From: Łukasz Bartosik <ukaszb(a)chromium.org>
When DbC is disconnected then xhci_dbc_tty_unregister_device()
is called. However if there is any user space process blocked
on write to DbC terminal device then it will never be signalled
and thus stay blocked indifinitely.
This fix adds a tty_vhangup() call in xhci_dbc_tty_unregister_device().
The tty_vhangup() wakes up any blocked writers and causes subsequent
write attempts to DbC terminal device to fail.
Cc: stable(a)vger.kernel.org
Fixes: dfba2174dc42 ("usb: xhci: Add DbC support in xHCI driver")
Signed-off-by: Łukasz Bartosik <ukaszb(a)chromium.org>
---
Changes in v2:
- Replaced tty_hangup() with tty_vhangup()
---
drivers/usb/host/xhci-dbgtty.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c
index d894081d8d15..ad86f315c26d 100644
--- a/drivers/usb/host/xhci-dbgtty.c
+++ b/drivers/usb/host/xhci-dbgtty.c
@@ -535,6 +535,12 @@ static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
if (!port->registered)
return;
+ /*
+ * Hang up the TTY. This wakes up any blocked
+ * writers and causes subsequent writes to fail.
+ */
+ tty_vhangup(port->port.tty);
+
tty_unregister_device(dbc_tty_driver, port->minor);
xhci_dbc_tty_exit_port(port);
port->registered = false;
--
2.52.0.rc1.455.g30608eb744-goog
The delayed work uec->work is scheduled in gaokun_ucsi_probe()
but never properly canceled in gaokun_ucsi_remove(). This creates
use-after-free scenarios where the ucsi and gaokun_ucsi structure
are freed after ucsi_destroy() completes execution, while the
gaokun_ucsi_register_worker() might be either currently executing
or still pending in the work queue. The already-freed gaokun_ucsi
or ucsi structure may then be accessed.
Furthermore, the race window is 3 seconds, which is sufficiently
long to make this bug easily reproducible. The following is the
trace captured by KASAN:
==================================================================
BUG: KASAN: slab-use-after-free in __run_timers+0x5ec/0x630
Write of size 8 at addr ffff00000ec28cc8 by task swapper/0/0
...
Call trace:
show_stack+0x18/0x24 (C)
dump_stack_lvl+0x78/0x90
print_report+0x114/0x580
kasan_report+0xa4/0xf0
__asan_report_store8_noabort+0x20/0x2c
__run_timers+0x5ec/0x630
run_timer_softirq+0xe8/0x1cc
handle_softirqs+0x294/0x720
__do_softirq+0x14/0x20
____do_softirq+0x10/0x1c
call_on_irq_stack+0x30/0x48
do_softirq_own_stack+0x1c/0x28
__irq_exit_rcu+0x27c/0x364
irq_exit_rcu+0x10/0x1c
el1_interrupt+0x40/0x60
el1h_64_irq_handler+0x18/0x24
el1h_64_irq+0x6c/0x70
arch_local_irq_enable+0x4/0x8 (P)
do_idle+0x334/0x458
cpu_startup_entry+0x60/0x70
rest_init+0x158/0x174
start_kernel+0x2f8/0x394
__primary_switched+0x8c/0x94
Allocated by task 72 on cpu 0 at 27.510341s:
kasan_save_stack+0x2c/0x54
kasan_save_track+0x24/0x5c
kasan_save_alloc_info+0x40/0x54
__kasan_kmalloc+0xa0/0xb8
__kmalloc_node_track_caller_noprof+0x1c0/0x588
devm_kmalloc+0x7c/0x1c8
gaokun_ucsi_probe+0xa0/0x840 auxiliary_bus_probe+0x94/0xf8
really_probe+0x17c/0x5b8
__driver_probe_device+0x158/0x2c4
driver_probe_device+0x10c/0x264
__device_attach_driver+0x168/0x2d0
bus_for_each_drv+0x100/0x188
__device_attach+0x174/0x368
device_initial_probe+0x14/0x20
bus_probe_device+0x120/0x150
device_add+0xb3c/0x10fc
__auxiliary_device_add+0x88/0x130
...
Freed by task 73 on cpu 1 at 28.910627s:
kasan_save_stack+0x2c/0x54
kasan_save_track+0x24/0x5c
__kasan_save_free_info+0x4c/0x74
__kasan_slab_free+0x60/0x8c
kfree+0xd4/0x410
devres_release_all+0x140/0x1f0
device_unbind_cleanup+0x20/0x190
device_release_driver_internal+0x344/0x460
device_release_driver+0x18/0x24
bus_remove_device+0x198/0x274
device_del+0x310/0xa84
...
