This is a follow-up to the discussion in [1], [2].
IOMMUs using ARMv7 short-descriptor format require page tables
(level 1 and 2) to be allocated within the first 4GB of RAM, even
on 64-bit systems.
For L1 tables that are bigger than a page, we can just use __get_free_pages
with GFP_DMA32 (on arm64 systems only, arm would still use GFP_DMA).
For L2 tables that only take 1KB, it would be a waste to allocate a full
page, so we considered 3 approaches:
1. This series, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2 page
tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable to reuse
freed fragments until the whole page is freed. [3]
This series is the most memory-efficient approach.
stable@ note:
We confirmed that this is a regression, and IOMMU errors happen on 4.19
and linux-next/master on MT8173 (elm, Acer Chromebook R13). The issue
most likely starts from commit ad67f5a6545f ("arm64: replace ZONE_DMA
with ZONE_DMA32"), i.e. 4.15, and presumably breaks a number of Mediatek
platforms (and maybe others?).
[1] https://lists.linuxfoundation.org/pipermail/iommu/2018-November/030876.html
[2] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html
[3] https://patchwork.codeaurora.org/patch/671639/
Changes since v1:
- Add support for SLAB_CACHE_DMA32 in slab and slub (patches 1/2)
- iommu/io-pgtable-arm-v7s (patch 3):
- Changed approach to use SLAB_CACHE_DMA32 added by the previous
commit.
- Use DMA or DMA32 depending on the architecture (DMA for arm,
DMA32 for arm64).
Changes since v2:
- Reworded and expanded commit messages
- Added cache_dma32 documentation in PATCH 2/3.
v3 used the page_frag approach, see [3].
Changes since v4:
- Dropped change that removed GFP_DMA32 from GFP_SLAB_BUG_MASK:
instead we can just call kmem_cache_*alloc without GFP_DMA32
parameter. This also means that we can drop PATCH v4 1/3, as we
do not make any changes in GFP flag verification.
- Dropped hunks that added cache_dma32 sysfs file, and moved
the hunks to PATCH v5 3/3, so that maintainer can decide whether
to pick the change independently.
Changes since v5:
- Rename ARM_V7S_TABLE_SLAB_CACHE to ARM_V7S_TABLE_SLAB_FLAGS.
- Add stable@ to cc.
Nicolas Boichat (3):
mm: Add support for kmem caches in DMA32 zone
iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging
mm: Add /sys/kernel/slab/cache/cache_dma32
Documentation/ABI/testing/sysfs-kernel-slab | 9 +++++++++
drivers/iommu/io-pgtable-arm-v7s.c | 19 +++++++++++++++----
include/linux/slab.h | 2 ++
mm/slab.c | 2 ++
mm/slab.h | 3 ++-
mm/slab_common.c | 2 +-
mm/slub.c | 16 ++++++++++++++++
tools/vm/slabinfo.c | 7 ++++++-
8 files changed, 53 insertions(+), 7 deletions(-)
--
2.20.0.rc2.403.gdbc3b29805-goog
The patch titled
Subject: iommu/io-pgtable-arm-v7s: request DMA32 memory, and improve debugging
has been added to the -mm tree. Its filename is
iommu-io-pgtable-arm-v7s-request-dma32-memory-and-improve-debugging.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/iommu-io-pgtable-arm-v7s-request-d…
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/iommu-io-pgtable-arm-v7s-request-d…
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Nicolas Boichat <drinkcat(a)chromium.org>
Subject: iommu/io-pgtable-arm-v7s: request DMA32 memory, and improve debugging
IOMMUs using ARMv7 short-descriptor format require page tables (level 1
and 2) to be allocated within the first 4GB of RAM, even on 64-bit
systems.
For level 1/2 pages, ensure GFP_DMA32 is used if CONFIG_ZONE_DMA32 is
defined (e.g. on arm64 platforms).
For level 2 pages, allocate a slab cache in SLAB_CACHE_DMA32. Note that
we do not explicitly pass GFP_DMA[32] to kmem_cache_zalloc, as this is not
strictly necessary, and would cause a warning in mm/sl*b.c, as we did not
update GFP_SLAB_BUG_MASK.
