Jay Lan wrote:
> Ken'ichi Ohmichi wrote:
>> Hi Dave, Jay,
>>
>> Dave Anderson wrote:
>>> We just ran into a similar problem using an older version of makedumpfile,
>>> but looking at the latest makedumpfile code, it's seems that you could
>>> run into the same problem.
>>>
>>> In exclude_unnecessary_pages(), if a physical page is in a memory
>>> hole, then it skips the page and continues. In our case, that happened,
>>> but when it started up again, the next legitimate pfn was well beyond
>>> the previously-read cache of 512 pages. But since the new legit page
>>> wasn't modulo-512, it didn't refresh the page cache, and it ended up
>>> using stale page data (page->flags) and ended up excluding legitimate
>>> pages:
>>>
>>> for (; pfn < mmd->pfn_end;
>>> pfn++, mem_map += SIZE(page),
>>> paddr += info->page_size) {
>>>
>>> /*
>>> * Exclude the memory hole.
>>> */
>>> if (!is_in_segs(paddr))
>>> continue;
>>>
>>> if ((pfn % PGMM_CACHED) == 0) {
>>> if (pfn + PGMM_CACHED < mmd->pfn_end)
>>> pfn_mm = PGMM_CACHED;
>>> else
>>> pfn_mm = mmd->pfn_end - pfn;
>>> if (!readmem(VADDR, mem_map, page_cache,
>>> SIZE(page) * pfn_mm))
>>> goto out;
>>> }
>>>
>>> We fixed it by doing something like this:
>>>
>>> if (!is_in_segs(paddr)) {
>>> reset_cache = 1;
>>> continue;
>>> }
>>>
>>> if (((pfn % PGMM_CACHED) == 0) || reset_cache) {
>>> reset_cache = 0;
>>> ...
>> Great, you are right.
>> Thank you for fixing it :-)
>>
>> Jay, could you try Dave's fixing like the attached patch ?
>
> Yes. I applied your version of Dave's patch and tried again.
> It failed at a different pfn f600315:
>
>
> a4700rac:/mnt/sda9/diskdump # rm dump.cd31; /var/tmp/jlan/makedumpfile
> -cd31 -e 0xe0000f60031502f0 -x vmlinux.3 vmcore-cp.3 dump.cd31
> Excluding unnecessary pages : [ 45 %]
> pfn=f600315 flags=3c000000001026c
>
> PAGE(vaddr:e0000f60031502f0, pfn:f600315) is excluded as CACHE PAGE.
>
> Copying data : [100 %]
>
> The dumpfile is saved to dump.cd31.
>
> makedumpfile Completed.
>
>
> Note the flags of pfn f600315. Crash checked on the pfn using the
> vmcore-cp.3 and showed different flags:
>
> crash> kmem -p f60031502f0
> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> a07ffffc45d00498 f6003150000 0 0 1 3c0000000000400
> crash>
>
I ran a testing on a 2-cpu machine. The legitimate page got excluded
is:
PAGE(vaddr:e00000300313fb70, pfn:300313) is excluded as CACHE PAGE
Values of some variables in the routine on processing that page are:
pfn=300313 flags=3026c, page.flags=0
page_cache=0x6000000000033f60, pcache=0x6000000000037b88
Hope these data help.
Thanks,
- jay
>
>>
>> Thanks
>> Ken'ichi Ohmichi
>>
>
