On Thu, Jan 12, 2017 at 06:02:38PM +0100, Vlastimil Babka wrote: > > Signed-off-by: Mel Gorman <[email protected]> > > Acked-by: Hillf Danton <[email protected]> > > Acked-by: Jesper Dangaard Brouer <[email protected]> > > Very promising! But I have some worries. Should we put something like > VM_BUG_ON(in_interrupt()) into free_hot_cold_page() and rmqueue_pcplist() to > catch future potential misuses and also document this requirement? Also > free_hot_cold_page() has other call sites besides __free_pages() and I'm not > sure if those are all guaranteed to be !IRQ? E.g. free_hot_cold_page_list() > which is called by release_page() which uses irq-safe lock operations... >
They are not guaranteed to be !irq but the API is easier to call incorrectly than it could be. I think the checks can be pushed further down without excessive overhead. > Smaller nit below: > > > @@ -2453,8 +2450,8 @@ void free_hot_cold_page(struct page *page, bool cold) > > > > migratetype = get_pfnblock_migratetype(page, pfn); > > set_pcppage_migratetype(page, migratetype); > > - local_irq_save(flags); > > - __count_vm_event(PGFREE); > > + preempt_disable(); > > + count_vm_event(PGFREE); > > AFAICS preempt_disable() is enough for using __count_vm_event(), no? > It is, I'll fix it. Thanks. -- Mel Gorman SUSE Labs
