BUG: 2.4.x NFS client mmap race
Hi,
While debugging a rather strange WINE problem I came across a 2.4.x
NFS race condition.
I trimmed down the WINE code to a very small testcase, attached below,
which has following test patterns:
ext2 local : SUCCESS
2.4.5-ac6 -> 2.2.10 (unfsd): FAIL
2.4.2-ac26 -> 2.4.2ac26 (knfsd) : FAIL
2.2.14 -> 2.4.2ac26 (knfsd) : SUCCESS
For me this looks like there is a problem in the 2.4 NFS client.
The sleep() appears to be a key part. If we only sleep 1 second the
test usually succeeds. With 5 it always fails.
I am using the default mount options for nfs.
Ciao, Marcus
#include
#include
#include
#include
#include
#include
#include
main() {
int fd;
unsigned char *ptr;
char buf[10];
memset(buf,'0',10);
fd = open("/home/lstcore/mm/test.out",O_RDWR|O_CREAT|O_TRUNC,0644);
assert(fd!=-1);
ftruncate(fd,512);
ptr=mmap(NULL,512,PROT_WRITE|PROT_READ,MAP_SHARED,fd,0);
ptr[0]=0x42;
munmap(ptr,512);
sleep(5);
ftruncate(fd,69632);
ptr=mmap(NULL,69632,PROT_WRITE|PROT_READ,MAP_SHARED,fd,0);
assert(ptr[0]==0x42);
fprintf(stderr,"There was no race. Lucky you!\n");
}
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BUG: 2.4.x NFS client mmap race
Hi,
While debugging a rather strange WINE problem I came across a 2.4.x
NFS race condition.
I trimmed down the WINE code to a very small testcase, attached below,
which has following test patterns:
ext2 local : SUCCESS
2.4.5-ac6 - 2.2.10 (unfsd): FAIL
2.4.2-ac26 - 2.4.2ac26 (knfsd) : FAIL
2.2.14 - 2.4.2ac26 (knfsd) : SUCCESS
For me this looks like there is a problem in the 2.4 NFS client.
The sleep() appears to be a key part. If we only sleep 1 second the
test usually succeeds. With 5 it always fails.
I am using the default mount options for nfs.
Ciao, Marcus
#include stdio.h
#include assert.h
#include fcntl.h
#include unistd.h
#include sys/types.h
#include sys/mman.h
#include sys/stat.h
main() {
int fd;
unsigned char *ptr;
char buf[10];
memset(buf,'0',10);
fd = open(/home/lstcore/mm/test.out,O_RDWR|O_CREAT|O_TRUNC,0644);
assert(fd!=-1);
ftruncate(fd,512);
ptr=mmap(NULL,512,PROT_WRITE|PROT_READ,MAP_SHARED,fd,0);
ptr[0]=0x42;
munmap(ptr,512);
sleep(5);
ftruncate(fd,69632);
ptr=mmap(NULL,69632,PROT_WRITE|PROT_READ,MAP_SHARED,fd,0);
assert(ptr[0]==0x42);
fprintf(stderr,There was no race. Lucky you!\n);
}
-
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
