From: Phil Auld <pauld@xxxxxxxxxx> commit d7f06bdd6ee87fbefa05af5f57361d85e7715b11 upstream. As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3. This leads to very large file sizes: topology$ ls -l total 0 -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list Adjust the inequality to catch the case when NR_CPUS is configured to a small value. Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist") Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> Cc: Yury Norov <yury.norov@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Cc: feng xiangjun <fengxj325@xxxxxxxxx> Reported-by: feng xiangjun <fengxj325@xxxxxxxxx> Signed-off-by: Phil Auld <pauld@xxxxxxxxxx> Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx> Link: https://lore.kernel.org/r/20220906203542.1796629-1-pauld@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/cpumask.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -1083,9 +1083,10 @@ cpumap_print_list_to_buf(char *buf, cons * cover a worst-case of every other cpu being on one of two nodes for a * very large NR_CPUS. * - * Use PAGE_SIZE as a minimum for smaller configurations. + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding + * unsigned comparison to -1. */ -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \ +#define CPUMAP_FILE_MAX_BYTES (((NR_CPUS * 9)/32 > PAGE_SIZE) \ ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE) #define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)