On 5/8/2022 7:09 PM, Muchun Song wrote:
On Sun, May 08, 2022 at 05:36:39PM +0800, Baolin Wang wrote:It is incorrect to use ptep_clear_flush() to nuke a hugetlb page table when unmapping or migrating a hugetlb page, and will change to use huge_ptep_clear_flush() instead in the following patches. So this is a preparation patch, which changes the huge_ptep_clear_flush() to return the original pte to help to nuke a hugetlb page table. Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> Acked-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Thanks for reviewing.
But one nit below: [...]diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 8605d7e..61a21af 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5342,7 +5342,7 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma, ClearHPageRestoreReserve(new_page);/* Break COW or unshare */- huge_ptep_clear_flush(vma, haddr, ptep); + (void)huge_ptep_clear_flush(vma, haddr, ptep);Why add a "(void)" here? Is there any warning if no "(void)"? IIUC, I think we can remove this, right?
I did not meet any warning without the casting, but this is per Mike's comment[1] to make the code consistent with other functions casting to void type explicitly in hugetlb.c file.
[1] https://lore.kernel.org/all/495c4ebe-a5b4-afb6-4cb0-956c1b18d0cc@xxxxxxxxxx/
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