On Tue, Oct 27, 2015 at 03:39:16PM +0800, yalin wang wrote: > > > On Oct 27, 2015, at 15:09, Minchan Kim <minchan@xxxxxxxxxx> wrote: > > > > Hello Yalin, > > > > Sorry for missing you in Cc list. > > IIRC, mails to send your previous mail address(Yalin.Wang@xxxxxxxxxxxxxx) > > were returned. > > > > You added comment bottom line so I'm not sure what PageDirty you meant. > > > >> it is wrong here if you only check PageDirty() to decide if the page is freezable or not . > >> The Anon page are shared by multiple process, _mapcount > 1 , > >> so you must check all pt_dirty bit during page_referenced() function, > >> see this mail thread: > >> http://ns1.ske-art.com/lists/kernel/msg1934021.html > > > > If one of pte among process sharing the page was dirty, the dirtiness should > > be propagated from pte to PG_dirty by try_to_unmap_one. > > IOW, if the page doesn't have PG_dirty flag, it means all of process did > > MADV_FREE. > > > > Am I missing something from you question? > > If so, could you show exact scenario I am missing? > > > > Thanks for the interest. > oh, yeah , that is right , i miss that , pte_dirty will propagate to PG_dirty , > so that is correct . > Generic to say this patch move set_page_dirty() from add_to_swap() to > try_to_unmap(), i think can change a little about this patch: > > @@ -1476,6 +1446,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, > ret = SWAP_FAIL; > goto out_unmap; > } > + if (!PageDirty(page)) > + SetPageDirty(page); > if (list_empty(&mm->mmlist)) { > spin_lock(&mmlist_lock); > if (list_empty(&mm->mmlist)) > > i think this 2 lines can be removed , > since pte_dirty have propagated to set_page_dirty() , we don’t need this line here , > otherwise you will always dirty a AnonPage, even it is clean, > then we will page out this clean page to swap partition one more , this is not needed. > am i understanding correctly ? Your understanding is correct. I will fix it in next spin. > > By the way, please change my mail address to yalin.wang2010@xxxxxxxxx in CC list . > Thanks a lot. :) Thanks for the review! > -- 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>