Re: [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end
Mike Rapoport writes: > On Sat, Jan 23, 2021 at 06:09:11PM -0800, Andrew Morton wrote: >> On Fri, 22 Jan 2021 01:37:14 -0300 Thiago Jung Bauermann >> wrote: >> >> > Mike Rapoport writes: >> > >> > > > Signed-off-by: Roman Gushchin >> > > >> > > Reviewed-by: Mike Rapoport >> > >> > I've seen a couple of spurious triggers of the WARN_ONCE() removed by this >> > patch. This happens on some ppc64le bare metal (powernv) server machines >> > with >> > CONFIG_SWIOTLB=y and crashkernel=4G, as described in a candidate patch I >> > posted >> > to solve this issue in a different way: >> > >> > https://lore.kernel.org/linuxppc-dev/20201218062103.76102-1-bauer...@linux.ibm.com/ >> > >> > Since this patch solves that problem, is it possible to include it in the >> > next >> > feasible v5.11-rcX, with the following tag? >> >> We could do this, if we're confident that this patch doesn't depend on >> [1/2] "mm: cma: allocate cma areas bottom-up"? I think it is... > > A think it does not depend on cma bottom-up allocation, it's rather the other > way around: without this CMA bottom-up allocation could fail with KASLR > enabled. I noticed that this patch is now upstream as: 2dcb39645441 memblock: do not start bottom-up allocations with kernel_end > Still, this patch may need updates to the way x86 does early reservations: > > https://lore.kernel.org/lkml/20210115083255.12744-1-r...@kernel.org ... but the patches from this link still aren't. Isn't this a potential problem for x86? The patch series on the link above is now superseded by v2: https://lore.kernel.org/linux-mm/20210128105711.10428-1-r...@kernel.org/ -- Thiago Jung Bauermann IBM Linux Technology Center
Re: [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end
Mike Rapoport writes:
> On Sat, Jan 23, 2021 at 06:09:11PM -0800, Andrew Morton wrote:
>> On Fri, 22 Jan 2021 01:37:14 -0300 Thiago Jung Bauermann
>> wrote:
>>
>> > Mike Rapoport writes:
>> >
>> > > > Signed-off-by: Roman Gushchin
>> > >
>> > > Reviewed-by: Mike Rapoport
>> >
>> > I've seen a couple of spurious triggers of the WARN_ONCE() removed by this
>> > patch. This happens on some ppc64le bare metal (powernv) server machines
>> > with
>> > CONFIG_SWIOTLB=y and crashkernel=4G, as described in a candidate patch I
>> > posted
>> > to solve this issue in a different way:
>> >
>> > https://lore.kernel.org/linuxppc-dev/20201218062103.76102-1-bauer...@linux.ibm.com/
>> >
>> > Since this patch solves that problem, is it possible to include it in the
>> > next
>> > feasible v5.11-rcX, with the following tag?
>>
>> We could do this,
Thanks!
>> if we're confident that this patch doesn't depend on
>> [1/2] "mm: cma: allocate cma areas bottom-up"? I think it is...
>
> A think it does not depend on cma bottom-up allocation, it's rather the other
> way around: without this CMA bottom-up allocation could fail with KASLR
> enabled.
I agree. Conceptually, this could have been patch 1 in this series.
> Still, this patch may need updates to the way x86 does early reservations:
>
> https://lore.kernel.org/lkml/20210115083255.12744-1-r...@kernel.org
Ah, I wasn't aware of this. Thanks for fixing those issues. That series
seems to be well accepted.
>> > Fixes: 8fabc623238e ("powerpc: Ensure that swiotlb buffer is allocated
>> > from low memory")
>>
>> I added that.
Thanks!
--
Thiago Jung Bauermann
IBM Linux Technology Center
Re: [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end
On Sat, Jan 23, 2021 at 06:09:11PM -0800, Andrew Morton wrote:
> On Fri, 22 Jan 2021 01:37:14 -0300 Thiago Jung Bauermann
> wrote:
>
> > Mike Rapoport writes:
> >
> > > > Signed-off-by: Roman Gushchin
> > >
> > > Reviewed-by: Mike Rapoport
> >
> > I've seen a couple of spurious triggers of the WARN_ONCE() removed by this
> > patch. This happens on some ppc64le bare metal (powernv) server machines
> > with
> > CONFIG_SWIOTLB=y and crashkernel=4G, as described in a candidate patch I
> > posted
> > to solve this issue in a different way:
> >
> > https://lore.kernel.org/linuxppc-dev/20201218062103.76102-1-bauer...@linux.ibm.com/
> >
> > Since this patch solves that problem, is it possible to include it in the
> > next
> > feasible v5.11-rcX, with the following tag?
>
> We could do this, if we're confident that this patch doesn't depend on
> [1/2] "mm: cma: allocate cma areas bottom-up"? I think it is...
A think it does not depend on cma bottom-up allocation, it's rather the other
way around: without this CMA bottom-up allocation could fail with KASLR
enabled.
Still, this patch may need updates to the way x86 does early reservations:
https://lore.kernel.org/lkml/20210115083255.12744-1-r...@kernel.org
> > Fixes: 8fabc623238e ("powerpc: Ensure that swiotlb buffer is allocated from
> > low memory")
>
> I added that.
>
>
--
Sincerely yours,
Mike.
Re: [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end
On Fri, 22 Jan 2021 01:37:14 -0300 Thiago Jung Bauermann
wrote:
> Mike Rapoport writes:
>
> > > Signed-off-by: Roman Gushchin
> >
> > Reviewed-by: Mike Rapoport
>
> I've seen a couple of spurious triggers of the WARN_ONCE() removed by this
> patch. This happens on some ppc64le bare metal (powernv) server machines with
> CONFIG_SWIOTLB=y and crashkernel=4G, as described in a candidate patch I
> posted
> to solve this issue in a different way:
>
> https://lore.kernel.org/linuxppc-dev/20201218062103.76102-1-bauer...@linux.ibm.com/
>
> Since this patch solves that problem, is it possible to include it in the next
> feasible v5.11-rcX, with the following tag?
We could do this, if we're confident that this patch doesn't depend on
[1/2] "mm: cma: allocate cma areas bottom-up"? I think it is...
> Fixes: 8fabc623238e ("powerpc: Ensure that swiotlb buffer is allocated from
> low memory")
I added that.
Re: [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end
Mike Rapoport writes:
> > Signed-off-by: Roman Gushchin
>
> Reviewed-by: Mike Rapoport
I've seen a couple of spurious triggers of the WARN_ONCE() removed by this
patch. This happens on some ppc64le bare metal (powernv) server machines with
CONFIG_SWIOTLB=y and crashkernel=4G, as described in a candidate patch I posted
to solve this issue in a different way:
https://lore.kernel.org/linuxppc-dev/20201218062103.76102-1-bauer...@linux.ibm.com/
Since this patch solves that problem, is it possible to include it in the next
feasible v5.11-rcX, with the following tag?
Fixes: 8fabc623238e ("powerpc: Ensure that swiotlb buffer is allocated from low
memory")
This is because reverting the commit above also solves the problem on the
machines where I've seen this issue.
--
Thiago Jung Bauermann
IBM Linux Technology Center
