From fcc2431d2213dc4d04250c4f1ae87d9c3ae0d455 Mon Sep 17 00:00:00 2001 From: Varun Gupta Date: Mon, 7 Sep 2026 10:30:12 +0530 Subject: [PATCH] drm/xe: Guard page-fault worker with runtime PM check MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit During VM teardown, the VM's runtime PM reference is dropped asynchronously, allowing the device to autosuspend while stale page faults belonging to the now-dead VM are still queued. When the page-fault worker later tries to ack one of these, it calls into guc_ct_send_locked() on an already-suspended device, tripping:   Assertion `!xe_pm_runtime_suspended(xe)` failed!   WARNING at xe_device.c:1267 xe_device_assert_mem_access+0x11c/0x140 [xe] A live VM/exec queue always holds a PM reference while it has outstanding work, so if the device is suspended at ack time, the owning context is already gone and the fault is stale. Take a runtime PM reference across the entire pagefault queue worker to safely deliver acks for torn-down VMs. v3: - Move PM ref to the generic xe_pagefault_queue_work using guard(xe_pm_runtime)(xe) instead of tracking it in the GuC backend(Matt Brost). v2: - Hold PM ref across the entire batch (begin/end) instead of per-ack. This prevents the device from autosuspending mid-batch, which would leave write_only acks written but the end flush skipped, and skip counter++, desyncing the cadence check.(Himal) - Add a comment explaining stale faults.(Himal) Fixes: f289f7807119 ("drm/xe: Add xe_guc_pagefault layer") Signed-off-by: Varun Gupta Reviewed-by: Matthew Brost Reviewed-by: Tejas Upadhyay Link: https://patch.msgid.link/20260907050011.497181-2-varun.gupta@intel.com Signed-off-by: Tejas Upadhyay --- drivers/gpu/drm/xe/xe_pagefault.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/xe/xe_pagefault.c b/drivers/gpu/drm/xe/xe_pagefault.c index e81ca24df37f..c82b8bc8bc70 100644 --- a/drivers/gpu/drm/xe/xe_pagefault.c +++ b/drivers/gpu/drm/xe/xe_pagefault.c @@ -17,6 +17,7 @@ #include "xe_log.h" #include "xe_pagefault.h" #include "xe_pagefault_types.h" +#include "xe_pm.h" #include "xe_svm.h" #include "xe_trace_bo.h" #include "xe_vm.h" @@ -610,6 +611,13 @@ static void xe_pagefault_queue_work(struct work_struct *w) u64 cache_start = XE_PAGEFAULT_CACHE_START_INVALID, cache_end = 0; u32 cache_asid = 0; + /* + * A live VM holds a PM reference, but a torn-down VM does not. + * Guard the entire worker loop to safely drain stale faults and + * prevent autosuspends from desyncing batched CT flushes. + */ + guard(xe_pm_runtime)(xe); + #define USM_QUEUE_MAX_RUNTIME_MS 20 threshold = jiffies + msecs_to_jiffies(USM_QUEUE_MAX_RUNTIME_MS);