle->start_pfn + info->pfn_cyclic;
@@ -55,7 +55,7 @@ static void update_cycle(unsigned long long max, struct cycle *cycle)
 		cycle->end_pfn = max;
 }
 
-static int end_cycle(unsigned long long max, struct cycle *cycle)
+static int end_cycle(pfn_t max, struct cycle *cycle)
 {
 	return (cycle->start_pfn >=  max)?TRUE:FALSE;
 }
@@ -67,15 +67,15 @@ static int end_cycle(unsigned long long max, struct cycle *cycle)
 /*
  * The numbers of the excluded pages
  */
-unsigned long long pfn_zero;
-unsigned long long pfn_memhole;
-unsigned long long pfn_cache;
-unsigned long long pfn_cache_private;
-unsigned long long pfn_user;
-unsigned long long pfn_free;
-unsigned long long pfn_hwpoison;
+pfn_t pfn_zero;
+pfn_t pfn_memhole;
+pfn_t pfn_cache;
+pfn_t pfn_cache_private;
+pfn_t pfn_user;
+pfn_t pfn_free;
+pfn_t pfn_hwpoison;
 
-unsigned long long num_dumped;
+pfn_t num_dumped;
 
 int retcd = FAILED;	/* return code */
 
@@ -122,7 +122,9 @@ unsigned long long
 ptom_xen(unsigned long long paddr)
 {
 	unsigned long mfn;
-	unsigned long long maddr, pfn, mfn_idx, frame_idx;
+	unsigned long long maddr;
+	pfn_t pfn;
+	unsigned long long mfn_idx, frame_idx;
 
 	pfn = paddr_to_pfn(paddr);
 	mfn_idx   = pfn / MFNS_PER_FRAME;
@@ -226,12 +228,13 @@ is_in_same_page(unsigned long vaddr1, unsigned long vaddr2)
 }
 
 #define BITMAP_SECT_LEN 4096
-static inline int is_dumpable(struct dump_bitmap *, unsigned long long);
-static inline int is_dumpable_cyclic(char *bitmap, unsigned long long, struct cycle *cycle);
+static inline int is_dumpable(struct dump_bitmap *, pfn_t);
+static inline int is_dumpable_cyclic(char *bitmap, pfn_t, struct cycle *cycle);
 unsigned long
-pfn_to_pos(unsigned long long pfn)
+pfn_to_pos(pfn_t pfn)
 {
-	unsigned long desc_pos, i;
+	unsigned long desc_pos;
+	pfn_t i;
 
 	desc_pos = info->valid_pages[pfn / BITMAP_SECT_LEN];
 	for (i = round(pfn, BITMAP_SECT_LEN); i < pfn; i++)
@@ -246,7 +249,7 @@ read_page_desc(unsigned long long paddr, page_desc_t *pd)
 {
 	struct disk_dump_header *dh;
 	unsigned long desc_pos;
-	unsigned long long pfn;
+	pfn_t pfn;
 	off_t offset;
 
 	/*
@@ -2375,8 +2378,7 @@ pgdat4:
 }
 
 void
-dump_mem_map(unsigned long long pfn_start,
-    unsigned long long pfn_end, unsigned long mem_map, int num_mm)
+dump_mem_map(pfn_t pfn_start, pfn_t pfn_end, unsigned long mem_map, int num_mm)
 {
 	struct mem_map_data *mmd;
 
@@ -2802,7 +2804,7 @@ int
 get_mm_sparsemem(void)
 {
 	unsigned int section_nr, mem_section_size, num_section;
-	unsigned long long pfn_start, pfn_end;
+	pfn_t pfn_start, pfn_end;
 	unsigned long section, mem_map;
 	unsigned long *mem_sec = NULL;
 
@@ -2886,7 +2888,7 @@ get_mem_map_without_mm(void)
 int
 get_mem_map(void)
 {
-	unsigned long long max_pfn = 0;
+	pfn_t max_pfn = 0;
 	unsigned int i;
 	int ret;
 
@@ -2944,7 +2946,7 @@ initialize_bitmap_memory(void)
 	struct dump_bitmap *bmp;
 	off_t bitmap_offset;
 	off_t bitmap_len, max_sect_len;
-	unsigned long pfn;
+	pfn_t pfn;
 	int i, j;
 	long block_size;
 
@@ -3309,8 +3311,7 @@ initialize_2nd_bitmap(struct dump_bitmap *bitmap)
 }
 
 int
-set_bitmap(struct dump_bitmap *bitmap, unsigned long long pfn,
-    int val)
+set_bitmap(struct dump_bitmap *bitmap, pfn_t pfn, int val)
 {
 	int byte, bit;
 	off_t old_offset, new_offset;
@@ -3358,7 +3359,7 @@ set_bitmap(struct dump_bitmap *bitmap, unsigned long long pfn,
 }
 
 int
-set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val, struct cycle *cycle)
+set_bitmap_cyclic(char *bitmap, pfn_t pfn, int val, struct cycle *cycle)
 {
 	int byte, bit;
 
