* [PATCH] security: device_cgroup: fix RCU lockdep splat
@ 2015-08-31 20:40 Felipe Balbi
2015-09-01 9:12 ` Sebastian Ott
0 siblings, 1 reply; 13+ messages in thread
From: Felipe Balbi @ 2015-08-31 20:40 UTC (permalink / raw)
To: James Morris
Cc: serge, linux-security-module, linux-kernel,
Linux OMAP Mailing List, Felipe Balbi
while booting AM437x device, the following splat
triggered:
[ 12.005238] ===============================
[ 12.009749] [ INFO: suspicious RCU usage. ]
[ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
[ 12.019050] -------------------------------
[ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
[ 12.033576] other info that might help us debug this:
[ 12.041942] rcu_scheduler_active = 1, debug_locks = 0
[ 12.048796] 4 locks held by systemd/1:
[ 12.052700] #0: (sb_writers#7){.+.+.+}, at: [<c017af84>] __sb_start_write+0x8c/0xb0
[ 12.060954] #1: (&of->mutex){+.+.+.}, at: [<c01f1600>] kernfs_fop_write+0x50/0x1b8
[ 12.069085] #2: (s_active#30){++++.+}, at: [<c01f1608>] kernfs_fop_write+0x58/0x1b8
[ 12.077310] #3: (devcgroup_mutex){+.+...}, at: [<c0317bfc>] devcgroup_access_write+0x20/0x658
[ 12.086575] stack backtrace:
[ 12.091124] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-next-20150831 #1154
[ 12.098609] Hardware name: Generic AM43 (Flattened Device Tree)
[ 12.104807] [<c001770c>] (unwind_backtrace) from [<c0013a58>] (show_stack+0x10/0x14)
[ 12.112924] [<c0013a58>] (show_stack) from [<c034f014>] (dump_stack+0x84/0x9c)
[ 12.120491] [<c034f014>] (dump_stack) from [<c0317a04>] (verify_new_ex+0xc4/0xdc)
[ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
[ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
[ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
[ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
[ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
[ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
[ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
Fix it by making sure rcu_read_lock() is held
around devcgroup_update_access().
Signed-off-by: Felipe Balbi <balbi@ti.com>
---
security/device_cgroup.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 73455089feef..0a6316b50357 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -766,8 +766,10 @@ static ssize_t devcgroup_access_write(struct kernfs_open_file *of,
int retval;
mutex_lock(&devcgroup_mutex);
+ rcu_read_lock();
retval = devcgroup_update_access(css_to_devcgroup(of_css(of)),
of_cft(of)->private, strstrip(buf));
+ rcu_read_unlock();
mutex_unlock(&devcgroup_mutex);
return retval ?: nbytes;
}
--
2.5.0
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH] security: device_cgroup: fix RCU lockdep splat
2015-08-31 20:40 [PATCH] security: device_cgroup: fix RCU lockdep splat Felipe Balbi
@ 2015-09-01 9:12 ` Sebastian Ott
2015-09-01 13:08 ` Felipe Balbi
0 siblings, 1 reply; 13+ messages in thread
From: Sebastian Ott @ 2015-09-01 9:12 UTC (permalink / raw)
To: Felipe Balbi
Cc: James Morris, serge, linux-security-module, linux-kernel,
Linux OMAP Mailing List
On Mon, 31 Aug 2015, Felipe Balbi wrote:
> while booting AM437x device, the following splat
> triggered:
>
> [ 12.005238] ===============================
> [ 12.009749] [ INFO: suspicious RCU usage. ]
> [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> [ 12.019050] -------------------------------
> [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> [ 12.033576] other info that might help us debug this:
>
> [ 12.041942] rcu_scheduler_active = 1, debug_locks = 0
> [ 12.048796] 4 locks held by systemd/1:
> [ 12.052700] #0: (sb_writers#7){.+.+.+}, at: [<c017af84>] __sb_start_write+0x8c/0xb0
> [ 12.060954] #1: (&of->mutex){+.+.+.}, at: [<c01f1600>] kernfs_fop_write+0x50/0x1b8
> [ 12.069085] #2: (s_active#30){++++.+}, at: [<c01f1608>] kernfs_fop_write+0x58/0x1b8
> [ 12.077310] #3: (devcgroup_mutex){+.+...}, at: [<c0317bfc>] devcgroup_access_write+0x20/0x658
> [ 12.086575] stack backtrace:
> [ 12.091124] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-next-20150831 #1154
> [ 12.098609] Hardware name: Generic AM43 (Flattened Device Tree)
> [ 12.104807] [<c001770c>] (unwind_backtrace) from [<c0013a58>] (show_stack+0x10/0x14)
> [ 12.112924] [<c0013a58>] (show_stack) from [<c034f014>] (dump_stack+0x84/0x9c)
> [ 12.120491] [<c034f014>] (dump_stack) from [<c0317a04>] (verify_new_ex+0xc4/0xdc)
> [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
>
> Fix it by making sure rcu_read_lock() is held
> around devcgroup_update_access().
