On Thu, 22 Oct 2015, Minchan Kim wrote: > Hello Hugh, > > On Wed, Oct 21, 2015 at 05:59:59PM -0700, Hugh Dickins wrote: > > On Thu, 22 Oct 2015, Minchan Kim wrote: > > > > > > I added the code to check it and queued it again but I had another oops > > > in this time but symptom is related to anon_vma, too. > > > (kernel is based on recent mmotm + unconditional mkdirty for bug fix) > > > It seems page_get_anon_vma returns NULL since the page was not page_mapped > > > at that time but second check of page_mapped right before try_to_unmap seems > > > to be true. > > > > > > Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS > > > Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS > > > page:ffffea0001cfbfc0 count:3 mapcount:1 mapping:ffff88007f1b5f51 index:0x600000aff > > > flags: 0x4000000000048019(locked|uptodate|dirty|swapcache|swapbacked) > > > page dumped because: VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma) > > > > That's interesting, that's one I added in my page migration series. > > Let me think on it, but it could well relate to the one you got before. > > I will roll back to mm/madv_free-v4.3-rc5-mmotm-2015-10-15-15-20 > instead of next-20151021 to remove noise from your migration cleanup > series and will test it again. > If it is fixed, I will test again with your migration patchset, then. Not a good use of your time, I think. It's sure to be fixed in the rc5-mmotm because that VM_BUG_ON_PAGE(blah) just does not exist in that tree: I added it to verify my reasoning in changing the comments about page_get_anon_vma() and PageSwapCache in mm/migrate.c. > > > > > > page->mem_cgroup:ffff88007f3dcc00 > > > ------------[ cut here ]------------ > > > kernel BUG at mm/migrate.c:889! > > > invalid opcode: 0000 [#1] SMP > > > Dumping ftrace buffer: > > > (ftrace buffer empty) > > > Modules linked in: > > > CPU: 11 PID: 59 Comm: khugepaged Not tainted 4.3.0-rc6-next-20151021-THP-ref-madv_free+ #1557 > > > > Hmm, it might be me to blame, or it might be Kirill, don't know yet. > > It might be me, either. > > > > > Oh, hold on, I think Andrew has just posted a new mmotm, and it includes > > an update to Kirill's migrate_pages-try-to-split-pages-on-queueing.patch: > > I haven't digested yet, but it might turn out to be relevant. Sorry, I think that was an irrelevant suggestion: today's new rc6-mmotm is identical to yesterday's there, and the patch that was removed appears to be identical to the one added. Hugh -- 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>