On Tue, Jan 29, 2002 at 12:23:26AM +1100, Keith Owens wrote:
> On Mon, 28 Jan 2002 07:11:17 -0600,
> Stephen Lord <lord@xxxxxxx> wrote:
> >Do we have any indication if this is something which has 'appeared' at
> >some point,
> >or has been around for a while?
>
> No idea, I have only just started using mdbm on 2.4.17-xfs.
>
> >Looks like a page dirtied only by mmap
> >is not
> >getting flushed by this code. Other user's of mmap (such as the loader)
> >appear not
> >to have problems like this.
> >
> >I will take a look, but I suspect an msync before unmap will work around
> >this for
> >now (not tested yet).
>
> I thought about adding msync but the strange thing is the data is
> available in the file after the program has exited but that data is
> later corrupted. The corruption does not appear immediately, only if
> the file is left alone for a long time or the system is rebooted does
> the corruption appear. Makes me think something is overwriting the
> pages later.
>
> Just added msync(m, size, MS_SYNC) before munmap, bug still exists.
>
this sounds as if it could be related to a obscure problem ive been
observing in apt-get since 2.4.17 (more so with the Dec 23 cvs patch,
and less so with both split patches).
apt-get starts segfaulting on all operations when it reads
/var/cache/apt/pkgcache.bin and cannot be used until this file is
removed and apt-get update is rerun, then it will function properly,
until it happens all over again.
someone i was talking to recently has been using the 2.4.17 xfs
patches with 2.4.18pre kernels and found apt-get failed due to errors
returned by msync() (which appears to be returning 1 (not -1)).
msync is involved in writing these apt binary cache files.
i have also had apt function fine for some time, then all of the
sudden start segfaulting, even when no operation which rewrites the
cache file was run for quite some time, this seems quite consistent
with the above description. i haven't reported this yet since its
been so inconclusive and difficult to reproduce as to not be a very
helpful bug report.
--
Ethan Benson
http://www.alaska.net/~erbenson/
pgpBVJjhAaXUP.pgp
Description: PGP signature
|