Question about Address Range Validation in Crash Kernel Allocation

["chenhaixiang (A)" <chenhaixiang3@huawei.com>]

Dear kexec Community Members,

I encountered an issue while using kexec-tools on my x86_64 machine.
When there is a segment marked as 'reserved' within the memory range allocated for the crash kernel in /proc/iomem,the output appears as follows:
2d4fd058-60efefff : System RAM
  2d4fd058-58ffffff : System RAM
    49000000-58ffffff : Crash kernel
      53cbd000-53ccffff : Reserved

The crash_memory_range array will encounter incorrect address ranges:
CRASH MEMORY RANGES
000000002d4fd058-0000000048ffffff (0)
0000000053cbd000-0000000048ffffff (1)
0000000059000000-0000000053ccffff (0)

Read the code, I noticed that the get_crash_memory_ranges() function invokes exclude_region() to handle the splitting of memory regions, but it seems unable to properly handle the scenario described above.
The code logic is as follows:
...
	if (start < mend && end > mstart) {
		if (start != mstart && end != mend) {
			/* Split memory region */
			crash_memory_range[i].end = start - 1;
			temp_region.start = end + 1;
			temp_region.end = mend;
			temp_region.type = RANGE_RAM;
			tidx = i+1;
		} else if (start != mstart)
			crash_memory_range[i].end = start - 1;
		else
			crash_memory_range[i].start = end + 1;
	}
...
If start < mstart < mend < end, resulting in crash_memory_range[i].end becoming less than crash_memory_range[i].start, leading to incorrect address ranges.
I would like to know if this behavior is reasonable and whether it is necessary to validate the address ranges for compliance at the end.

Thank you for your time and assistance.

Chen Haixiang

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