DAMON debugfs interface increases the reference counts of 'struct pid's
for targets from the 'target_ids' file write callback
('dbgfs_target_ids_write()'), but decreases the counts only in DAMON
monitoring termination callback ('dbgfs_before_terminate()').
Therefore, when 'target_ids' file is repeatedly written without DAMON
monitoring start/termination, the reference count is not decreased and
therefore memory for the 'struct pid' cannot be freed. This commit
fixes this issue by decreasing the reference counts when 'target_ids' is
written.
Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 5.15.x
---
mm/damon/dbgfs.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 489be9c830c4..751c7b835684 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -362,6 +362,7 @@ static ssize_t dbgfs_target_ids_write(struct file *file,
const char __user *buf, size_t count, loff_t *ppos)
{
struct damon_ctx *ctx = file->private_data;
+ struct damon_target *t, *next_t;
bool id_is_pid = true;
char *kbuf, *nrs;
unsigned long *targets;
@@ -406,8 +407,12 @@ static ssize_t dbgfs_target_ids_write(struct file *file,
goto unlock_out;
}
- /* remove targets with previously-set primitive */
- damon_set_targets(ctx, NULL, 0);
+ /* remove previously set targets */
+ damon_for_each_target_safe(t, next_t, ctx) {
+ if (targetid_is_pid(ctx))
+ put_pid((struct pid *)t->id);
+ damon_destroy_target(t);
+ }
/* Configure the context for the address space type */
if (id_is_pid)
--
2.17.1
