From 320661b08dd6f1746d5c7ab4eb435ec64b97cd45 Mon Sep 17 00:00:00 2001 From: Tahsin Erdogan Date: Sat, 25 Feb 2017 13:00:19 -0800 Subject: [PATCH] percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages Update to pcpu_nr_empty_pop_pages in pcpu_alloc() is currently done without holding pcpu_lock. This can lead to bad updates to the variable. Add missing lock calls. Fixes: b539b87fed37 ("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated") Signed-off-by: Tahsin Erdogan Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org # v3.18+ --- mm/percpu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/percpu.c b/mm/percpu.c index 5696039b5c07..60a6488e9e6d 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1011,8 +1011,11 @@ area_found: mutex_unlock(&pcpu_alloc_mutex); } - if (chunk != pcpu_reserved_chunk) + if (chunk != pcpu_reserved_chunk) { + spin_lock_irqsave(&pcpu_lock, flags); pcpu_nr_empty_pop_pages -= occ_pages; + spin_unlock_irqrestore(&pcpu_lock, flags); + } if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW) pcpu_schedule_balance_work();