WARNING: CPU: 1 PID: 813 at kernel/module.c:291 module_assert_mutex_or_preempt+0x49/0x90()
------------[ cut here ]------------ WARNING: CPU: 1 PID: 813 at kernel/module.c:291 module_assert_mutex_or_preempt+0x49/0x90() Modules linked in: mxl5007t af9013 ... dvb_usb_af9015(+) ... dvb_usb_v2 dvb_core rc_core ... CPU: 1 PID: 813 Comm: systemd-udevd Not tainted 4.2.0-0.rc6.git0.1.fc24.x86_64+debug #1 ... Call Trace: [<ffffffff81868d8e>] dump_stack+0x4c/0x65 [<ffffffff810ab406>] warn_slowpath_common+0x86/0xc0 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff810ab53a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81150529>] module_assert_mutex_or_preempt+0x49/0x90 [<ffffffff81150822>] __module_address+0x32/0x150 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff81150956>] __module_text_address+0x16/0x70 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff81150f19>] symbol_put_addr+0x29/0x40 [<ffffffffa04b77ad>] dvb_frontend_detach+0x7d/0x90 [dvb_core] [<ffffffffa04cdfd5>] dvb_usbv2_probe+0xc85/0x11a0 [dvb_usb_v2] [<ffffffffa05607c4>] af9015_probe+0x84/0xf0 [dvb_usb_af9015] [<ffffffff8161c03b>] usb_probe_interface+0x1bb/0x2e0 [<ffffffff81579f26>] driver_probe_device+0x1f6/0x450 [<ffffffff8157a214>] __driver_attach+0x94/0xa0 [<ffffffff8157a180>] ? driver_probe_device+0x450/0x450 [<ffffffff815778f3>] bus_for_each_dev+0x73/0xc0 [<ffffffff815796fe>] driver_attach+0x1e/0x20 [<ffffffff8157922e>] bus_add_driver+0x1ee/0x280 [<ffffffff8157b0a0>] driver_register+0x60/0xe0 [<ffffffff8161a87d>] usb_register_driver+0xad/0x160 [<ffffffffa0567000>] ? 0xffffffffa0567000 [<ffffffffa056701e>] af9015_usb_driver_init+0x1e/0x1000 [dvb_usb_af9015] [<ffffffff81002123>] do_one_initcall+0xb3/0x200 [<ffffffff8124ac65>] ? kmem_cache_alloc_trace+0x355/0x380 [<ffffffff81867c37>] ? do_init_module+0x28/0x1e9 [<ffffffff81867c6f>] do_init_module+0x60/0x1e9 [<ffffffff81154167>] load_module+0x21f7/0x28d0 [<ffffffff8114f600>] ? m_show+0x1b0/0x1b0 [<ffffffff81026d79>] ? sched_clock+0x9/0x10 [<ffffffff810e6ddc>] ? local_clock+0x1c/0x20 [<ffffffff811549b8>] SyS_init_module+0x178/0x1c0 [<ffffffff8187282e>] entry_SYSCALL_64_fastpath+0x12/0x76 ---[ end trace 31a9dd90d4f559f5 ]---
Ref.
https://bugzilla.redhat.com/show_bug.cgi?id=1252167
https://bugzilla.kernel.org/show_bug.cgi?id=102631
Quoted 47 lines · poma
------------[ cut here ]------------ WARNING: CPU: 1 PID: 813 at kernel/module.c:291 module_assert_mutex_or_preempt+0x49/0x90() Modules linked in: mxl5007t af9013 ... dvb_usb_af9015(+) ... dvb_usb_v2 dvb_core rc_core ... CPU: 1 PID: 813 Comm: systemd-udevd Not tainted 4.2.0-0.rc6.git0.1.fc24.x86_64+debug #1 ... Call Trace: [<ffffffff81868d8e>] dump_stack+0x4c/0x65 [<ffffffff810ab406>] warn_slowpath_common+0x86/0xc0 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff810ab53a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81150529>] module_assert_mutex_or_preempt+0x49/0x90 [<ffffffff81150822>] __module_address+0x32/0x150 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff81150956>] __module_text_address+0x16/0x70 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff81150f19>] symbol_put_addr+0x29/0x40 [<ffffffffa04b77ad>] dvb_frontend_detach+0x7d/0x90 [dvb_core] [<ffffffffa04cdfd5>] dvb_usbv2_probe+0xc85/0x11a0 [dvb_usb_v2] [<ffffffffa05607c4>] af9015_probe+0x84/0xf0 [dvb_usb_af9015] [<ffffffff8161c03b>] usb_probe_interface+0x1bb/0x2e0 [<ffffffff81579f26>] driver_probe_device+0x1f6/0x450 [<ffffffff8157a214>] __driver_attach+0x94/0xa0 [<ffffffff8157a180>] ? driver_probe_device+0x450/0x450 [<ffffffff815778f3>] bus_for_each_dev+0x73/0xc0 [<ffffffff815796fe>] driver_attach+0x1e/0x20 [<ffffffff8157922e>] bus_add_driver+0x1ee/0x280 [<ffffffff8157b0a0>] driver_register+0x60/0xe0 [<ffffffff8161a87d>] usb_register_driver+0xad/0x160 [<ffffffffa0567000>] ? 