From: Yifan Zhang yifan1.zhang@amd.com
[ Upstream commit 99d7181bca34e96fbf61bdb6844918bdd4df2814 ]
There is race in amdgpu_amdkfd_device_fini_sw and interrupt. if amdgpu_amdkfd_device_fini_sw run in b/w kfd_cleanup_nodes and kfree(kfd), and KGD interrupt generated.
kernel panic log:
BUG: kernel NULL pointer dereference, address: 0000000000000098 amdgpu 0000:c8:00.0: amdgpu: Requesting 4 partitions through PSP
PGD d78c68067 P4D d78c68067
kfd kfd: amdgpu: Allocated 3969056 bytes on gart
PUD 1465b8067 PMD @
Oops: @002 [#1] SMP NOPTI
kfd kfd: amdgpu: Total number of KFD nodes to be created: 4 CPU: 115 PID: @ Comm: swapper/115 Kdump: loaded Tainted: G S W OE K
RIP: 0010:_raw_spin_lock_irqsave+0x12/0x40
Code: 89 e@ 41 5c c3 cc cc cc cc 66 66 2e Of 1f 84 00 00 00 00 00 OF 1f 40 00 Of 1f 44% 00 00 41 54 9c 41 5c fa 31 cO ba 01 00 00 00 <fO> OF b1 17 75 Ba 4c 89 e@ 41 Sc
89 c6 e8 07 38 5d
RSP: 0018: ffffc90@1a6b0e28 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000018 0000000000000001 RSI: ffff8883bb623e00 RDI: 0000000000000098 ffff8883bb000000 RO8: ffff888100055020 ROO: ffff888100055020 0000000000000000 R11: 0000000000000000 R12: 0900000000000002 ffff888F2b97da0@ R14: @000000000000098 R15: ffff8883babdfo00
CS: 010 DS: 0000 ES: 0000 CRO: 0000000080050033
CR2: 0000000000000098 CR3: 0000000e7cae2006 CR4: 0000000002770ce0 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 0000000000000000 DR6: 00000000fffeO7FO DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<IRQ>
kgd2kfd_interrupt+@x6b/0x1f@ [amdgpu]
? amdgpu_fence_process+0xa4/0x150 [amdgpu]
kfd kfd: amdgpu: Node: 0, interrupt_bitmap: 3 YcpxFl Rant tErace
amdgpu_irq_dispatch+0x165/0x210 [amdgpu]
amdgpu_ih_process+0x80/0x100 [amdgpu]
amdgpu: Virtual CRAT table created for GPU
amdgpu_irq_handler+0x1f/@x60 [amdgpu]
__handle_irq_event_percpu+0x3d/0x170
amdgpu: Topology: Add dGPU node [0x74a2:0x1002]
handle_irq_event+0x5a/@xcO
handle_edge_irq+0x93/0x240
kfd kfd: amdgpu: KFD node 1 partition @ size 49148M
asm_call_irq_on_stack+0xf/@x20
</IRQ>
common_interrupt+0xb3/0x130
asm_common_interrupt+0x1le/0x40
5.10.134-010.a1i5000.a18.x86_64 #1
Signed-off-by: Yifan Zhang yifan1.zhang@amd.com Reviewed-by: Philip YangPhilip.Yang@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org ---
LLM Generated explanations, may be completely bogus:
YES
- `kfd_cleanup_nodes` nulls out each entry in `kfd->nodes` while tearing the device down (`drivers/gpu/drm/amd/amdkfd/kfd_device.c:654-676`). If an interrupt fires in that window, the old code in `kgd2kfd_interrupt` still dereferences the stale slot and immediately touches `node->interrupt_lock`, so a NULL entry explodes exactly as shown in the panic log (offset 0x98 into a NULL `node`). - The patch now defends that loop: before grabbing the lock it verifies the slot is still populated and bails out if it is already NULL (`drivers/gpu/drm/amd/amdkfd/kfd_device.c:1137-1144`). That mirrors the teardown progress—once the first node is gone we are already in device finalization—so dropping the interrupt is harmless, and more importantly it eliminates the crash. - The change is tiny, self-contained, and has no functional impact while the device is operational because `kfd->nodes[i]` remains non-NULL outside of teardown. It only touches this ISR path and does not rely on newer framework helpers, so it applies cleanly to older trees. - The bug has already been observed on production kernels (panic log from 5.10), making this a real user-visible regression. Given the severity (interrupt-time NULL dereference) and the minimal risk of the guard, it is a strong stable backport candidate.
drivers/gpu/drm/amd/amdkfd/kfd_device.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c index 349c351e242b5..051a00152b089 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c @@ -1133,7 +1133,15 @@ void kgd2kfd_interrupt(struct kfd_dev *kfd, const void *ih_ring_entry) }
for (i = 0; i < kfd->num_nodes; i++) { - node = kfd->nodes[i]; + /* Race if another thread in b/w + * kfd_cleanup_nodes and kfree(kfd), + * when kfd->nodes[i] = NULL + */ + if (kfd->nodes[i]) + node = kfd->nodes[i]; + else + return; + spin_lock_irqsave(&node->interrupt_lock, flags);
if (node->interrupts_active