fixup_mmaps_after_fork failure with cygwin-3.0.0

[Corinna Vinschen]

On Feb 17 10:08, Corinna Vinschen wrote:
> On Feb 17 00:11, Ken Brown wrote:
> > I'm getting a lot of errors like this when building emacs from its git repo:
> > 
> > EMACSLOADPATH= '../src/emacs.exe' -batch --no-site-file --no-site-lisp --eval 
> > '(setq load-prefer-newer t)'  -f batch-byte-compile ../../master/lisp/finder.el
> >        1 [main] emacs 26848 fixup_mmaps_after_fork: VirtualProtectEx failed for 
> > MAP_PRIVATE address 0x6FFFFCD0000, Win32 error 5
> >      190 [main] emacs 26848 C:\Users\kbrown\src\emacs\x86_64\src\emacs.exe: *** 
> > fatal error in forked process - recreate_mmaps_after_fork_failed
> >      619 [main] emacs 26848 cygwin_exception::open_stackdumpfile: Dumping stack 
> > trace to emacs.exe.stackdump
> >        1 [main] emacs 27052 fork: child -1 - forked process 26848 died 
> > unexpectedly, retry 0, exit code 0x100, errno 11
> 
> Weird.  I built at least gawk and openssh with 3.0 already and I
> didn't notice this problem.
> 
> > A bisection points to the following as the first bad commit:
> > 
> > commit 69cc7a068656b5c6ef07ca079a213f801e02e650
> > Author: Corinna Vinschen <corinna@vinschen.de>
> > Date:   Sun Jan 27 13:15:15 2019 +0100
> > 
> >      Cygwin: fork: restrict parent handle perms and drop handle after use
> > 
> > 
> > I'll try to do some debugging and/or provide further information tomorrow, but I 
> > thought I'd start with this preliminary report.
> 
> That would be nice.  It's not clear to me which permission is missing.
> The first part of the patch has been reverted in 3.0.0, so 
> child_info_spawn::get_parent_handle opens the parent with
> PROCESS_VM_READ again.  The second patch has been reworked as well,m
> the current perms are
> 
> PROCESS_QUERY_LIMITED_INFORMATION | PROCESS_VM_READ | SYNCHRONIZE
> 
> If I may place a bet, please try to replace
> PROCESS_QUERY_LIMITED_INFORMATION with PROCESS_QUERY_INFORMATION

On second thought, an even better candidate may be PROCESS_VM_OPERATION.

> What OS is that?  W7?


Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
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