With this patch applied I got the following:
[ 4.079102] BUG: sleeping function called from invalid context at mm/slub.c:1266
[ 4.079105] in_atomic(): 0, irqs_disabled(): 0, pid: 1, name: systemd
[ 4.079108] 5 locks held by systemd/1:
[ 4.079110] #0: (sb_writers#7){.+.+.+}, at: [<00000000002c4450>] vfs_write+0x180/0x1a8
[ 4.079120] #1: (&of->mutex){+.+.+.}, at: [<0000000000354d32>] kernfs_fop_write+0x6a/0x1a0
[ 4.079127] #2: (s_active#7){++++.+}, at: [<0000000000354d3e>] kernfs_fop_write+0x76/0x1a0
[ 4.079133] #3: (devcgroup_mutex){+.+.+.}, at: [<00000000003f3f7e>] devcgroup_access_write+0x46/0x7b8
[ 4.079143] #4: (rcu_read_lock){......}, at: [<00000000003f3f38>] devcgroup_access_write+0x0/0x7b8
[ 4.079149] Preemption disabled at:[<00000000001ab52c>] vprintk_default+0x44/0x58
[ 4.079155] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-02744-g65a9959-dirty #170
[ 4.079157] 0000000075c079b0 0000000075c07a40 0000000000000002 0000000000000000
0000000075c07ae0 0000000075c07a58 0000000075c07a58 0000000000113e9e
0000000000000000 000000000089c4f4 000000000087b700 000000000000000b
0000000075c07aa0 0000000075c07a40 0000000000000000 0000000000000000
0000000000000000 0000000000113e9e 0000000075c07a40 0000000075c07aa0
[ 4.079239] Call Trace:
[ 4.079242] ([<0000000000113d7e>] show_trace+0xfe/0x160)
[ 4.079244] [<0000000000113e50>] show_stack+0x70/0xf0
[ 4.079247] [<00000000006bb184>] dump_stack+0x7c/0xd8
[ 4.079250] [<0000000000164e42>] ___might_sleep+0x19a/0x268
[ 4.079255] [<00000000002bbc06>] __kmalloc_track_caller+0x2fe/0x460
[ 4.079258] [<0000000000275fee>] kmemdup+0x3e/0x68
[ 4.079260] [<00000000003f3dda>] dev_exception_add+0x4a/0x130
[ 4.079262] [<00000000003f459e>] devcgroup_access_write+0x666/0x7b8
[ 4.079265] [<00000000001ea100>] cgroup_file_write+0x50/0x1f0
[ 4.079267] [<0000000000354e1a>] kernfs_fop_write+0x152/0x1a0
[ 4.079269] [<00000000002c38f2>] __vfs_write+0x42/0x108
[ 4.079272] [<00000000002c4362>] vfs_write+0x92/0x1a8
[ 4.079274] [<00000000002c50fe>] SyS_write+0x66/0xd8
[ 4.079277] [<00000000006c4f26>] system_call+0xd6/0x258
[ 4.079279] [<000003fffd5cda58>] 0x3fffd5cda58
[ 4.079281] 5 locks held by systemd/1:
[ 4.079282] #0: (sb_writers#7){.+.+.+}, at: [<00000000002c4450>] vfs_write+0x180/0x1a8
[ 4.079289] #1: (&of->mutex){+.+.+.}, at: [<0000000000354d32>] kernfs_fop_write+0x6a/0x1a0
[ 4.079295] #2: (s_active#7){++++.+}, at: [<0000000000354d3e>] kernfs_fop_write+0x76/0x1a0
[ 4.079301] #3: (devcgroup_mutex){+.+.+.}, at: [<00000000003f3f7e>] devcgroup_access_write+0x46/0x7b8
[ 4.079307] #4: (rcu_read_lock){......}, at: [<00000000003f3f38>] devcgroup_access_write+0x0/0x7b8
grep RCU .config
# RCU Subsystem
CONFIG_PREEMPT_RCU=y
# CONFIG_RCU_EXPERT is not set
CONFIG_SRCU=y
CONFIG_TASKS_RCU=y
CONFIG_RCU_STALL_COMMON=y
