Re: [PATCH] makedumpfile: fix max_mapnr issue on system has over 44-bit addressing

HATAYAMA Daisuke
2013-09-25T00:36:57Z

(2013/09/24 21:49), Jingbai Ma wrote:
> This patch will fix a bug of makedumpfile doesn't work correctly on system
> has over 44-bit addressing in compression dump mode.
> This bug was posted here:
> http://lists.infradead.org/pipermail/kexec/2013-September/009587.html
>
> This patch will add a new field in struct kdump_sub_header.
> unsigned long max_mapnr;
>
> And the old "unsigned int max_mapnr" in struct disk_dump_header will
> not be used anymore. But still be there for compatibility purpose.
>
> This patch will change the header_version to 6.
>
> The corresponding patch for crash utility will be sent out separately.
>
> This patch doesn't change sadump_header.
> Because of in sadump file, there is no any sub-header, it has to change
> the sadump_header itself.
> And if do so, will cause backwards-compatibility issue.
> So it could be a separate patch if needed.
>
> Signed-off-by: Jingbai Ma <jingbai.ma@hp.com>
> ---
> IMPLEMENTATION | 1 +
> diskdump_mod.h | 5 ++++-
> makedumpfile.c | 28 ++++++++++++++++++++++------
> 3 files changed, 27 insertions(+), 7 deletions(-)
>
> diff --git a/IMPLEMENTATION b/IMPLEMENTATION
> index f0f3135..d576811 100644
> --- a/IMPLEMENTATION
> +++ b/IMPLEMENTATION
> @@ -77,6 +77,7 @@
> unsigned long size_note; /* header_version 4 and later */
> off_t offset_eraseinfo; /* header_version 5 and later */
> unsigned long size_eraseinfo; /* header_version 5 and later */
> + unsigned long max_mapnr; /* header_version 6 and later */

x86 PAE mode can represents 52-bit physical addresses and so 40-bit physical
page frames. On x86_32 unsigned long has 32-bit length only. So, you should
define max_mapnr as unsigned long long.

> };
>
> - 1st-bitmap
> diff --git a/diskdump_mod.h b/diskdump_mod.h
> index af060b6..30306a5 100644
> --- a/diskdump_mod.h
> +++ b/diskdump_mod.h
> @@ -48,7 +48,9 @@ struct disk_dump_header {
> header in blocks */
> unsigned int bitmap_blocks; /* Size of Memory bitmap in
> block */
> - unsigned int max_mapnr; /* = max_mapnr */
> + unsigned int max_mapnr; /* = max_mapnr, 32bit only,
> + full 64bit in sub header.
> + Do not use this anymore! */
> unsigned int total_ram_blocks;/* Number of blocks should be
> written */
> unsigned int device_blocks; /* Number of total blocks in
> @@ -75,6 +77,7 @@ struct kdump_sub_header {
> unsigned long size_note; /* header_version 4 and later */
> off_t offset_eraseinfo; /* header_version 5 and later */
> unsigned long size_eraseinfo; /* header_version 5 and later */
> + unsigned long max_mapnr; /* header_version 6 and later */

This, too.

> @@ -5153,10 +5160,11 @@ write_kdump_header(void)
> * Write common header
> */
> strncpy(dh->signature, KDUMP_SIGNATURE, strlen(KDUMP_SIGNATURE));
> - dh->header_version = 5;
> + dh->header_version = 6;
> dh->block_size = info->page_size;
> dh->sub_hdr_size = sizeof(kh) + size_note;
> dh->sub_hdr_size = divideup(dh->sub_hdr_size, dh->block_size);
> + /* dh->max_mapnr may be truncated here, full 64bit in kh.max_mapnr */
> dh->max_mapnr = info->max_mapnr;

dh->max_mapnr = MIN(info->max_mapnr, UINT_MAX) seems better for old versions of crash utitlity.

--
Thanks.
HATAYAMA, Daisuke