Don't use kmap_atomic() for doorbell & process descriptor access.
This patch fixes the BUG shown below, where the thread could sleep
while holding a kmap_atomic mapping. In order not to need to call
kmap_atomic() in this code path, we now set up a permanent kernel
mapping of the shared doorbell and process-descriptor page, and
use that in all doorbell and process-descriptor related code.
BUG: scheduling while atomic: gem_close_race/1941/0x00000002
Modules linked in: hid_generic usbhid i915 asix usbnet libphy mii
i2c_algo_bit drm_kms_helper cfbfillrect syscopyarea cfbimgblt
sysfillrect sysimgblt fb_sys_fops cfbcopyarea drm coretemp i2c_hid
hid video pinctrl_sunrisepoint pinctrl_intel acpi_pad nls_iso8859_1
e1000e ptp psmouse pps_core ahci libahci
CPU: 0 PID: 1941 Comm: gem_close_race Tainted: G U 4.4.0-160121+ #123
Hardware name: Intel Corporation Skylake Client platform/Skylake AIO
DDR3L RVP10, BIOS SKLSE2R1.R00.X100.B01.1509220551 09/22/2015
0000000000013e40 ffff880166c27a78 ffffffff81280d02 ffff880172c13e40
ffff880166c27a88 ffffffff810c203a ffff880166c27ac8 ffffffff814ec808
ffff88016b7c6000 ffff880166c28000 00000000000f4240 0000000000000001
Call Trace:
[<ffffffff81280d02>] dump_stack+0x4b/0x79
[<ffffffff810c203a>] __schedule_bug+0x41/0x4f
[<ffffffff814ec808>] __schedule+0x5a8/0x690
[<ffffffff814ec927>] schedule+0x37/0x80
[<ffffffff814ef3fd>] schedule_hrtimeout_range_clock+0xad/0x130
[<ffffffff81090be0>] ? hrtimer_init+0x10/0x10
[<ffffffff814ef3f1>] ? schedule_hrtimeout_range_clock+0xa1/0x130
[<ffffffff814ef48e>] schedule_hrtimeout_range+0xe/0x10
[<ffffffff814eef9b>] usleep_range+0x3b/0x40
[<ffffffffa01ec109>] i915_guc_wq_check_space+0x119/0x210 [i915]
[<ffffffffa01da47c>] intel_logical_ring_alloc_request_extras+0x5c/0x70 [i915]
[<ffffffffa01cdbf1>] i915_gem_request_alloc+0x91/0x170 [i915]
[<ffffffffa01c1c07>] i915_gem_do_execbuffer.isra.25+0xbc7/0x12a0 [i915]
[<ffffffffa01cb785>] ? i915_gem_object_get_pages_gtt+0x225/0x3c0 [i915]
[<ffffffffa01d1fb6>] ? i915_gem_pwrite_ioctl+0xd6/0x9f0 [i915]
[<ffffffffa01c2e68>] i915_gem_execbuffer2+0xa8/0x250 [i915]
[<ffffffffa00f65d8>] drm_ioctl+0x258/0x4f0 [drm]
[<ffffffffa01c2dc0>] ? i915_gem_execbuffer+0x340/0x340 [i915]
[<ffffffff8111590d>] do_vfs_ioctl+0x2cd/0x4a0
[<ffffffff8111eac2>] ? __fget+0x72/0xb0
[<ffffffff81115b1c>] SyS_ioctl+0x3c/0x70
[<ffffffff814effd7>] entry_SYSCALL_64_fastpath+0x12/0x6a
------------[ cut here ]------------
v4:
Only tear down doorbell & kunmap() client object if we actually
succeeded in allocating a client object (Tvrtko Ursulin)
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93847
Original-version-by: Alex Dai <yu.dai@xxxxxxxxx>
Signed-off-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
Cc: Tvtrko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_guc_submission.c | 66 +++++++++++++-----------------
drivers/gpu/drm/i915/intel_guc.h | 2 +
2 files changed, 30 insertions(+), 38 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index da86bdb..d251699 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -179,15 +179,11 @@ static void guc_init_doorbell(struct intel_guc *guc,
struct i915_guc_client *client)
{
struct guc_doorbell_info *doorbell;
- void *base;
- base = kmap_atomic(i915_gem_object_get_page(client->client_obj, 0));
- doorbell = base + client->doorbell_offset;
+ doorbell = client->client_base + client->doorbell_offset;
- doorbell->db_status = 1;
+ doorbell->db_status = GUC_DOORBELL_ENABLED;
doorbell->cookie = 0;
-
- kunmap_atomic(base);
}
static int guc_ring_doorbell(struct i915_guc_client *gc)
@@ -195,11 +191,9 @@ static int guc_ring_doorbell(struct i915_guc_client *gc)
struct guc_process_desc *desc;
union guc_doorbell_qw db_cmp, db_exc, db_ret;
union guc_doorbell_qw *db;
- void *base;
int attempt = 2, ret = -EAGAIN;
- base = kmap_atomic(i915_gem_object_get_page(gc->client_obj, 0));
- desc = base + gc->proc_desc_offset;
+ desc = gc->client_base + gc->proc_desc_offset;
/* Update the tail so it is visible to GuC */
desc->tail = gc->wq_tail;
@@ -215,7 +209,7 @@ static int guc_ring_doorbell(struct i915_guc_client *gc)
db_exc.cookie = 1;
/* pointer of current doorbell cacheline */
- db = base + gc->doorbell_offset;
+ db = gc->client_base + gc->doorbell_offset;
while (attempt--) {
/* lets ring the doorbell */
@@ -247,7 +241,6 @@ static int guc_ring_doorbell(struct i915_guc_client *gc)