0xffffffffa0567000 [<ffffffffa056701e>] af9015_usb_driver_init+0x1e/0x1000 [dvb_usb_af9015] [<ffffffff81002123>] do_one_initcall+0xb3/0x200 [<ffffffff8124ac65>] ? kmem_cache_alloc_trace+0x355/0x380 [<ffffffff81867c37>] ? do_init_module+0x28/0x1e9 [<ffffffff81867c6f>] do_init_module+0x60/0x1e9 [<ffffffff81154167>] load_module+0x21f7/0x28d0 [<ffffffff8114f600>] ? m_show+0x1b0/0x1b0 [<ffffffff81026d79>] ? sched_clock+0x9/0x10 [<ffffffff810e6ddc>] ? local_clock+0x1c/0x20 [<ffffffff811549b8>] SyS_init_module+0x178/0x1c0 [<ffffffff8187282e>] entry_SYSCALL_64_fastpath+0x12/0x76 ---[ end trace 31a9dd90d4f559f5 ]---
Quoted 4 lines
Ref.
https://bugzilla.redhat.com/show_bug.cgi?id=1252167
https://bugzilla.kernel.org/show_bug.cgi?id=102631
You guys are really something.
First of all, as is evident here, I am the original reporter, not Laura Abbott <[email protected]>.
-All- your comments including the final patch on this issue, are just plain wrong.[1]
This patch only hides the actual problem with this particular device - the dual tuner combination driven by dvb_usb_af9015 & mxl5007t, broken by design since day one.
Read the entire https://bugzilla.redhat.com/show_bug.cgi?id=1252167
and stop this nonsense.
NACK "module: Fix locking in symbol_put_addr()"
[1] http://www.gossamer-threads.com/lists/linux/kernel/2241154
Quoted 59 lines · poma
Quoted 47 lines · poma
------------[ cut here ]------------ WARNING: CPU: 1 PID: 813 at kernel/module.c:291 module_assert_mutex_or_preempt+0x49/0x90() Modules linked in: mxl5007t af9013 ... dvb_usb_af9015(+) ... dvb_usb_v2 dvb_core rc_core ... CPU: 1 PID: 813 Comm: systemd-udevd Not tainted 4.2.0-0.rc6.git0.1.fc24.x86_64+debug #1 ... Call Trace: [<ffffffff81868d8e>] dump_stack+0x4c/0x65 [<ffffffff810ab406>] warn_slowpath_common+0x86/0xc0 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff810ab53a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81150529>] module_assert_mutex_or_preempt+0x49/0x90 [<ffffffff81150822>] __module_address+0x32/0x150 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff81150956>] __module_text_address+0x16/0x70 [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffffa057d0b0>] ? af9013_read_ucblocks+0x20/0x20 [af9013] [<ffffffff81150f19>] symbol_put_addr+0x29/0x40 [<ffffffffa04b77ad>] dvb_frontend_detach+0x7d/0x90 [dvb_core] [<ffffffffa04cdfd5>] dvb_usbv2_probe+0xc85/0x11a0 [dvb_usb_v2] [<ffffffffa05607c4>] af9015_probe+0x84/0xf0 [dvb_usb_af9015] [<ffffffff8161c03b>] usb_probe_interface+0x1bb/0x2e0 [<ffffffff81579f26>] driver_probe_device+0x1f6/0x450 [<ffffffff8157a214>] __driver_attach+0x94/0xa0 [<ffffffff8157a180>] ? driver_probe_device+0x450/0x450 [<ffffffff815778f3>] bus_for_each_dev+0x73/0xc0 [<ffffffff815796fe>] driver_attach+0x1e/0x20 [<ffffffff8157922e>] bus_add_driver+0x1ee/0x280 [<ffffffff8157b0a0>] driver_register+0x60/0xe0 [<ffffffff8161a87d>] usb_register_driver+0xad/0x160 [<ffffffffa0567000>] ? 0xffffffffa0567000 [<ffffffffa056701e>] af9015_usb_driver_init+0x1e/0x1000 [dvb_usb_af9015] [<ffffffff81002123>] do_one_initcall+0xb3/0x200 [<ffffffff8124ac65>] ? kmem_cache_alloc_trace+0x355/0x380 [<ffffffff81867c37>] ? do_init_module+0x28/0x1e9 [<ffffffff81867c6f>] do_init_module+0x60/0x1e9 [<ffffffff81154167>] load_module+0x21f7/0x28d0 [<ffffffff8114f600>] ? m_show+0x1b0/0x1b0 [<ffffffff81026d79>] ? sched_clock+0x9/0x10 [<ffffffff810e6ddc>] ? local_clock+0x1c/0x20 [<ffffffff811549b8>] SyS_init_module+0x178/0x1c0 [<ffffffff8187282e>] entry_SYSCALL_64_fastpath+0x12/0x76 ---[ end trace 31a9dd90d4f559f5 ]---Quoted 4 lines
Ref.
