When a GPU fault or timeout happens, the driver creates a devcoredump
to collect debug information.
During this, amdgpu_devcoredump_format() calls
amdgpu_discovery_dump() to print IP discovery data.
amdgpu_discovery_dump() uses:
adev->discovery.ip_top
and then accesses:
ip_top->die_kset
amdgpu_discovery_dump() uses adev->discovery.ip_top. However,
ip_top may be NULL if the discovery topology was never initialized.
The current code does not check for this before using ip_top. As a
result, when ip_top is NULL, the coredump worker crashes while taking
the spinlock for ip_top->die_kset.
Fix this by checking for a missing ip_top before walking the discovery
topology. If it is unavailable, print a short message in the dump and
return safely.
- If ip_top is NULL, print a message and skip the dump
- Also add the same check in the cleanup path
This makes the coredump and cleanup paths safe even when the
discovery topology is not available.
KASAN trace:
[ 522.228252] [IGT] amd_deadlock: starting subtest amdgpu-deadlock-sdma
[ 522.240681] [IGT] amd_deadlock: starting dynamic subtest amdgpu-deadlock-sdma
...
[ 522.952317] Write of size 4 at addr 0000000000000050 by task
kworker/u129:5/5434
[ 522.937526] BUG: KASAN: null-ptr-deref in _raw_spin_lock+0x66/0xc0
[ 522.967659] Workqueue: events_unbound amdgpu_devcoredump_deferred_work
[amdgpu]
...
[ 522.969445] Call Trace:
[ 522.969508] _raw_spin_lock+0x66/0xc0
[ 522.969518] ? __pfx__raw_spin_lock+0x10/0x10
[ 522.969534] amdgpu_discovery_dump+0x61/0x530 [amdgpu]
[ 522.971346] ? pick_next_task_fair+0x3f6/0x1c60
[ 522.971363] amdgpu_devcoredump_format+0x84f/0x26f0 [amdgpu]
[ 522.973188] ? __pfx_amdgpu_devcoredump_format+0x10/0x10 [amdgpu]
[ 522.975012] ? psi_task_switch+0x2b5/0x9b0
[ 522.975027] ? __pfx___drm_printfn_coredump+0x10/0x10 [drm]
[ 522.975198] ? __pfx___drm_puts_coredump+0x10/0x10 [drm]
[ 522.975366] ? __schedule+0x113c/0x38d0
[ 522.975381] amdgpu_devcoredump_deferred_work+0x4c/0x1f0 [amdgpu]
v2: Updated commit message - Clarified that ip_top is not freed, it can
just be NULL if discovery was not initialized. (Christian/Lijo)
v3: Removed the extra drm_warn() for sysfs init failure as sysfs already
reports errors. (Christian)
Fixes: 7083eb8982fb ("drm/amdgpu: include ip discovery data in devcoredump")
Cc: Pierre-Eric Pelloux-Prayer <[email protected]>
Cc: Christian König <[email protected]>
Cc: Alex Deucher <[email protected]>
Signed-off-by: Srinivasan Shanmugam <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
index f7f37d93d0ce..6be1f971a31a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
@@ -1395,6 +1395,9 @@ static void amdgpu_discovery_sysfs_fini(struct
amdgpu_device *adev)
struct list_head *el, *tmp;
struct kset *die_kset;
+ if (!ip_top)
+ return;
+
die_kset = &ip_top->die_kset;
spin_lock(&die_kset->list_lock);
list_for_each_prev_safe(el, tmp, &die_kset->list) {
@@ -1419,9 +1422,15 @@ void amdgpu_discovery_dump(struct amdgpu_device *adev,
struct drm_printer *p)
struct ip_hw_instance *ip_inst;
int i = 0, j;
+ drm_printf(p, "\nHW IP Discovery\n");
+
+ if (!ip_top) {
+ drm_printf(p, "ip discovery topology unavailable\n");
+ return;
+ }
+
die_kset = &ip_top->die_kset;
- drm_printf(p, "\nHW IP Discovery\n");
spin_lock(&die_kset->list_lock);
list_for_each(el_die, &die_kset->list) {
drm_printf(p, "die %d\n", i++);
--
2.34.1
