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| author | Tejun Heo <tj@kernel.org> | 2015-09-29 18:47:50 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-10-12 18:31:09 +0200 |
| commit | 9ad18ab938375502c03cf467abecbb77264c9475 (patch) | |
| tree | 206aee6499b2e56d42de486ec4495e282ca27b61 /mm/page-writeback.c | |
| parent | nbd: Add locking for tasks (diff) | |
| download | linux-9ad18ab938375502c03cf467abecbb77264c9475.tar.xz linux-9ad18ab938375502c03cf467abecbb77264c9475.zip | |
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>
Diffstat (limited to 'mm/page-writeback.c')
| -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) if (!bdi_has_dirty_io(&q->backing_dev_info)) return; + rcu_read_lock(); bdi_for_each_wb(wb, &q->backing_dev_info, &iter, 0) if (wb_has_dirty_io(wb)) wb_start_writeback(wb, nr_pages, true, WB_REASON_LAPTOP_TIMER); + rcu_read_unlock(); } /* |