Bug#247300: libc6: malloc() never fails on 2.4 kernels, making processes crash
On Fri, May 07, 2004 at 09:25:11AM +0200, Vincent Lefevre wrote:
> On 2004-05-06 19:05:53 -0400, Daniel Jacobowitz wrote:
> > On Fri, May 07, 2004 at 12:58:28AM +0200, Vincent Lefevre wrote:
> > > On 2004-05-06 16:44:54 -0400, Daniel Jacobowitz wrote:
> > > > The documentation in the 2.4 kernel is, indeed, wrong IIRC.
> > > >
> > > > BTW, from 2.6:
> > > > In mode 2 the MAP_NORESERVE flag is ignored.
> > >
> > > This is precisely what I thought to be the bug in glibc: the fact
> > > (at least with the 2.4 kernel) that this flag is used by glibc.
> > > On which documentation is glibc based (in particular, concerning
> > > old_mmap)?
> >
> > I don't know. The comments suggest malloc made the choice
> > deliberately, though, so I don't think it's appropriate to reverse it.
>
> But there are no explanations concerning this choice. And without
> explanations, it is difficult to say if this is right or wrong.
>
> The malloc(3) man page more or less says that this is a kernel bug
> and a kernel with strict overcommit is necessary. But this is a
> contradiction with the 2.4 kernel documentation, which says that
> the kernel checks if there's enough memory left (if the memory is
> really reserved -- so the problem of reserving memory comes from
> the caller, here glibc).
Since I don't know enough to continue this discussion, I'm copying
someone who does!
Wolfram, is there documentation describing the choice of MAP_NORESERVE
in glibc's malloc, or do you know someone else I should ask? Thanks in
advance.
--
Daniel Jacobowitz
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