The patch titled
SLUB: Treat SLAB_HWCACHE_ALIGN as a mininum and not as *the* alignment
has been added to the -mm tree. Its filename is
slub-treat-slab_hwcache_align-as-a-mininum-and-not-as-the-alignment.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: SLUB: Treat SLAB_HWCACHE_ALIGN as a mininum and not as *the* alignment
From: Christoph Lameter <clameter@xxxxxxx>
Checking for slabs used in powerpc arch code:
The pgtable cache is configured as
pgtable_cache[i] = kmem_cache_create(name,
size, size,
SLAB_HWCACHE_ALIGN |
SLAB_MUST_HWCACHE_ALIGN,
zero_ctor,
NULL);
Hmmm.... aligned slabs at size and then we MUST_HWCACHE_ALIGN?? Two
competing alignment requirements and a constructor. Constructor requires
the moving of the free pointer after the slab and thus increases the slab
size.
Sigh. IF SLAB_HWCACHE_ALIGN is set then SLUB believes this to be the
ultimate demand that overrides all other alignments and only aligns to the
cacheline. Try the following fix:
SLUB: Treat SLAB_HWCACHE_ALIGN as a mininum and not as *the* alignment
If the specified alignment is higher than L1_CACHE_BYTES and
SLAB_HWCACHE_ALIGN is set then use the higher alignment.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff -puN mm/slub.c~slub-treat-slab_hwcache_align-as-a-mininum-and-not-as-the-alignment mm/slub.c
--- a/mm/slub.c~slub-treat-slab_hwcache_align-as-a-mininum-and-not-as-the-alignment
+++ a/mm/slub.c
@@ -1373,10 +1373,7 @@ static int calculate_order(int size)
static unsigned long calculate_alignment(unsigned long flags,
unsigned long align)
{
- if (flags & SLAB_HWCACHE_ALIGN)
- return L1_CACHE_BYTES;
-
- if (flags & SLAB_MUST_HWCACHE_ALIGN)
+ if (flags & (SLAB_MUST_HWCACHE_ALIGN | SLAB_HWCACHE_ALIGN))
return max_t(unsigned long, align, L1_CACHE_BYTES);
if (align < ARCH_SLAB_MINALIGN)
_
Patches currently in -mm which might be from clameter@xxxxxxx are
slab-introduce-krealloc.patch
slab-introduce-krealloc-fix.patch
safer-nr_node_ids-and-nr_node_ids-determination-and-initial.patch
use-zvc-counters-to-establish-exact-size-of-dirtyable-pages.patch
slab-ensure-cache_alloc_refill-terminates.patch
smaps-extract-pmd-walker-from-smaps-code.patch
smaps-add-pages-referenced-count-to-smaps.patch
smaps-add-clear_refs-file-to-clear-reference.patch
smaps-add-clear_refs-file-to-clear-reference-fix.patch
smaps-add-clear_refs-file-to-clear-reference-fix-fix.patch
slab-use-num_possible_cpus-in-enable_cpucache.patch
slub-core.patch
slub-fix-numa-bootstrap.patch
slub-use-correct-flags-to-check-for-dma-cache.patch
slub-treat-slab_hwcache_align-as-a-mininum-and-not-as-the-alignment.patch
slub-add-slabinfo-tool.patch
extend-print_symbol-capability-fix.patch
slab-shutdown-cache_reaper-when-cpu-goes-down.patch
mm-implement-swap-prefetching.patch
readahead-state-based-method-aging-accounting.patch
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