The bdi_writeback_thread function does not use spin_lock to
see if the work_list is empty.
If the list is not empty, and if an interrupt happens before we
set the current->state to TASK_RUNNING then we could be stuck in
a schedule() due to kernel preemption.
This patch acquires and releases the wb_lock to avoid this scenario.
Signed-off-by: Rajan Aggarwal <rajan.aggarwal85@xxxxxxxxx>
---
fs/fs-writeback.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 04cf3b9..e333898 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -936,11 +936,14 @@ int bdi_writeback_thread(void *data)
if (pages_written)
wb->last_active = jiffies;
+ spin_lock_bh(&bdi->wb_lock);
set_current_state(TASK_INTERRUPTIBLE);
if (!list_empty(&bdi->work_list) || kthread_should_stop()) {
__set_current_state(TASK_RUNNING);
+ spin_unlock_bh(&bdi->wb_lock);
continue;
}
+ spin_unlock_bh(&bdi->wb_lock);
if (wb_has_dirty_io(wb) && dirty_writeback_interval)
schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10));
--
1.7.4.1
--
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