On Tue, 20 Sep 2016 10:37:04 -0700 Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote: > > Cc'ed Rui Teng and Dave Hansen as they were discussing the issue in > this thread: > https://lkml.org/lkml/2016/9/13/146 Ah, thanks, I didn't see that. > > Their approach (I believe) would be to fail the offline operation in > this case. However, I could argue that failing the operation, or > dissolving the unused huge page containing the area to be offlined is > the right thing to do. > > I never thought too much about the VM_BUG_ON(), but you are correct in > that it should be removed in either case. > > The other thing that needs to be changed is the locking in > dissolve_free_huge_page(). I believe the lock only needs to be held if > we are removing the huge page from the pool. It is not a correctness > but performance issue. > Yes, that looks odd, that's why in my patch I moved the PageHuge() check out from dissolve_free_huge_page(), up into the loop in dissolve_free_huge_pages(). This way dissolve_free_huge_page() with its locking should only be called once per memory block, in the case where this memory block is part of a gigantic hugepage. -- 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>