Properly handle module_kboject creation #55
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February 4, 2025 12:18
locate_module_kobject() look up for existing module_kobject For given module name locate_module_kobject() look up for corresponding module_kobject if it exists. If it coudln't find its corresponding module_kobject then it creates one for the given name. Rename locate_module_kobject() to lookup_or_create_module_kobject(), to better describe its operations. This doesn't change anything functionality wise. Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Shyam Saini <shyamsaini@linux.microsoft.com>
Move the following to module.h to allow common usages: - lookup_or_create_module_kobject() - to_module_attr - to_module_kobject This makes lookup_or_create_module_kobject() as inline. Signed-off-by: Shyam Saini <shyamsaini@linux.microsoft.com>
module_add_driver() relies on module_kset list for /sys/module/<built-in-module>/drivers directory creation. Since, commit 96a1a24 ("kernel/params.c: defer most of param_sysfs_init() to late_initcall time") drivers which are initialized from subsys_initcall() or any other higher precedence initcall couldn't find the related kobject entry in the module_kset list because module_kset is not fully populated by the time module_add_driver() refers it. As a consequence, module_add_driver() returns early without calling make_driver_name(). Therefore, /sys/module/<built-in-module>/drivers is never created. Fix this issue by letting module_add_driver() handle module_kobject creation itself. Fixes: 96a1a24 ("kernel/params.c: defer most of param_sysfs_init() to late_initcall time") Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Shyam Saini <shyamsaini@linux.microsoft.com>
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At least one diff in series https://patchwork.kernel.org/project/linux-modules/list/?series=930305 irrelevant now. Closing PR. |
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Commit <d74169ceb0d2> ("iommu/vt-d: Allocate DMAR fault interrupts
locally") moved the call to enable_drhd_fault_handling() to a code
path that does not hold any lock while traversing the drhd list. Fix
it by ensuring the dmar_global_lock lock is held when traversing the
drhd list.
Without this fix, the following warning is triggered:
=============================
WARNING: suspicious RCU usage
6.14.0-rc3 #55 Not tainted
-----------------------------
drivers/iommu/intel/dmar.c:2046 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
2 locks held by cpuhp/1/23:
#0: ffffffff84a67c50 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0
#1: ffffffff84a6a380 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0
stack backtrace:
CPU: 1 UID: 0 PID: 23 Comm: cpuhp/1 Not tainted 6.14.0-rc3 #55
Call Trace:
<TASK>
dump_stack_lvl+0xb7/0xd0
lockdep_rcu_suspicious+0x159/0x1f0
? __pfx_enable_drhd_fault_handling+0x10/0x10
enable_drhd_fault_handling+0x151/0x180
cpuhp_invoke_callback+0x1df/0x990
cpuhp_thread_fun+0x1ea/0x2c0
smpboot_thread_fn+0x1f5/0x2e0
? __pfx_smpboot_thread_fn+0x10/0x10
kthread+0x12a/0x2d0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x4a/0x60
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Holding the lock in enable_drhd_fault_handling() triggers a lockdep splat
about a possible deadlock between dmar_global_lock and cpu_hotplug_lock.
This is avoided by not holding dmar_global_lock when calling
iommu_device_register(), which initiates the device probe process.
