[PATCH 5.10 049/103] drm/i915: Fix syncmap memory leak

From: Greg Kroah-Hartman
Date: Wed Sep 01 2021 - 08:41:33 EST


From: Matthew Brost <matthew.brost@xxxxxxxxx>

[ Upstream commit a63bcf08f0efb5348105bb8e0e1e8c6671077753 ]

A small race exists between intel_gt_retire_requests_timeout and
intel_timeline_exit which could result in the syncmap not getting
free'd. Rather than work to hard to seal this race, simply cleanup the
syncmap on fini.

unreferenced object 0xffff88813bc53b18 (size 96):
comm "gem_close_race", pid 5410, jiffies 4294917818 (age 1105.600s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 00 00 00 00 0a 00 00 00 ................
00 00 00 00 00 00 00 00 6b 6b 6b 6b 06 00 00 00 ........kkkk....
backtrace:
[<00000000120b863a>] __sync_alloc_leaf+0x1e/0x40 [i915]
[<00000000042f6959>] __sync_set+0x1bb/0x240 [i915]
[<0000000090f0e90f>] i915_request_await_dma_fence+0x1c7/0x400 [i915]
[<0000000056a48219>] i915_request_await_object+0x222/0x360 [i915]
[<00000000aaac4ee3>] i915_gem_do_execbuffer+0x1bd0/0x2250 [i915]
[<000000003c9d830f>] i915_gem_execbuffer2_ioctl+0x405/0xce0 [i915]
[<00000000fd7a8e68>] drm_ioctl_kernel+0xb0/0xf0 [drm]
[<00000000e721ee87>] drm_ioctl+0x305/0x3c0 [drm]
[<000000008b0d8986>] __x64_sys_ioctl+0x71/0xb0
[<0000000076c362a4>] do_syscall_64+0x33/0x80
[<00000000eb7a4831>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Fixes: 531958f6f357 ("drm/i915/gt: Track timeline activeness in enter/exit")
Cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20210730195342.110234-1-matthew.brost@xxxxxxxxx
(cherry picked from commit faf890985e30d5e88cc3a7c50c1bcad32f89ab7c)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_timeline.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c
index 8015964043eb..e25385ad2c1e 100644
--- a/drivers/gpu/drm/i915/gt/intel_timeline.c
+++ b/drivers/gpu/drm/i915/gt/intel_timeline.c
@@ -296,6 +296,14 @@ static void intel_timeline_fini(struct intel_timeline *timeline)
i915_gem_object_unpin_map(timeline->hwsp_ggtt->obj);

i915_vma_put(timeline->hwsp_ggtt);
+
+ /*
+ * A small race exists between intel_gt_retire_requests_timeout and
+ * intel_timeline_exit which could result in the syncmap not getting
+ * free'd. Rather than work to hard to seal this race, simply cleanup
+ * the syncmap on fini.
+ */
+ i915_syncmap_free(&timeline->sync);
}

struct intel_timeline *
--
2.30.2