@@ -3418,7 +3419,7 @@ sync_2nd_bitmap(void)
 }
 
 int
-set_bit_on_1st_bitmap(unsigned long long pfn, struct cycle *cycle)
+set_bit_on_1st_bitmap(pfn_t pfn, struct cycle *cycle)
 {
 	if (info->flag_cyclic) {
 		return set_bitmap_cyclic(info->partial_bitmap1, pfn, 1, cycle);
@@ -3428,7 +3429,7 @@ set_bit_on_1st_bitmap(unsigned long long pfn, struct cycle *cycle)
 }
 
 int
-clear_bit_on_1st_bitmap(unsigned long long pfn, struct cycle *cycle)
+clear_bit_on_1st_bitmap(pfn_t pfn, struct cycle *cycle)
 {
 	if (info->flag_cyclic) {
 		return set_bitmap_cyclic(info->partial_bitmap1, pfn, 0, cycle);
@@ -3438,7 +3439,7 @@ clear_bit_on_1st_bitmap(unsigned long long pfn, struct cycle *cycle)
 }
 
 int
-clear_bit_on_2nd_bitmap(unsigned long long pfn, struct cycle *cycle)
+clear_bit_on_2nd_bitmap(pfn_t pfn, struct cycle *cycle)
 {
 	if (info->flag_cyclic) {
 		return set_bitmap_cyclic(info->partial_bitmap2, pfn, 0, cycle);
@@ -3448,7 +3449,7 @@ clear_bit_on_2nd_bitmap(unsigned long long pfn, struct cycle *cycle)
 }
 
 int
-clear_bit_on_2nd_bitmap_for_kernel(unsigned long long pfn, struct cycle *cycle)
+clear_bit_on_2nd_bitmap_for_kernel(pfn_t pfn, struct cycle *cycle)
 {
 	unsigned long long maddr;
 
@@ -3465,7 +3466,7 @@ clear_bit_on_2nd_bitmap_for_kernel(unsigned long long pfn, struct cycle *cycle)
 }
 
 int
-set_bit_on_2nd_bitmap(unsigned long long pfn, struct cycle *cycle)
+set_bit_on_2nd_bitmap(pfn_t pfn, struct cycle *cycle)
 {
 	if (info->flag_cyclic) {
 		return set_bitmap_cyclic(info->partial_bitmap2, pfn, 1, cycle);
@@ -3475,7 +3476,7 @@ set_bit_on_2nd_bitmap(unsigned long long pfn, struct cycle *cycle)
 }
 
 int
-set_bit_on_2nd_bitmap_for_kernel(unsigned long long pfn, struct cycle *cycle)
+set_bit_on_2nd_bitmap_for_kernel(pfn_t pfn, struct cycle *cycle)
 {
 	unsigned long long maddr;
 
@@ -3786,11 +3787,11 @@ rearrange_dumpdata(void)
 	return TRUE;
 }
 
-unsigned long long
+pfn_t
 page_to_pfn(unsigned long page)
 {
 	unsigned int num;
-	unsigned long long pfn = ULONGLONG_MAX;
+	pfn_t pfn = ULONGLONG_MAX;
 	unsigned long long index = 0;
 	struct mem_map_data *mmd;
 
@@ -3820,7 +3821,7 @@ reset_bitmap_of_free_pages(unsigned long node_zones, struct cycle *cycle)
 	int order, i, migrate_type, migrate_types;
 	unsigned long curr, previous, head, curr_page, curr_prev;
 	unsigned long addr_free_pages, free_pages = 0, found_free_pages = 0;
-	unsigned long long pfn, start_pfn;
+	pfn_t pfn, start_pfn;
 
 	/*
 	 * On linux-2.6.24 or later, free_list is divided into the array.
@@ -4423,7 +4424,7 @@ create_1st_bitmap(void)
 	int i;
 	unsigned int num_pt_loads = get_num_pt_loads();
  	char buf[info->page_size];
-	unsigned long long pfn, pfn_start, pfn_end, pfn_bitmap1;
+	pfn_t pfn, pfn_start, pfn_end, pfn_bitmap1;
 	unsigned long long phys_start, phys_end;
 	struct timeval tv_start;
 	off_t offset_page;
@@ -4495,10 +4496,10 @@ int
 create_1st_bitmap_cyclic(struct cycle *cycle)
 {
 	int i;
-	unsigned long long pfn, pfn_bitmap1;
+	pfn_t pfn, pfn_bitmap1;
 	unsigned long long phys_start, phys_end;
-	unsigned long long pfn_start, pfn_end;
-	unsigned long long pfn_start_roundup, pfn_end_round;
+	pfn_t pfn_start, pfn_end;
+	pfn_t pfn_start_roundup, pfn_end_round;
 	unsigned long pfn_start_byte, pfn_end_byte;
 
 	/*
@@ -4556,7 +4557,8 @@ create_1st_bitmap_cyclic(struct cycle *cycle)
 int
 exclude_zero_pages(void)
 {
-	unsigned long long pfn, paddr;
+	pfn_t pfn;
+	unsigned long long paddr;
 	struct dump_bitmap bitmap2;
 	struct timeval tv_start;
 	unsigned char buf[info->page_size];
@@ -4608,10 +4610,10 @@ static int
 initialize_2nd_bitmap_cyclic(struct cycle *cycle)
 {
 	int i;
-	unsigned long long pfn;
+	pfn_t pfn;
 	unsigned long long phys_start, phys_end;
-	unsigned long long pfn_start, pfn_end;
-	unsigned long long pfn_start_roundup, pfn_end_round;
+	pfn_t pfn_start, pfn_end;
+	pfn_t pfn_start_roundup, pfn_end_round;
 	unsigned long pfn_start_byte, pfn_end_byte;
 
 	/*
@@ -4659,10 +4661,12 @@ initialize_2nd_bitmap_cyclic(struct cycle *cycle)
 
 int
 __exclude_unnecessary_pages(unsigned long mem_map,
-    unsigned long long pfn_start, unsigned long long pfn_end, struct cycle *cycle)
+    pfn_t pfn_start, pfn_t pfn_end, struct cycle *cycle)
 {
-	unsigned long long pfn, pfn_mm, maddr;
-	unsigned long long pfn_read_start, pfn_read_end, index_pg;
+	pfn_t pfn;
+	unsigned long index_pg, pfn_mm;
+	unsigned long long maddr;
+	pfn_t pfn_read_start, pfn_read_end;
 	unsigned char page_cache[SIZE(page) * PGMM_CACHED];
 	unsigned char *pcache;
 	unsigned int _count, _mapcount = 0;
@@ -5162,7 +5166,7 @@ get_loads_dumpfile(void)
 {
 	int i, phnum, num_new_load = 0;
 	long page_size = info->page_size;
-	unsigned long long pfn, pfn_start, pfn_end, num_excluded;
+	pfn_t pfn, pfn_start, pfn_end, num_excluded;
 	unsigned long frac_head, frac_tail;
 	Elf64_Phdr load;
 	struct dump_bitmap bitmap2;
@@ -5612,10 +5616,10 @@ out:
 	return ret;
 }
 