Also, print an error when the physical address does not fit in
32-bit, to make debugging easier in the future.
Link: http://lkml.kernel.org/r/20181210011504.122604-3-drinkcat@chromium.org
Fixes: ad67f5a6545f ("arm64: replace ZONE_DMA with ZONE_DMA32")
Signed-off-by: Nicolas Boichat <drinkcat(a)chromium.org>
Cc: Christoph Hellwig <hch(a)infradead.org>
Cc: Christoph Lameter <cl(a)linux.com>
Cc: David Rientjes <rientjes(a)google.com>
Cc: Hsin-Yi Wang <hsinyi(a)chromium.org>
Cc: Huaisheng Ye <yehs1(a)lenovo.com>
Cc: Joerg Roedel <joro(a)8bytes.org>
Cc: Joonsoo Kim <iamjoonsoo.kim(a)lge.com>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Matthias Brugger <matthias.bgg(a)gmail.com>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Michal Hocko <mhocko(a)suse.com>
Cc: Mike Rapoport <rppt(a)linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg(a)kernel.org>
Cc: Robin Murphy <robin.murphy(a)arm.com>
Cc: Sasha Levin <Alexander.Levin(a)microsoft.com>
Cc: Tomasz Figa <tfiga(a)google.com>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: Will Deacon <will.deacon(a)arm.com>
Cc: Yingjoe Chen <yingjoe.chen(a)mediatek.com>
Cc: Yong Wu <yong.wu(a)mediatek.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
drivers/iommu/io-pgtable-arm-v7s.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
--- a/drivers/iommu/io-pgtable-arm-v7s.c~iommu-io-pgtable-arm-v7s-request-dma32-memory-and-improve-debugging
+++ a/drivers/iommu/io-pgtable-arm-v7s.c
@@ -160,6 +160,14 @@
#define ARM_V7S_TCR_PD1 BIT(5)
+#ifdef CONFIG_ZONE_DMA32
+#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32
+#define ARM_V7S_TABLE_SLAB_FLAGS SLAB_CACHE_DMA32
+#else
+#define ARM_V7S_TABLE_GFP_DMA GFP_DMA
+#define ARM_V7S_TABLE_SLAB_FLAGS SLAB_CACHE_DMA
+#endif
+
typedef u32 arm_v7s_iopte;
static bool selftest_running;
@@ -197,13 +205,16 @@ static void *__arm_v7s_alloc_table(int l
void *table = NULL;
if (lvl == 1)
- table = (void *)__get_dma_pages(__GFP_ZERO, get_order(size));
+ table = (void *)__get_free_pages(
+ __GFP_ZERO | ARM_V7S_TABLE_GFP_DMA, get_order(size));
else if (lvl == 2)
- table = kmem_cache_zalloc(data->l2_tables, gfp | GFP_DMA);
+ table = kmem_cache_zalloc(data->l2_tables, gfp);
phys = virt_to_phys(table);
- if (phys != (arm_v7s_iopte)phys)
+ if (phys != (arm_v7s_iopte)phys) {
/* Doesn't fit in PTE */
+ dev_err(dev, "Page table does not fit in PTE: %pa", &phys);
goto out_free;
+ }
if (table && !(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) {
dma = dma_map_single(dev, table, size, DMA_TO_DEVICE);
if (dma_mapping_error(dev, dma))
@@ -733,7 +744,7 @@ static struct io_pgtable *arm_v7s_alloc_
data->l2_tables = kmem_cache_create("io-pgtable_armv7s_l2",
ARM_V7S_TABLE_SIZE(2),
ARM_V7S_TABLE_SIZE(2),
- SLAB_CACHE_DMA, NULL);
+ ARM_V7S_TABLE_SLAB_FLAGS, NULL);
if (!data->l2_tables)
goto out_free_data;
_
Patches currently in -mm which might be from drinkcat(a)chromium.org are
mm-add-support-for-kmem-caches-in-dma32-zone.patch
iommu-io-pgtable-arm-v7s-request-dma32-memory-and-improve-debugging.patch
mm-add-sys-kernel-slab-cache-cache_dma32.patch
The patch titled
Subject: mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified
has been added to the -mm tree. Its filename is
mm-mempolicy-make-mbind-return-eio-when-mpol_mf_strict-is-specified.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-mempolicy-make-mbind-return-eio…
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-mempolicy-make-mbind-return-eio…
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Yang Shi <yang.shi(a)linux.alibaba.com>
Subject: mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified
When MPOL_MF_STRICT was specified and an existing page was already on a
node that does not follow the policy, mbind() should return -EIO. But
6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
broke the rule.
