[PATCH] crash utility: fix max_mapnr issue on system has over 44-bit addressing
jingbai.ma at hp.com
Wed Sep 25 04:01:36 EDT 2013
On 09/24/2013 09:58 PM, Dave Anderson wrote:
> ----- Original Message -----
>> The patch will add support for new compressed dumpfile header_version 6.
>> This bug was posted here:
>> 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.
>> Signed-off-by: Jingbai Ma<jingbai.ma at hp.com>
> Hello Jingbai,
> This patch needs to be backwards-compatible with respect
> to diskdump dumpfiles. Your patch presumes that it's always
> dealing with a compressed kdump, and as a result it immediately
> generates a SIGSEGV when presented with a diskdump dumpfile:
> $ crash vmcore vmlinux.gz
> crash 7.0.3rc5
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> Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
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> Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
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> Segmentation fault (core dumped)
> The SIGSEGV is generated from this patch to read_dump_header():
> + if (header->header_version< 6)
> + sub_header_kdump->max_mapnr = header->max_mapnr;
> because the sub_header_kdump pointer is only malloc'd if the
> dumpfile is a compressed kdump.
> And after that, all of the presumptive usages of the kdump_sub_header
> must be handled differently, e.g., this will fail:
> static inline int
> -dump_is_partial(const struct disk_dump_header *header)
> +dump_is_partial(const struct disk_dump_header *header,
> + const struct kdump_sub_header *sub_header)
> return header->bitmap_blocks>=
> - divideup(divideup(header->max_mapnr, 8), dd->block_size) * 2;
> + divideup(divideup(sub_header->max_mapnr, 8), dd->block_size) * 2;
> So pretty much everywhere that you've replaced "dd->header->max_mapnr"
> with either "sub_header_kdump->max_mapnr" or "dd->sub_header_kdump->max_mapnr"
> needs to be changed to use something like a pre-initialized local variable
> "max_mapnr" that gets set appropriately to the dumpfile type.
Got it, I will fix all these issues and submit a new patch.
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