-unsigned long long
+pfn_t
 get_num_dumpable(void)
 {
-	unsigned long long pfn, num_dumpable;
+	pfn_t pfn, num_dumpable;
 	struct dump_bitmap bitmap2;
 
 	initialize_2nd_bitmap(&bitmap2);
@@ -5627,10 +5631,10 @@ get_num_dumpable(void)
 	return num_dumpable;
 }
 
-unsigned long long
+pfn_t
 get_num_dumpable_cyclic(void)
 {
-	unsigned long long pfn, num_dumpable=0;
+	pfn_t pfn, num_dumpable=0;
 	struct cycle cycle = {0};
 
 	for_each_cycle(0, info->max_mapnr, &cycle)
@@ -5692,8 +5696,9 @@ write_elf_pages(struct cache_data *cd_header, struct cache_data *cd_page)
 {
 	int i, phnum;
 	long page_size = info->page_size;
-	unsigned long long pfn, pfn_start, pfn_end, paddr, num_excluded;
-	unsigned long long num_dumpable, per;
+	pfn_t pfn, pfn_start, pfn_end, num_excluded;
+	unsigned long long paddr;
+	pfn_t num_dumpable, per;
 	unsigned long long memsz, filesz;
 	unsigned long frac_head, frac_tail;
 	off_t off_seg_load, off_memory;
@@ -5878,7 +5883,7 @@ write_elf_pages(struct cache_data *cd_header, struct cache_data *cd_page)
 }
 
 int
-read_pfn(unsigned long long pfn, unsigned char *buf)
+read_pfn(pfn_t pfn, unsigned char *buf)
 {
 	unsigned long long paddr;
 
@@ -5897,7 +5902,7 @@ get_loads_dumpfile_cyclic(void)
 	int i, phnum, num_new_load = 0;
 	long page_size = info->page_size;
 	unsigned char buf[info->page_size];
-	unsigned long long pfn, pfn_start, pfn_end, num_excluded;
+	pfn_t pfn, pfn_start, pfn_end, num_excluded;
 	unsigned long frac_head, frac_tail;
 	Elf64_Phdr load;
 	struct cycle cycle = {0};
@@ -5969,8 +5974,8 @@ write_elf_pages_cyclic(struct cache_data *cd_header, struct cache_data *cd_page)
 	int i, phnum;
 	long page_size = info->page_size;
 	unsigned char buf[info->page_size];
-	unsigned long long pfn, pfn_start, pfn_end, paddr, num_excluded;
-	unsigned long long num_dumpable, per;
+	pfn_t pfn, pfn_start, pfn_end, num_excluded, num_dumpable, per;
+	unsigned long long paddr;
 	unsigned long long memsz, filesz;
 	unsigned long frac_head, frac_tail;
 	off_t off_seg_load, off_memory;
@@ -6190,8 +6195,8 @@ write_elf_pages_cyclic(struct cache_data *cd_header, struct cache_data *cd_page)
 int
 write_kdump_pages(struct cache_data *cd_header, struct cache_data *cd_page)
 {
- 	unsigned long long pfn, per, num_dumpable;
-	unsigned long long start_pfn, end_pfn;
+ 	pfn_t pfn, per, num_dumpable;
+	pfn_t start_pfn, end_pfn;
 	unsigned long size_out;
 	struct page_desc pd, pd_zero;
 	off_t offset_data = 0;
@@ -6397,8 +6402,8 @@ int
 write_kdump_pages_cyclic(struct cache_data *cd_header, struct cache_data *cd_page,
 			 struct page_desc *pd_zero, off_t *offset_data, struct cycle *cycle)
 {
-	unsigned long long pfn, per;
-	unsigned long long start_pfn, end_pfn;
+	pfn_t pfn, per;
+	pfn_t start_pfn, end_pfn;
 	unsigned long size_out;
 	struct page_desc pd;
 	unsigned char buf[info->page_size], *buf_out = NULL;
@@ -7504,7 +7509,7 @@ read_vmcoreinfo_xen(void)
 }
 
 int
-allocated_in_map(unsigned long long pfn)
+allocated_in_map(pfn_t pfn)
 {
 	static unsigned long long cur_idx = -1;
 	static unsigned long cur_word;
@@ -7550,8 +7555,8 @@ exclude_xen3_user_domain(void)
 	unsigned int num_pt_loads = get_num_pt_loads();
 	unsigned long page_info_addr;
 	unsigned long long phys_start, phys_end;
-	unsigned long long pfn, pfn_end;
-	unsigned long long j, size;
+	pfn_t pfn, pfn_end;
+	pfn_t j, size;
 
 	/*
 	 * NOTE: the first half of bitmap is not used for Xen extraction
@@ -7614,8 +7619,8 @@ exclude_xen4_user_domain(void)
 	unsigned int num_pt_loads = get_num_pt_loads();
 	unsigned long page_info_addr;
 	unsigned long long phys_start, phys_end;
-	unsigned long long pfn, pfn_end;
-	unsigned long long j, size;
+	pfn_t pfn, pfn_end;
+	pfn_t j, size;
 
