| From 320661b08dd6f1746d5c7ab4eb435ec64b97cd45 Mon Sep 17 00:00:00 2001 |
| From: Tahsin Erdogan <tahsin@google.com> |
| Date: Sat, 25 Feb 2017 13:00:19 -0800 |
| Subject: percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages |
| |
| From: Tahsin Erdogan <tahsin@google.com> |
| |
| commit 320661b08dd6f1746d5c7ab4eb435ec64b97cd45 upstream. |
| |
| 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 <tahsin@google.com> |
| Signed-off-by: Tejun Heo <tj@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/percpu.c | 5 ++++- |
| 1 file changed, 4 insertions(+), 1 deletion(-) |
| |
| --- 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(); |