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This series introduces a PMD-level swap entry so the >> huge mapping can survive the swap round-trip and do_huge_pmd_swap_page() >> can restore the PMD mapping directly on swap-in, without waiting for >> khugepaged to collapse the range later. >> >> The PMD swap entry is a compact page-table encoding for HPAGE_PMD_NR >> consecutive swap slots. swap_map accounting remains per-slot and is >> unchanged. Importantly, a PMD swap entry does not promise that the swap >> cache always contains one PMD-sized folio. While the cache is empty or >> contains one PMD-sized folio, PMD-level handling can proceed. Once the >> cache has split/per-slot state, users either inspect the individual >> slots directly (mincore) or split the PMD swap entry and retry through >> the PTE path (fault, swapoff, MADV_WILLNEED, UFFDIO_MOVE). MADV_FREE >> does not consult the cache at all: it frees a whole PMD swap entry in >> place and only splits when the advised range covers part of the PMD. >> Likewise, if any slot is still backed by zswap's per-page >> store, PMD-order swap-in consumers split and let the PTE path load the >> range page by page; an all-on-disk range can still be read back as one >> PMD-sized folio. >> >> The series is ordered so every consumer can handle PMD swap entries >> before the swap-out producer starts installing them. The swap-out patch >> is the last functional change. >> > > I was hoping that we could get this into the next merge window, but as we are > approach rc6 and I didn't even manage to review all patches (shame on me), I > assume this would be a quite fit. > > So I assume this series is one of the things that we'll try to get in shape over > the next merge window to queue it early after rc1. I am going to review this series, since I have done with Lorenzo’s VM_SPECIAL one. Best Regards, Yan, Zi