On Sat, Jun 09, 2012 at 02:29:47PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> The current use of VM_FAULT_* codes with ERR_PTR requires us to ensure
> VM_FAULT_* values will not exceed MAX_ERRNO value. Decouple the
> VM_FAULT_* values from MAX_ERRNO.
I see you using the -ENOMEM|-ENOSPC, but I don't see any reference in the
code to MAX_ERRNO? Can you provide a comment explaining in a tad little
bit about the interaction of MAX_ERRNO and VM_FAULT?
>
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> ---
> mm/hugetlb.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index c868309..34a7e23 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1123,10 +1123,10 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> */
> chg = vma_needs_reservation(h, vma, addr);
> if (chg < 0)
> - return ERR_PTR(-VM_FAULT_OOM);
> + return ERR_PTR(-ENOMEM);
> if (chg)
> if (hugepage_subpool_get_pages(spool, chg))
> - return ERR_PTR(-VM_FAULT_SIGBUS);
> + return ERR_PTR(-ENOSPC);
>
> spin_lock(&hugetlb_lock);
> page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
> @@ -1136,7 +1136,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
> if (!page) {
> hugepage_subpool_put_pages(spool, chg);
> - return ERR_PTR(-VM_FAULT_SIGBUS);
> + return ERR_PTR(-ENOSPC);
> }
> }
>
> @@ -2496,6 +2496,7 @@ retry_avoidcopy:
> new_page = alloc_huge_page(vma, address, outside_reserve);
>
> if (IS_ERR(new_page)) {
> + long err = PTR_ERR(new_page);
> page_cache_release(old_page);
>
> /*
> @@ -2524,7 +2525,10 @@ retry_avoidcopy:
>
> /* Caller expects lock to be held */
> spin_lock(&mm->page_table_lock);
> - return -PTR_ERR(new_page);
> + if (err == -ENOMEM)
> + return VM_FAULT_OOM;
> + else
> + return VM_FAULT_SIGBUS;
> }
>
> /*
> @@ -2642,7 +2646,11 @@ retry:
> goto out;
> page = alloc_huge_page(vma, address, 0);
> if (IS_ERR(page)) {
> - ret = -PTR_ERR(page);
> + ret = PTR_ERR(page);
> + if (ret == -ENOMEM)
> + ret = VM_FAULT_OOM;
> + else
> + ret = VM_FAULT_SIGBUS;
> goto out;
> }
> clear_huge_page(page, address, pages_per_huge_page(h));
> --
> 1.7.10
>
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