Messages in this thread | | | Date | Tue, 04 Mar 2014 22:53:41 -0500 | From | Sasha Levin <> | Subject | Re: mm: kernel BUG at mm/huge_memory.c:2785! |
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On 03/04/2014 10:16 PM, Bob Liu wrote: > On Thu, Feb 27, 2014 at 11:03 PM, Kirill A. Shutemov > <kirill.shutemov@linux.intel.com> wrote: >> Sasha Levin wrote: >>> Hi all, >>> >>> While fuzzing with trinity inside a KVM tools guest running latest -next kernel I've stumbled on the >>> following spew: >>> >>> [ 1428.146261] kernel BUG at mm/huge_memory.c:2785! >> >> Hm, interesting. >> >> It seems we either failed to split huge page on vma split or it >> materialized from under us. I don't see how it can happen: >> >> - it seems we do the right thing with vma_adjust_trans_huge() in >> __split_vma(); >> - we hold ->mmap_sem all the way from vm_munmap(). At least I don't see >> a place where we could drop it; >> > > Enable CONFIG_DEBUG_VM may show some useful information, at least we > can confirm weather rwsem_is_locked(&tlb->mm->mmap_sem) before > split_huge_page_pmd().
I have CONFIG_DEBUG_VM enabled and that code you're talking is not triggering, so mmap_sem is locked.
Thanks, Sasha
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