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CAT:NONE; SFS:(4636009)(46966006)(36840700001)(70206006)(1076003)(70586007)(82310400003)(8676002)(2906002)(6916009)(47076005)(6666004)(16526019)(186003)(81166007)(2616005)(5660300002)(83380400001)(508600001)(7696005)(86362001)(36756003)(26005)(36860700001)(356005)(44832011)(8936002)(426003)(316002)(4326008)(336012)(36900700001); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Nov 2021 02:40:52.5070 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 0f6159cb-46eb-47b6-24a7-08d99daa300e 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: DM6NAM11FT048.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4497 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alex Sierra Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" [Why]: When we call hmm_range_fault to map memory after a migration, we don't expect memory to be migrated again as a result of hmm_range_fault. The driver ensures that all memory is in GPU-accessible locations so that no migration should be needed. However, there is one corner case where hmm_range_fault can unexpectedly cause a migration from DEVICE_PRIVATE back to system memory due to a write-fault when a system memory page in the same range was mapped read-only (e.g. COW). Ranges with individual pages in different locations are usually the result of failed page migrations (e.g. page lock contention). The unexpected migration back to system memory causes a deadlock from recursive locking in our driver. [How]: Creating a task reference new member under svm_range_list_init struct. Setting this with "current" reference, right before the hmm_range_fault is called. This member is checked against "current" reference at svm_migrate_to_ram callback function. If equal, the migration will be ignored. Signed-off-by: Alex Sierra --- drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 4 ++++ drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 1 + drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 2 ++ 3 files changed, 7 insertions(+) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c index bff40e8bca67..eb19f44ec86d 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c @@ -936,6 +936,10 @@ static vm_fault_t svm_migrate_to_ram(struct vm_fault *vmf) pr_debug("failed find process at fault address 0x%lx\n", addr); return VM_FAULT_SIGBUS; } + if (READ_ONCE(p->svms.faulting_task) == current) { + pr_debug("skipping ram migration\n"); + return 0; + } addr >>= PAGE_SHIFT; pr_debug("CPU page fault svms 0x%p address 0x%lx\n", &p->svms, addr); diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h index f88666bdf57c..7b41a58b1ade 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h @@ -858,6 +858,7 @@ struct svm_range_list { atomic_t evicted_ranges; struct delayed_work restore_work; DECLARE_BITMAP(bitmap_supported, MAX_GPU_INSTANCE); + struct task_struct *faulting_task; }; /* Process data */ diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c index 939c863315ba..4031c2a67af4 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c @@ -1492,9 +1492,11 @@ static int svm_range_validate_and_map(struct mm_struct *mm, next = min(vma->vm_end, end); npages = (next - addr) >> PAGE_SHIFT; + WRITE_ONCE(p->svms.faulting_task, current); r = amdgpu_hmm_range_get_pages(&prange->notifier, mm, NULL, addr, npages, &hmm_range, readonly, true, owner); + WRITE_ONCE(p->svms.faulting_task, NULL); if (r) { pr_debug("failed %d to get svm range pages\n", r); goto unreserve_out; -- 2.32.0