From: catalin.marinas@arm•com (Catalin Marinas)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: Do not call flush_cache_user_range with mmap_sem held
Date: Thu, 17 Nov 2011 10:26:23 +0000 [thread overview]
Message-ID: <20111117102623.GG4748@arm.com> (raw)
In-Reply-To: <CAOesGMgmVdck4rP9iQ+eBc+R1p-eVChnumiszB_D77Q0Rtyf3Q@mail.gmail.com>
On Thu, Nov 17, 2011 at 12:16:17AM +0000, Olof Johansson wrote:
> On Wed, Nov 16, 2011 at 3:50 PM, Russell King - ARM Linux
> <linux@arm•linux.org.uk> wrote:
> > On Wed, Nov 16, 2011 at 01:23:02PM -0800, Olof Johansson wrote:
> >> Agreed. Russell, please consider picking this up -- the bug is very
> >> real and it sounds like the objection is vague.
> >
> > No, it isn't. ?It's creating an unsafe situation. ?If we're going to do
> > this, we might as well give up on architecture correctness because we're
> > throwing out locking correctness.
> >
> > 1. We look up the VMA.
> > 2. We pass the VMA to the cache operation.
> > 3. The cache operation dereferences the VMA to obtain the VMA flags.
...
> We also don't continue iterating over the vmas, we only flush for the
> first one in the range that we find. That is possibly a bug.
I don't remember the details but couple of years ago someone working on
Java in ARM pointed out that a cache operation spanning two vmas only
flushes a single one. I think the JIT was modified since as I haven't
heard back but I would be more in favour of just dropping the vma
checks altogether.
--
Catalin
next prev parent reply other threads:[~2011-11-17 10:26 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-07 17:33 [PATCH] ARM: Do not call flush_cache_user_range with mmap_sem held Catalin Marinas
2011-11-16 21:23 ` Olof Johansson
2011-11-16 23:50 ` Russell King - ARM Linux
2011-11-17 0:16 ` Olof Johansson
2011-11-17 0:20 ` Olof Johansson
2011-11-17 10:26 ` Catalin Marinas [this message]
2011-11-17 10:49 ` Russell King - ARM Linux
2011-11-17 10:45 ` Russell King - ARM Linux
2011-11-20 17:54 ` Olof Johansson
2011-11-17 10:22 ` Catalin Marinas
2011-11-17 10:42 ` Russell King - ARM Linux
2011-11-17 10:59 ` Catalin Marinas
2011-11-17 11:03 ` Russell King - ARM Linux
2011-11-17 11:25 ` Catalin Marinas
2012-04-09 5:58 ` Dirk Behme
2012-04-09 14:24 ` Olof Johansson
2012-04-10 17:17 ` Will Deacon
2012-04-18 15:05 ` Will Deacon
2012-04-18 15:27 ` Russell King - ARM Linux
2012-04-18 16:27 ` Will Deacon
2012-04-18 17:15 ` Catalin Marinas
2012-04-18 8:40 ` Catalin Marinas
-- strict thread matches above, loose matches on Subject: below --
2010-04-28 7:32 [PATCH] [ARM] " Dima Zavin
2010-04-28 7:35 ` Dima Zavin
2010-04-29 13:00 ` Russell King - ARM Linux
2010-04-29 18:16 ` Jamie Lokier
2010-04-29 18:24 ` Russell King - ARM Linux
2010-04-29 19:23 ` Dima Zavin
2010-05-04 4:07 ` Dima Zavin
2010-05-04 7:40 ` Russell King - ARM Linux
2010-05-06 15:08 ` Catalin Marinas
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