From: Peter Zijlstra <peterz@infradead.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Marc Gonzalez <marc.w.gonzalez@free.fr>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rafael Wysocki <rjw@rjwysocki.net>,
LKML <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Alexey Brodkin <alexey.brodkin@synopsys.com>,
Will Deacon <will@kernel.org>,
Russell King <rmk+kernel@armlinux.org.uk>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Tejun Heo <tj@kernel.org>, Mark Brown <broonie@kernel.org>
Subject: Re: [RFC PATCH v1] devres: align devres.data strictly only for devm_kmalloc()
Date: Fri, 20 Dec 2019 18:13:59 +0100 [thread overview]
Message-ID: <20191220171359.GP2827@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <9be1d523-e92c-836b-b79d-37e880d092a0@arm.com>
On Fri, Dec 20, 2019 at 03:01:03PM +0000, Robin Murphy wrote:
> On 2019-12-20 2:06 pm, Peter Zijlstra wrote:
> > data = kmalloc(size + sizeof(struct devres), GFP_KERNEL);
>
> At this point, you'd still need to special-case devm_kmalloc() to ensure
> size is rounded up to the next ARCH_KMALLOC_MINALIGN granule, or you'd go
> back to the original problem of the struct devres fields potentially sharing
> a cache line with the data buffer. That needs to be avoided, because if the
> devres list is modified while the buffer is mapped for noncoherent DMA
> (which could legitimately happen as they are nominally distinct allocations
> with different owners) there's liable to be data corruption one way or the
> other.
Wait up, why are you allowing non-coherent DMA at less than page size
granularity? Is that really sane? Is this really supported behaviour for
devm ?
next prev parent reply other threads:[~2019-12-20 17:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 15:30 [RFC PATCH v1] devres: align devres.data strictly only for devm_kmalloc() Marc Gonzalez
2019-12-17 15:45 ` Greg Kroah-Hartman
2019-12-17 16:17 ` Marc Gonzalez
2019-12-18 14:20 ` Alexey Brodkin
2019-12-18 15:40 ` Marc Gonzalez
2019-12-20 10:19 ` Marc Gonzalez
2019-12-20 10:22 ` Greg Kroah-Hartman
2019-12-20 10:22 ` Greg Kroah-Hartman
2019-12-20 12:05 ` Marc Gonzalez
2019-12-20 17:19 ` Peter Zijlstra
2019-12-20 14:06 ` Peter Zijlstra
2019-12-20 14:16 ` Greg Kroah-Hartman
2019-12-20 15:01 ` Robin Murphy
2019-12-20 17:13 ` Peter Zijlstra [this message]
2019-12-20 22:02 ` Robin Murphy
2020-01-06 10:05 ` Peter Zijlstra
2019-12-20 19:32 ` Alexey Brodkin
2019-12-20 20:23 ` Peter Zijlstra
2019-12-20 21:02 ` Alexey Brodkin
2019-12-20 21:47 ` Dmitry Torokhov
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