Le 04/03/2025 à 15:54, José Expósito a écrit :
Hi Louis,
On Mon, Mar 03, 2025 at 11:34:50AM +0100, Louis Chauvet wrote:
Le 03/03/2025 à 09:50, José Expósito a écrit :
Hi Louis,
On Fri, Feb 28, 2025 at 03:43:25PM +0100, Louis Chauvet wrote:
Le 25/02/2025 à 18:59, José Expósito a écrit :
Create a default subgroup at /config/vkms/planes to allow to create as
many planes as required.
Reviewed-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
Co-developed-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx>
[...]
diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index 92512d52ddae..4f9d3341e6c0 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
[...]
+static void plane_release(struct config_item *item)
+{
+ struct vkms_configfs_plane *plane;
+ struct mutex *lock;
+
+ plane = plane_item_to_vkms_configfs_plane(item);
+ lock = &plane->dev->lock;
+
+ guard(mutex)(lock);
+ vkms_config_destroy_plane(plane->config);
+ kfree(plane);
+}
I just found a flaw in our work: there is currently no way to forbid the
deletion of item/symlinks...
If you do:
modprobe vkms
cd /sys/kernel/config/vkms/
mkdir DEV
mkdir DEV/connectors/CON
mkdir DEV/planes/PLA
mkdir DEV/crtcs/CRT
mkdir DEV/encoders/ENC
ln -s DEV/crtcs/CRT DEV/planes/PLA/possible_crtcs/
ln -s DEV/crtcs/CRT DEV/encoders/ENC/possible_crtcs
ln -s DEV/encoders/ENC DEV/connectors/CON/possible_encoders
echo 1 > DEV/planes/PLA/type
tree
echo 1 > DEV/enabled
modetest -M vkms
=> everything fine
rm DEV/connectors/CON/possible_encoders/ENC
rmdir DEV/connectors/CON
modetest -M vkms
=> BUG: KASAN: slab-use-after-free
I'm trying to reproduce this issue, but those commands don't show any BUG
in dmesg. This is my Kasan .config:
CONFIG_HAVE_ARCH_KASAN=y
CONFIG_HAVE_ARCH_KASAN_VMALLOC=y
CONFIG_CC_HAS_KASAN_GENERIC=y
CONFIG_CC_HAS_KASAN_SW_TAGS=y
CONFIG_CC_HAS_WORKING_NOSANITIZE_ADDRESS=y
CONFIG_KASAN=y
CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX=y
CONFIG_KASAN_GENERIC=y
# CONFIG_KASAN_OUTLINE is not set
CONFIG_KASAN_INLINE=y
CONFIG_KASAN_STACK=y
CONFIG_KASAN_VMALLOC=y
# CONFIG_KASAN_KUNIT_TEST is not set
CONFIG_KASAN_EXTRA_INFO=y
I tryed to delete even more items:
root@kernel-dev:/sys/kernel/config/vkms# tree
.
└── DEV
├── connectors
├── crtcs
├── enabled
├── encoders
└── planes
root@kernel-dev:/sys/kernel/config/vkms# cat DEV/enabled
1
And I still don't see any errors. Is it possible that we are running different
branches? Asking because of the failing IGT tests you reported. There seems to
be a difference in our code or setup that is creating these differences.
I just re-applied your last vkms-config version and this series on top
of drm-misc-next. See [1] for the exact commits.
Argg sorry, I just noticed something: you need to disable the default
vkms device (I had this option in my kernel command line...), otherwise
modetest only use the first vkms gpu...
