[PATCH] mm: vmscan: Avoid signedness error for GCC 5.4

WangYuli
2025-05-06T16:03:58Z

To the compiler, (MAX_NR_TIERS - 1) (i.e., (4U - 1)) is unsigned,
whereas tier is a signed integer.

GCC 5.4 does not permit the minimum operation on such
type-inconsistent operands.

Cast it to a signed integer to circumvent this compiler error.

Fix follow error with gcc 5.4:
mm/vmscan.c: In function ‘read_ctrl_pos’:
mm/vmscan.c:3166:728: error: call to ‘__compiletime_assert_887’ declared with attribute error: min(tier, 4U - 1) signedness error

Fixes: 37a260870f2c ("mm/mglru: rework type selection")
Signed-off-by: WangYuli <wangyuli@uniontech.com>
---
mm/vmscan.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3783e45bfc92..29dce1aed962 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3163,7 +3163,7 @@ static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain,
pos->gain = gain;
pos->refaulted = pos->total = 0;

- for (i = tier % MAX_NR_TIERS; i <= min(tier, MAX_NR_TIERS - 1); i++) {
+ for (i = tier % MAX_NR_TIERS; i <= min(tier, (int)(MAX_NR_TIERS - 1)); i++) {
pos->refaulted += lrugen->avg_refaulted[type][i] +
atomic_long_read(&lrugen->refaulted[hist][type][i]);
pos->total += lrugen->avg_total[type][i] +
--
2.49.0