https://bugzilla.redhat.com/show_bug.cgi?id=1252167
https://bugzilla.kernel.org/show_bug.cgi?id=102631You guys are really something.
First of all, as is evident here, I am the original reporter, not Laura Abbott <[email protected]>.
-All- your comments including the final patch on this issue, are just plain wrong.[1]
This patch only hides the actual problem with this particular device - the dual tuner combination driven bydvb_usb_af9015& mxl5007t, broken by design since day one.
Quoted 8 lines
Read the entire https://bugzilla.redhat.com/show_bug.cgi?id=1252167
and stop this nonsense.NACK "module: Fix locking in
symbol_put_addr()"[1] http://www.gossamer-threads.com/lists/linux/kernel/2241154
Sorry, I've been delayed with conferences and have been avoiding e-mails and bugzilla. I missed sending out the Tested-by tag.
You are welcome to drop the reported-by if you don't think it is appropriate.
Laura
Quoted 6 lines · poma
Quoted 4 lines
Ref.
https://bugzilla.redhat.com/show_bug.cgi?id=1252167
https://bugzilla.kernel.org/show_bug.cgi?id=102631You guys are really something.
Hi Poma,
I understand your frustration!
I got involved via the other thread which didn't mention your bug report anywhere. I'm sure Laura was trying to be helpful by creating a minimal report, but the resulting patch erred in not crediting you.
Quoted 1 line
First of all, as is evident here, I am the original reporter, not Laura Abbott <[email protected]>.
Thanks for clarifying that. I have fixed the commit message to credit you. See below.
Quoted 3 lines
-All- your comments including the final patch on this issue, are just plain wrong.[1]
This patch only hides the actual problem with this particular device - the dual tuner combination driven by
dvb_usb_af9015& mxl5007t, broken by design since day one.
Oh, there's definitely a real issue in the driver; this one is cosmetic.
Quoted 4 lines
Read the entire https://bugzilla.redhat.com/show_bug.cgi?id=1252167
and stop this nonsense.NACK "module: Fix locking in
symbol_put_addr()"
Yeah, I've had days like this, too :(
Anyway, thanks for finding this bug: if the driver init hadn't been screwed it wouldn't have taken that path and found this for us.
Good luck with the other issue!
Rusty.
Quoted 1 line
From
275d7d44d802ef271a42dc87ac091a495ba72fc5Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <[email protected]>
Date: Thu, 20 Aug 2015 10:34:59 +0930
Subject: [PATCH] module: Fix locking in symbol_put_addr()
Poma (on the way to another bug) reported an assertion triggering:
[<ffffffff81150529>] module_assert_mutex_or_preempt+0x49/0x90 [<ffffffff81150822>] __module_address+0x32/0x150 [<ffffffff81150956>] __module_text_address+0x16/0x70 [<ffffffff81150f19>] symbol_put_addr+0x29/0x40 [<ffffffffa04b77ad>] dvb_frontend_detach+0x7d/0x90 [dvb_core]
Laura Abbott <[email protected]> produced a patch which lead us to inspect symbol_put_addr(). This function has a comment claiming it doesn't need to disable preemption around the module lookup because it holds a reference to the module it wants to find, which therefore cannot go away.
This is wrong (and a false optimization too, preempt_disable() is really rather cheap, and I doubt any of this is on uber critical paths, otherwise it would've retained a pointer to the actual module anyway and avoided the second lookup).
While its true that the module cannot go away while we hold a reference on it, the data structure we do the lookup in very much _CAN_ change while we do the lookup. Therefore fix the comment and add the required preempt_disable().
kernel/module.c +6 -2
@@ -1063,11 +1063,15 @@ void symbol_put_addr(void *addr)if (core_kernel_text (a))return ; -/* module_text_address is safe here: we're supposed to have reference -* to module from symbol_get, so it can't go away. */ +/* +* Even though we hold a reference on the module; we still need to +* disable preemption in order to safely traverse the data structure. +*/ +preempt_disable (); modaddr =__module_text_address (a);BUG_ON (!modaddr);module_put (modaddr); +preempt_enable (); }EXPORT_SYMBOL_GPL (symbol_put_addr);