From 43c95bcc51e4e7f3e3cbce01515fe429a4cf12a7 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@techsingularity.net>
Date: Mon, 28 Jun 2021 19:41:54 -0700
Subject: [PATCH] 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@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/page_alloc.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6bb9b87cf7d5d..161bcda61520a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3530,11 +3530,11 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
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 *preferred_zone,
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 @@ struct page *rmqueue(struct zone *preferred_zone,
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 gfp, int preferred_nid,
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:
--
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