While reading OOM report from Jan Stancek, I noticed that
NR_MLOCK statistics shows bogus values.
Steps to reproduce:
(1) Check Mlocked: field of /proc/meminfo or mlocked: field of SysRq-m.
(2) Compile and run below program with appropriate size as argument.
There is no need to invoke the OOM killer.
----------
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
int main(int argc, char *argv[])
{
unsigned long length = atoi(argv[1]);
void *addr = mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (addr == MAP_FAILED)
printf("mmap() failed\n");
else if (mlock(addr, length) == -1)
printf("mlock() failed\n");
else
printf("MLocked %lu bytes\n", length);
return 0;
}
----------
(3) Check Mlocked: field or mlocked: field again.
You can see the value became very large due to
NR_MLOCK counter going negative.
--
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>