Messages in this thread | | | Date | Tue, 15 Nov 2005 10:02:48 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/5] Swap Migration V5: LRU operations |
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Christoph Lameter <clameter@engr.sgi.com> wrote: > > On Mon, 14 Nov 2005, Andrew Morton wrote: > > > > +int isolate_lru_page(struct page *page) > > > +{ > > > + int rc = 0; > > > + struct zone *zone = page_zone(page); > > > + > > > +redo: > > > + spin_lock_irq(&zone->lru_lock); > > > + rc = __isolate_lru_page(zone, page); > > > + spin_unlock_irq(&zone->lru_lock); > > > + if (rc == 0) { > > > + /* > > > + * Maybe this page is still waiting for a cpu to drain it > > > + * from one of the lru lists? > > > + */ > > > + smp_call_function(&lru_add_drain_per_cpu, NULL, 0 , 1); > > > > lru_add_drain() ends up doing spin_unlock_irq(), so we'll enable interrupts > > within the smp_call_function() handler. Is that legal on all > > architectures? > > isolate_lru_pages() is only called within a process context in the swap > migration patches. The hotplug folks may have to address this if they want > to isolate pages from interrupts etc.
But lru_add_drain_per_cpu() will be called from interrupt context: the IPI handler.
I'm asking whether it is safe for the IPI handler to reenable interupts on all architectures. It might be so, but I don't recall ever having seen it discussed, nor have I seen code which does it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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