The buggy address belongs to the object at ffff00000ec28c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 200 bytes inside of
freed 512-byte region
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4ec28
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x3fffe0000000040(head|node=0|zone=0|lastcpupid=0x1ffff)
page_type: f5(slab)
raw: 03fffe0000000040 ffff000008801c80 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 03fffe0000000040 ffff000008801c80 dead000000000122 0000000000000000
head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 03fffe0000000002 fffffdffc03b0a01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff00000ec28b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff00000ec28c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff00000ec28c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff00000ec28d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff00000ec28d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Add disable_delayed_work_sync() in gaokun_ucsi_remove() to ensure
that uec->work is properly canceled and prevented from executing
after the ucsi and gaokun_ucsi structure have been deallocated.
Fixes: 00327d7f2c8c ("usb: typec: ucsi: add Huawei Matebook E Go ucsi driver")
Cc: stable(a)vger.kernel.org
Signed-off-by: Duoming Zhou <duoming(a)zju.edu.cn>
---
drivers/usb/typec/ucsi/ucsi_huawei_gaokun.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/usb/typec/ucsi/ucsi_huawei_gaokun.c b/drivers/usb/typec/ucsi/ucsi_huawei_gaokun.c
index 8401ab414bd..c5965656bab 100644
--- a/drivers/usb/typec/ucsi/ucsi_huawei_gaokun.c
+++ b/drivers/usb/typec/ucsi/ucsi_huawei_gaokun.c
@@ -503,6 +503,7 @@ static void gaokun_ucsi_remove(struct auxiliary_device *adev)
{
struct gaokun_ucsi *uec = auxiliary_get_drvdata(adev);
+ disable_delayed_work_sync(&uec->work);
gaokun_ec_unregister_notify(uec->ec, &uec->nb);
ucsi_unregister(uec->ucsi);
ucsi_destroy(uec->ucsi);
--
2.34.1
Hi Sergey,
On 11/21/25 03:55, Sergey Senozhatsky wrote:
> Hi Christian,
>
> On (25/11/20 10:15), Christian Loehle wrote:
>> On 11/20/25 04:45, Sergey Senozhatsky wrote:
>>> Hi,
>>>
>>> We are observing a performance regression on one of our arm64 boards.
>>> We tracked it down to the linux-6.6.y commit ada8d7fa0ad4 ("sched/cpufreq:
>>> Rework schedutil governor performance estimation").
>>>
>>> UI speedometer benchmark:
>>> w/commit: 395 +/-38
>>> w/o commit: 439 +/-14
>>>
>>
>> Hi Sergey,
>> Would be nice to get some details. What board?
>
> It's an MT8196 chromebook.
>
>> What do the OPPs look like?
>
> How do I find that out?
>
>> Does this system use uclamp during the benchmark? How?
>
> How do I find that out?
>
>> Given how large the stddev given by speedometer (version 3?) itself is, can we get the
>> stats of a few runs?
>
> v2.1
>
> w/o patch w/ patch
> 440 +/-30 406 +/-11
> 440 +/-14 413 +/-16
> 444 +/-12 403 +/-14
> 442 +/-12 412 +/-15
>
>> Maybe traces of cpu_frequency for both w/ and w/o?
>
> trace-cmd record -e power:cpu_frequency attached.
>
> "base" is with ada8d7fa0ad4
> "revert" is ada8d7fa0ad4 reverted.
I did some analysis based on your trace files.
I have been playing some time ago with speedometer performance
issues so that's why I'm curious about your report here.
I've filtered your trace purely based on cpu7 (the single biggest cpu).
Then I have cut the data from the 'warm-up' phase in both traces, to
have similar start point (I think).
It looks like the 2 traces can show similar 'pattern' of that benchmark
which is good for analysis. If you align the timestamp:
176.051s and 972.465s then both plots (frequency changes in time) look
similar.
There are some differences, though:
1. there are more deeps in the freq in time, so more often you would
pay extra penalty for the ramp-up again
2. some of the ramp-up phases are a bit longer ~100ms instead of ~80ms
going from 2GHz to 3.6GHz
3.
There are idle phases missing in the trace, so we have to be careful
when e.g. comparing avg frequency, because that might not be the real
indication of the delivered computation and not indicate the gap in the
score.
Here are the stats:
1. revert:
frequency
count 1.318000e+03
mean 2.932240e+06
std 5.434045e+05
min 2.000000e+06
50% 3.000000e+06
85% 3.600000e+06
90% 3.626000e+06
95% 3.626000e+06
99% 3.626000e+06
max 3.626000e+06
2. base:
frequency
count 1.551000e+03
mean 2.809391e+06
std 5.369750e+05
min 2.000000e+06
50% 2.800000e+06
85% 3.500000e+06
90% 3.600000e+06
95% 3.626000e+06
99% 3.626000e+06
max 3.626000e+06
A better indication in this case would be comparison of the frequency
residency in time, especially for the max freq:
1. revert: 11.92s
2. base: 9.11s
So there is 2.8s longer residency for that fmax (while we even have
longer period for finishing that Speedometer 2 test on 'base').