 	/*
 	 * NOTE: the first half of bitmap is not used for Xen extraction
@@ -7840,7 +7845,7 @@ print_vtop(void)
 void
 print_report(void)
 {
-	unsigned long long pfn_original, pfn_excluded, shrinking;
+	pfn_t pfn_original, pfn_excluded, shrinking;
 
 	/*
 	 * /proc/vmcore doesn't contain the memory hole area.
@@ -7945,9 +7950,9 @@ int
 setup_splitting(void)
 {
 	int i;
-	unsigned long long j, pfn_per_dumpfile;
-	unsigned long long start_pfn, end_pfn;
-	unsigned long long num_dumpable = get_num_dumpable();
+	pfn_t j, pfn_per_dumpfile;
+	pfn_t start_pfn, end_pfn;
+	pfn_t num_dumpable = get_num_dumpable();
 	struct dump_bitmap bitmap2;
 
 	if (info->num_dumpfile <= 1)
@@ -8274,7 +8279,7 @@ void
 sort_splitting_info(void)
 {
 	int i, j;
-	unsigned long long start_pfn, end_pfn;
+	pfn_t start_pfn, end_pfn;
 	char *name_dumpfile;
 
 	/*
@@ -8310,7 +8315,7 @@ int
 check_splitting_info(void)
 {
 	int i;
-	unsigned long long end_pfn;
+	pfn_t end_pfn;
 
 	/*
 	 * Check whether there are not lack of /proc/vmcore.
@@ -8537,8 +8542,8 @@ reassemble_kdump_pages(void)
 	int i, fd = 0, ret = FALSE;
 	off_t offset_first_ph, offset_ph_org, offset_eraseinfo;
 	off_t offset_data_new, offset_zero_page = 0;
-	unsigned long long pfn, start_pfn, end_pfn;
-	unsigned long long num_dumpable;
+	pfn_t pfn, start_pfn, end_pfn;
+	pfn_t num_dumpable;
 	unsigned long size_eraseinfo;
 	struct dump_bitmap bitmap2;
 	struct disk_dump_header dh;
diff --git a/makedumpfile.h b/makedumpfile.h
index 951ed1b..2e59627 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -767,13 +767,15 @@ unsigned long long vaddr_to_paddr_ia64(unsigned long vaddr);
 #define VADDR_REGION(X)		(((unsigned long)(X)) >> REGION_SHIFT)
 #endif          /* ia64 */
 
+typedef unsigned long long pfn_t;
+
 #ifndef ARCH_PFN_OFFSET
 #define ARCH_PFN_OFFSET		0
 #endif
 #define paddr_to_pfn(X) \
 	(((unsigned long long)(X) >> PAGESHIFT()) - ARCH_PFN_OFFSET)
 #define pfn_to_paddr(X) \
-	(((unsigned long long)(X) + ARCH_PFN_OFFSET) << PAGESHIFT())
+	(((pfn_t)(X) + ARCH_PFN_OFFSET) << PAGESHIFT())
 
 /* Format of Xen crash info ELF note */
 typedef struct {
@@ -813,8 +815,8 @@ typedef struct {
 } xen_crash_info_v2_t;
 
 struct mem_map_data {
-	unsigned long long	pfn_start;
-	unsigned long long	pfn_end;
+	pfn_t		pfn_start;
+	pfn_t		pfn_end;
 	unsigned long	mem_map;
 };
 
@@ -866,8 +868,8 @@ struct makedumpfile_data_header {
 struct splitting_info {
 	char			*name_dumpfile;
 	int 			fd_bitmap;
-	unsigned long long	start_pfn;
-	unsigned long long	end_pfn;
+	pfn_t			start_pfn;
+	pfn_t			end_pfn;
 	off_t			offset_eraseinfo;
 	unsigned long		size_eraseinfo;
 } splitting_info_t;
@@ -914,7 +916,7 @@ struct DumpInfo {
 	unsigned long	vaddr_for_vtop;      /* virtual address for debugging */
 	long		page_size;           /* size of page */
 	long		page_shift;
-	unsigned long long	max_mapnr;   /* number of page descriptor */
+	pfn_t		max_mapnr;   /* number of page descriptor */
 	unsigned long   page_offset;
 	unsigned long   section_size_bits;
 	unsigned long   max_physmem_bits;
@@ -1025,10 +1027,10 @@ struct DumpInfo {
 					 *   1 .. xen_crash_info_t
 					 *   2 .. xen_crash_info_v2_t */
 
-	unsigned long long	dom0_mapnr;  /* The number of page in domain-0.
-					      * Different from max_mapnr.
-					      * max_mapnr is the number of page
-					      * in system. */
+	pfn_t		dom0_mapnr;	/* The number of page in domain-0.
+					 * Different from max_mapnr.
+					 * max_mapnr is the number of page
+					 * in system. */
 	unsigned long xen_phys_start;
 	unsigned long xen_heap_start;	/* start mfn of xen heap area */
 	unsigned long xen_heap_end;	/* end mfn(+1) of xen heap area */
@@ -1048,15 +1050,15 @@ struct DumpInfo {
 	/*
 	 * for splitting
 	 */
-	unsigned long long split_start_pfn;  
-	unsigned long long split_end_pfn;  
+	pfn_t split_start_pfn;
+	pfn_t split_end_pfn;
 
 	/*
 	 * for cyclic processing
 	 */
 	char               *partial_bitmap1;
 	char               *partial_bitmap2;
-	unsigned long long num_dumpable;
+	pfn_t              num_dumpable;
 	unsigned long      bufsize_cyclic;
 	unsigned long      pfn_cyclic;
 
