On Fri, Jan 21, 2011 at 1:14 AM, Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote: > Hello Minchan, > > On Fri, Jan 21, 2011 at 12:49:35AM +0900, Minchan Kim wrote: >> Hi Andrea, >> >> I hit thg BUG 2 time during 5 booting. >> I applied khugepaged: fix pte_unmap for highpte x86_32 based on 2.6.38-rc1. > > This is again 32bit which rings a bell because clearly it didn't have > a whole lot of testing (not remotely comparable to the amount of > testing x86-64 had), but it's not necessarily 32bit related. It still > would be worth to know if it still happens after you disable > CONFIG_HIGHMEM (to rule out 32bit issues in not well tested kmaps). > I wii try it at tomorrow. > The rmap walk simply didn't find an hugepmd pointing to the page. Or > the mapcount was left pinned after the page got somehow unmapped. > > I wonder why pages are added to swap and the system is so low on > memory during boot. How much memory do you have in the 32bit system? That was my curiosity, too. > Do you boot with something like mem=256m? This is also the Xorg No. I didn't limit mem size. My system has a 2G memory. > process, which is a bit more special than most and it may have device > drivers attached to the pages. Both bugs are hit by Xorg. I doubt it. > > One critical thing is that split_huge_page must be called when > splitting vmas, see split_huge_page_address and > __vma_adjust_trans_huge, right now it's called from vma_adjust > only. If anything is wrong in that function, or if any place adjusting > the vma is not covered by that function, it may result in exactly the > problem you run into. If drivers are mangling over the vmas that would > also explain it. > > If you happen to have crash dump with vmlinux that would be the best > debug option for this, also if you can reproduce it in a VM that will > make it easier to reproduce without your hardware. Otherwise we'll > find another way. I will investigate it after out of office at tomorrow. Sorry but here is 1:40 am. :) If you have a any guess or good method to investigate the bug, please reply