On 02/21/2014 12:25 PM, Naoya Horiguchi wrote: > On Fri, Feb 21, 2014 at 12:18:11PM -0500, Sasha Levin wrote: >> On 02/21/2014 11:58 AM, Naoya Horiguchi wrote: >>> On Fri, Feb 21, 2014 at 01:30:53AM -0500, Sasha Levin wrote: >>>> On 02/10/2014 04:44 PM, Naoya Horiguchi wrote: >>>>> queue_pages_range() does page table walking in its own way now, >>>>> so this patch rewrites it with walk_page_range(). >>>>> One difficulty was that queue_pages_range() needed to check vmas >>>>> to determine whether we queue pages from a given vma or skip it. >>>>> Now we have test_walk() callback in mm_walk for that purpose, >>>>> so we can do the replacement cleanly. queue_pages_test_walk() >>>>> depends on not only the current vma but also the previous one, >>>>> so we use queue_pages->prev to keep it. >>>>> >>>>> ChangeLog v2: >>>>> - rebase onto mmots >>>>> - add VM_PFNMAP check on queue_pages_test_walk() >>>>> >>>>> Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> >>>>> --- >>>> >>>> Hi Naoya, >>>> >>>> I'm seeing another spew in today's -next, and it seems to be related >>>> to this patch. Here's the spew (with line numbers instead of kernel >>>> addresses): >>> >>> Thanks. (line numbers translation is very helpful.) >>> >>> This bug looks strange to me. >>> "kernel BUG at mm/hugetlb.c:3580" means we try to do isolate_huge_page() >>> for !PageHead page. But the caller queue_pages_hugetlb() gets the page >>> with "page = pte_page(huge_ptep_get(pte))", so it should be the head page! >>> >>> mm/hugetlb.c:3580 is VM_BUG_ON_PAGE(!PageHead(page), page), so we expect to >>> have dump_page output at this point, is that in your kernel log? >> >> This is usually a sign of a race between that code and thp splitting, see >> https://lkml.org/lkml/2013/12/23/457 for example. > > queue_pages_hugetlb() is for hugetlbfs, not for thp, so I don't think that > it's related to thp splitting, but I agree it's a race. > >> I forgot to add the dump_page output to my extraction process and the complete logs all long gone. >> I'll grab it when it happens again. > > Thank you. It'll be useful. And here it is: [ 755.524966] page:ffffea0000000000 count:0 mapcount:1 mapping: (null) index:0x0 [ 755.526067] page flags: 0x0() Followed by the same stack trace as before. Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>