Fixes: d74169c ("iommu/vt-d: Allocate DMAR fault interrupts locally")
Reported-and-tested-by: Ido Schimmel <idosch@nvidia.com>
Closes: https://lore.kernel.org/linux-iommu/Zx9OwdLIc_VoQ0-a@shredder.mtl.com/
Tested-by: Breno Leitao <leitao@debian.org>
Cc: stable@vger.kernel.org
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20250218022422.2315082-1-baolu.lu@linux.intel.com
Tested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Dec 2, 2025
A synchronous external abort occurs on the Renesas RZ/G3S SoC if unbind is
executed after the configuration sequence described above:
modprobe usb_f_ecm
modprobe libcomposite
modprobe configfs
cd /sys/kernel/config/usb_gadget
mkdir -p g1
cd g1
echo "0x1d6b" > idVendor
echo "0x0104" > idProduct
mkdir -p strings/0x409
echo "0123456789" > strings/0x409/serialnumber
echo "Renesas." > strings/0x409/manufacturer
echo "Ethernet Gadget" > strings/0x409/product
mkdir -p functions/ecm.usb0
mkdir -p configs/c.1
mkdir -p configs/c.1/strings/0x409
echo "ECM" > configs/c.1/strings/0x409/configuration
if [ ! -L configs/c.1/ecm.usb0 ]; then
ln -s functions/ecm.usb0 configs/c.1
fi
echo 11e20000.usb > UDC
echo 11e20000.usb > /sys/bus/platform/drivers/renesas_usbhs/unbind
The displayed trace is as follows:
Internal error: synchronous external abort: 0000000096000010 [#1] SMP
CPU: 0 UID: 0 PID: 188 Comm: sh Tainted: G M 6.17.0-rc7-next-20250922-00010-g41050493b2bd #55 PREEMPT
Tainted: [M]=MACHINE_CHECK
Hardware name: Renesas SMARC EVK version 2 based on r9a08g045s33 (DT)
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : usbhs_sys_function_pullup+0x10/0x40 [renesas_usbhs]
lr : usbhsg_update_pullup+0x3c/0x68 [renesas_usbhs]
sp : ffff8000838b3920
x29: ffff8000838b3920 x28: ffff00000d585780 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000000 x24: ffff00000c3e3810
x23: ffff00000d5e5c80 x22: ffff00000d5e5d40 x21: 0000000000000000
x20: 0000000000000000 x19: ffff00000d5e5c80 x18: 0000000000000020
x17: 2e30303230316531 x16: 312d7968703a7968 x15: 3d454d414e5f4344
x14: 000000000000002c x13: 0000000000000000 x12: 0000000000000000
x11: ffff00000f358f38 x10: ffff00000f358db0 x9 : ffff00000b41f418
x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : fefefeff6364626d
x5 : 8080808000000000 x4 : 000000004b5ccb9d x3 : 0000000000000000
x2 : 0000000000000000 x1 : ffff800083790000 x0 : ffff00000d5e5c80
Call trace:
usbhs_sys_function_pullup+0x10/0x40 [renesas_usbhs] (P)
usbhsg_pullup+0x4c/0x7c [renesas_usbhs]
usb_gadget_disconnect_locked+0x48/0xd4
gadget_unbind_driver+0x44/0x114
device_remove+0x4c/0x80
device_release_driver_internal+0x1c8/0x224
device_release_driver+0x18/0x24
bus_remove_device+0xcc/0x10c
device_del+0x14c/0x404
usb_del_gadget+0x88/0xc0
usb_del_gadget_udc+0x18/0x30
usbhs_mod_gadget_remove+0x24/0x44 [renesas_usbhs]
usbhs_mod_remove+0x20/0x30 [renesas_usbhs]
usbhs_remove+0x98/0xdc [renesas_usbhs]
platform_remove+0x20/0x30
device_remove+0x4c/0x80
device_release_driver_internal+0x1c8/0x224
device_driver_detach+0x18/0x24
unbind_store+0xb4/0xb8
drv_attr_store+0x24/0x38
sysfs_kf_write+0x7c/0x94
kernfs_fop_write_iter+0x128/0x1b8
vfs_write+0x2ac/0x350
ksys_write+0x68/0xfc
__arm64_sys_write+0x1c/0x28
invoke_syscall+0x48/0x110
el0_svc_common.constprop.0+0xc0/0xe0
do_el0_svc+0x1c/0x28
el0_svc+0x34/0xf0
el0t_64_sync_handler+0xa0/0xe4
el0t_64_sync+0x198/0x19c
Code: 7100003f 1a9f07e1 531c6c22 f9400001 (79400021)
---[ end trace 0000000000000000 ]---
note: sh[188] exited with irqs disabled
note: sh[188] exited with preempt_count 1
The issue occurs because usbhs_sys_function_pullup(), which accesses the IP
registers, is executed after the USBHS clocks have been disabled. The
problem is reproducible on the Renesas RZ/G3S SoC starting with the
addition of module stop in the clock enable/disable APIs. With module stop
functionality enabled, a bus error is expected if a master accesses a
module whose clock has been stopped and module stop activated.
Disable the IP clocks at the end of remove.
Cc: stable <stable@kernel.org>
Fixes: f1407d5 ("usb: renesas_usbhs: Add Renesas USBHS common code")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://patch.msgid.link/20251027140741.557198-1-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Pull request for series with
subject: Properly handle module_kboject creation
version: 1
url: https://patchwork.kernel.org/project/linux-modules/list/?series=930305