Hello, Andreas

Sorry for long delay. I was on vacation.

On Fri, Dec 16, 2016 at 03:16:20PM +0100, Andreas Schwab wrote:

On Dez 16 2016, Minchan Kim [off-list ref] wrote:

quoted

Below helps?

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e10a4fe..dc37c9a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c

@@ -1611,6 +1611,7 @@ int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			tlb->fullmm);
 		orig_pmd = pmd_mkold(orig_pmd);
 		orig_pmd = pmd_mkclean(orig_pmd);
+		orig_pmd = pmd_wrprotect(orig_pmd);
 
 		set_pmd_at(mm, addr, pmd, orig_pmd);
 		tlb_remove_pmd_tlb_entry(tlb, pmd, addr);

Thanks, this fixes the issue (tested with 4.9).

It was a quick hack to know what exact problem is there and your confirming
helped a lot to understand the problem clear.

More right approach is to support pmd dirty handling in general page fault
handler rather than tweaking MADV_FREE. I just sent a new patch with Ccing
you.

Could you test it, please?
Thanks!