@@ -1453,7 +1455,7 @@ int readmem(int type_addr, unsigned long long addr, void *bufptr, size_t size);
 int get_str_osrelease_from_vmlinux(void);
 int read_vmcoreinfo_xen(void);
 int exclude_xen_user_domain(void);
-unsigned long long get_num_dumpable(void);
+pfn_t get_num_dumpable(void);
 int __read_disk_dump_header(struct disk_dump_header *dh, char *filename);
 int read_disk_dump_header(struct disk_dump_header *dh, char *filename);
 int read_kdump_sub_header(struct kdump_sub_header *kh, char *filename);
@@ -1589,8 +1591,8 @@ int get_xen_info_ia64(void);
 #endif	/* s390x */
 
 struct cycle {
-	unsigned long long start_pfn;
-	unsigned long long end_pfn;
+	pfn_t start_pfn;
+	pfn_t end_pfn;
 };
 
 static inline int
@@ -1600,7 +1602,7 @@ is_on(char *bitmap, int i)
 }
 
 static inline int
-is_dumpable(struct dump_bitmap *bitmap, unsigned long long pfn)
+is_dumpable(struct dump_bitmap *bitmap, pfn_t pfn)
 {
 	off_t offset;
 	if (pfn == 0 || bitmap->no_block != pfn/PFN_BUFBITMAP) {
@@ -1616,7 +1618,7 @@ is_dumpable(struct dump_bitmap *bitmap, unsigned long long pfn)
 }
 
 static inline int
-is_dumpable_cyclic(char *bitmap, unsigned long long pfn, struct cycle *cycle)
+is_dumpable_cyclic(char *bitmap, pfn_t pfn, struct cycle *cycle)
 {
 	if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn)
 		return FALSE;
@@ -1625,7 +1627,7 @@ is_dumpable_cyclic(char *bitmap, unsigned long long pfn, struct cycle *cycle)
 }
 
 static inline int
-is_cyclic_region(unsigned long long pfn, struct cycle *cycle)
+is_cyclic_region(pfn_t pfn, struct cycle *cycle)
 {
 	if (pfn < cycle->start_pfn || cycle->end_pfn <= pfn)
 		return FALSE;
@@ -1647,8 +1649,8 @@ is_zero_page(unsigned char *buf, long page_size)
 }
 
 void write_vmcoreinfo_data(void);
-int set_bit_on_1st_bitmap(unsigned long long pfn, struct cycle *cycle);
-int clear_bit_on_1st_bitmap(unsigned long long pfn, struct cycle *cycle);
+int set_bit_on_1st_bitmap(pfn_t pfn, struct cycle *cycle);
+int clear_bit_on_1st_bitmap(pfn_t pfn, struct cycle *cycle);
 
 #ifdef __x86__
 
@@ -1759,7 +1761,7 @@ struct elf_prstatus {
 /*
  * Function Prototype.
  */
-unsigned long long get_num_dumpable_cyclic(void);
+pfn_t get_num_dumpable_cyclic(void);
 int get_loads_dumpfile_cyclic(void);
 int initial_xen(void);
 unsigned long long get_free_memory_size(void);
diff --git a/sadump_info.c b/sadump_info.c
index f14ffc9..7477b8f 100644
--- a/sadump_info.c
+++ b/sadump_info.c
@@ -94,7 +94,7 @@ static int read_device_diskset(struct sadump_diskset_info *sdi, void *buf,
 			       size_t bytes, ulong *offset);
 static int read_sadump_header(char *filename);
 static int read_sadump_header_diskset(int diskid, struct sadump_diskset_info *sdi);
-static unsigned long long pfn_to_block(unsigned long long pfn);
+static unsigned long long pfn_to_block(pfn_t pfn);
 static int lookup_diskset(unsigned long long whole_offset, int *diskid,
 			  unsigned long long *disk_offset);
 static int max_mask_cpu(void);
@@ -202,7 +202,8 @@ sadump_copy_1st_bitmap_from_memory(void)
 	 * modify bitmap accordingly.
 	 */
 	if (si->kdump_backed_up) {
-		unsigned long long paddr, pfn, backup_src_pfn;
+		unsigned long long paddr;
+		pfn_t pfn, backup_src_pfn;
 
 		for (paddr = si->backup_src_start;
 		     paddr < si->backup_src_start + si->backup_src_size;
@@ -754,7 +755,8 @@ sadump_initialize_bitmap_memory(void)
 	struct sadump_header *sh = si->sh_memory;
 	struct dump_bitmap *bmp;
 	unsigned long dumpable_bitmap_offset;
-	unsigned long long section, max_section, pfn;
+	unsigned long long section, max_section;
+	pfn_t pfn;
 	unsigned long long *block_table;
 
 	dumpable_bitmap_offset =
@@ -901,7 +903,7 @@ sadump_set_timestamp(struct timeval *ts)
 	return TRUE;
 }
 
-unsigned long long
+pfn_t
 sadump_get_max_mapnr(void)
 {
 	return si->sh_memory->max_mapnr;
@@ -951,7 +953,8 @@ failed:
 int
 readpage_sadump(unsigned long long paddr, void *bufptr)
 {
-	unsigned long long pfn, block, whole_offset, perdisk_offset;
+	pfn_t pfn;
+	unsigned long long block, whole_offset, perdisk_offset;
 	int fd_memory;
 
 	if (si->kdump_backed_up &&
@@ -1117,7 +1120,7 @@ sadump_check_debug_info(void)
 }
 
 static unsigned long long
-pfn_to_block(unsigned long long pfn)
+pfn_to_block(pfn_t pfn)
 {
 	unsigned long long block, section, p;
 
diff --git a/sadump_info.h b/sadump_info.h
index c0175dd..953e4d8 100644
--- a/sadump_info.h
+++ b/sadump_info.h
@@ -42,7 +42,7 @@ int sadump_copy_1st_bitmap_from_memory(void);
 int sadump_initialize_bitmap_memory(void);
 int sadump_num_online_cpus(void);
 int sadump_set_timestamp(struct timeval *ts);
-unsigned long long sadump_get_max_mapnr(void);
+pfn_t sadump_get_max_mapnr(void);
 int readpage_sadump(unsigned long long paddr, void *bufptr);
 int sadump_check_debug_info(void);
 int sadump_generate_vmcoreinfo_from_vmlinux(size_t *vmcoreinfo_size);
@@ -92,7 +92,7 @@ static inline int sadump_set_timestamp(struct timeval *ts)
 	return FALSE;
 }
 
