On Wed, Sep 05, 2018 at 03:00:08PM -0700, Andrew Morton wrote: > On Wed, 5 Sep 2018 14:35:11 -0700 Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote: > > > > so perhaps we could put some > > > stopgap workaround into that site and add a runtime warning into the > > > put_page() code somewhere to detect puttage of huge pages from hardirq > > > and softirq contexts. > > > > I think we would add the warning/etc at free_huge_page. The issue would > > only apply to hugetlb pages, not THP. > > > > But, the more I think about it the more I think Aneesh's patch to do > > spin_lock/unlock_irqsave is the right way to go. Currently, we only > > know of one place where a put_page of hugetlb pages is done from softirq > > context. So, we could take the spin_lock/unlock_bh as Matthew suggested. > > When the powerpc iommu code was added, I doubt this was taken into account. > > I would be afraid of someone adding put_page from hardirq context. > > Me too. If we're going to do this, surely we should make hugepages > behave in the same fashion as PAGE_SIZE pages. But these aren't vanilla hugepages, they're specifically hugetlbfs pages. I don't believe there's any problem with calling put_page() on a normally allocated huge page or THP.
