[PATCH] mm: slab: Only move management objects off-slab for sizes larger than KMALLOC_MIN_SIZE
akpm at linux-foundation.org
Thu Nov 5 05:31:39 PST 2015
On Thu, 5 Nov 2015 11:50:35 +0000 Catalin Marinas <catalin.marinas at arm.com> wrote:
> Commit 8fc9cf420b36 ("slab: make more slab management structure off the
> slab") enables off-slab management objects for sizes starting with
> PAGE_SIZE >> 5. This means 128 bytes for a 4KB page configuration.
> However, on systems with a KMALLOC_MIN_SIZE of 128 (arm64 in 4.4), such
> optimisation does not make sense since the slab management allocation
> would take 128 bytes anyway (even though freelist_size is 32) with the
> additional overhead of another allocation.
> This patch introduces an OFF_SLAB_MIN_SIZE macro which takes
> KMALLOC_MIN_SIZE into account. It also solves a slab bug on arm64 where
> the first kmalloc_cache to be initialised after slab_early_init = 0,
> "kmalloc-128", fails to allocate off-slab management objects from the
> same "kmalloc-128" cache.
That all seems to be quite minor stuff.
> Fixes: 8fc9cf420b36 ("slab: make more slab management structure off the slab")
> Cc: <stable at vger.kernel.org> # 3.15+
Yet you believe the fix should be backported.
So, the usual refrain: when fixing a bug, please describe the end-user
visible effects of that bug.
More information about the linux-arm-kernel