Randy Dunlap <rdunlap@xxxxxxxxxxxxx> writes: > On 04/16/18 19:02, Huang, Ying wrote: >> From: Huang Ying <ying.huang@xxxxxxxxx> >> >> A huge PMD need to be split when zap a part of the PMD mapping etc. >> If the PMD mapping is a swap mapping, we need to split it too. This >> patch implemented the support for this. This is similar as splitting >> the PMD page mapping, except we need to decrease the PMD swap mapping >> count for the huge swap cluster too. If the PMD swap mapping count >> becomes 0, the huge swap cluster will be split. >> >> Notice: is_huge_zero_pmd() and pmd_page() doesn't work well with swap >> PMD, so pmd_present() check is called before them. > > FWIW, I would prefer to see that comment in the source code, not just > in the commit description. Sure. I will add comment in source code too. Best Regards, Huang, Ying >> >> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> >> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> >> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> >> Cc: Michal Hocko <mhocko@xxxxxxxx> >> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> >> Cc: Shaohua Li <shli@xxxxxxxxxx> >> Cc: Hugh Dickins <hughd@xxxxxxxxxx> >> Cc: Minchan Kim <minchan@xxxxxxxxxx> >> Cc: Rik van Riel <riel@xxxxxxxxxx> >> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> >> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> >> Cc: Zi Yan <zi.yan@xxxxxxxxxxxxxx> >> --- >> include/linux/swap.h | 6 +++++ >> mm/huge_memory.c | 54 ++++++++++++++++++++++++++++++++++++++++---- >> mm/swapfile.c | 28 +++++++++++++++++++++++ >> 3 files changed, 83 insertions(+), 5 deletions(-)
