Hi KOSAKI, On 05/11/2012 02:53 AM, KOSAKI Motohiro wrote: >>>> let's assume that one application want to allocate user space memory >>>> region using malloc() and then write something on the region. as you >>>> may know, user space buffer doen't have real physical pages once >>>> malloc() call so if user tries to access the region then page fault >>>> handler would be triggered >>> >>> >>> Understood. >>> >>>> and then in turn next process like swap in to fill physical frame >>>> number >>> into entry of the page faulted. >>> >>> >>> Sorry, I can't understand your point due to my poor English. >>> Could you rewrite it easiliy? :) >>> >> >> Simply saying, handle_mm_fault would be called to update pte after >> finding >> vma and checking access right. and as you know, there are many cases to >> process page fault such as COW or demand paging. > > Hmm. If I understand correctly, you guys misunderstand mlock. it doesn't > page pinning > nor prevent pfn change. It only guarantee to don't make swap out. e.g. Symantic point of view, you're right but the implementation makes sure page pinning. > memory campaction > feature may automatically change page physical address. I tried it last year but decided drop by realtime issue. https://lkml.org/lkml/2011/8/29/295 so I think mlock is a kind of page pinning. If elsewhere I don't realized is doing, that place should be fixed. Or my above patch should go ahead. > > > -- > 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/ . > Fight unfair telecom internet charges in Canada: sign > http://stopthemeter.ca/ > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > -- Kind regards, Minchan Kim -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>