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Date:   Mon, 11 May 2020 09:42:43 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     Joerg Roedel <jroedel@suse.de>, Joerg Roedel <joro@8bytes.org>,
        X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Arnd Bergmann <arnd@arndb.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux ACPI <linux-acpi@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>
Subject: Re: [RFC PATCH 0/7] mm: Get rid of vmalloc_sync_(un)mappings()
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On Sat, May 09, 2020 at 12:05:29PM -0700, Andy Lutomirski wrote:

> On x86_64, the only real advantage is that the handful of corner cases
> that make vmalloc faults unpleasant (mostly relating to vmap stacks)
> go away.  On x86_32, a bunch of mind-bending stuff (everything your
> series deletes but also almost everything your series *adds*) goes
> away.  There may be a genuine tiny performance hit on 2-level systems
> due to the loss of huge pages in vmalloc space, but I'm not sure I
> care or that we use them anyway on these systems.  And PeterZ can stop
> even thinking about RCU.
> 
> Am I making sense?

I think it'll work for x86_64 and that is really all I care about :-)