diff mbox series

[slab/for-next,09/14] iommu: specify SLAB_MAY_ACCOUNT for slab-backed page table caches

Message ID 20261021-memalloc-prof-dont-waste-slabobj-ext-metadata-v1-9-096800aa3330@kernel.org (mailing list archive)
State New
Headers
Series mm/slab: mandate SLAB_MAY_ACCOUNT for __GFP_ACCOUNT allocations to avoid wasting memory for slab metadata |

Commit Message

Harry Yoo (Meta) Oct. 21, 2026, 11:46 a.m. UTC 
vfio, iommufd and vhost-vdpa call iommu_map() with GFP_KERNEL_ACCOUNT
and the gfp is passed down to the drivers' page table allocations.
Specify SLAB_MAY_ACCOUNT when the object may be charged to a memcg.
__GFP_ACCOUNT without SLAB_MAY_ACCOUNT will not be allowed.

Paths:
  VFIO_IOMMU_MAP_DMA -> iommu_map(GFP_KERNEL_ACCOUNT)
    -> s390_iommu_map_pages() -> dma_walk_cpu_trans()
    -> kmem_cache_alloc(dma_{region,page}_table_cache)
  iommu_map(GFP_KERNEL_ACCOUNT) -> arm_v7s_map_pages()
    -> __arm_v7s_alloc_table() -> kmem_cache_zalloc(data->l2_tables)
  iommu_map(GFP_KERNEL_ACCOUNT) -> sun50i_iommu_map()
    -> sun50i_dte_get_page_table() -> kmem_cache_zalloc(iommu->pt_pool)

Assisted-by: LLM
Cc: Will Deacon <will@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: "Joerg Roedel (AMD)" <joro@8bytes.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Matthew Rosato <mjrosato@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Chen-Yu Tsai <wens@kernel.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Samuel Holland <samuel@sholland.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: iommu@lists.linux.dev
Cc: linux-s390@vger.kernel.org
Cc: linux-sunxi@lists.linux.dev
Signed-off-by: Harry Yoo (Meta) <harry@kernel.org>
---
 drivers/iommu/io-pgtable-arm-v7s.c | 2 +-
 drivers/iommu/s390-iommu.c         | 4 ++--
 drivers/iommu/sun50i-iommu.c       | 3 ++-
 3 files changed, 5 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index 1dbef8c55007..b544e5da237a 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -706,7 +706,7 @@  static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
 	data->l2_tables = kmem_cache_create("io-pgtable_armv7s_l2",
 					    ARM_V7S_TABLE_SIZE(2, cfg),
 					    ARM_V7S_TABLE_SIZE(2, cfg),
-					    slab_flag, NULL);
+					    slab_flag | SLAB_MAY_ACCOUNT, NULL);
 	if (!data->l2_tables)
 		goto out_free_data;
 
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index f148f559ac56..f308efadc87b 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -198,14 +198,14 @@  static int __init dma_alloc_cpu_table_caches(void)
 	dma_region_table_cache = kmem_cache_create("PCI_DMA_region_tables",
 						   ZPCI_TABLE_SIZE,
 						   ZPCI_TABLE_ALIGN,
-						   0, NULL);
+						   SLAB_MAY_ACCOUNT, NULL);
 	if (!dma_region_table_cache)
 		return -ENOMEM;
 
 	dma_page_table_cache = kmem_cache_create("PCI_DMA_page_tables",
 						 ZPCI_PT_SIZE,
 						 ZPCI_PT_ALIGN,
-						 0, NULL);
+						 SLAB_MAY_ACCOUNT, NULL);
 	if (!dma_page_table_cache) {
 		kmem_cache_destroy(dma_region_table_cache);
 		return -ENOMEM;
diff --git a/drivers/iommu/sun50i-iommu.c b/drivers/iommu/sun50i-iommu.c
index be3f1ce696ba..51a30969dde4 100644
--- a/drivers/iommu/sun50i-iommu.c
+++ b/drivers/iommu/sun50i-iommu.c
@@ -1011,7 +1011,8 @@  static int sun50i_iommu_probe(struct platform_device *pdev)
 
 	iommu->pt_pool = kmem_cache_create(dev_name(&pdev->dev),
 					   PT_SIZE, PT_SIZE,
-					   SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA32,
+					   SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA32 |
+					   SLAB_MAY_ACCOUNT,
 					   NULL);
 	if (!iommu->pt_pool)
 		return -ENOMEM;