slob: implement RCU freeing

The SLOB allocator should implement SLAB_DESTROY_BY_RCU correctly, because
even on UP, RCU freeing semantics are not equivalent to simply freeing
immediately.  This also allows SLOB to be used on SMP.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 4e009fde4b69..9264895ab331 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -577,14 +577,11 @@ config SLUB
            and has enhanced diagnostics.
 
 config SLOB
-#
-#       SLOB does not support SMP because SLAB_DESTROY_BY_RCU is unsupported
-#
-        depends on EMBEDDED && !SMP && !SPARSEMEM
+        depends on EMBEDDED && !SPARSEMEM
         bool "SLOB (Simple Allocator)"
         help
            SLOB replaces the SLAB allocator with a drastically simpler
-           allocator.  SLOB is more space efficient that SLAB but does not
+           allocator.  SLOB is more space efficient than SLAB but does not
            scale well (single lock for all operations) and is also highly
            susceptible to fragmentation. SLUB can accomplish a higher object
            density. It is usually better to use SLUB instead of SLOB.