On Wed, Aug 24, 2022 at 10:58:26PM -0600, Yu Zhao wrote: > On Wed, Aug 24, 2022 at 8:18 AM Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote: > > > > The pcp_spin_lock_irqsave protecting the PCP lists is IRQ-safe as a task > > allocating from the PCP must not re-enter the allocator from IRQ context. > > In each instance where IRQ-reentrancy is possible, the lock is acquired using > > pcp_spin_trylock_irqsave() even though IRQs are disabled and re-entrancy > > is impossible. > > > > Demote the lock to pcp_spin_lock avoids an IRQ disable/enable in the common > > case at the cost of some IRQ allocations taking a slower path. If the PCP > > lists need to be refilled, the zone lock still needs to disable IRQs but > > that will only happen on PCP refill and drain. If an IRQ is raised when > > a PCP allocation is in progress, the trylock will fail and fallback to > > using the buddy lists directly. Note that this may not be a universal win > > if an interrupt-intensive workload also allocates heavily from interrupt > > context and contends heavily on the zone->lock as a result. > > Hi, > > This patch caused the following warning. Please take a look. > Thanks. I see the patch is already taken out of mm-unstable so back to the drawing board! -- Mel Gorman SUSE Labs
