Re: [dpdk-dev] [PATCH v3 0/6] use IOVAs check based on DMA mask

[Alejandro Lucero <alejandro.lucero@netronome.com>]

Can we have the configuration triggering this issue?

On Mon, Oct 29, 2018 at 9:07 AM Thomas Monjalon <thomas@monjalon.net> wrote:

> One more comment about this issue,
>
> There was no reply to the question asked by Alejandro on October 11th:
>         http://mails.dpdk.org/archives/dev/2018-October/115402.html
> and there were no more reviews despite all my requests:
>         http://mails.dpdk.org/archives/dev/2018-October/117475.html
> Without any more comment, I had to apply the patchset.
>
> Now we need to find a solution. Please suggest.
>
>
> 29/10/2018 09:42, Thomas Monjalon:
> > 29/10/2018 09:23, Yao, Lei A:
> > > Hi, Lucero, Thomas
> > >
> > > This patch set will cause deadlock during memory initialization.
> > > rte_memseg_walk and try_expand_heap both will lock
> > > the file &mcfg->memory_hotplug_lock. So dead lock will occur.
> > >
> > > #0       rte_memseg_walk
> > > #1  <-rte_eal_check_dma_mask
> > > #2  <-alloc_pages_on_heap
> > > #3  <-try_expand_heap_primary
> > > #4  <-try_expand_heap
> > >
> > > Log as following:
> > > EAL: TSC frequency is ~2494156 KHz
> > > EAL: Master lcore 0 is ready (tid=7ffff7fe3c00;cpuset=[0])
> > > [New Thread 0x7ffff5e0d700 (LWP 330350)]
> > > EAL: lcore 1 is ready (tid=7ffff5e0d700;cpuset=[1])
> > > EAL: Trying to obtain current memory policy.
> > > EAL: Setting policy MPOL_PREFERRED for socket 0
> > > EAL: Restoring previous memory policy: 0
> > >
> > > Could you have a check on this? A lot of test cases in our validation
> > > team fail because of this. Thanks a lot!
> >
> > Can we just call rte_memseg_walk_thread_unsafe()?
> >
> > +Cc Anatoly
> >
> >
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Thomas Monjalon
> > > > 05/10/2018 14:45, Alejandro Lucero:
> > > > > I sent a patchset about this to be applied on 17.11 stable. The
> memory
> > > > > code has had main changes since that version, so here it is the
> patchset
> > > > > adjusted to current master repo.
> > > > >
> > > > > This patchset adds, mainly, a check for ensuring IOVAs are within a
> > > > > restricted range due to addressing limitations with some devices.
> There
> > > > > are two known cases: NFP and IOMMU VT-d emulation.
> > > > >
> > > > > With this check IOVAs out of range are detected and PMDs can abort
> > > > > initialization. For the VT-d case, IOVA VA mode is allowed as long
> as
> > > > > IOVAs are within the supported range, avoiding to forbid IOVA VA by
> > > > > default.
> > > > >
> > > > > For the addressing limitations known cases, there are just 40(NFP)
> or
> > > > > 39(VT-d) bits for handling IOVAs. When using IOVA PA, those
> limitations
> > > > > imply 1TB(NFP) or 512M(VT-d) as upper limits, which is likely
> enough for
> > > > > most systems. With machines using more memory, the added check will
> > > > > ensure IOVAs within the range.
> > > > >
> > > > > With IOVA VA, and because the way the Linux kernel serves mmap
> calls
> > > > > in 64 bits systems, 39 or 40 bits are not enough. It is possible to
> > > > > give an address hint with a lower starting address than the
> default one
> > > > > used by the kernel, and then ensuring the mmap uses that hint or
> hint plus
> > > > > some offset. With 64 bits systems, the process virtual address
> space is
> > > > > large enoguh for doing the hugepages mmaping within the supported
> > > > range
> > > > > when those addressing limitations exist. This patchset also adds a
> change
> > > > > for using such a hint making the use of IOVA VA a more than likely
> > > > > possibility when there are those addressing limitations.
> > > > >
> > > > > The check is not done by default but just when it is required. This
> > > > > patchset adds the check for NFP initialization and for setting the
> IOVA
> > > > > mode is an emulated VT-d is detected. Also, because the recent
> patchset
> > > > > adding dynamic memory allocation, the check is also invoked for
> ensuring
> > > > > the new memsegs are within the required range.
> > > > >
> > > > > This patchset could be applied to stable 18.05.
> > > >
> > > > Applied, thanks
>
>
>
>