Messages in this thread | | | Date | Fri, 8 Jul 2022 16:58:35 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH] mm/page_alloc: replace local_lock with normal spinlock -fix -fix |
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On Fri, Jul 08, 2022 at 04:54:47PM +0200, Vlastimil Babka wrote: > On 7/8/22 16:44, Mel Gorman wrote: > > pcpu_spin_unlock and pcpu_spin_unlock_irqrestore both unlock > > pcp->lock and then enable preemption. This lacks symmetry against > > both the pcpu_spin helpers and differs from how local_unlock_* is > > implemented. While this is harmless, it's unnecessary and it's generally > > better to unwind locks and preemption state in the reverse order as > > they were acquired. > > Hm I'm confused, it seems it's done in reverse order (which I agree with) > before this -fix-fix, but not after it? > > before, pcpu_spin_lock() (and variants) do pcpu_task_pin() and then > spin_lock() (or variant), and pcpu_spin_unlock() does spin_unlock() and then > pcpu_task_unpin(). That seems symmetrical, i.e. reverse order to me? And > seems to match what local_lock family does too. >
You're not confused, I am. The patch and the changelog are outright brain damage from excessive context switching and a sign that it's time for the weekend to start.
Sorry for this absolute misfortune.
-- Mel Gorman SUSE Labs
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