From: Lee Jones <lee.jones@xxxxxxxxxx> > Sent: 22 April 2020 12:20 > From: Alexey Brodkin <alexey.brodkin@xxxxxxxxxxxx> > > [ 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. Anyone any idea how much difference it would actually make to align all architectures to at least 32-bits (or even 64-bits)? I think the only times it would make a difference would be for allocations that (for example, 62 bytes on m68k) just fit in a 64 byte block - so suddenly grow to 128 bytes. (Or whatever granularity the allocator uses). I suspect they are rarer than allocations of an arbitrary 2^n bytes that get a lot of bloat padding if the allocator adds a header. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
