Re: [Crash-utility] makedumpfile: 4.5 kernel commit breaks page filtering

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/ Thanks, Atsushi Kumagai >>As it is now, makedumpfile runs amok filtering pages that still have >>stuff left in page->mapping. For example, all of the addresses in >>my "filtered.list" input file are those of legitimate kernel data >>structures that have been incorrectly filtered because PAGE_MAPPING_ANON >>(bit 1) has been left set: >> >>crash> kmem -p < filtered.list >> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >>ffffea0011b29040 46ca41000 dead0000ffffffff 0 0 3ffff800000000 >> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >>ffffea0011b29040 46ca41000 dead0000ffffffff 0 0 3ffff800000000 >> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >>ffffea0011b29640 46ca59000 dead0000ffffffff 0 0 3ffff800000000 >> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >>ffffea0011b29640 46ca59000 dead0000ffffffff 0 0 3ffff800000000 >> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >>ffffea0001d51640 75459000 dead0000ffffffff 0 0 1ffff800000000 >>... >> >>In earlier kernels, the page->mapping fields above would not have >>their PAGE_MAPPING_ANON set. >> >>Dave > >-- >Crash-utility mailing list &gt;Crash-utility(a)redhat.com >https://www.redhat.com/mailman/listinfo/crash-utility