diff options
author | Tejun Heo <tj@kernel.org> | 2015-09-29 12:47:50 -0400 |
---|---|---|
committer | Jens Axboe <axboe@fb.com> | 2015-10-12 12:31:09 -0400 |
commit | 9ad18ab938375502c03cf467abecbb77264c9475 (patch) | |
tree | 206aee6499b2e56d42de486ec4495e282ca27b61 | |
parent | dcc909d90ccdbb73226397ff6d298f7af35b0e11 (diff) |
writeback: laptop_mode_timer_fn() needs rcu_read_lock() around bdi_writeback iteration
laptop_mode_timer_fn() was using bdi_for_each_wb() without the
required RCU locking leading to the following warning.
WARNING: CPU: 0 PID: 0 at include/linux/backing-dev.h:415 laptop_mode_timer_fn+0x106/0x170()
...
Call Trace:
<IRQ> [<ffffffff81480cdc>] dump_stack+0x4e/0x82
[<ffffffff81051912>] warn_slowpath_common+0x82/0xc0
[<ffffffff81051a0a>] warn_slowpath_null+0x1a/0x20
[<ffffffff8115f0e6>] laptop_mode_timer_fn+0x106/0x170
[<ffffffff810ca8e3>] call_timer_fn+0xb3/0x2f0
[<ffffffff810cad25>] run_timer_softirq+0x205/0x370
[<ffffffff81056854>] __do_softirq+0xd4/0x460
[<ffffffff81056d69>] irq_exit+0x89/0xa0
[<ffffffff8185a892>] smp_apic_timer_interrupt+0x42/0x50
[<ffffffff81858a44>] apic_timer_interrupt+0x84/0x90
...
Fix it by adding rcu_read_lock() around the iteration.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: a06fd6b10228 ("writeback: make laptop_mode_timer_fn() handle multiple bdi_writeback's")
Reviewed-by: Jan Kara <jack@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r-- | mm/page-writeback.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 0a931cdd4f6b..902e5f215e57 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c | |||
@@ -1965,10 +1965,12 @@ void laptop_mode_timer_fn(unsigned long data) | |||
1965 | if (!bdi_has_dirty_io(&q->backing_dev_info)) | 1965 | if (!bdi_has_dirty_io(&q->backing_dev_info)) |
1966 | return; | 1966 | return; |
1967 | 1967 | ||
1968 | rcu_read_lock(); | ||
1968 | bdi_for_each_wb(wb, &q->backing_dev_info, &iter, 0) | 1969 | bdi_for_each_wb(wb, &q->backing_dev_info, &iter, 0) |
1969 | if (wb_has_dirty_io(wb)) | 1970 | if (wb_has_dirty_io(wb)) |
1970 | wb_start_writeback(wb, nr_pages, true, | 1971 | wb_start_writeback(wb, nr_pages, true, |
1971 | WB_REASON_LAPTOP_TIMER); | 1972 | WB_REASON_LAPTOP_TIMER); |
1973 | rcu_read_unlock(); | ||
1972 | } | 1974 | } |
1973 | 1975 | ||
1974 | /* | 1976 | /* |