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.
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@xxxxxxxxxx>
> ---
> 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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