From 8b724349229bb6ebbf781178be011ba9bc2cca57 Mon Sep 17 00:00:00 2001 From: SJ Park Date: Sun, 28 Jun 2026 14:54:41 -0700 Subject: samples/damon/prcl: handle damon_start() failure damon_sample_prcl_start() callers assume it will clean up resources when it fails. And the function does the cleanup for context buildup failures. However, it is not doing the cleanup for damon_start() failure. As a result, when damon_start() fails, it leaks the memory for DAMON context. Free the context in case of the failure to fix the issues. Note that the issue can reliably be reproduced because the module calls damon_start() in the exclusive mode. For example, $ sudo damo start $ echo $$ | sudo tee /sys/module/damon_sample_prcl/parameters/target_pid $ echo Y | sudo tee /sys/module/damon_sample_prcl/parameters/enabled $ sudo cat /proc/allocinfo | grep damon_new_ctx Because the first command is running another DAMON instance, the third command fails the damon_start() call because the new DAMON instance cannot exclusively run. And without this fix, by repeating the third and the fourth commands above, we can show the memory consumption is only increasing due to the leaks. It requires the sudo permission though. The issue was discovered [1] by Sashiko. Link: https://lore.kernel.org/20260628215447.96166-3-sj@kernel.org Link: https://lore.kernel.org/20260609145814.70163-1-sj@kernel.org [1] Fixes: 2aca254620a8 ("samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation") Signed-off-by: SJ Park Reviewed-by: Zenghui Yu Cc: # 6.14.x Signed-off-by: Andrew Morton --- samples/damon/prcl.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'samples') diff --git a/samples/damon/prcl.c b/samples/damon/prcl.c index b7c50f2656ce..0db259894691 100644 --- a/samples/damon/prcl.c +++ b/samples/damon/prcl.c @@ -106,8 +106,10 @@ static int damon_sample_prcl_start(void) damon_set_schemes(ctx, &scheme, 1); err = damon_start(&ctx, 1, true); - if (err) + if (err) { + damon_destroy_ctx(ctx); return err; + } repeat_call_control.data = ctx; return damon_call(ctx, &repeat_call_control); -- cgit