-static inline unsigned long long sadump_get_max_mapnr(void)
+static inline pfn_t sadump_get_max_mapnr(void)
 {
 	return 0;
 }
-- 
1.8.4.5


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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[HATAYAMA Daisuke]

From: Petr Tesarik <ptesarik@suse.cz>
Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
Date: Thu, 10 Apr 2014 12:47:17 +0200

> On Tue, 8 Apr 2014 07:06:34 +0000
> Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> wrote:
> 
>> [...]
>> > diff --git a/makedumpfile.h b/makedumpfile.h
>> >> index 951ed1b..dfad569 100644
>> >> --- a/makedumpfile.h
>> >> +++ b/makedumpfile.h
>> >> @@ -816,6 +816,13 @@ struct mem_map_data {
>> >>  	unsigned long long	pfn_start;
>> >>  	unsigned long long	pfn_end;
>> >>  	unsigned long	mem_map;
>> >> +
>> >> +	/*
>> >> +	 * for excluding multi-page regions
>> >> +	 */
>> >> +	unsigned long		exclude_pfn_start;
>> >> +	unsigned long		exclude_pfn_end;
>> >
>> >unsigned long long		exclude_pfn_start;
>> >unsigned long long		exclude_pfn_end;
>> >
>> >The integers representing page frame numbers need to be defined as
>> >unsigned long long for architectures where physical address can have
>> >64-bit length but unsigned long has 32-bit only, such as x86 PAE.
>> >
>> >Kumagai-san, I saw this sometimes in the past. How about introducing
>> >specific abstract type for page frame number like below?
>> >
>> >typedef unsigned long long pfn_t;
>> 
>> Good idea! We should do it.
> 
> Like the following patch?
> 
> From 9f3f6876bf1e8c93690097c510dff9982651bfa5 Mon Sep 17 00:00:00 2001
> From: Petr Tesarik <ptesarik@suse.cz>
> Date: Thu, 10 Apr 2014 12:40:31 +0200
> Subject: [PATCH] Introduce the pfn_t type
> 
> Replace unsigned long long with pfn_t where:
> 
>   a. the variable denotes a PFN
>   b. the variable is a number of pages
> 
> The number of pages is converted to a pfn_t, because it is a result of
> subtracting two PFNs or incremented in a loop over a range of PFNs, so
> it can get as large as a PFN.
> 
> Signed-off-by: Petr Tesarik <ptesarik@suse.cz>

Thanks!

Only concern is that pfn_t could be too generic; could collide with
symbols from any other libraries. On kernel, I found that kvm and um
defines pfn_t.

So, it's better to prefix pfn_t with the letters indicating that this
is relevant to makedumpfile.

But I don't come up with good prefix...

Thanks.
HATAYAMA, Daisuke


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RE: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Atsushi Kumagai]

>From: Petr Tesarik <ptesarik@suse.cz>
>Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
>Date: Thu, 10 Apr 2014 12:47:17 +0200
>
>> On Tue, 8 Apr 2014 07:06:34 +0000
>> Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> wrote:
>>
>>> [...]
>>> > diff --git a/makedumpfile.h b/makedumpfile.h
>>> >> index 951ed1b..dfad569 100644
>>> >> --- a/makedumpfile.h
>>> >> +++ b/makedumpfile.h
>>> >> @@ -816,6 +816,13 @@ struct mem_map_data {
>>> >>  	unsigned long long	pfn_start;
>>> >>  	unsigned long long	pfn_end;
>>> >>  	unsigned long	mem_map;
>>> >> +
>>> >> +	/*
>>> >> +	 * for excluding multi-page regions
>>> >> +	 */
>>> >> +	unsigned long		exclude_pfn_start;
>>> >> +	unsigned long		exclude_pfn_end;
>>> >
>>> >unsigned long long		exclude_pfn_start;
>>> >unsigned long long		exclude_pfn_end;
>>> >
>>> >The integers representing page frame numbers need to be defined as
>>> >unsigned long long for architectures where physical address can have
>>> >64-bit length but unsigned long has 32-bit only, such as x86 PAE.
>>> >
>>> >Kumagai-san, I saw this sometimes in the past. How about introducing
>>> >specific abstract type for page frame number like below?
>>> >
>>> >typedef unsigned long long pfn_t;
>>>
>>> Good idea! We should do it.
>>
>> Like the following patch?
>>
>> From 9f3f6876bf1e8c93690097c510dff9982651bfa5 Mon Sep 17 00:00:00 2001
>> From: Petr Tesarik <ptesarik@suse.cz>
>> Date: Thu, 10 Apr 2014 12:40:31 +0200
>> Subject: [PATCH] Introduce the pfn_t type
>>
>> Replace unsigned long long with pfn_t where:
>>
>>   a. the variable denotes a PFN
>>   b. the variable is a number of pages
>>
>> The number of pages is converted to a pfn_t, because it is a result of
>> subtracting two PFNs or incremented in a loop over a range of PFNs, so
>> it can get as large as a PFN.
>>
>> Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
>
>Thanks!
>
>Only concern is that pfn_t could be too generic; could collide with
>symbols from any other libraries. On kernel, I found that kvm and um
>defines pfn_t.
>
>So, it's better to prefix pfn_t with the letters indicating that this
>is relevant to makedumpfile.
>
>But I don't come up with good prefix...