And c8633798497c ("mm: mempolicy: mbind and migrate_pages support thp
migration") didn't return the correct value for THP mbind() too.
If MPOL_MF_STRICT is set, ignore vma_migratable() to make sure it reaches
queue_pages_to_pte_range() or queue_pages_pmd() to check if an existing
page was already on a node that does not follow the policy. And,
non-migratable vma may be used, return -EIO too if MPOL_MF_MOVE or
MPOL_MF_MOVE_ALL was specified.
Tested with https://github.com/metan-ucw/ltp/blob/master/testcases/kernel/syscalls/mbin…
Link: http://lkml.kernel.org/r/1553020556-38583-1-git-send-email-yang.shi@linux.a…
Fixes: 6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
Signed-off-by: Yang Shi <yang.shi(a)linux.alibaba.com>
Signed-off-by: Oscar Salvador <osalvador(a)suse.de>
Reported-by: Cyril Hrubis <chrubis(a)suse.cz>
Suggested-by: Kirill A. Shutemov <kirill(a)shutemov.name>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/mempolicy.c | 40 +++++++++++++++++++++++++++++++++-------
1 file changed, 33 insertions(+), 7 deletions(-)
--- a/mm/mempolicy.c~mm-mempolicy-make-mbind-return-eio-when-mpol_mf_strict-is-specified
+++ a/mm/mempolicy.c
@@ -428,6 +428,13 @@ static inline bool queue_pages_required(
return node_isset(nid, *qp->nmask) == !(flags & MPOL_MF_INVERT);
}
+/*
+ * The queue_pages_pmd() may have three kind of return value.
+ * 1 - pages are placed on he right node or queued successfully.
+ * 0 - THP get split.
+ * -EIO - is migration entry or MPOL_MF_STRICT was specified and an existing
+ * page was already on a node that does not follow the policy.
+ */
static int queue_pages_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
@@ -437,7 +444,7 @@ static int queue_pages_pmd(pmd_t *pmd, s
unsigned long flags;
if (unlikely(is_pmd_migration_entry(*pmd))) {
- ret = 1;
+ ret = -EIO;
goto unlock;
}
page = pmd_page(*pmd);
@@ -454,8 +461,15 @@ static int queue_pages_pmd(pmd_t *pmd, s
ret = 1;
flags = qp->flags;
/* go to thp migration */
- if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+ if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+ if (!vma_migratable(walk->vma)) {
+ ret = -EIO;
+ goto unlock;
+ }
+
migrate_page_add(page, qp->pagelist, flags);
+ } else
+ ret = -EIO;
unlock:
spin_unlock(ptl);
out:
@@ -480,8 +494,10 @@ static int queue_pages_pte_range(pmd_t *
ptl = pmd_trans_huge_lock(pmd, vma);
if (ptl) {
ret = queue_pages_pmd(pmd, ptl, addr, end, walk);
- if (ret)
+ if (ret > 0)
return 0;
+ else if (ret < 0)
+ return ret;
}
if (pmd_trans_unstable(pmd))
@@ -502,11 +518,16 @@ static int queue_pages_pte_range(pmd_t *
continue;
if (!queue_pages_required(page, qp))
continue;
- migrate_page_add(page, qp->pagelist, flags);
+ if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+ if (!vma_migratable(vma))
+ break;
+ migrate_page_add(page, qp->pagelist, flags);
+ } else
+ break;
}
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
- return 0;
+ return addr != end ? -EIO : 0;
}
static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
@@ -576,7 +597,12 @@ static int queue_pages_test_walk(unsigne
unsigned long endvma = vma->vm_end;
unsigned long flags = qp->flags;
- if (!vma_migratable(vma))
+ /*
+ * Need check MPOL_MF_STRICT to return -EIO if possible
+ * regardless of vma_migratable
+ */
+ if (!vma_migratable(vma) &&
+ !(flags & MPOL_MF_STRICT))
return 1;
if (endvma > end)
@@ -603,7 +629,7 @@ static int queue_pages_test_walk(unsigne
}
/* queue pages from current vma */
- if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+ if (flags & MPOL_MF_VALID)
return 0;
return 1;
}
_
Patches currently in -mm which might be from yang.shi(a)linux.alibaba.com are
mm-mempolicy-make-mbind-return-eio-when-mpol_mf_strict-is-specified.patch
The patch titled
Subject: mm: add support for kmem caches in DMA32 zone
has been added to the -mm tree. Its filename is
mm-add-support-for-kmem-caches-in-dma32-zone.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-add-support-for-kmem-caches-in-…
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-add-support-for-kmem-caches-in-…
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Nicolas Boichat <drinkcat(a)chromium.org>
Subject: mm: add support for kmem caches in DMA32 zone
Patch series "iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables",
v6.
