Messages in this thread | | | Date | Sat, 8 Apr 2023 12:42:11 +0800 | Subject | Re: [PATCH v5 1/6] userfaultfd: convert mfill_atomic_pte_copy() to use a folio | From | "zhangpeng (AS)" <> |
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On 2023/4/7 5:31, Mike Kravetz wrote:
> On 03/31/23 17:39, Peng Zhang wrote: >> From: ZhangPeng <zhangpeng362@huawei.com> >> >> Call vma_alloc_folio() directly instead of alloc_page_vma() and convert >> page_kaddr to kaddr in mfill_atomic_pte_copy(). Removes several calls to >> compound_head(). >> >> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com> >> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com> >> --- >> mm/userfaultfd.c | 33 +++++++++++++++++---------------- >> 1 file changed, 17 insertions(+), 16 deletions(-) > Looks good, > > Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> > >> } else { >> - page = *pagep; >> + folio = page_folio(*pagep); >> + VM_BUG_ON_FOLIO(folio_test_large(folio), folio); >> *pagep = NULL; >> } > However, I am still unsure about the reason for adding the VM_BUG_ON_FOLIO > here.
VM_BUG_ON_FOLIO was added to ensure that folio is a single-page folio. However, the folio corresponding to the foliop is always a single-page folio. We just don't need this check. I'll drop VM_BUG_ON_FOLIO.
Thanks for your review.
Best Regards, Peng
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