/* Finally, update the cached copy of the GuC's WQ head */
gc->wq_head = desc->head;
- kunmap_atomic(base);
return ret;
}
@@ -256,16 +249,12 @@ static void guc_disable_doorbell(struct intel_guc *guc,
{
struct drm_i915_private *dev_priv = guc_to_i915(guc);
struct guc_doorbell_info *doorbell;
- void *base;
i915_reg_t drbreg = GEN8_DRBREGL(client->doorbell_id);
int value;
- base = kmap_atomic(i915_gem_object_get_page(client->client_obj, 0));
- doorbell = base + client->doorbell_offset;
+ doorbell = client->client_base + client->doorbell_offset;
- doorbell->db_status = 0;
-
- kunmap_atomic(base);
+ doorbell->db_status = GUC_DOORBELL_DISABLED;
I915_WRITE(drbreg, I915_READ(drbreg) & ~GEN8_DRB_VALID);
@@ -341,10 +330,8 @@ static void guc_init_proc_desc(struct intel_guc *guc,
struct i915_guc_client *client)
{
struct guc_process_desc *desc;
- void *base;
- base = kmap_atomic(i915_gem_object_get_page(client->client_obj, 0));
- desc = base + client->proc_desc_offset;
+ desc = client->client_base + client->proc_desc_offset;
memset(desc, 0, sizeof(*desc));
@@ -361,8 +348,6 @@ static void guc_init_proc_desc(struct intel_guc *guc,
desc->wq_size_bytes = client->wq_size;
desc->wq_status = WQ_STATUS_ACTIVE;
desc->priority = client->priority;
-
- kunmap_atomic(base);
}
/*
@@ -474,7 +459,6 @@ static void guc_fini_ctx_desc(struct intel_guc *guc,
int i915_guc_wq_check_space(struct i915_guc_client *gc)
{
struct guc_process_desc *desc;
- void *base;
u32 size = sizeof(struct guc_wq_item);
int ret = -ETIMEDOUT, timeout_counter = 200;
@@ -486,8 +470,7 @@ int i915_guc_wq_check_space(struct i915_guc_client *gc)
if (CIRC_SPACE(gc->wq_tail, gc->wq_head, gc->wq_size) >= size)
return 0;
- base = kmap_atomic(i915_gem_object_get_page(gc->client_obj, 0));
- desc = base + gc->proc_desc_offset;
+ desc = gc->client_base + gc->proc_desc_offset;
while (timeout_counter-- > 0) {
gc->wq_head = desc->head;
@@ -501,8 +484,6 @@ int i915_guc_wq_check_space(struct i915_guc_client *gc)
usleep_range(1000, 2000);
};
- kunmap_atomic(base);
-
return ret;
}
@@ -661,21 +642,28 @@ static void guc_client_free(struct drm_device *dev,
if (!client)
return;
- if (client->doorbell_id != GUC_INVALID_DOORBELL_ID) {
- /*
- * First disable the doorbell, then tell the GuC we've
- * finished with it, finally deallocate it in our bitmap
- */
- guc_disable_doorbell(guc, client);
- host2guc_release_doorbell(guc, client);
- release_doorbell(guc, client->doorbell_id);
- }
-
/*
* XXX: wait for any outstanding submissions before freeing memory.
* Be sure to drop any locks
*/
+ if (client->client_base) {
+ /*
+ * If we got as far as setting up a doorbell, make sure
+ * we shut it down before unmapping & deallocating the
+ * memory. So first disable the doorbell, then tell the
+ * GuC that we've finished with it, finally deallocate
+ * it in our bitmap
+ */
+ if (client->doorbell_id != GUC_INVALID_DOORBELL_ID) {
+ guc_disable_doorbell(guc, client);
+ host2guc_release_doorbell(guc, client);
+ release_doorbell(guc, client->doorbell_id);
+ }
+
+ kunmap(kmap_to_page(client->client_base));
+ }
+
gem_release_guc_obj(client->client_obj);
if (client->ctx_index != GUC_INVALID_CTX_ID) {
@@ -696,7 +684,7 @@ static void guc_client_free(struct drm_device *dev,
* @ctx: the context that owns the client (we use the default render
* context)
*
- * Return: An i915_guc_client object if success.
+ * Return: An i915_guc_client object if success, else NULL.
*/
static struct i915_guc_client *guc_client_alloc(struct drm_device *dev,
uint32_t priority,
@@ -728,7 +716,9 @@ static struct i915_guc_client *guc_client_alloc(struct drm_device *dev,
if (!obj)
goto err;
+ /* We'll keep just the first (doorbell/proc) page permanently kmap'd. */
client->client_obj = obj;
+ client->client_base = kmap(i915_gem_object_get_page(obj, 0));
client->wq_offset = GUC_DB_SIZE;
client->wq_size = GUC_WQ_SIZE;
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index 3bb85b1..06050c241a 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -31,6 +31,7 @@ struct drm_i915_gem_request;
struct i915_guc_client {
struct drm_i915_gem_object *client_obj;
+ void *client_base; /* first page (only) of above */
struct intel_context *owner;
struct intel_guc *guc;
uint32_t priority;
@@ -52,6 +53,7 @@ struct i915_guc_client {
uint32_t q_fail;
uint32_t b_fail;
int retcode;
+ int spare; /* pad to 32 DWords */
};
enum intel_guc_fw_status {