This is a followup to the discussion in [1], [2].
IOMMUs using ARMv7 short-descriptor format require page tables (level 1
and 2) to be allocated within the first 4GB of RAM, even on 64-bit
systems.
For L1 tables that are bigger than a page, we can just use
__get_free_pages with GFP_DMA32 (on arm64 systems only, arm would still
use GFP_DMA).
For L2 tables that only take 1KB, it would be a waste to allocate a full
page, so we considered 3 approaches:
1. This series, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2 page
tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable to reuse
freed fragments until the whole page is freed. [3]
This series is the most memory-efficient approach.
stable@ note:
We confirmed that this is a regression, and IOMMU errors happen on 4.19
and linux-next/master on MT8173 (elm, Acer Chromebook R13). The issue
most likely starts from commit ad67f5a6545f ("arm64: replace ZONE_DMA
with ZONE_DMA32"), i.e. 4.15, and presumably breaks a number of Mediatek
platforms (and maybe others?).
[1] https://lists.linuxfoundation.org/pipermail/iommu/2018-November/030876.html
[2] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html
[3] https://patchwork.codeaurora.org/patch/671639/
This patch (of 3):
IOMMUs using ARMv7 short-descriptor format require page tables to be
allocated within the first 4GB of RAM, even on 64-bit systems. On arm64,
this is done by passing GFP_DMA32 flag to memory allocation functions.
For IOMMU L2 tables that only take 1KB, it would be a waste to allocate
a full page using get_free_pages, so we considered 3 approaches:
1. This patch, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2
page tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable
to reuse freed fragments until the whole page is freed.
This change makes it possible to create a custom cache in DMA32 zone using
kmem_cache_create, then allocate memory using kmem_cache_alloc.
We do not create a DMA32 kmalloc cache array, as there are currently no
users of kmalloc(..., GFP_DMA32). These calls will continue to trigger a
warning, as we keep GFP_DMA32 in GFP_SLAB_BUG_MASK.
This implies that calls to kmem_cache_*alloc on a SLAB_CACHE_DMA32
kmem_cache must _not_ use GFP_DMA32 (it is anyway redundant and
unnecessary).
