On Fri, Jun 20, 2014 at 09:24:36AM -0500, Christoph Lameter wrote:
> On Thu, 19 Jun 2014, Naoya Horiguchi wrote:
>
> > I'm suspecting that mbind_range() do something wrong around vma handling,
> > but I don't have enough luck yet. Anyone has an idea?
>
> Well memory policy data corrupted. This looks like you were trying to do
> page migration via mbind()?
Right.
> Could we get some more details as to what is
> going on here? Specifically the parameters passed to mbind would be
> interesting.
My view about the kernel behavior was in another email a few hours ago.
And as for what userspace did, I attach the reproducer below. It's simply
doing mbind(mode=MPOL_BIND, flags=MPOL_MF_MOVE_ALL) on random address/length/node.
What I did to trigger the bug is like below:
while true ; do
dd if=/dev/urandom of=testfile bs=4096 count=1000
for i in $(seq 10) ; do
./mbind_bug_reproducer testfile > /dev/null &
done
sleep 3
pkill -SIGUSR1 -f mbind_bug_reproducer
done
mbind_bug_reproducer.c
---
#include <stdio.h>
#include <signal.h>
#include <sys/mman.h>
#include <numa.h>
#include <numaif.h>
#include <fcntl.h>
#define ADDR_INPUT 0x700000000000
#define PS 4096
#define err(x) perror(x),exit(EXIT_FAILURE)
#define errmsg(x, ...) fprintf(stderr, x, ##__VA_ARGS__),exit(EXIT_FAILURE)
int flag = 1;
void sig_handle_flag(int signo) { flag = 0; }
void set_new_nodes(struct bitmask *mask, unsigned long node) {
numa_bitmask_clearall(mask);
numa_bitmask_setbit(mask, node);
}
int main(int argc, char *argv[]) {
int nr = 1000;
int fd = -1;
char *pfile;
struct timeval tv;
struct bitmask *nodes;
unsigned long nr_nodes;
unsigned long memsize = nr * PS;
nr_nodes = numa_max_node() + 1; /* numa_num_possible_nodes(); */
nodes = numa_bitmask_alloc(nr_nodes);
if (nr_nodes < 2)
errmsg("A minimum of 2 nodes is required for this test.\n");
gettimeofday(&tv, NULL);
srandom(tv.tv_usec);
fd = open(argv[1], O_RDWR, S_IRWXU);
if (fd < 0)
err("open");
pfile = mmap((void *)ADDR_INPUT, memsize, PROT_READ|PROT_WRITE,
MAP_SHARED, fd, 0);
if (pfile == (void*)-1L)
err("mmap");
signal(SIGUSR1, sig_handle_flag);
while (flag) {
int node;
unsigned long offset;
unsigned long length;
memset(pfile, 'a', memsize);
node = random() % nr_nodes;
set_new_nodes(nodes, random() & nr_nodes);
offset = (random() % nr) * PS;
length = (random() % (nr - offset/PS)) * PS;
printf("[%d] node:%x, offset:%x, length:%x\n",
getpid(), node, offset, length);
mbind(pfile + offset, length, MPOL_BIND, nodes->maskp,
nodes->size + 1, MPOL_MF_MOVE_ALL);
}
munmap(pfile, memsize);
return 0;
}
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