Commit 2f69fa82 authored Mar 17, 2014 by Al Viro Committed by Tejun Heo Mar 17, 2014

percpu: allocation size should be even



723ad1d9 ("percpu: store offsets instead of lengths in ->map[]")
updated percpu area allocator to use the lowest bit, instead of sign,
to signify whether the area is occupied and forced min align to 2;
unfortunately, it forgot to force the allocation size to be even
causing malfunctions for the very rare odd-sized allocations.

Always force the allocations to be even sized.

tj: Wrote patch description.

Original-patch-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 3d331ad7

mm/percpu.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -713,11 +713,14 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)

		/*
		* We want the lowest bit of offset available for in-use/free
		* indicator.
		* indicator, so force >= 16bit alignment and make size even.
		*/
		if (unlikely(align < 2))
		align = 2;

		if (unlikely(size & 1))
		size++;

		if (unlikely(!size \|\| size > PCPU_MIN_UNIT_SIZE \|\| align > PAGE_SIZE)) {
		WARN(true, "illegal size (%zu) or align (%zu) for "
		"percpu allocation\n", size, align);