[RFC PATCH v3 2/4] mm/damon: fix esz=0 quota bypass allowing unlimited migration

[Ravi Jonnalagadda <ravis.opensrc@gmail.com>]

When the TEMPORAL goal tuner sets esz_bp=0 to signal that a goal has
been achieved, the quota check was not actually stopping migration.

The condition:
    if (quota->esz && quota->charged_sz >= quota->esz)

When esz=0, this evaluates to (false && ...) = false, so the continue
is never executed and migration proceeds without limit.

Change the logic to:
    if (!quota->esz || quota->charged_sz >= quota->esz)

Now when esz=0, (!0 = true) causes the continue to execute, properly
stopping migration when the goal is achieved.

This is critical for the TEMPORAL tuner to work correctly - without
this fix, setting esz=0 has no effect and migration continues until
all hot memory is moved, overshooting the target goal.

Signed-off-by: Ravi Jonnalagadda <ravis.opensrc@gmail.com>
---
 mm/damon/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 614f1f08eee9..b438355ab54a 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2394,8 +2394,8 @@ static void damon_do_apply_schemes(struct damon_ctx *c,
 		if (!s->wmarks.activated)
 			continue;
 
-		/* Check the quota */
-		if (quota->esz && quota->charged_sz >= quota->esz)
+		/* Check the quota: skip if esz=0 (goal achieved) or exhausted */
+		if (!quota->esz || quota->charged_sz >= quota->esz)
 			continue;
 
 		if (damos_skip_charged_region(t, r, s, c->min_region_sz))
-- 
2.43.0