On Mon, Feb 27, 2017 at 08:19:08AM -0800, Shaohua Li wrote: > On Mon, Feb 27, 2017 at 03:33:15PM +0900, Minchan Kim wrote: > > Hi Shaohua, > > > > On Fri, Feb 24, 2017 at 01:31:47PM -0800, Shaohua Li wrote: > > > When memory pressure is high, we free MADV_FREE pages. If the pages are > > > not dirty in pte, the pages could be freed immediately. Otherwise we > > > can't reclaim them. We put the pages back to anonumous LRU list (by > > > setting SwapBacked flag) and the pages will be reclaimed in normal > > > swapout way. > > > > > > We use normal page reclaim policy. Since MADV_FREE pages are put into > > > inactive file list, such pages and inactive file pages are reclaimed > > > according to their age. This is expected, because we don't want to > > > reclaim too many MADV_FREE pages before used once pages. > > > > > > Based on Minchan's original patch > > > > > > Cc: Michal Hocko <mhocko@xxxxxxxx> > > > Cc: Minchan Kim <minchan@xxxxxxxxxx> > > > Cc: Hugh Dickins <hughd@xxxxxxxxxx> > > > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > > > Cc: Rik van Riel <riel@xxxxxxxxxx> > > > Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> > > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > > Signed-off-by: Shaohua Li <shli@xxxxxx> > > > --- > > > include/linux/rmap.h | 2 +- > > > mm/huge_memory.c | 2 ++ > > > mm/madvise.c | 1 + > > > mm/rmap.c | 40 +++++++++++++++++----------------------- > > > mm/vmscan.c | 34 ++++++++++++++++++++++------------ > > > 5 files changed, 43 insertions(+), 36 deletions(-) > > > > > > diff --git a/include/linux/rmap.h b/include/linux/rmap.h > > > index 7a39414..fee10d7 100644 > > > --- a/include/linux/rmap.h > > > +++ b/include/linux/rmap.h > > > @@ -298,6 +298,6 @@ static inline int page_mkclean(struct page *page) > > > #define SWAP_AGAIN 1 > > > #define SWAP_FAIL 2 > > > #define SWAP_MLOCK 3 > > > -#define SWAP_LZFREE 4 > > > +#define SWAP_DIRTY 4 > > > > I still don't convinced why we should introduce SWAP_DIRTY in try_to_unmap. > > https://marc.info/?l=linux-mm&m=148797879123238&w=2 > > > > We have been SetPageMlocked in there but why cannot we SetPageSwapBacked > > in there? It's not a thing to change LRU type but it's just indication > > we found the page's status changed in late. > > This one I don't have strong preference. Personally I agree with Johannes, > handling failure in vmscan sounds better. But since the failure handling is > just one statement, this probably doesn't make too much difference. If Johannes > and you made an agreement, I'll follow. I don't want to add unnecessary new return value(i.e., SWAP_DIRTY). If VM found lazyfree page dirty in try_to_unmap_one, it means "non-swappable page" so it's natural to set SetPageSwapBacked in there and return just SWAP_FAIL to activate it in vmscan.c. SWAP_FAIL means the page is non-swappable so it should be activated. I don't see any problem in there like software engineering pov. However, it seems everyone are happy with introdcuing SWAP_DIRTY so I don't insist on it which is not critical for this patchset. I looked over try_to_unmap and callers. Now, I think we could remove SWAP_MLOCK and maybe SWAP_AGAIN as well as SWAP_DIRTY that is to make try_to_unmap *bool*. So, it could be done by separate patchset. I will look into that in more. Acked-by: Minchan Kim <minchan@xxxxxxxxxx> Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
