On Thu, Apr 23, 2020 at 09:40:01PM +0100, Lee Jones wrote:
From: Alexey Brodkin alexey.brodkin@synopsys.com
[ Upstream commit a66d972465d15b1d89281258805eb8b47d66bd36 ]
Initially we bumped into problem with 32-bit aligned atomic64_t on ARC, see [1]. And then during quite lengthly discussion Peter Z. mentioned ARCH_KMALLOC_MINALIGN which IMHO makes perfect sense. If allocation is done by plain kmalloc() obtained buffer will be ARCH_KMALLOC_MINALIGN aligned and then why buffer obtained via devm_kmalloc() should have any other alignment?
This way we at least get the same behavior for both types of allocation.
[1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-July/004009.html [2] http://lists.infradead.org/pipermail/linux-snps-arc/2018-July/004036.html
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Geert Uytterhoeven geert@linux-m68k.org Cc: David Laight David.Laight@ACULAB.COM Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Vineet Gupta vgupta@synopsys.com Cc: Will Deacon will.deacon@arm.com Cc: Greg KH greg@kroah.com Cc: stable@vger.kernel.org # 4.8+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Lee Jones lee.jones@linaro.org
drivers/base/devres.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/base/devres.c b/drivers/base/devres.c index 8fc654f0807bf..9763325a9c944 100644 --- a/drivers/base/devres.c +++ b/drivers/base/devres.c @@ -24,8 +24,14 @@ struct devres_node { struct devres { struct devres_node node;
- /* -- 3 pointers */
- unsigned long long data[]; /* guarantee ull alignment */
- /*
* Some archs want to perform DMA into kmalloc caches* and need a guaranteed alignment larger than* the alignment of a 64-bit integer.* Thus we use ARCH_KMALLOC_MINALIGN here and get exactly the same* buffer alignment as if it was allocated by plain kmalloc().*/- u8 __aligned(ARCH_KMALLOC_MINALIGN) data[];
}; struct devres_group { -- 2.25.1
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 :(
greg k-h