On 2021/4/9 12:37, Mike Kravetz wrote: > On 4/8/21 8:01 PM, Miaohe Lin wrote: >> On 2021/4/9 6:53, Mike Kravetz wrote: >>> >>> Yes, add a comment to hugetlb_unreserve_pages saying that !resv_map >>> implies freed == 0. >>> >> >> Sounds good! >> >>> It would also be helpful to check for (chg - freed) == 0 and skip the >>> calls to hugepage_subpool_put_pages() and hugetlb_acct_memory(). Both >>> of those routines may perform an unnecessary lock/unlock cycle in this >>> case. >>> >>> A simple >>> if (chg == free) >>> return 0; >>> before the call to hugepage_subpool_put_pages would work. >> >> This may not be really helpful because hugepage_subpool_put_pages() and hugetlb_acct_memory() >> both would handle delta == 0 case without unnecessary lock/unlock cycle. >> Does this make sense for you? If so, I will prepare v2 with the changes to add a comment >> to hugetlb_unreserve_pages() __without__ the check for (chg - freed) == 0. > > Sorry, I forgot about the recent changes to check for delta == 0. > No need for the check here, just the comment. > That's all right. Will add the comment in V2. Thanks.
