On 23/05/2019 07:49, Chris Wilson wrote:
We rearranged the vm_destroy_ioctl to avoid taking struct_mutex, little
realising that buried underneath the gen6 ppgtt release path was a
struct_mutex requirement (to remove its GGTT vma). Until that
struct_mutex is vanquished, take a detour in gen6_ppgtt_cleanup to do
the i915_vma_destroy from inside a worker under the struct_mutex.
<4> [257.740160] WARN_ON(debug_locks &&
!lock_is_held(&(&vma->vm->i915->drm.struct_mutex)->dep_map))
<4> [257.740213] WARNING: CPU: 3 PID: 1507 at
drivers/gpu/drm/i915/i915_vma.c:841 i915_vma_destroy+0x1ae/0x3a0 [i915]
<4> [257.740214] Modules linked in: snd_hda_codec_hdmi i915
x86_pkg_temp_thermal mei_hdcp coretemp crct10dif_pclmul crc32_pclmul
ghash_clmulni_intel snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel
snd_hda_codec snd_hwdep snd_hda_core r8169 realtek snd_pcm mei_me mei prime_numbers
lpc_ich
<4> [257.740224] CPU: 3 PID: 1507 Comm: gem_vm_create Tainted: G U
5.2.0-rc1-CI-CI_DRM_6118+ #1
<4> [257.740225] Hardware name: MSI MS-7924/Z97M-G43(MS-7924), BIOS V1.12
02/15/2016
<4> [257.740249] RIP: 0010:i915_vma_destroy+0x1ae/0x3a0 [i915]
<4> [257.740250] Code: 00 00 00 48 81 c7 c8 00 00 00 e8 ed 08 f0 e0 85 c0 0f 85 78 fe
ff ff 48 c7 c6 e8 ec 30 a0 48 c7 c7 da 55 33 a0 e8 42 8c e9 e0 <0f> 0b 8b 83 40 01 00
00 85 c0 0f 84 63 fe ff ff 48 c7 c1 c1 58 33
<4> [257.740251] RSP: 0018:ffffc90000aafc68 EFLAGS: 00010282
<4> [257.740252] RAX: 0000000000000000 RBX: ffff8883f7957840 RCX:
0000000000000003
<4> [257.740253] RDX: 0000000000000046 RSI: 0000000000000006 RDI:
ffffffff8212d1b9
<4> [257.740254] RBP: ffffc90000aafcc8 R08: 0000000000000000 R09:
0000000000000000
<4> [257.740255] R10: 0000000000000000 R11: 0000000000000000 R12:
ffff8883f4d5c2a8
<4> [257.740256] R13: ffff8883f4d5d680 R14: ffff8883f4d5c668 R15:
ffff8883f4d5c2f0
<4> [257.740257] FS: 00007f777fa8fe40(0000) GS:ffff88840f780000(0000)
knlGS:0000000000000000
<4> [257.740258] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4> [257.740259] CR2: 00007f777f6522b0 CR3: 00000003c612a006 CR4:
00000000001606e0
<4> [257.740260] Call Trace:
<4> [257.740283] gen6_ppgtt_cleanup+0x25/0x60 [i915]
<4> [257.740306] i915_ppgtt_release+0x102/0x290 [i915]
<4> [257.740330] i915_gem_vm_destroy_ioctl+0x7c/0xa0 [i915]
<4> [257.740376] ? i915_gem_vm_create_ioctl+0x160/0x160 [i915]
<4> [257.740379] drm_ioctl_kernel+0x83/0xf0
<4> [257.740382] drm_ioctl+0x2f3/0x3b0
<4> [257.740422] ? i915_gem_vm_create_ioctl+0x160/0x160 [i915]
<4> [257.740426] ? _raw_spin_unlock_irqrestore+0x39/0x60
<4> [257.740430] do_vfs_ioctl+0xa0/0x6e0
<4> [257.740433] ? lock_acquire+0xa6/0x1c0
<4> [257.740436] ? __task_pid_nr_ns+0xb9/0x1f0
<4> [257.740439] ksys_ioctl+0x35/0x60
<4> [257.740441] __x64_sys_ioctl+0x11/0x20
<4> [257.740443] do_syscall_64+0x55/0x1c0
<4> [257.740445] entry_SYSCALL_64_after_hwframe+0x49/0xbe
References: e0695db7298e ("drm/i915: Create/destroy VM (ppGTT) for use with
contexts")
Fixes: 7f3f317a66ca ("drm/i915: Restore control over ppgtt for context creation
ABI")
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
---
drivers/gpu/drm/i915/i915_gem_gtt.c | 32 +++++++++++++++++++++++++++--
drivers/gpu/drm/i915/i915_gem_gtt.h | 2 ++
2 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c
b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 9ed41aefb456..5a350251766a 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1828,11 +1828,33 @@ static void gen6_ppgtt_free_pd(struct gen6_hw_ppgtt
*ppgtt)
free_pt(&ppgtt->base.vm, pt);
}
+struct gen6_ppgtt_cleanup_work {
+ struct work_struct base;
+ struct i915_vma *vma;
+};
+
+static void gen6_ppgtt_cleanup_work(struct work_struct *wrk)
+{
+ struct gen6_ppgtt_cleanup_work *work =
+ container_of(wrk, typeof(*work), base);
+ struct drm_i915_private *i915 = work->vma->vm->i915;
Does the sequence need an extra reference on ppgtt for dereferencing the
vm here? Alternatively storing i915 in the work struct could work around
that.
Regards,
Tvrtko
+
+ mutex_lock(&i915->drm.struct_mutex);
+ i915_vma_destroy(work->vma);
+ mutex_unlock(&i915->drm.struct_mutex);
+
+ kfree(work);
+}
+
static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
{
struct gen6_hw_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
+ struct gen6_ppgtt_cleanup_work *work = ppgtt->work;
- i915_vma_destroy(ppgtt->vma);
+ /* FIXME remove the struct_mutex to bring the locking under control */
+ INIT_WORK(&work->base, gen6_ppgtt_cleanup_work);
+ work->vma = ppgtt->vma;
+ schedule_work(&work->base);
gen6_ppgtt_free_pd(ppgtt);
gen6_ppgtt_free_scratch(vm);
@@ -2011,9 +2033,13 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct
drm_i915_private *i915)
ppgtt->base.vm.pte_encode = ggtt->vm.pte_encode;
+ ppgtt->work = kmalloc(sizeof(*ppgtt->work), GFP_KERNEL);
+ if (!ppgtt->work)
+ goto err_free;
+
err = gen6_ppgtt_init_scratch(ppgtt);
if (err)
- goto err_free;
+ goto err_work;
ppgtt->vma = pd_vma_create(ppgtt, GEN6_PD_SIZE);
if (IS_ERR(ppgtt->vma)) {
@@ -2025,6 +2051,8 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct
drm_i915_private *i915)
err_scratch:
gen6_ppgtt_free_scratch(&ppgtt->base.vm);
+err_work:
+ kfree(ppgtt->work);
err_free:
kfree(ppgtt);
return ERR_PTR(err);
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h
b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 98fc71053f7c..38496039456b 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -424,6 +424,8 @@ struct gen6_hw_ppgtt {
unsigned int pin_count;
bool scan_for_unused_pt;
+
+ struct gen6_ppgtt_cleanup_work *work;
};
#define __to_gen6_ppgtt(base) container_of(base, struct gen6_hw_ppgtt, base)
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