Messages in this thread | | | Date | Sun, 8 May 2022 21:09:55 +0800 | Subject | Re: [PATCH v2 1/3] mm: change huge_ptep_clear_flush() to return the original pte | From | Baolin Wang <> |
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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@linux.alibaba.com> >> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> > > Reviewed-by: Muchun Song <songmuchun@bytedance.com>
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@oracle.com/
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