Unverified Commit 9eed043d authored by Huacai Chen's avatar Huacai Chen Committed by Christian Brauner
Browse files

writeback: Fix wakeup and logging timeouts for !DETECT_HUNG_TASK 



Recent changes of fs-writeback cause such warnings if DETECT_HUNG_TASK
is not enabled:

INFO: The task sync:1342 has been waiting for writeback completion for more than 1 seconds.

The reason is sysctl_hung_task_timeout_secs is 0 when DETECT_HUNG_TASK
is not enabled, then it causes the warning message even if the writeback
lasts for only one second.

Guard the wakeup and logging with "#ifdef CONFIG_DETECT_HUNG_TASK" can
eliminate the warning messages. But on the other hand, it is possible
that sysctl_hung_task_timeout_secs be also 0 when DETECT_HUNG_TASK is
enabled. So let's just check the value of sysctl_hung_task_timeout_secs
to decide whether do wakeup and logging.

Fixes: 18886355 ("writeback: Wake up waiting tasks when finishing the writeback of a chunk.")
Fixes: d6e62159 ("writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs)")
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
Link: https://patch.msgid.link/20260203094014.2273240-1-chenhuacai@loongson.cn


Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent cb184dd1

fs/fs-writeback.c

+5 −4
Original line number Diff line number Diff line
@@ -198,10 +198,11 @@ static void wb_queue_work(struct bdi_writeback *wb, 


static bool wb_wait_for_completion_cb(struct wb_completion *done)

{

	unsigned long timeout = sysctl_hung_task_timeout_secs;

	unsigned long waited_secs = (jiffies - done->wait_start) / HZ;



	done->progress_stamp = jiffies;

	if (waited_secs > sysctl_hung_task_timeout_secs)

	if (timeout && (waited_secs > timeout))

		pr_info("INFO: The task %s:%d has been waiting for writeback "

			"completion for more than %lu seconds.",

			current->comm, current->pid, waited_secs);
@@ -1955,6 +1956,7 @@ static long writeback_sb_inodes(struct super_block *sb, 
		.range_end		= LLONG_MAX,

	};

	unsigned long start_time = jiffies;

	unsigned long timeout = sysctl_hung_task_timeout_secs;

	long write_chunk;

	long total_wrote = 0;  /* count both pages and inodes */

	unsigned long dirtied_before = jiffies;
@@ -2041,9 +2043,8 @@ static long writeback_sb_inodes(struct super_block *sb, 
		__writeback_single_inode(inode, &wbc);



		/* Report progress to inform the hung task detector of the progress. */

		if (work->done && work->done->progress_stamp &&

		   (jiffies - work->done->progress_stamp) > HZ *

		   sysctl_hung_task_timeout_secs / 2)

		if (work->done && work->done->progress_stamp && timeout &&

		   (jiffies - work->done->progress_stamp) > HZ * timeout / 2)

			wake_up_all(work->done->waitq);



		wbc_detach_inode(&wbc);