Commit 3f380998 authored by Kautuk Consul's avatar Kautuk Consul Committed by Linus Torvalds

vmscan.c: fix invalid strict_strtoul() check in write_scan_unevictable_node()

write_scan_unevictable_node() checks the value req returned by
strict_strtoul() and returns 1 if req is 0.

However, when strict_strtoul() returns 0, it means successful conversion
of buf to unsigned long.

Due to this, the function was not proceeding to scan the zones for
unevictable pages even though we write a valid value to the
scan_unevictable_pages sys file.

Change this check slightly to check for invalid value in buf as well as 0
value stored in res after successful conversion via strict_strtoul.  In
both cases, we do not perform the scanning of this node's zones.
Signed-off-by: default avatarKautuk Consul <>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <>
Cc: Johannes Weiner <>
Cc: Lee Schermerhorn <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 4e9dc5df
......@@ -3520,8 +3520,8 @@ static ssize_t write_scan_unevictable_node(struct sys_device *dev,
unsigned long res;
unsigned long req = strict_strtoul(buf, 10, &res);
if (!req)
return 1; /* zero is no-op */
if (req || !res)
return 1; /* Invalid input or zero is no-op */
for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
if (!populated_zone(zone))
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