From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Subject: mm/page_alloc: reduce duration that IRQs are disabled for VM counters IRQs are left disabled for the zone and node VM event counters. This is unnecessary as the affected counters are allowed to race for preemmption and IRQs. This patch reduces the scope of IRQs being disabled via local_[lock|unlock]_irq on !PREEMPT_RT kernels. One __mod_zone_freepage_state is still called with IRQs disabled. While this could be moved out, it's not free on all architectures as some require IRQs to be disabled for mod_zone_page_state on !PREEMPT_RT kernels. Link: https://lkml.kernel.org/r/20210512095458.30632-7-mgorman@xxxxxxxxxxxxxxxxxxx Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Chuck Lever <chuck.lever@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-reduce-duration-that-irqs-are-disabled-for-vm-counters +++ a/mm/page_alloc.c @@ -3530,11 +3530,11 @@ static struct page *rmqueue_pcplist(stru pcp = this_cpu_ptr(zone->per_cpu_pageset); list = &pcp->lists[migratetype]; page = __rmqueue_pcplist(zone, migratetype, alloc_flags, pcp, list); + local_unlock_irqrestore(&pagesets.lock, flags); if (page) { __count_zid_vm_events(PGALLOC, page_zonenum(page), 1); zone_statistics(preferred_zone, zone, 1); } - local_unlock_irqrestore(&pagesets.lock, flags); return page; } @@ -3586,15 +3586,15 @@ struct page *rmqueue(struct zone *prefer if (!page) page = __rmqueue(zone, order, migratetype, alloc_flags); } while (page && check_new_pages(page, order)); - spin_unlock(&zone->lock); if (!page) goto failed; + __mod_zone_freepage_state(zone, -(1 << order), get_pcppage_migratetype(page)); + spin_unlock_irqrestore(&zone->lock, flags); __count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order); zone_statistics(preferred_zone, zone, 1); - local_irq_restore(flags); out: /* Separate test+clear to avoid unnecessary atomics */ @@ -3607,7 +3607,7 @@ out: return page; failed: - local_irq_restore(flags); + spin_unlock_irqrestore(&zone->lock, flags); return NULL; } @@ -5165,11 +5165,11 @@ unsigned long __alloc_pages_bulk(gfp_t g nr_populated++; } + local_unlock_irqrestore(&pagesets.lock, flags); + __count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account); zone_statistics(ac.preferred_zoneref->zone, zone, nr_account); - local_unlock_irqrestore(&pagesets.lock, flags); - return nr_populated; failed_irq: _
