From: Sha Zhengju <handai.szj@xxxxxxxxxx> While writing memory.limit_in_bytes, a confusing result may happen: $ mkdir /memcg/test $ cat /memcg/test/memory.limit_in_bytes 9223372036854775807 $ cat /memcg/test/memory.memsw.limit_in_bytes 9223372036854775807 $ echo 18446744073709551614 > /memcg/test/memory.limit_in_bytes $ cat /memcg/test/memory.limit_in_bytes 0 Strangely, the write successed and reset the limit to 0. The patch corrects RESOURCE_MAX and fixes this kind of overflow. Signed-off-by: Sha Zhengju <handai.szj@xxxxxxxxxx> Reported-by: Li Wenpeng < xingke.lwp@xxxxxxxxxx> Cc: Jie Liu <jeff.liu@xxxxxxxxxx> --- include/linux/res_counter.h | 2 +- kernel/res_counter.c | 8 +++++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h index c230994..c2f01fc 100644 --- a/include/linux/res_counter.h +++ b/include/linux/res_counter.h @@ -54,7 +54,7 @@ struct res_counter { struct res_counter *parent; }; -#define RESOURCE_MAX (unsigned long long)LLONG_MAX +#define RESOURCE_MAX (unsigned long long)ULLONG_MAX /** * Helpers to interact with userspace diff --git a/kernel/res_counter.c b/kernel/res_counter.c index ff55247..6c35310 100644 --- a/kernel/res_counter.c +++ b/kernel/res_counter.c @@ -195,6 +195,12 @@ int res_counter_memparse_write_strategy(const char *buf, if (*end != '\0') return -EINVAL; - *res = PAGE_ALIGN(*res); + /* Since PAGE_ALIGN is aligning up(the next page boundary), + * check the left space to avoid overflow to 0. */ + if (RESOURCE_MAX - *res < PAGE_SIZE - 1) + *res = RESOURCE_MAX; + else + *res = PAGE_ALIGN(*res); + return 0; } -- 1.7.9.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>