On Mon, May 14, 2012 at 3:34 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote: > On Mon, 2012-05-14 at 15:29 -0700, Pravin B Shelar wrote: >> On arches that do not support this_cpu_cmpxchg_double slab_lock is used >> to do atomic cmpxchg() on double word which contains page->_count. >> page count can be changed from get_page() or put_page() without taking >> slab_lock. That corrupts page counter. >> >> Following patch fixes it by moving page->_count out of cmpxchg_double >> data. So that slub does no change it while updating slub meta-data in >> struct page. > > I say again : Page is owned by slub, so get_page() or put_page() is not > allowed ? > This is already done in multiple subsystem in Linux kernel. e.g. ocfs, xfs, etc. So object from slab can be passed to IO using DMA. I don't think this rule you referring to is enforced anywhere. Thanks, Pravin. -- 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>