# CONFIG_TREE_RCU_TRACE is not set
# CONFIG_RCU_EXPEDITE_BOOT is not set
# RCU Debugging
CONFIG_PROVE_RCU=y
# CONFIG_PROVE_RCU_REPEATEDLY is not set
# CONFIG_SPARSE_RCU_POINTER is not set
CONFIG_RCU_TORTURE_TEST=m
# CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is not set
# CONFIG_RCU_TORTURE_TEST_SLOW_INIT is not set
# CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is not set
CONFIG_RCU_CPU_STALL_TIMEOUT=300
# CONFIG_RCU_TRACE is not set
# CONFIG_RCU_EQS_DEBUG is not set
Regards,
Sebastian
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH] security: device_cgroup: fix RCU lockdep splat
2015-09-01 9:12 ` Sebastian Ott
@ 2015-09-01 13:08 ` Felipe Balbi
2015-09-02 12:29 ` Josh Boyer
0 siblings, 1 reply; 13+ messages in thread
From: Felipe Balbi @ 2015-09-01 13:08 UTC (permalink / raw)
To: Sebastian Ott
Cc: Felipe Balbi, James Morris, serge, linux-security-module,
linux-kernel, Linux OMAP Mailing List
[-- Attachment #1: Type: text/plain, Size: 2632 bytes --]
On Tue, Sep 01, 2015 at 11:12:18AM +0200, Sebastian Ott wrote:
> On Mon, 31 Aug 2015, Felipe Balbi wrote:
> > while booting AM437x device, the following splat
> > triggered:
> >
> > [ 12.005238] ===============================
> > [ 12.009749] [ INFO: suspicious RCU usage. ]
> > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> > [ 12.019050] -------------------------------
> > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> > [ 12.033576] other info that might help us debug this:
> >
> > [ 12.041942] rcu_scheduler_active = 1, debug_locks = 0
> > [ 12.048796] 4 locks held by systemd/1:
> > [ 12.052700] #0: (sb_writers#7){.+.+.+}, at: [<c017af84>] __sb_start_write+0x8c/0xb0
> > [ 12.060954] #1: (&of->mutex){+.+.+.}, at: [<c01f1600>] kernfs_fop_write+0x50/0x1b8
> > [ 12.069085] #2: (s_active#30){++++.+}, at: [<c01f1608>] kernfs_fop_write+0x58/0x1b8
> > [ 12.077310] #3: (devcgroup_mutex){+.+...}, at: [<c0317bfc>] devcgroup_access_write+0x20/0x658
> > [ 12.086575] stack backtrace:
> > [ 12.091124] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-next-20150831 #1154
> > [ 12.098609] Hardware name: Generic AM43 (Flattened Device Tree)
> > [ 12.104807] [<c001770c>] (unwind_backtrace) from [<c0013a58>] (show_stack+0x10/0x14)
> > [ 12.112924] [<c0013a58>] (show_stack) from [<c034f014>] (dump_stack+0x84/0x9c)
> > [ 12.120491] [<c034f014>] (dump_stack) from [<c0317a04>] (verify_new_ex+0xc4/0xdc)
> > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
> >
> > Fix it by making sure rcu_read_lock() is held
> > around devcgroup_update_access().
>
> With this patch applied I got the following:
>
> [ 4.079102] BUG: sleeping function called from invalid context at mm/slub.c:1266
> [ 4.079105] in_atomic(): 0, irqs_disabled(): 0, pid: 1, name: systemd
that didn't trigger here. maybe I didn't have lock debugging enabled.
I'll have a look.
