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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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Srinivasan Shanmugam
809773e066
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: e81eff80aa ("drm/amdgpu: include ip discovery data in devcoredump")
Cc: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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