percpu: allocation size should be even

723ad1d90b56 ("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>

diff --git a/mm/percpu.c b/mm/percpu.c
index c7206d06f8de54c84ac882c6ae21386b54c50607..202e104df8a7a765d680ca6b18526636a5b12634 100644 (file)
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -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);