Re: [PATCH] eal: zero out new added memory

[David Marchand <david.marchand@redhat.com>]

On Mon, Aug 29, 2022 at 2:37 PM Morten Brørup <mb@smartsharesystems.com> wrote:
>
> > From: David Marchand [mailto:david.marchand@redhat.com]
> > Sent: Monday, 29 August 2022 13.58
> >
> > On Mon, Aug 29, 2022 at 1:38 PM lic121 <chengtcli@qq.com> wrote:
> > >
> > > On Mon, Aug 29, 2022 at 01:18:36AM +0000, lic121 wrote:
> > > > On Sat, Aug 27, 2022 at 05:56:54PM +0300, Dmitry Kozlyuk wrote:
> > > > > 2022-08-27 13:31 (UTC+0000), lic121:
> > > > > > On Sat, Aug 27, 2022 at 12:57:50PM +0300, Dmitry Kozlyuk wrote:
> > > > > > > 2022-08-27 09:25 (UTC+0000), chengtcli@qq.com:
> > > > > > > > From: lic121 <lic121@chinatelecom.cn>
> > > > > > > >
> > > > > > > > When RTE_MALLOC_DEBUG not configured, rte_zmalloc_socket()
> > doens't
> > > > > > > > zero oute allocaed memory. Because memory are zeroed out
> > when free
> > > > > > > > in malloc_elem_free(). But seems the initial allocated
> > memory is
> > > > > > > > not zeroed out as expected.
> > > > > > > >
> > > > > > > > This patch zero out initial allocated memory in
> > > > > > > > malloc_heap_add_memory().
> > > > > > > >
>
> [...]
>
> > > > > > > Hi,
> > > > > > >
> > > > > > > The kernel ensures that the newly mapped memory is zeroed,
> > > > > > > and DPDK ensures that files in hugetlbfs are not re-mapped.
>
> David, are you suggesting that this invariant - guaranteeing that DPDK memory is zeroed - was violated by SELinux in the SELinux/container issue you were tracking?
>
> If so, the method to ensure the invariant is faulty for SELinux. Assuming DPDK supports SELinux, this bug should be fixed.

SELinux was preventing some file manipulations.
And I found the fix I had sent, which is already in 20.11, so it is
not the same issue.
aa48ddf4f0d2 ("mem: fix allocation in container with SELinux")

On the other hand, it is the kind of side effect to keep in mind when
debugging those "my memory is not zero'd" issues.


-- 
David Marchand