On Wed, 2010-09-29 at 18:17 +0800, Johannes Weiner wrote: > On Wed, Sep 29, 2010 at 10:57:40AM +0800, Shaohua Li wrote: > > With commit 645747462435, pte referenced file page isn't activated in inactive > > list scan. For VM_EXEC page, if it can't get a chance to active list, the > > executable page protect loses its effect. We protect such page in inactive scan > > here, now such page will be guaranteed cached in a full scan of active and > > inactive list, which restores previous behavior. > > This change was in the back of my head since the used-once detection > was merged but there were never any regressions reported that would > indicate a requirement for it. The executable page protect is to improve responsibility. I would expect it's hard for user to report such regression. > Does this patch fix a problem you observed? No, I haven't done test where Fengguang does in commit 8cab4754d24a0f. > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -608,8 +608,15 @@ static enum page_references page_check_references(struct page *page, > > * quickly recovered. > > */ > > SetPageReferenced(page); > > - > > - if (referenced_page) > > + /* > > + * Identify pte referenced and file-backed pages and give them > > + * one trip around the active list. So that executable code get > > + * better chances to stay in memory under moderate memory > > + * pressure. JVM can create lots of anon VM_EXEC pages, so we > > + * ignore them here. > > PTE-referenced PageAnon() pages are activated unconditionally a few > lines further up, so the page_is_file_cache() check filters only shmem > pages. I doubt this was your intention...? This is intented. the executable page protect is just to protect executable file pages. please see 8cab4754d24a0f. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>