4.19-stable review patch. If anyone has any objections, please let me know.
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From: Alexey Brodkin alexey.brodkin@synopsys.com
commit a66d972465d15b1d89281258805eb8b47d66bd36 upstream.
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
--- drivers/base/devres.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- 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 {