Hi Kirill,
Your patch 6dc296e7df4c ("mm: make sure all file VMAs have ->vm_ops set")
causes some mmap regressions in LTP, which appears to use a MAP_PRIVATE
mmap of /dev/zero as a way to get anonymous pages in some of its tests
(specifically mmap10 [1]).
Dead simple reproducer below. Is this change in behaviour intentional?
Will
[1]
http://sourceforge.net/p/ltp/git/ci/1eb440c2b5fe43a3e5023015a16aa5d7d3385b1e/tree/testcases/kernel/syscalls/mmap/mmap10.c
--->8
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#define MAP_SZ 5*1024*1024
int main(void)
{
char *foo;
int fd;
fd = open("/dev/zero", O_RDWR, 0666);
if (fd < 0) {
perror(NULL);
return fd;
}
foo = mmap(NULL, MAP_SZ, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
if (foo == MAP_FAILED) {
perror(NULL);
return -1;
}
foo[MAP_SZ >> 1] = 0; // Generates SIGBUS with 4.3-rc1
return 0;
}
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