[Deepin-Kernel-SIG] [linux 6.6-y] [Upstream] drm/amdgpu: fix task hang from failed job submission during process kill

[opsiff]

[6.6.103]

mainline inclusion
from mainline-v6.17-rc2
category: bugfix

During process kill, drm_sched_entity_flush() will kill the vm entities. The following job submissions of this process will fail, and the resources of these jobs have not been released, nor have the fences been signalled, causing tasks to hang and timeout.

Fix by check entity status in amdgpu_vm_ready() and avoid submit jobs to stopped entity.

v2: add amdgpu_vm_ready() check before amdgpu_vm_clear_freed() in function amdgpu_cs_vm_handling().

Fixes: 1f02f2044bda ("drm/amdgpu: Avoid extra evict-restore process.")

Reviewed-by: Christian König [email protected]

(cherry picked from commit f101c13a8720c73e67f8f9d511fbbeda95bcedb1) (cherry picked from commit aa5fc4362fac9351557eb27c745579159a2e4520)

Summary by Sourcery

Bug Fixes:

• Prevent hung tasks after process kill by avoiding job submissions to stopped VM entities in amdgpu

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这段代码的修改主要是增加了对虚拟机(VM)状态的检查，确保在处理命令提交(cs)时VM处于就绪状态。我来分析一下代码的改进：

1. 在amdgpu_cs_vm_handling函数中添加了对amdgpu_vm_ready的检查：

if (!amdgpu_vm_ready(vm))
    return -EINVAL;

这是一个很好的防御性编程实践，确保在继续处理之前VM处于就绪状态。

2. 在amdgpu_vm_ready函数中：

• 移除了不必要的empty变量
• 增加了对immediate和delayed状态的检查
• 改进了返回值的计算逻辑

改进建议：

1. 代码安全性：

• 在amdgpu_vm_ready函数中，多个spin_lock/unlock操作可能导致潜在的死锁风险。建议考虑使用spin_lock_irqsave/spin_unlock_irqsave来替代，以避免在持有锁时被中断。

2. 代码性能：

• 当前实现需要获取多个锁，这可能会影响性能。可以考虑将相关状态变量放在同一个数据结构中，使用单个锁来保护，减少锁的获取/释放次数。

3. 代码逻辑：

• 在amdgpu_vm_ready函数中，ret变量在第一次使用前没有初始化，这可能导致未定义行为。应该在使用前初始化为true：

bool ret = true;

4. 代码可读性：

• 可以添加注释来解释immediate和delayed状态的含义，以及为什么需要检查这些状态。

5. 错误处理：

• amdgpu_cs_vm_handling函数中对amdgpu_vm_ready的检查应该在获取vm之后立即进行，而不是在其他操作之后。这样可以尽早失败，避免不必要的资源消耗。

6. 同步机制：

• 考虑使用更高级别的同步机制，如RCU(Read-Copy-Update)，如果这些状态主要是读操作的话，可以提高并发性能。

总体而言，这个改进增加了对VM状态的更全面检查，提高了系统的健壮性。但需要注意锁的使用和初始化问题，以避免潜在的bug。

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Adds entity stop status checks to VM readiness and prevents job submission to stopped entities to avoid hangs and resource leaks during process kill.

File-Level Changes

Change	Details	Files
Extend amdgpu_vm_ready() to verify VM entities aren’t stopped	Remove redundant empty variable Include eviction list status in ret Lock and check immediate.stopped flag Lock and check delayed.stopped flag Simplify return to ret	drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
Guard job submission in amdgpu_cs_vm_handling() against stopped VMs	Invoke amdgpu_vm_ready() before clearing freed VMs Return -EINVAL when VM is not ready	drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c

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