Date: Wed, 10 May 1995 11:31:54 -0700 (PDT) From: John Dyson <dyson@Root.COM> To: adhir@romulus.worldbank.org (Alok K. Dhir) Cc: hackers@FreeBSD.org, erandall@reo.dec.com Subject: Re: (fwd) mmap() problem [940412-SNAP, pdksh] Message-ID: <199505101831.LAA05484@Root.COM> In-Reply-To: <9505101712.AA29887@romulus.worldbank.org> from "Alok K. Dhir" at May 10, 95 01:12:25 pm
next in thread | previous in thread | raw e-mail | index | archive | help
>
>
> Not sure - but this looks like a possible bug? Has this been addressed
> already?
>
> Thanks...
This problem has been fixed in -current for about 3-4wks now. It has
to do with recursive locking of vnodes necessary to afford read/write
of files that have been mmaped into the mmaped region:
fd = open("badfile", O_RDWR);
addr = mmap(...,fd,...);
write(fd,addr,size_of_write);
>
> Problem #2 - During the "configure" script, it hangs when scanning for
> "mmap()". A "kill -9" of the parent shell of the "configure" process
> will bring back a prompt ... but the "configure" process is still there.
> Any attempt to "ls" the directory it was in, or "cat" any files in that
> directory, result in another hang. Oh dear !
>
> I investigated this in more depth (adding printf's to the .c file used
> by "configure" for testing "mmap()") and it seems that the hang occurs
> in the read() performed just after the call to "mmap()".
>
> "Oh well, it's obviously broken" I thought, and hacked "configure" so
> that "HAVE_MMAP" doesn't get defined, and the problematical test is skipped.
> I now have a working "ksh", all seems well.
>
> But what of the miscreant "mmap()" ? Is this a known bug, or should it
> work ? Has anybody else had similar problems when running the "configure"
> scripts provided with most ports ?
It works now in -current and of course in release.
I did extensive testing on mmap for coherency, etc because of all of the
new code for the merged, fully coherent buffer cache scheme -- but
did not check this specific case. It does work now.
John
dyson@root.com
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199505101831.LAA05484>