We don't need to be serious, just keeping identity is the important
thing. So how about kdump_pfn_t or mdf_pfn_t?
("makedumpfile" is a long name and it hasn't a good shortening,
it might be better to rename it :-P)


Thanks
Atsushi Kumagai

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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[Petr Tesarik]

V Tue, 15 Apr 2014 01:20:46 +0000
Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> napsáno:

> >From: Petr Tesarik <ptesarik@suse.cz>
> >Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
> >Date: Thu, 10 Apr 2014 12:47:17 +0200
> >
> >> On Tue, 8 Apr 2014 07:06:34 +0000
> >> Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> wrote:
> >>
> >>> [...]
> >>> > diff --git a/makedumpfile.h b/makedumpfile.h
> >>> >> index 951ed1b..dfad569 100644
> >>> >> --- a/makedumpfile.h
> >>> >> +++ b/makedumpfile.h
> >>> >> @@ -816,6 +816,13 @@ struct mem_map_data {
> >>> >>  	unsigned long long	pfn_start;
> >>> >>  	unsigned long long	pfn_end;
> >>> >>  	unsigned long	mem_map;
> >>> >> +
> >>> >> +	/*
> >>> >> +	 * for excluding multi-page regions
> >>> >> +	 */
> >>> >> +	unsigned long		exclude_pfn_start;
> >>> >> +	unsigned long		exclude_pfn_end;
> >>> >
> >>> >unsigned long long		exclude_pfn_start;
> >>> >unsigned long long		exclude_pfn_end;
> >>> >
> >>> >The integers representing page frame numbers need to be defined as
> >>> >unsigned long long for architectures where physical address can have
> >>> >64-bit length but unsigned long has 32-bit only, such as x86 PAE.
> >>> >
> >>> >Kumagai-san, I saw this sometimes in the past. How about introducing
> >>> >specific abstract type for page frame number like below?
> >>> >
> >>> >typedef unsigned long long pfn_t;
> >>>
> >>> Good idea! We should do it.
> >>
> >> Like the following patch?
> >>
> >> From 9f3f6876bf1e8c93690097c510dff9982651bfa5 Mon Sep 17 00:00:00 2001
> >> From: Petr Tesarik <ptesarik@suse.cz>
> >> Date: Thu, 10 Apr 2014 12:40:31 +0200
> >> Subject: [PATCH] Introduce the pfn_t type
> >>
> >> Replace unsigned long long with pfn_t where:
> >>
> >>   a. the variable denotes a PFN
> >>   b. the variable is a number of pages
> >>
> >> The number of pages is converted to a pfn_t, because it is a result of
> >> subtracting two PFNs or incremented in a loop over a range of PFNs, so
> >> it can get as large as a PFN.
> >>
> >> Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
> >
> >Thanks!
> >
> >Only concern is that pfn_t could be too generic; could collide with
> >symbols from any other libraries. On kernel, I found that kvm and um
> >defines pfn_t.
> >
> >So, it's better to prefix pfn_t with the letters indicating that this
> >is relevant to makedumpfile.
> >
> >But I don't come up with good prefix...
> 
> We don't need to be serious, just keeping identity is the important
> thing. So how about kdump_pfn_t or mdf_pfn_t?

I vote for mdf_pfn_t, because MDF is already used as an abbreviation
for makedumpfile in the crash utility source files.

My two cents,
Petr T

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Re: [PATCH v2 2/3] Generic handling of multi-page exclusions

[HATAYAMA Daisuke]

From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Subject: RE: [PATCH v2 2/3] Generic handling of multi-page exclusions
Date: Tue, 15 Apr 2014 01:20:46 +0000

>>From: Petr Tesarik <ptesarik@suse.cz>
>>Subject: Re: [PATCH v2 2/3] Generic handling of multi-page exclusions
>>Date: Thu, 10 Apr 2014 12:47:17 +0200
>>
>>> On Tue, 8 Apr 2014 07:06:34 +0000
>>> Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> wrote:
>>>
>>>> [...]
>>>> > diff --git a/makedumpfile.h b/makedumpfile.h
>>>> >> index 951ed1b..dfad569 100644
>>>> >> --- a/makedumpfile.h
>>>> >> +++ b/makedumpfile.h
>>>> >> @@ -816,6 +816,13 @@ struct mem_map_data {
>>>> >>  	unsigned long long	pfn_start;
>>>> >>  	unsigned long long	pfn_end;
>>>> >>  	unsigned long	mem_map;
>>>> >> +
>>>> >> +	/*
>>>> >> +	 * for excluding multi-page regions
>>>> >> +	 */
>>>> >> +	unsigned long		exclude_pfn_start;
>>>> >> +	unsigned long		exclude_pfn_end;
>>>> >
>>>> >unsigned long long		exclude_pfn_start;
>>>> >unsigned long long		exclude_pfn_end;
>>>> >
>>>> >The integers representing page frame numbers need to be defined as
>>>> >unsigned long long for architectures where physical address can have
>>>> >64-bit length but unsigned long has 32-bit only, such as x86 PAE.
>>>> >
>>>> >Kumagai-san, I saw this sometimes in the past. How about introducing
>>>> >specific abstract type for page frame number like below?
>>>> >
>>>> >typedef unsigned long long pfn_t;
>>>>
>>>> Good idea! We should do it.
>>>
>>> Like the following patch?
>>>
>>> From 9f3f6876bf1e8c93690097c510dff9982651bfa5 Mon Sep 17 00:00:00 2001
>>> From: Petr Tesarik <ptesarik@suse.cz>
>>> Date: Thu, 10 Apr 2014 12:40:31 +0200
>>> Subject: [PATCH] Introduce the pfn_t type
>>>
>>> Replace unsigned long long with pfn_t where:
>>>
>>>   a. the variable denotes a PFN
>>>   b. the variable is a number of pages
>>>
>>> The number of pages is converted to a pfn_t, because it is a result of
>>> subtracting two PFNs or incremented in a loop over a range of PFNs, so
>>> it can get as large as a PFN.
>>>
>>> Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
>>
>>Thanks!
>>
>>Only concern is that pfn_t could be too generic; could collide with
>>symbols from any other libraries. On kernel, I found that kvm and um
>>defines pfn_t.
>>
>>So, it's better to prefix pfn_t with the letters indicating that this
>>is relevant to makedumpfile.
>>
>>But I don't come up with good prefix...
> 
> We don't need to be serious, just keeping identity is the important
> thing. So how about kdump_pfn_t or mdf_pfn_t?
> ("makedumpfile" is a long name and it hasn't a good shortening,
> it might be better to rename it :-P)
> 