--
balbi
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^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH] security: device_cgroup: fix RCU lockdep splat
2015-09-01 13:08 ` Felipe Balbi
@ 2015-09-02 12:29 ` Josh Boyer
2015-09-02 12:56 ` Felipe Balbi
0 siblings, 1 reply; 13+ messages in thread
From: Josh Boyer @ 2015-09-02 12:29 UTC (permalink / raw)
To: Felipe Balbi
Cc: Sebastian Ott, James Morris, Serge E. Hallyn,
linux-security-module, Linux-Kernel@Vger. Kernel. Org,
Linux OMAP Mailing List
On Tue, Sep 1, 2015 at 9:08 AM, Felipe Balbi <balbi@ti.com> wrote:
> On Tue, Sep 01, 2015 at 11:12:18AM +0200, Sebastian Ott wrote:
>> On Mon, 31 Aug 2015, Felipe Balbi wrote:
>> > while booting AM437x device, the following splat
>> > triggered:
>> >
>> > [ 12.005238] ===============================
>> > [ 12.009749] [ INFO: suspicious RCU usage. ]
>> > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
>> > [ 12.019050] -------------------------------
>> > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
>> > [ 12.033576] other info that might help us debug this:
>> >
>> > [ 12.041942] rcu_scheduler_active = 1, debug_locks = 0
>> > [ 12.048796] 4 locks held by systemd/1:
>> > [ 12.052700] #0: (sb_writers#7){.+.+.+}, at: [<c017af84>] __sb_start_write+0x8c/0xb0
>> > [ 12.060954] #1: (&of->mutex){+.+.+.}, at: [<c01f1600>] kernfs_fop_write+0x50/0x1b8
>> > [ 12.069085] #2: (s_active#30){++++.+}, at: [<c01f1608>] kernfs_fop_write+0x58/0x1b8
>> > [ 12.077310] #3: (devcgroup_mutex){+.+...}, at: [<c0317bfc>] devcgroup_access_write+0x20/0x658
>> > [ 12.086575] stack backtrace:
>> > [ 12.091124] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-next-20150831 #1154
>> > [ 12.098609] Hardware name: Generic AM43 (Flattened Device Tree)
>> > [ 12.104807] [<c001770c>] (unwind_backtrace) from [<c0013a58>] (show_stack+0x10/0x14)
>> > [ 12.112924] [<c0013a58>] (show_stack) from [<c034f014>] (dump_stack+0x84/0x9c)
>> > [ 12.120491] [<c034f014>] (dump_stack) from [<c0317a04>] (verify_new_ex+0xc4/0xdc)
>> > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
>> > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
>> > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
>> > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
>> > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
>> > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
>> > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
>> >
>> > Fix it by making sure rcu_read_lock() is held
>> > around devcgroup_update_access().
>>
>> With this patch applied I got the following:
>>
>> [ 4.079102] BUG: sleeping function called from invalid context at mm/slub.c:1266
>> [ 4.079105] in_atomic(): 0, irqs_disabled(): 0, pid: 1, name: systemd
>
> that didn't trigger here. maybe I didn't have lock debugging enabled.
> I'll have a look.
Did you happen to get a chance to poke further? I'm seeing the
original splat on all my machines as well.
josh
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH] security: device_cgroup: fix RCU lockdep splat
2015-09-02 12:29 ` Josh Boyer
@ 2015-09-02 12:56 ` Felipe Balbi
2015-09-02 13:12 ` [PATCH v2] " Felipe Balbi
0 siblings, 1 reply; 13+ messages in thread
From: Felipe Balbi @ 2015-09-02 12:56 UTC (permalink / raw)
To: Josh Boyer
Cc: Felipe Balbi, Sebastian Ott, James Morris, Serge E. Hallyn,
linux-security-module, Linux-Kernel@Vger. Kernel. Org,
Linux OMAP Mailing List
[-- Attachment #1: Type: text/plain, Size: 3024 bytes --]
On Wed, Sep 02, 2015 at 08:29:14AM -0400, Josh Boyer wrote:
> On Tue, Sep 1, 2015 at 9:08 AM, Felipe Balbi <balbi@ti.com> wrote:
> > On Tue, Sep 01, 2015 at 11:12:18AM +0200, Sebastian Ott wrote:
> >> On Mon, 31 Aug 2015, Felipe Balbi wrote:
> >> > while booting AM437x device, the following splat
> >> > triggered:
> >> >
> >> > [ 12.005238] ===============================
> >> > [ 12.009749] [ INFO: suspicious RCU usage. ]
> >> > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> >> > [ 12.019050] -------------------------------
> >> > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> >> > [ 12.033576] other info that might help us debug this:
> >> >
> >> > [ 12.041942] rcu_scheduler_active = 1, debug_locks = 0
> >> > [ 12.048796] 4 locks held by systemd/1:
> >> > [ 12.052700] #0: (sb_writers#7){.+.+.+}, at: [<c017af84>] __sb_start_write+0x8c/0xb0
> >> > [ 12.060954] #1: (&of->mutex){+.+.+.}, at: [<c01f1600>] kernfs_fop_write+0x50/0x1b8
> >> > [ 12.069085] #2: (s_active#30){++++.+}, at: [<c01f1608>] kernfs_fop_write+0x58/0x1b8
> >> > [ 12.077310] #3: (devcgroup_mutex){+.+...}, at: [<c0317bfc>] devcgroup_access_write+0x20/0x658
> >> > [ 12.086575] stack backtrace:
> >> > [ 12.091124] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-next-20150831 #1154
> >> > [ 12.098609] Hardware name: Generic AM43 (Flattened Device Tree)
> >> > [ 12.104807] [<c001770c>] (unwind_backtrace) from [<c0013a58>] (show_stack+0x10/0x14)
> >> > [ 12.112924] [<c0013a58>] (show_stack) from [<c034f014>] (dump_stack+0x84/0x9c)
> >> > [ 12.120491] [<c034f014>] (dump_stack) from [<c0317a04>] (verify_new_ex+0xc4/0xdc)
> >> > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> >> > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> >> > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> >> > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> >> > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> >> > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> >> > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
> >> >
> >> > Fix it by making sure rcu_read_lock() is held
> >> > around devcgroup_update_access().
