From: Peter Zijlstra <peterz@infradead.org>
To: Jon Masters <jcm@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
gary.robertson@linaro.org, Steve Capper <steve.capper@linaro.org>,
mark.rutland@arm.com, hughd@google.com,
christoffer.dall@linaro.org, akpm@linux-foundation.org,
mgorman@suse.de, linux@arm.linux.org.uk,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
linux-arm-kernel@lists.infradead.org, will.deacon@arm.com,
dann.frazier@canonical.com, anders.roxell@linaro.org
Subject: Re: PMD update corruption (sync question)
Date: Mon, 2 Mar 2015 13:31:49 +0100 [thread overview]
Message-ID: <20150302123149.GK21418@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1172437505.28092883.1425294374323.JavaMail.zimbra@zmail15.collab.prod.int.phx2.redhat.com>
On Mon, Mar 02, 2015 at 06:06:14AM -0500, Jon Masters wrote:
> 64-bit writes are /usually/ atomic but alignment or compiler emiting
> 32-bit opcodes could also do it. I agree there are a few other pieces
> to this we will chat about separately and come back to this thread.
Looking at the asm will quickly tell you if its emitting 32bit stores or
not. If it is, use WRITE_ONCE() (you should anyway I suppose) and see if
that cures it, if not file a compiler bug, volatile stores should never
be split.
As to alignment, you can simply put a BUG_ON((unsigned long)ptep & 7);
in there.
Also:
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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next prev parent reply other threads:[~2015-03-02 12:32 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-26 14:03 [PATCH V4 0/6] RCU get_user_pages_fast and __get_user_pages_fast Steve Capper
2014-09-26 14:03 ` [PATCH V4 1/6] mm: Introduce a general RCU get_user_pages_fast Steve Capper
2014-09-29 21:51 ` Hugh Dickins
2014-10-01 11:11 ` Catalin Marinas
2014-10-02 16:00 ` Steve Capper
2014-10-02 12:19 ` Andrea Arcangeli
2014-10-02 16:18 ` Steve Capper
2014-10-02 16:54 ` Andrea Arcangeli
2014-10-13 5:15 ` Aneesh Kumar K.V
2014-10-13 5:21 ` David Miller
2014-10-13 11:44 ` Steve Capper
2014-10-13 16:06 ` David Miller
2014-10-14 12:38 ` Steve Capper
2014-10-14 16:30 ` David Miller
2014-10-13 17:04 ` Aneesh Kumar K.V
2014-10-13 6:22 ` Aneesh Kumar K.V
2014-09-26 14:03 ` [PATCH V4 2/6] arm: mm: Introduce special ptes for LPAE Steve Capper
2014-09-26 14:03 ` [PATCH V4 3/6] arm: mm: Enable HAVE_RCU_TABLE_FREE logic Steve Capper
2014-09-26 14:03 ` [PATCH V4 4/6] arm: mm: Enable RCU fast_gup Steve Capper
2014-09-26 14:03 ` [PATCH V4 5/6] arm64: mm: Enable HAVE_RCU_TABLE_FREE logic Steve Capper
2014-09-26 14:03 ` [PATCH V4 6/6] arm64: mm: Enable RCU fast_gup Steve Capper
2015-02-27 12:42 ` [PATCH V4 0/6] RCU get_user_pages_fast and __get_user_pages_fast Jon Masters
2015-02-27 13:20 ` Mark Rutland
2015-03-02 14:16 ` Mark Rutland
2015-03-02 2:10 ` PMD update corruption (sync question) Jon Masters
2015-03-02 5:58 ` Jon Masters
2015-03-02 10:50 ` Catalin Marinas
2015-03-02 11:06 ` Jon Masters
2015-03-02 12:31 ` Peter Zijlstra [this message]
2015-03-02 12:40 ` Geert Uytterhoeven
2015-03-02 22:21 ` Jon Masters
2015-03-02 22:29 ` Jon Masters
2015-03-03 9:06 ` Arnd Bergmann
2015-03-03 15:46 ` Jon Masters
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