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Date:   Sun, 27 Feb 2022 10:32:52 -0800 (PST)
From:   Hugh Dickins <hughd@google.com>
To:     Liam Howlett <liam.howlett@oracle.com>
cc:     Nathan Chancellor <nathan@kernel.org>,
        Qian Cai <quic_qiancai@quicinc.com>,
        "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mark Brown <broonie@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Suren Baghdasaryan <surenb@google.com>,
        Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v6 00/71] Introducing the Maple Tree
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On Sat, 26 Feb 2022, Hugh Dickins wrote:
> 
> I say "often": it's very erratic.  Once, a machine booted with mem=1G
> ran kernel builds successfully swapping for 4.5 hours before faulting
> in __nr_to_section in virt_to_folio ... while doing a __vma_adjust() -
> you'll ask me for a full stacktrace, and I'll answer sorry, too many,
> please try for yourself.  Another time, for 1.5 hours before hitting
> the BUG_ON(is_migration_entry(entry) && !PageLocked(p)) in
> pfn_swap_entry_to_page() - suggesting anon_vma locking had not been
> right while doing page migration (I was exercising THPs a lot).
> But now, can I even get it to complete the boot sequence?

Sorry, I never mentioned the architecture: x86_64 throughout for me.