Messages in this thread | | | Subject | Re: [PATCH 7/7] mm/page_alloc: Replace local_lock with normal spinlock | From | Nicolas Saenz Julienne <> | Date | Fri, 17 Jun 2022 11:39:03 +0200 |
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Hi Mel,
On Mon, 2022-06-13 at 13:56 +0100, Mel Gorman wrote: > @@ -3446,12 +3490,16 @@ void free_unref_page(struct page *page, unsigned int order) > migratetype = MIGRATE_MOVABLE; > } > > - local_lock_irqsave(&pagesets.lock, flags); > - freed_pcp = free_unref_page_commit(page, migratetype, order, false); > - local_unlock_irqrestore(&pagesets.lock, flags); > - > - if (unlikely(!freed_pcp)) > + zone = page_zone(page); > + pcp_trylock_prepare(UP_flags);
Now that you're calling the *_irqsave() family of function you can drop pcp_trylock_prepare/finish()
For the record in UP:
#define spin_trylock_irqsave(lock, flags) \ ({ \ local_irq_save(flags); \ 1; })
> + pcp = pcpu_spin_trylock_irqsave(struct per_cpu_pages, lock, zone->per_cpu_pageset, flags); > + if (pcp) { > + free_unref_page_commit(pcp, zone, page, migratetype, order); > + pcp_spin_unlock_irqrestore(pcp, flags); > + } else { > free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE); > + } > + pcp_trylock_finish(UP_flags); > } > > /*
As Vlastimil mentioned elsewhere, I also wonder if it makes sense to just bypass patch #5. Especially as its intent isn't true anymore:
"As preparation for dealing with both of those problems, protect the lists with a spinlock. The IRQ-unsafe version of the lock is used because IRQs are already disabled by local_lock_irqsave. spin_trylock is used in preparation for a time when local_lock could be used instead of lock_lock_irqsave."
-- Nicolás Sáenz
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