> >>
> >> With this patch applied I got the following:
> >>
> >> [ 4.079102] BUG: sleeping function called from invalid context at mm/slub.c:1266
> >> [ 4.079105] in_atomic(): 0, irqs_disabled(): 0, pid: 1, name: systemd
> >
> > that didn't trigger here. maybe I didn't have lock debugging enabled.
> > I'll have a look.
>
> Did you happen to get a chance to poke further? I'm seeing the
> original splat on all my machines as well.
in today's TODO.
--
balbi
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[-- Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-02 12:56 ` Felipe Balbi
@ 2015-09-02 13:12 ` Felipe Balbi
2015-09-02 15:27 ` Josh Boyer
2015-09-02 16:24 ` Tejun Heo
0 siblings, 2 replies; 13+ messages in thread
From: Felipe Balbi @ 2015-09-02 13:12 UTC (permalink / raw)
To: James Morris
Cc: serge, linux-security-module, linux-kernel,
Linux OMAP Mailing List, Felipe Balbi
while booting AM437x device, the following splat
triggered:
[ 12.005238] ===============================
[ 12.009749] [ INFO: suspicious RCU usage. ]
[ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
[ 12.019050] -------------------------------
[ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
[ 12.033576] other info that might help us debug this:
[ 12.041942] rcu_scheduler_active = 1, debug_locks = 0
[ 12.048796] 4 locks held by systemd/1:
[ 12.052700] #0: (sb_writers#7){.+.+.+}, at: [<c017af84>] __sb_start_write+0x8c/0xb0
[ 12.060954] #1: (&of->mutex){+.+.+.}, at: [<c01f1600>] kernfs_fop_write+0x50/0x1b8
[ 12.069085] #2: (s_active#30){++++.+}, at: [<c01f1608>] kernfs_fop_write+0x58/0x1b8
[ 12.077310] #3: (devcgroup_mutex){+.+...}, at: [<c0317bfc>] devcgroup_access_write+0x20/0x658
[ 12.086575] stack backtrace:
[ 12.091124] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-next-20150831 #1154
[ 12.098609] Hardware name: Generic AM43 (Flattened Device Tree)
[ 12.104807] [<c001770c>] (unwind_backtrace) from [<c0013a58>] (show_stack+0x10/0x14)
[ 12.112924] [<c0013a58>] (show_stack) from [<c034f014>] (dump_stack+0x84/0x9c)
[ 12.120491] [<c034f014>] (dump_stack) from [<c0317a04>] (verify_new_ex+0xc4/0xdc)
[ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
[ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
[ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
[ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
[ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
[ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
[ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
Fix it by making sure rcu_read_lock() is held
around calls to parent_has_perm().