Link: http://lkml.kernel.org/r/20181210011504.122604-2-drinkcat@chromium.org
Signed-off-by: Nicolas Boichat <drinkcat(a)chromium.org>
Acked-by: Vlastimil Babka <vbabka(a)suse.cz>
Acked-by: Will Deacon <will.deacon(a)arm.com>
Cc: Robin Murphy <robin.murphy(a)arm.com>
Cc: Joerg Roedel <joro(a)8bytes.org>
Cc: Christoph Lameter <cl(a)linux.com>
Cc: Pekka Enberg <penberg(a)kernel.org>
Cc: David Rientjes <rientjes(a)google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim(a)lge.com>
Cc: Michal Hocko <mhocko(a)suse.com>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Sasha Levin <Alexander.Levin(a)microsoft.com>
Cc: Huaisheng Ye <yehs1(a)lenovo.com>
Cc: Mike Rapoport <rppt(a)linux.vnet.ibm.com>
Cc: Yong Wu <yong.wu(a)mediatek.com>
Cc: Matthias Brugger <matthias.bgg(a)gmail.com>
Cc: Tomasz Figa <tfiga(a)google.com>
Cc: Yingjoe Chen <yingjoe.chen(a)mediatek.com>
Cc: Christoph Hellwig <hch(a)infradead.org>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Hsin-Yi Wang <hsinyi(a)chromium.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
include/linux/slab.h | 2 ++
mm/slab.c | 2 ++
mm/slab.h | 3 ++-
mm/slab_common.c | 2 +-
mm/slub.c | 5 +++++
5 files changed, 12 insertions(+), 2 deletions(-)
--- a/include/linux/slab.h~mm-add-support-for-kmem-caches-in-dma32-zone
+++ a/include/linux/slab.h
@@ -32,6 +32,8 @@
#define SLAB_HWCACHE_ALIGN ((slab_flags_t __force)0x00002000U)
/* Use GFP_DMA memory */
#define SLAB_CACHE_DMA ((slab_flags_t __force)0x00004000U)
+/* Use GFP_DMA32 memory */
+#define SLAB_CACHE_DMA32 ((slab_flags_t __force)0x00008000U)
/* DEBUG: Store the last owner for bug hunting */
#define SLAB_STORE_USER ((slab_flags_t __force)0x00010000U)
/* Panic if kmem_cache_create() fails */
--- a/mm/slab.c~mm-add-support-for-kmem-caches-in-dma32-zone
+++ a/mm/slab.c
@@ -2117,6 +2117,8 @@ done:
cachep->allocflags = __GFP_COMP;
if (flags & SLAB_CACHE_DMA)
cachep->allocflags |= GFP_DMA;
+ if (flags & SLAB_CACHE_DMA32)
+ cachep->allocflags |= GFP_DMA32;
if (flags & SLAB_RECLAIM_ACCOUNT)
cachep->allocflags |= __GFP_RECLAIMABLE;
cachep->size = size;
--- a/mm/slab_common.c~mm-add-support-for-kmem-caches-in-dma32-zone
+++ a/mm/slab_common.c
@@ -53,7 +53,7 @@ static DECLARE_WORK(slab_caches_to_rcu_d
SLAB_FAILSLAB | SLAB_KASAN)
#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
- SLAB_ACCOUNT)
+ SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
/*
* Merge control. If this is set then no merging of slab caches will occur.
--- a/mm/slab.h~mm-add-support-for-kmem-caches-in-dma32-zone
+++ a/mm/slab.h
@@ -127,7 +127,8 @@ static inline slab_flags_t kmem_cache_fl
/* Legal flag mask for kmem_cache_create(), for various configurations */
-#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
+#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \
+ SLAB_CACHE_DMA32 | SLAB_PANIC | \
SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )
#if defined(CONFIG_DEBUG_SLAB)
--- a/mm/slub.c~mm-add-support-for-kmem-caches-in-dma32-zone
+++ a/mm/slub.c
@@ -3589,6 +3589,9 @@ static int calculate_sizes(struct kmem_c
if (s->flags & SLAB_CACHE_DMA)
s->allocflags |= GFP_DMA;
+ if (s->flags & SLAB_CACHE_DMA32)
+ s->allocflags |= GFP_DMA32;
+
if (s->flags & SLAB_RECLAIM_ACCOUNT)
s->allocflags |= __GFP_RECLAIMABLE;
@@ -5679,6 +5682,8 @@ static char *create_unique_id(struct kme
*/
if (s->flags & SLAB_CACHE_DMA)
*p++ = 'd';
+ if (s->flags & SLAB_CACHE_DMA32)
+ *p++ = 'D';
if (s->flags & SLAB_RECLAIM_ACCOUNT)
*p++ = 'a';
if (s->flags & SLAB_CONSISTENCY_CHECKS)
_
Patches currently in -mm which might be from drinkcat(a)chromium.org are
mm-add-support-for-kmem-caches-in-dma32-zone.patch
iommu-io-pgtable-arm-v7s-request-dma32-memory-and-improve-debugging.patch
mm-add-sys-kernel-slab-cache-cache_dma32.patch