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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Apr 2025 21:02:30.4072 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ad8895bd-4c25-458c-1232-08dd7df32ad3 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF000026CA.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR12MB6898 Eder Zulian writes: > The SLAB_TYPESAFE_BY_RCU flag prevents a change of type for objects > allocated from the slab cache (although the memory may be reallocated to > a completetly different object of the same type.) Moreover, when the > last reference to an object is dropped the finalization code must not > run until all __rcu pointers referencing the object have been updated, > and then a grace period has passed. > > Signed-off-by: Eder Zulian > --- > drivers/dma/amd/ptdma/ptdma-dmaengine.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/dma/amd/ptdma/ptdma-dmaengine.c b/drivers/dma/amd/ptdma/ptdma-dmaengine.c > index 715ac3ae067b..b70dd1b0b9fb 100644 > --- a/drivers/dma/amd/ptdma/ptdma-dmaengine.c > +++ b/drivers/dma/amd/ptdma/ptdma-dmaengine.c > @@ -597,7 +597,8 @@ int pt_dmaengine_register(struct pt_device *pt) > > pt->dma_desc_cache = kmem_cache_create(desc_cache_name, > sizeof(struct pt_dma_desc), 0, > - SLAB_HWCACHE_ALIGN, NULL); > + SLAB_HWCACHE_ALIGN | > + SLAB_TYPESAFE_BY_RCU, NULL); No, this code wasn't written to exploit SLAB_TYPESAFE_BY_RCU and this change can only obscure the problem. There's likely a data race in the driver. I suspect pt_cmd_callback_work() has a bug: spin_lock_irqsave(&chan->vc.lock, flags); if (desc) { if (desc->status != DMA_COMPLETE) { if (desc->status != DMA_ERROR) desc->status = DMA_COMPLETE; dma_cookie_complete(tx_desc); dma_descriptor_unmap(tx_desc); } else { tx_desc = NULL; } } spin_unlock_irqrestore(&chan->vc.lock, flags); if (tx_desc) { dmaengine_desc_get_callback_invoke(tx_desc, NULL); dma_run_dependencies(tx_desc); >>>> list_del(&desc->vd.node); <<< must be done under vc.lock vchan_vdesc_fini(vd); } But that's relatively new code that may not be in the kernel you're running.