diff options
| author | Mel Gorman <[email protected]> | 2021-05-04 18:39:30 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2021-05-05 11:27:26 -0700 |
| commit | 8ca559132a2d9b56732d35e2b947af96acb9b80b (patch) | |
| tree | 37f21af4ddc0a8aecb62388736c9967c8685b39f | |
| parent | e44605a8b1aa13d892addc59ec3d416cb186c77b (diff) | |
mm/memory_hotplug: remove broken locking of zone PCP structures during hot remove
zone_pcp_reset allegedly protects against a race with drain_pages using
local_irq_save but this is bogus. local_irq_save only operates on the
local CPU. If memory hotplug is running on CPU A and drain_pages is
running on CPU B, disabling IRQs on CPU A does not affect CPU B and
offers no protection.
This patch deletes IRQ disable/enable on the grounds that IRQs protect
nothing and assumes the existing hotplug paths guarantees the PCP cannot
be used after zone_pcp_enable(). That should be the case already
because all the pages have been freed and there is no page to put on the
PCP lists.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Alexander Duyck <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | mm/page_alloc.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 81db38926266..b012805a11ad 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -9020,12 +9020,9 @@ void zone_pcp_enable(struct zone *zone) void zone_pcp_reset(struct zone *zone) { - unsigned long flags; int cpu; struct per_cpu_pageset *pset; - /* avoid races with drain_pages() */ - local_irq_save(flags); if (zone->pageset != &boot_pageset) { for_each_online_cpu(cpu) { pset = per_cpu_ptr(zone->pageset, cpu); @@ -9034,7 +9031,6 @@ void zone_pcp_reset(struct zone *zone) free_percpu(zone->pageset); zone->pageset = &boot_pageset; } - local_irq_restore(flags); } #ifdef CONFIG_MEMORY_HOTREMOVE |