On Oct 29, 2022, at 5:15 PM, Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote: > zap_page_range is a bit confusing. It appears that the passed range can > span multiple vmas. Otherwise, there would be no do while loop. Yet, there > is only one mmu_notifier_range_init call specifying the passed vma. > > It appears all callers pass a range entirely within a single vma. > > The modifications above would work for a range within a single vma. However, > things would be more complicated if the range can indeed span multiple vmas. > For multiple vmas, we would need to check the first and last vmas for > pmd sharing. > > Anyone know more about this seeming confusing behavior? Perhaps, range > spanning multiple vmas was left over earlier code? I don’t have personal knowledge, but I noticed that it does not make much sense, at least for MADV_DONTNEED. I tried to batch the TLB flushes across VMAs for madvise’s. [1] Need to get to it sometime. [1] https://lore.kernel.org/lkml/20210926161259.238054-7-namit@xxxxxxxxxx/
