Hello Joe, >On 02/25/2016 07:35 PM, Atsushi Kumagai wrote: >> Hello Dave, >> >>>> Note that PAGE_MAPPING_ANON is now only set in the compound_head page, >>>> so when makedumpfile walks though the pages, it will have to look >>>> at each page's head page for the bit setting. >>> >>> Thanks for your report. >>> As you said, it seems checking the head page like kernel does is necessary. >>> I'll try to work it out, please give me some time. >> >> Reading head page's page->mapping for each tail page will take extra time, >> so I contrived another way. >> >> It's just skipping compound tail pages for filtering. >> If makedumpfile excludes compound pages, it will be done at a time by >> exclude_range() at the time of checking the compound head page. We don't >> need to check compound tail pages individually. >> >> I made the patch, could you test the *compound* branch below ? >> This version requires a new unexported symbol, you need to specify >> -x vmlinux for now. >> >> https://sourceforge.net/p/makedumpfile/code/ci/compound/tree/ > >Hi Atsushi, Dave, > >Running the makedumpfile compound branch on 4.5-rc5 and this kdump.conf >setting: > >core_collector makedumpfile -l --message-level 1 -d 31 -x >/kdumproot/var/crash/vmlinux > >I was able to collect and successfully read a few test dumps without >incident. This was inside a VM without any interesting system load, but >was regularly giving me issues before the patch. Great, thanks for your help. I'll post the kernel side patch to export the necessary symbol "OFFSET(page.compound_head)" soon. Thanks, Atsushi Kumagai