It seems to me the latter mdf_ is better.

Thanks.
HATAYAMA, Daisuke


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[PATCH v2 3/3] Get rid of overrun adjustments

[Petr Tesarik]

Thanks to the previous commit, __exclude_unnecessary_pages does not
require any specific size of the cycle.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
---
 makedumpfile.c | 59 ----------------------------------------------------------
 1 file changed, 59 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 9ffb901..6ebf76f 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -88,7 +88,6 @@ do { \
 		*ptr_long_table = value; \
 } while (0)
 
-static void check_cyclic_buffer_overrun(void);
 static void setup_page_is_buddy(void);
 
 void
@@ -3254,9 +3253,6 @@ out:
 		    !sadump_generate_elf_note_from_dumpfile())
 			return FALSE;
 
-		if (info->flag_cyclic && info->dump_level & DL_EXCLUDE_FREE)
-			check_cyclic_buffer_overrun();
-
 	} else {
 		if (!get_mem_map_without_mm())
 			return FALSE;
@@ -4274,61 +4270,6 @@ exclude_free_page(struct cycle *cycle)
 }
 
 /*
- * Let C be a cyclic buffer size and B a bitmap size used for
- * representing maximum block size managed by buddy allocator.
- *
- * For some combinations of C and B, clearing operation can overrun
- * the cyclic buffer. Let's consider three cases.
- *
- *   - If C == B, this is trivially safe.
- *
- *   - If B > C, overrun can easily happen.
- *
- *   - In case of C > B, if C mod B != 0, then there exist n > m > 0,
- *     B > b > 0 such that n x C = m x B + b. This means that clearing
- *     operation overruns cyclic buffer (B - b)-bytes in the
- *     combination of n-th cycle and m-th block.
- *
- *     Note that C mod B != 0 iff (m x C) mod B != 0 for some m.
- *
- * If C == B, C mod B == 0 always holds. Again, if B > C, C mod B != 0
- * always holds. Hence, it's always sufficient to check the condition
- * C mod B != 0 in order to determine whether overrun can happen or
- * not.
- *
- * The bitmap size used for maximum block size B is calculated from
- * MAX_ORDER as:
- *
- *   B := DIVIDE_UP((1 << (MAX_ORDER - 1)), BITS_PER_BYTE)
- *
- * Normally, MAX_ORDER is 11 at default. This is configurable through
- * CONFIG_FORCE_MAX_ZONEORDER.
- */
-static void
-check_cyclic_buffer_overrun(void)
-{
-	int max_order = ARRAY_LENGTH(zone.free_area);
-	int max_order_nr_pages = 1 << (max_order - 1);
-	unsigned long max_block_size = divideup(max_order_nr_pages, BITPERBYTE);
-
-	if (info->bufsize_cyclic % max_block_size) {
-		unsigned long bufsize;
-
-		if (max_block_size > info->bufsize_cyclic) {
-			MSG("WARNING: some free pages are not filtered.\n");
-			return;
-		}
-
-		bufsize = info->bufsize_cyclic;
-		info->bufsize_cyclic = round(bufsize, max_block_size);
-		info->pfn_cyclic = info->bufsize_cyclic * BITPERBYTE;
-
-		MSG("cyclic buffer size has been changed: %lu => %lu\n",
-		    bufsize, info->bufsize_cyclic);
-	}
-}
-
-/*
  * For the kernel versions from v2.6.17 to v2.6.37.
  */
 static int
-- 
1.8.4.5


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RE: [PATCH v2 0/3] Generic multi-page exclusion

[Atsushi Kumagai]

Hello Petr,

>Kumagai-san,
>
>this patch was inspired by this post of yours:
>
>http://lists.infradead.org/pipermail/kexec/2013-November/010445.html
>
>Unfortunately, this rewrite never happened, so I took the liberty of
>overtaking the job. I hope you don't mind.
>
>This is in fact a preparatory series to add hugepage support without
>having to care about the appropriate size of the cyclic buffer.

First, I'm sorry for my late work. This patch set will be very helpful
to me, so I'll wait for the fixed version.

I'm preparing to release v1.5.6 now and I'll focus on the work for
hugepage support after releasing v1.5.6.


Thanks
Atsushi Kumagai

>Changelog:
>* v2:
>  - Keep excluded regions per mem_map_data
>  - Process excluded pages in chunks
>
>Petr Tesarik (3):
>  Pass mmd pointer to __exclude_unnecessary_pages
>  Generic handling of multi-page exclusions
>  Get rid of overrun adjustments
>
> makedumpfile.c | 118 +++++++++++++++++++--------------------------------------
> makedumpfile.h |   7 ++++
> 2 files changed, 46 insertions(+), 79 deletions(-)
>
>--
>1.8.4.5
>
>
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