From: David Gibson This patch adds a debugging message to the ppc64 hugepage code when we attempt to open the "low" (32-bit) hugepage window on PPC64, but can't because a (non-hugepage) mapping already exists in the region. --- 25-akpm/arch/ppc64/mm/hugetlbpage.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletion(-) diff -puN arch/ppc64/mm/hugetlbpage.c~ppc64-hugepage-useful-warning arch/ppc64/mm/hugetlbpage.c --- 25/arch/ppc64/mm/hugetlbpage.c~ppc64-hugepage-useful-warning 2004-03-31 22:55:56.308004096 -0800 +++ 25-akpm/arch/ppc64/mm/hugetlbpage.c 2004-03-31 22:55:56.312003488 -0800 @@ -253,8 +253,11 @@ static int open_32bit_htlbpage_range(str /* Check no VMAs are in the region */ vma = find_vma(mm, TASK_HPAGE_BASE_32); - if (vma && (vma->vm_start < TASK_HPAGE_END_32)) + if (vma && (vma->vm_start < TASK_HPAGE_END_32)) { + printk(KERN_DEBUG "Low HTLB region busy: PID=%d vma @ %lx-%lx\n", + current->pid, vma->vm_start, vma->vm_end); return -EBUSY; + } /* Clean up any leftover PTE pages in the region */ spin_lock(&mm->page_table_lock); _