Tom reported this finding from clang 10's static analysis [1].
Due to the way the code is written, it will always see a successful loop
iteration. Instead of setting an initial value, check that it was set
instead with BUG_ON() because 0 units per allocation is bogus.
[1] https://lore.kernel.org/lkml/[email protected]/
Reported-by: Tom Rix <[email protected]>
Signed-off-by: Dennis Zhou <[email protected]>
---
Sorry this hasn't been my highest priority. I'll apply this shortly to
for-5.14.
mm/percpu.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/mm/percpu.c b/mm/percpu.c
index e7b9ca82e9aa..6667dfa0fcec 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -2888,6 +2888,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
* Related to atom_size, which could be much larger than the unit_size.
*/
last_allocs = INT_MAX;
+ best_upa = 0;
for (upa = max_upa; upa; upa--) {
int allocs = 0, wasted = 0;
@@ -2914,6 +2915,7 @@ static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
last_allocs = allocs;
best_upa = upa;
}
+ BUG_ON(!best_upa);
upa = best_upa;
/* allocate and fill alloc_info */
--
2.32.0.272.g935e593368-goog