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. Naoya -- 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>