[PATCH 5.15 44/66] dm stats: add cond_resched when looping over entries

Greg Kroah-Hartman
2022-06-03T18:01:33Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit bfe2b0146c4d0230b68f5c71a64380ff8d361f8b upstream.

dm-stats can be used with a very large number of entries (it is only
limited by 1/4 of total system memory), so add rescheduling points to
the loops that iterate over the entries.

Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-stats.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -225,6 +225,7 @@ void dm_stats_cleanup(struct dm_stats *s
atomic_read(&shared->in_flight[READ]),
atomic_read(&shared->in_flight[WRITE]));
}
+ cond_resched();
}
dm_stat_free(&s->rcu_head);
}
@@ -330,6 +331,7 @@ static int dm_stats_create(struct dm_sta
for (ni = 0; ni < n_entries; ni++) {
atomic_set(&s->stat_shared[ni].in_flight[READ], 0);
atomic_set(&s->stat_shared[ni].in_flight[WRITE], 0);
+ cond_resched();
}

if (s->n_histogram_entries) {
@@ -342,6 +344,7 @@ static int dm_stats_create(struct dm_sta
for (ni = 0; ni < n_entries; ni++) {
s->stat_shared[ni].tmp.histogram = hi;
hi += s->n_histogram_entries + 1;
+ cond_resched();
}
}

@@ -362,6 +365,7 @@ static int dm_stats_create(struct dm_sta
for (ni = 0; ni < n_entries; ni++) {
p[ni].histogram = hi;
hi += s->n_histogram_entries + 1;
+ cond_resched();
}
}
}
@@ -497,6 +501,7 @@ static int dm_stats_list(struct dm_stats
}
DMEMIT("\n");
}
+ cond_resched();
}
mutex_unlock(&stats->mutex);

@@ -774,6 +779,7 @@ static void __dm_stat_clear(struct dm_st
local_irq_enable();
}
}
+ cond_resched();
}
}

@@ -889,6 +895,8 @@ static int dm_stats_print(struct dm_stat

if (unlikely(sz + 1 >= maxlen))
goto buffer_overflow;
+
+ cond_resched();
}

if (clear)