Here is some detail about that run*:
+---------------+---------------------+---------------+----------------+
| Trace | Total Trace | Time at Max | % of Total |
| | Duration (s) | Freq (s) | Time |
+---------------+---------------------+---------------+----------------+
| Base Trace | 24.72 | 9.11 | 36.9% |
| Revert Trace | 22.88 | 11.92 | 52.1% |
+---------------+---------------------+---------------+----------------+
*We don't know the idle periods which might happen for those frequencies
I wonder if you had a fix patch for the util_est in your kernel...
That fix has been recently backported to 6.6 stable [1].
You might want to try that patch as well, w/ or w/o this revert.
IMHO it might be worth to have it on top. It might help
the main Chrome task ('CrRendererMain') to stay longer on the biggest
cpu, since the util_est would be higher. You can read the discussion
that I had back then with PeterZ and VincentG [2].
Regards,
Lukasz
[1]
https://lore.kernel.org/stable/20251121130232.828187990@linuxfoundation.org/
[2]
https://lore.kernel.org/lkml/20230912142821.GA22166@noisy.programming.kicks…
This is v2 of a series to address multiple reports [0][1]
(+ 2 offlist) of suspend failing when NBCON console drivers are
in use. With the help of NXP and NVIDIA we were able to isolate
the problem and verify the fix.
v1 is here [2].
The first NBCON drivers appeared in 6.13, so currently there is
no LTS kernel that requires this series. But it should go into
6.17.x and 6.18.
The changes since v1:
- For printk_trigger_flush() add support for all flush types
that are available. This will prevent printk_trigger_flush()
from trying to inappropriately queue irq_work after this
series is applied.
- Add WARN_ON_ONCE() to the printk irq_work queueing functions
in case they are called when irq_work is blocked. There
should never be (and currently are no) such callers, but
these functions are externally available.
John Ogness
[0] https://lore.kernel.org/lkml/80b020fc-c18a-4da4-b222-16da1cab2f4c@nvidia.com
[1] https://lore.kernel.org/lkml/DB9PR04MB8429E7DDF2D93C2695DE401D92C4A@DB9PR04…
[2] https://lore.kernel.org/lkml/20251111144328.887159-1-john.ogness@linutronix…
John Ogness (2):
printk: Allow printk_trigger_flush() to flush all types
printk: Avoid scheduling irq_work on suspend
kernel/printk/internal.h | 8 ++--
kernel/printk/nbcon.c | 9 ++++-
kernel/printk/printk.c | 81 ++++++++++++++++++++++++++++++++--------
3 files changed, 78 insertions(+), 20 deletions(-)
base-commit: e9a6fb0bcdd7609be6969112f3fbfcce3b1d4a7c
--
2.47.3
media_pad_remote_pad_first() may return NULL when the media link is absent
or disabled. The code dereferenced remote_pad->entity unconditionally in
ipu6_isys_csi2_enable_streams() and ipu6_isys_csi2_disable_streams(),
leading to a possible NULL dereference.
Guard the remote pad/subdev: in enable path return -ENOLINK/-ENODEV, in
disable path always shut down the local stream first and return 0 if the
remote side is missing. This keeps local shutdown semantics intact and
prevents a crash when the graph is partially torn down.
