Messages in this thread |  | | Date | Fri, 4 May 2001 10:16:51 +0200 | From | Andi Kleen <> | Subject | Re: 2.4 and 2GB swap partition limit |
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On Wed, May 02, 2001 at 04:17:21PM -0600, Andreas Dilger wrote: > Andi Kleen writes: > > On Mon, Apr 30, 2001 at 12:07:44PM -0700, David S. Miller wrote: > > But something must have been not working with it for mmaps/shlibs > > (not executables); at least historically. > > At least I remember that all hell broke lose when you tried to update > > libc by cp'ing a new one to /lib/libc.so in the 1.2 days. cp should create a > > new inode (it uses O_CREAT) so in theory it should be coherent by the inode > > reference; but somehow it didn't use to work and random already running > > programs started to segfault. This was long ago. I wonder if old > > GNU cp used O_TRUNC instead of O_CREAT, or was there some other kernel bug > > with mappings (hopefully long since fixed). Anybody remembers? > > No, "cp" is still not a safe way to update libc, and I doubt it ever will be. > cp does _not_ create a new inode (unlike mv), so you are writing "garbage" > into the currently running executables.
Ok, the bug is that executable shlibs mappings do not get EBUSY as when you try to write into a running executable and it's still not fixed.
> NB: my open(2) says for O_CREAT "If the file does not exist it will be > created". This is _not_ the same as O_EXCL, which will only mean that > open(2) will fail when it tries to create a new file.
I assumed it would just create a new inode; but seems I was wrong. Thanks for the clarification.
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