On Nov 10 12:14, Corinna Vinschen wrote: > On Nov 7 16:16, Tim Prince wrote: > > > > On 11/7/2014 4:11 AM, Corinna Vinschen wrote: > > > > > > - GCC 4.9.2-1 DLLs accidentally call __cxa_atexit with the wrong DSO > > > handle value. This Cygwin update allows this scenario throughout. > > > It now understands *any* DSO handle value, as long as it's a pointer > > > into the DSO's address space. > > > This fixes: https://cygwin.com/ml/cygwin/2014-11/msg00122.html > > > > > > If you don't build applications or DLLs with Cygwin, you can safely > > > ignore this change. > > > > > > > > > If you want to help testing this new release (which I seriously hope > > > for), you can find it in your setup-x86.exe or setup-x86_64.exe as > > > "test" release. > > > > > > > > > > > I take it from now on it should be OK to take the default for > > > > __cxa_atexit > > > > when configuring to build gcc. Thanks for explanation. > > I'm repeating some tests with 1.7.33-0.8 and gcc/gfortran 4.9.2-1 > > > > no surprises, thanks (following segfault apparently unchanged, running with > > AV and Defender disabled, but failure not seen with gfortran 5.0): > > > > Program received signal SIGSEGV: Segmentation fault - invalid memory > > reference. > > > > Backtrace for this error: > > 1181925 [main] profile_omp 3684 fixup_mmaps_after_fork: ReadProcessMemory > > failed > > for MAP_PRIVATE address 0x6FE5FC60000, Win32 error 998 > > This probably means that there's an mmap'ed memory region which Cygwin > has in its bookkeeping list, but which doesn't exist in the parent > process anymore. The problem here is that it's totally unclear how > something like this could have happened. > [...] > Does that happen under Cygwin 1.7.32 as well? Can you create a simple > testcase, preferredly in plain C, which allows to reproduce this?
The only reason I can think of would be the fork synchronization between
parent and child allowing the parent to unmap memory before the child
copied it.
However, I fail to reproduce this with default application means:
#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/mman.h>
int
main ()
{
int status;
void *addr;
addr = mmap (NULL, 65536, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, (size_t) 0);
printf ("Address %p\n", addr);
switch (fork ())
{
case 0: // child
printf ("child %p\n", addr);
break;
case -1:
break;
default: // parent
munmap (addr, 65536);
wait (&status);
break;
}
return 0;
}
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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