Also, ipu6_isys_csi2_calc_timing() passes link_freq into calc_timing()
where it is used as a divisor. v4l2_get_link_freq() may yield 0; add an
explicit check and return -EINVAL to avoid division by zero.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: 3a5c59ad926b ("media: ipu6: Rework CSI-2 sub-device streaming control")
Cc: stable(a)vger.kernel.org
Signed-off-by: Alexei Safin <a.safin(a)rosa.ru>
---
drivers/media/pci/intel/ipu6/ipu6-isys-csi2.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/media/pci/intel/ipu6/ipu6-isys-csi2.c b/drivers/media/pci/intel/ipu6/ipu6-isys-csi2.c
index d1fece6210ab..58944918c344 100644
--- a/drivers/media/pci/intel/ipu6/ipu6-isys-csi2.c
+++ b/drivers/media/pci/intel/ipu6/ipu6-isys-csi2.c
@@ -171,6 +171,10 @@ ipu6_isys_csi2_calc_timing(struct ipu6_isys_csi2 *csi2,
if (link_freq < 0)
return link_freq;
+ /* Avoid division by zero in calc_timing() if link frequency is zero */
+ if (!link_freq)
+ return -EINVAL;
+
timing->ctermen = calc_timing(CSI2_CSI_RX_DLY_CNT_TERMEN_CLANE_A,
CSI2_CSI_RX_DLY_CNT_TERMEN_CLANE_B,
link_freq, accinv);
@@ -352,7 +356,12 @@ static int ipu6_isys_csi2_enable_streams(struct v4l2_subdev *sd,
int ret;
remote_pad = media_pad_remote_pad_first(&sd->entity.pads[CSI2_PAD_SINK]);
+ if (!remote_pad)
+ return -ENOLINK;
+
remote_sd = media_entity_to_v4l2_subdev(remote_pad->entity);
+ if (!remote_sd)
+ return -ENODEV;
sink_streams =
v4l2_subdev_state_xlate_streams(state, pad, CSI2_PAD_SINK,
@@ -389,7 +398,16 @@ static int ipu6_isys_csi2_disable_streams(struct v4l2_subdev *sd,
&streams_mask);
remote_pad = media_pad_remote_pad_first(&sd->entity.pads[CSI2_PAD_SINK]);
+ if (!remote_pad) {
+ ipu6_isys_csi2_set_stream(sd, NULL, 0, false);
+ return 0;
+ }
+
remote_sd = media_entity_to_v4l2_subdev(remote_pad->entity);
+ if (!remote_sd) {
+ ipu6_isys_csi2_set_stream(sd, NULL, 0, false);
+ return 0;
+ }
ipu6_isys_csi2_set_stream(sd, NULL, 0, false);
--
2.50.1 (Apple Git-155)
This reverts commit 7777f47f2ea64efd1016262e7b59fab34adfb869.
The commit 1a721de8489f ("block: don't add or resize partition on the disk
with GENHD_FL_NO_PART") and the commit 7777f47f2ea6 ("block: Move checking
GENHD_FL_NO_PART to bdev_add_partition()") used the flag GENHD_FL_NO_PART
to prevent the add or resize of partitions in 5.15 stable kernels.But in
these 5.15 kernels, this is giving an issue with the following error
where the loop driver wants to create a partition when the partscan is
disabled on the loop device:
dd if=/dev/zero of=loopDisk.dsk bs=1M count=1 seek=10240;
losetup -f loopDisk.dsk;parted -s /dev/loop0 -- mklabel gpt mkpart primary
2048s 4096s
1+0 records in
1+0 records out
1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0016293 s, 644 MB/s
""
Error: Partition(s) 1 on /dev/loop0 have been written, but we have been
unable to inform the kernel of the change, probably because it/they are
in use. As a result, the old partition(s) will remain in use. You should
reboot now before making further changes.
""
If the partition scan is not enabled on the loop device, this flag
GENHD_FL_NO_PART is getting set and when partition creation is tried,
it returns an error EINVAL thereby preventing the creation of partitions.
So, there is no such distinction between disabling of partition scan and
partition creation.
Later in 6.xxx kernels, the commit b9684a71fca7 ("block, loop: support
partitions without scanning") a new flag GD_SUPPRESS_PART_SCAN was
introduced that just disables the partition scan and uses GENHD_FL_NO_PART
only to prevent creating partition scan. So, the partition creationg can
proceed with even if partition scan is disabled.
As the commit b9684a71fca7 ("block, loop: support partitions without
scanning") is not available in 5.15 stable kernel, and since there is no
distinction between disabling of "partition scan" and "partition
creation", we need to revert the commits 1a721de8489f and 7777f47f2ea6
from 5.15 stable kernel to allow partition creation when partscan is
disabled.
Cc: stable(a)vger.kernel.org
Signed-off-by: Gulam Mohamed <gulam.mohamed(a)oracle.com>
---
block/ioctl.c | 2 ++
block/partitions/core.c | 5 -----
2 files changed, 2 insertions(+), 5 deletions(-)
diff --git a/block/ioctl.c b/block/ioctl.c
index a260e39e56a4..d25b84441237 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -20,6 +20,8 @@ static int blkpg_do_ioctl(struct block_device *bdev,
struct blkpg_partition p;
sector_t start, length;
+ if (disk->flags & GENHD_FL_NO_PART)
+ return -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (copy_from_user(&p, upart, sizeof(struct blkpg_partition)))
diff --git a/block/partitions/core.c b/block/partitions/core.c
index 0d1fe2b42b85..7b5750db7eaf 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -463,11 +463,6 @@ int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
goto out;
}
- if (disk->flags & GENHD_FL_NO_PART) {
- ret = -EINVAL;
- goto out;
- }
-
if (partition_overlaps(disk, start, length, -1)) {
ret = -EBUSY;
goto out;
--
2.47.3