Re: [PATCH 2/2] makedumpfile: Use max_pfn from mem_map array

[Michael Holzheu <holzheu@linux.vnet.ibm.com>]

On Fri, 28 Mar 2014 12:00:47 +0100
Petr Tesarik <ptesarik@suse.cz> wrote:

> On Thu, 27 Mar 2014 14:54:41 +0100
> Michael Holzheu <holzheu@linux.vnet.ibm.com> wrote:

[snip]

> > > >Here the fixed patch:
> > > 
> > > Thanks, I'll merge the fixed version into v1.5.6.
> > 
> > Great!
> 
> I'm sorry to spoil the party, but this patch broke Xen dumps for me.
> I'm getting an long series of these messages:
> 
> set_bitmap: Can't read the bitmap(/tmp/kdump_bitmap91pbsO). Invalid argument
> set_bitmap: Can't read the bitmap(/tmp/kdump_bitmap91pbsO). Invalid argument
> set_bitmap: Can't read the bitmap(/tmp/kdump_bitmap91pbsO). Invalid argument
> ...
> 
> In fact, it most likely broke all non-cyclic dumps.
> 
> That's because the bitmap length is calculated in prepare_bitmap_buffer
> using info->max_mapnr, but create_1st_bitmap() still loops over all
> PT_LOAD segments, calling set_bit_on_1st_bitmap() for each PFN. The
> offset may easily fall beyond the bitmap size.

What about the following patch. It works for me when I specify
the "--non-cyclic" option.

Michael
---
[PATCH] makedumpfile: Fix bitmap create for adjusted info->max_mapnr

If info->max_mapnr has been adjusted, for example because the dumped
system has specified the "mem=" kernel parameter, makedumpfile writes
the following error messages for Xen dumps or when the "--non-cyclic"
option has been specified:

set_bitmap: Can't read the bitmap(/tmp/kdump_bitmap96s9V8). Success

Fix this and consider "info->max_mapnr" in the create bitmap functions.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
---
 makedumpfile.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -4402,6 +4402,9 @@ create_1st_bitmap(void)
 
 		pfn_start = paddr_to_pfn(phys_start);
 		pfn_end   = paddr_to_pfn(phys_end);
+		if (pfn_start > info->max_mapnr)
+			continue;
+		pfn_end = MIN(phys_end, info->max_mapnr);
 
 		for (pfn = pfn_start; pfn < pfn_end; pfn++) {
 			set_bit_on_1st_bitmap(pfn);
@@ -7511,6 +7514,9 @@ exclude_xen3_user_domain(void)
 		pfn     = paddr_to_pfn(phys_start);
 		pfn_end = paddr_to_pfn(phys_end);
 		size    = pfn_end - pfn;
+		if (pfn > info->max_mapnr)
+			continue;
+		pfn_end = MIN(phys_end, info->max_mapnr);
 
 		for (j = 0; pfn < pfn_end; pfn++, j++) {
 			print_progress(PROGRESS_XEN_DOMAIN, j + (size * i),
@@ -7575,6 +7581,9 @@ exclude_xen4_user_domain(void)
 		pfn     = paddr_to_pfn(phys_start);
 		pfn_end = paddr_to_pfn(phys_end);
 		size    = pfn_end - pfn;
+		if (pfn > info->max_mapnr)
+			continue;
+		pfn_end = MIN(phys_end, info->max_mapnr);
 
 		for (j = 0; pfn < pfn_end; pfn++, j++) {
 			print_progress(PROGRESS_XEN_DOMAIN, j + (size * i),


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