I will check again the igt tests, but I don't think this is the same
issue (it should not use the default device to test)
So, with [1] and the defconfig below, I have this:
1 modprobe vkms create_default_dev=0
2 cd /sys/kernel/config/vkms/
3 mkdir DEV
4 mkdir DEV/connectors/CON
5 mkdir DEV/planes/PLA
6 mkdir DEV/crtcs/CRT
7 mkdir DEV/encoders/ENC
8 ln -s DEV/crtcs/CRT DEV/planes/PLA/possible_crtcs/
9 ln -s DEV/crtcs/CRT DEV/encoders/ENC/possible_crtcs
10 ln -s DEV/encoders/ENC DEV/connectors/CON/possible_encoders
11 echo 1 > DEV/planes/PLA/type
12 tree
13 echo 1 > DEV/enabled
14 modetest -M vkms
15 rm DEV/connectors/CON/possible_encoders/ENC
16 rmdir DEV/connectors/CON
17 modetest -M vkms
KASAN: slab-use-after-free
[1]:https://github.com/Fomys/linux/tree/20250225175936.7223-1-jose.exposito89%40gmail.com
===== defconfig =====
CONFIG_SYSVIPC=y
CONFIG_CGROUPS=y
CONFIG_KALLSYMS_ALL=y
CONFIG_SMP=y
CONFIG_HYPERVISOR_GUEST=y
CONFIG_PARAVIRT=y
# CONFIG_VIRTUALIZATION is not set
CONFIG_JUMP_LABEL=y
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
CONFIG_NET=y
CONFIG_PACKET=y
# CONFIG_WIRELESS is not set
CONFIG_NET_9P=y
CONFIG_NET_9P_VIRTIO=y
CONFIG_PCI=y
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
CONFIG_VIRTIO_BLK=y
# CONFIG_INTEL_MEI is not set
CONFIG_NETDEVICES=y
CONFIG_VIRTIO_NET=y
# CONFIG_ETHERNET is not set
# CONFIG_WLAN is not set
CONFIG_INPUT_EVDEV=y
CONFIG_SERIAL_8250=y
CONFIG_SERIAL_8250_CONSOLE=y
CONFIG_VIRTIO_CONSOLE=y
CONFIG_HW_RANDOM_VIRTIO=m
CONFIG_PTP_1588_CLOCK=y
# CONFIG_HWMON is not set
CONFIG_THERMAL_GOV_USER_SPACE=y
CONFIG_DRM=y
CONFIG_DRM_KUNIT_TEST=m
CONFIG_DRM_VKMS=m
CONFIG_DRM_VKMS_KUNIT_TEST=m
# CONFIG_USB_SUPPORT is not set
CONFIG_VIRTIO_PCI=y
CONFIG_VIRTIO_BALLOON=y
CONFIG_VIRTIO_INPUT=y
CONFIG_VIRTIO_MMIO=y
CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
# CONFIG_SURFACE_PLATFORMS is not set
CONFIG_EXT4_FS=y
CONFIG_FUSE_FS=y
CONFIG_VIRTIO_FS=y
CONFIG_OVERLAY_FS=y
CONFIG_TMPFS=y
CONFIG_TMPFS_POSIX_ACL=y
CONFIG_CONFIGFS_FS=y
CONFIG_9P_FS=y
CONFIG_CRYPTO=y
CONFIG_CRYPTO_CRC32C=y
CONFIG_DYNAMIC_DEBUG=y
CONFIG_DEBUG_KERNEL=y
CONFIG_DEBUG_INFO_DWARF5=y
CONFIG_MAGIC_SYSRQ=y
CONFIG_DEBUG_FS=y
CONFIG_DEBUG_PAGEALLOC=y
CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT=y
CONFIG_PAGE_POISONING=y
CONFIG_DEBUG_OBJECTS=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
CONFIG_SCHED_STACK_END_CHECK=y
CONFIG_KASAN=y
CONFIG_KASAN_VMALLOC=y
CONFIG_KASAN_EXTRA_INFO=y
CONFIG_KFENCE=y
# CONFIG_FTRACE is not set
CONFIG_UNWINDER_FRAME_POINTER=y
CONFIG_KUNIT=y
CONFIG_TEST_DYNAMIC_DEBUG=m
