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Date:   Sat, 23 Jan 2021 18:09:11 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc:     rppt@kernel.org, guro@fb.com, iamjoonsoo.kim@lge.com,
        Ram Pai <linuxram@us.ibm.com>,
        Konrad Rzeszutek Wilk <konrad@darnok.org>,
        Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
        kernel-team@fb.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
        mhocko@kernel.org, riel@surriel.com
Subject: Re: [PATCH v2 2/2] memblock: do not start bottom-up allocations
 with kernel_end
Message-Id: <20210123180911.aafa8404a3a7a30779713456@linux-foundation.org>
In-Reply-To: <20210122043714.266075-1-bauerman@linux.ibm.com>
References: <20201220064959.GB392325@kernel.org>
        <20210122043714.266075-1-bauerman@linux.ibm.com>
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On Fri, 22 Jan 2021 01:37:14 -0300 Thiago Jung Bauermann <bauerman@linux.ibm.com> wrote:

> Mike Rapoport <rppt@kernel.org> writes:
> 
> > > Signed-off-by: Roman Gushchin <guro@fb.com>
> > 
> > Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
> 
> 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-bauerman@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.