From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Lancelot SIX <lancelot.six@amd.com>,
Felix Kuehling <felix.kuehling@amd.com>,
Alex Deucher <alexander.deucher@amd.com>,
Sasha Levin <sashal@kernel.org>,
Felix.Kuehling@amd.com, christian.koenig@amd.com,
Xinhui.Pan@amd.com, airlied@gmail.com, daniel@ffwll.ch,
amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 35/43] drm/amdkfd: Flush the process wq before creating a kfd_process
Date: Tue, 7 May 2024 19:09:56 -0400 [thread overview]
Message-ID: <20240507231033.393285-35-sashal@kernel.org> (raw)
In-Reply-To: <20240507231033.393285-1-sashal@kernel.org>
From: Lancelot SIX <lancelot.six@amd.com>
[ Upstream commit f5b9053398e70a0c10aa9cb4dd5910ab6bc457c5 ]
There is a race condition when re-creating a kfd_process for a process.
This has been observed when a process under the debugger executes
exec(3). In this scenario:
- The process executes exec.
- This will eventually release the process's mm, which will cause the
kfd_process object associated with the process to be freed
(kfd_process_free_notifier decrements the reference count to the
kfd_process to 0). This causes kfd_process_ref_release to enqueue
kfd_process_wq_release to the kfd_process_wq.
- The debugger receives the PTRACE_EVENT_EXEC notification, and tries to
re-enable AMDGPU traps (KFD_IOC_DBG_TRAP_ENABLE).
- When handling this request, KFD tries to re-create a kfd_process.
This eventually calls kfd_create_process and kobject_init_and_add.
At this point the call to kobject_init_and_add can fail because the
old kfd_process.kobj has not been freed yet by kfd_process_wq_release.
This patch proposes to avoid this race by making sure to drain
kfd_process_wq before creating a new kfd_process object. This way, we
know that any cleanup task is done executing when we reach
kobject_init_and_add.
Signed-off-by: Lancelot SIX <lancelot.six@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdkfd/kfd_process.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 7a1a574106fac..d98e45aec76b4 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -828,6 +828,14 @@ struct kfd_process *kfd_create_process(struct task_struct *thread)
if (process) {
pr_debug("Process already found\n");
} else {
+ /* If the process just called exec(3), it is possible that the
+ * cleanup of the kfd_process (following the release of the mm
+ * of the old process image) is still in the cleanup work queue.
+ * Make sure to drain any job before trying to recreate any
+ * resource for this process.
+ */
+ flush_workqueue(kfd_process_wq);
+
process = create_process(thread);
if (IS_ERR(process))
goto out;
--
2.43.0
prev parent reply other threads:[~2024-05-07 23:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240507231033.393285-1-sashal@kernel.org>
2024-05-07 23:09 ` [PATCH AUTOSEL 6.6 28/43] drm/amdgpu: Fix VRAM memory accounting Sasha Levin
2024-05-07 23:09 ` [PATCH AUTOSEL 6.6 29/43] drm/amd/display: Add dtbclk access to dcn315 Sasha Levin
2024-05-07 23:09 ` [PATCH AUTOSEL 6.6 30/43] drm/amd/display: Atom Integrated System Info v2_2 for DCN35 Sasha Levin
2024-05-07 23:09 ` [PATCH AUTOSEL 6.6 31/43] drm/amd/display: Allocate zero bw after bw alloc enable Sasha Levin
2024-05-07 23:09 ` [PATCH AUTOSEL 6.6 32/43] drm/amd/display: Add VCO speed parameter for DCN31 FPU Sasha Levin
2024-05-07 23:09 ` [PATCH AUTOSEL 6.6 33/43] drm/amd/display: Fix DC mode screen flickering on DCN321 Sasha Levin
2024-05-07 23:09 ` [PATCH AUTOSEL 6.6 34/43] drm/amd/display: Disable seamless boot on 128b/132b encoding Sasha Levin
2024-05-07 23:09 ` Sasha Levin [this message]
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