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Message-ID: <20170316172046.sl7j5elg77yjevau@hirez.programming.kicks-ass.net>
Date: Thu, 16 Mar 2017 18:20:46 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Dave Hansen <dave.hansen@...el.com>,
"Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
Steve Capper <steve.capper@...aro.org>,
Dann Frazier <dann.frazier@...onical.com>,
Catalin Marinas <catalin.marinas@....com>,
linux-arch@...r.kernel.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Paul McKenney <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH 7/7] x86/mm: Switch to generic get_user_page_fast()
implementation
On Thu, Mar 16, 2017 at 06:26:55PM +0300, Kirill A. Shutemov wrote:
> +config HAVE_GENERIC_RCU_GUP
> + def_bool y
> +
Nothing immediately jumped out to me; except that this option might be
misnamed.
AFAICT that code does not in fact rely on HAVE_RCU_TABLE_FREE; it will
happily work with the (x86) broadcast IPI invalidate model, as you show
here.
Architectures that do not do that obviously need HAVE_RCU_TABLE_FREE,
but that is not the point I feel.
Also, this code hard relies on IRQ-disable delaying grace periods, which
is mostly true I think, but has always been something Paul didn't really
want to commit too firmly to.
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