Hi Will, On Mon, Oct 01, 2012 at 02:51:45PM +0100, Will Deacon wrote: > +void huge_pmd_set_accessed(struct mm_struct *mm, struct vm_area_struct *vma, > + unsigned long address, pmd_t *pmd, pmd_t orig_pmd) > +{ > + pmd_t entry; > + > + spin_lock(&mm->page_table_lock); > + entry = pmd_mkyoung(orig_pmd); > + if (pmdp_set_access_flags(vma, address & HPAGE_PMD_MASK, pmd, entry, 0)) > + update_mmu_cache(vma, address, pmd);
If the pmd is being splitted, this may not be a trasnhuge pmd anymore by the time you obtained the lock. (orig_pmd could be stale, and it wasn't verified with pmd_same either) The lock should be obtained through pmd_trans_huge_lock. if (pmd_trans_huge_lock(orig_pmd, vma) == 1) { set young bit spin_unlock(&mm->page_table_lock); } On x86: int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp, pmd_t entry, int dirty) { int changed = !pmd_same(*pmdp, entry); VM_BUG_ON(address & ~HPAGE_PMD_MASK); if (changed && dirty) { *pmdp = entry; with dirty == 0 it looks like it won't make any difference, but I guess your arm pmdp_set_access_flag is different. However it seems "dirty" means write access and so the invocation would better match the pte case: if (pmdp_set_access_flags(vma, address & HPAGE_PMD_MASK, pmd, entry, flags & FAULT_FLAG_WRITE)) But note, you still have to update it even when "dirty" == 0, or it'll still infinite loop for read accesses. > + spin_unlock(&mm->page_table_lock); > +} > + > int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, > unsigned long address, pmd_t *pmd, pmd_t orig_pmd) > { > diff --git a/mm/memory.c b/mm/memory.c > index 5736170..d5c007d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3537,7 +3537,11 @@ retry: > if (unlikely(ret & VM_FAULT_OOM)) > goto retry; > return ret; > + } else { > + huge_pmd_set_accessed(mm, vma, address, pmd, > + orig_pmd); > } > + > return 0; Thanks, Andrea -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/