From: Geert Uytterhoeven <geert@linux-m68k.org>
To: David Laight <David.Laight@aculab.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Lee Jones <lee.jones@linaro.org>, stable <stable@vger.kernel.org>,
Alexey Brodkin <alexey.brodkin@synopsys.com>,
Alexey Brodkin <abrodkin@synopsys.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Vineet Gupta <vgupta@synopsys.com>,
Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH 4.4 03/16] devres: Align data[] to ARCH_KMALLOC_MINALIGN
Date: Wed, 13 May 2020 13:06:46 +0200 [thread overview]
Message-ID: <CAMuHMdUJeJaxtOLVfEkJgXw=A7YO93pD2C11wYCDr3VR7mOJ5g@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdV+FAjBtp-yzp+57o19gcasq15-9rDM58NbJsOwBu=vUQ@mail.gmail.com>
Hi David,
On Wed, May 13, 2020 at 1:05 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Wed, May 13, 2020 at 12:10 PM David Laight <David.Laight@aculab.com> wrote:
> > From: Geert Uytterhoeven
> > > Sent: 13 May 2020 10:49
> > ...
> > > > I don't want to apply this to older kernels as it could cause extra
> > > > memory usage for no good reason. I have no idea why a non ARC system
> > > > would want it :(
> > >
> > > I think the reference to ARC is a red herring.
> > > The real issue is that buffers used for DMA may not have the required
> > > alignment, which is not limited to ARC systems.
> > >
> > > Note that I'm also not super happy with the extra memory usage.
> > > But devm_*() conveniences come with their penalties...
> >
> > Interesting thought.
> > Could the devm 'header' be put right at the end of the kmalloc()
> > buffer?
> >
> > Then the driver would be given aligned address.
>
> Yes, if the header is extended to contain the real start address of the
> allocated block.
But that would break explicit freeing through devm_kfree(), as that is
passed a pointer to the payload, not the header.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2020-05-13 11:07 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-23 20:39 [PATCH 4.4 00/16] Backported fixes taken from Sony's Vendor tree Lee Jones
2020-04-23 20:39 ` [PATCH 4.4 01/16] drm/msm: stop abusing dma_map/unmap for cache Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 02/16] gpiolib: Fix references to gpiod_[gs]et_*value_cansleep() variants Lee Jones
2020-05-13 9:34 ` Greg KH
2020-05-18 10:23 ` [PATCH 4.4 02/16 (v2)] " Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 03/16] devres: Align data[] to ARCH_KMALLOC_MINALIGN Lee Jones
2020-05-13 9:35 ` Greg Kroah-Hartman
2020-05-13 9:48 ` Geert Uytterhoeven
2020-05-13 10:10 ` David Laight
2020-05-13 11:05 ` Geert Uytterhoeven
2020-05-13 11:06 ` Geert Uytterhoeven [this message]
2020-05-13 12:37 ` David Laight
2020-05-13 13:26 ` Geert Uytterhoeven
2020-05-13 13:35 ` David Laight
2020-05-13 13:36 ` Peter Zijlstra
2020-05-13 13:50 ` David Laight
2020-04-23 20:40 ` [PATCH 4.4 04/16] crypto: talitos - Delete an error message for a failed memory allocation in talitos_edesc_alloc() Lee Jones
2020-05-13 9:36 ` Greg KH
2020-05-18 10:17 ` Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 05/16] drm: NULL pointer dereference [null-pointer-deref] (CWE 476) problem Lee Jones
2020-05-13 9:36 ` Greg KH
2020-04-23 20:40 ` [PATCH 4.4 06/16] clk: Fix debugfs_create_*() usage Lee Jones
2020-05-13 9:37 ` Greg KH
2020-05-18 10:08 ` Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 07/16] arm64: traps: Don't print stack or raw PC/LR values in backtraces Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 08/16] serial/sunsu: add missing of_node_put() Lee Jones
2020-05-06 8:23 ` Greg Kroah-Hartman
2020-05-06 9:02 ` Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 09/16] wil6210: increase firmware ready timeout Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 10/16] wil6210: fix temperature debugfs Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 11/16] scsi: ufs: ufs-qcom: remove broken hci version quirk Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 12/16] wil6210: rate limit wil_rx_refill error Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 13/16] rtc: pm8xxx: Fix issue in RTC write path Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 14/16] soc: qcom: smem: Use le32_to_cpu for comparison Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 15/16] of: fix missing kobject init for !SYSFS && OF_DYNAMIC config Lee Jones
2020-04-23 20:40 ` [PATCH 4.4 16/16] mm/vmalloc.c: move 'area->pages' after if statement Lee Jones
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