[PATCH] makedumpfile: when using refiltering, initialize bitmap1 from the kdump file's bitmap2

Kazuhito Hagio k-hagio at ab.jp.nec.com
Thu Aug 2 12:22:24 PDT 2018


On 8/2/2018 3:36 AM, piliu wrote:
> 
> 
> On 08/02/2018 04:45 AM, Kazuhito Hagio wrote:
> > Hi Pingfan,
> >
> > Thank you for the patch.
> >
> > On 7/31/2018 4:44 AM, Pingfan Liu wrote:
> >> When refiltering on kdump format file, there is no info about pt_load[] for
> >> exclude_nodata_pages(), and also we can not expect more data than the kdump
> >> file can provide, hence this patch suggests to initialize the refiltered
> >> bitmap1 from the kdump file's bitmap2.
> >
> > I understood the issue (I don't have any vmcore which can reproduce it,
> > though), but since the bitmap1 is written to the refiltered dump file,
> > I think that we should not change the meaning of bitmap1 if possible,
> > which is "a page on memory hole".
> >
> > For instance, with the patch, crash using the bitmaps prints a different
> > message for the same "excluded" paddr:
> >
> >   -read_diskdump: PAGE_EXCLUDED: paddr/pfn: 2613e130/2613e
> >   +read_diskdump: SEEK_ERROR: paddr/pfn: 2613e130/2613e !page_is_ram
> >
> > and makedumpfile's -e option using the bitmap1 cannot be utilized when
> > refiltering, these are not favorable.
> >
> > So how about initializing the refiltered *bitmap2* from the kdump file's
> > bitmap2 ?  I'm checking if this works.
> >
> Yes, it sounds a good idea.

OK, as far as I've looked into it, this way looks good.
Can you modify the patch?

Thanks,
Kazu

> 
> Thanks,
> Pingfan
> 
> > Thanks,
> > Kazu
> >
> >>
> >> Note about the bug reported by the following ops:
> >>   makedumpfile -l --message-level 1 -d 31 /proc/vmcore /path/to/vmcore
> >>   makedumpfile  --split  -d 31 ./vmcore dumpfile_{1,2,3} 2>&1
> >> and hit the following error:
> >>   Excluding unnecessary pages                       : [100.0 %] \
> >>   readpage_kdump_compressed: pfn(9b) is excluded from
> /var/crash/127.0.0.1-2018-07-02-22:10:38/vmcore.
> >>   readmem: type_addr: 1, addr:9b000, size:4096
> >>   read_pfn: Can't get the page data.
> >>   writeout_multiple_dumpfiles: Child process(2277) finished incompletely.(256)
> >>   Copying data                                      : [ 24.6 %] -           eta: 2s
> >>   makedumpfile Failed.
> >>
> >> Signed-off-by: Pingfan Liu <piliu at redhat.com>
> >> ---
> >>  makedumpfile.c | 6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/makedumpfile.c b/makedumpfile.c
> >> index 101fa7c..af24359 100644
> >> --- a/makedumpfile.c
> >> +++ b/makedumpfile.c
> >> @@ -5544,6 +5544,7 @@ copy_1st_bitmap_from_memory(void)
> >>
> >>  	bitmap_offset = (DISKDUMP_HEADER_BLOCKS + dh->sub_hdr_size)
> >>  			 * dh->block_size;
> >> +	bitmap_offset += info->len_bitmap / 2;
> >>
> >>  	if (lseek(info->fd_memory, bitmap_offset, SEEK_SET) < 0) {
> >>  		ERRMSG("Can't seek %s. %s\n",
> >> @@ -5593,8 +5594,11 @@ create_1st_bitmap_file(void)
> >>  	struct timespec ts_start;
> >>  	off_t offset_page;
> >>
> >> -	if (info->flag_refiltering)
> >> +	if (info->flag_refiltering) {
> >> +		/* no hole info in kdump file, set it as 0 for refiltering */
> >> +		pfn_memhole = 0;
> >>  		return copy_1st_bitmap_from_memory();
> >> +	}
> >>
> >>  	if (info->flag_sadump)
> >>  		return sadump_copy_1st_bitmap_from_memory();
> >> --
> >> 2.7.4
> >>
> >
> >
> >
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> >
> 
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