Signed-off-by: Felipe Balbi <balbi@ti.com>
---
Changes since v1:
- move rcu_read_lock/unlock to wrap parent_has_perm()
security/device_cgroup.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 73455089feef..dd77ed206fa4 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -608,6 +608,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
int count, rc = 0;
struct dev_exception_item ex;
struct dev_cgroup *parent = css_to_devcgroup(devcgroup->css.parent);
+ int ret;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -734,7 +735,11 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
break;
}
- if (!parent_has_perm(devcgroup, &ex))
+ rcu_read_lock();
+ ret = parent_has_perm(devcgroup, &ex);
+ rcu_read_unlock();
+
+ if (!ret)
return -EPERM;
rc = dev_exception_add(devcgroup, &ex);
break;
--
2.5.0
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-02 13:12 ` [PATCH v2] " Felipe Balbi
@ 2015-09-02 15:27 ` Josh Boyer
2015-09-02 16:24 ` Tejun Heo
1 sibling, 0 replies; 13+ messages in thread
From: Josh Boyer @ 2015-09-02 15:27 UTC (permalink / raw)
To: Felipe Balbi
Cc: James Morris, Serge E. Hallyn, linux-security-module,
Linux-Kernel@Vger. Kernel. Org, Linux OMAP Mailing List
On Wed, Sep 2, 2015 at 9:12 AM, Felipe Balbi <balbi@ti.com> wrote:
> while booting AM437x device, the following splat
> triggered:
>
> [ 12.005238] ===============================
> [ 12.009749] [ INFO: suspicious RCU usage. ]
> [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> [ 12.019050] -------------------------------
> [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> [ 12.033576] other info that might help us debug this:
>
> [ 12.041942] rcu_scheduler_active = 1, debug_locks = 0
> [ 12.048796] 4 locks held by systemd/1:
> [ 12.052700] #0: (sb_writers#7){.+.+.+}, at: [<c017af84>] __sb_start_write+0x8c/0xb0
> [ 12.060954] #1: (&of->mutex){+.+.+.}, at: [<c01f1600>] kernfs_fop_write+0x50/0x1b8
> [ 12.069085] #2: (s_active#30){++++.+}, at: [<c01f1608>] kernfs_fop_write+0x58/0x1b8
> [ 12.077310] #3: (devcgroup_mutex){+.+...}, at: [<c0317bfc>] devcgroup_access_write+0x20/0x658
> [ 12.086575] stack backtrace:
> [ 12.091124] CPU: 0 PID: 1 Comm: systemd Not tainted 4.2.0-next-20150831 #1154
> [ 12.098609] Hardware name: Generic AM43 (Flattened Device Tree)
> [ 12.104807] [<c001770c>] (unwind_backtrace) from [<c0013a58>] (show_stack+0x10/0x14)
> [ 12.112924] [<c0013a58>] (show_stack) from [<c034f014>] (dump_stack+0x84/0x9c)
> [ 12.120491] [<c034f014>] (dump_stack) from [<c0317a04>] (verify_new_ex+0xc4/0xdc)
> [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
>
> Fix it by making sure rcu_read_lock() is held
> around calls to parent_has_perm().
>
> Signed-off-by: Felipe Balbi <balbi@ti.com>
This cleared up the splat on all my machines and I don't see any other
side effects (even with lockdep enabled). Thanks!
Tested-by: Josh Boyer <jwboyer@fedoraproject.org>
josh
> ---
>
> Changes since v1:
> - move rcu_read_lock/unlock to wrap parent_has_perm()
>
> security/device_cgroup.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 73455089feef..dd77ed206fa4 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -608,6 +608,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
> int count, rc = 0;
> struct dev_exception_item ex;
> struct dev_cgroup *parent = css_to_devcgroup(devcgroup->css.parent);
> + int ret;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -734,7 +735,11 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
> break;
> }
>
> - if (!parent_has_perm(devcgroup, &ex))
> + rcu_read_lock();
> + ret = parent_has_perm(devcgroup, &ex);
> + rcu_read_unlock();
> +
> + if (!ret)
> return -EPERM;
> rc = dev_exception_add(devcgroup, &ex);
> break;
> --
> 2.5.0
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-02 13:12 ` [PATCH v2] " Felipe Balbi
2015-09-02 15:27 ` Josh Boyer
@ 2015-09-02 16:24 ` Tejun Heo
2015-09-03 0:14 ` Paul E. McKenney
1 sibling, 1 reply; 13+ messages in thread
From: Tejun Heo @ 2015-09-02 16:24 UTC (permalink / raw)
To: Felipe Balbi
Cc: James Morris, serge, linux-security-module, linux-kernel,
Linux OMAP Mailing List, Paul E. McKenney
cc'ing Paul.
On Wed, Sep 02, 2015 at 08:12:28AM -0500, Felipe Balbi wrote:
> while booting AM437x device, the following splat
> triggered:
>
> [ 12.005238] ===============================
> [ 12.009749] [ INFO: suspicious RCU usage. ]
> [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> [ 12.019050] -------------------------------
> [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
...
> [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
This shouldn't be happening because devcgroup_access_write() always
grabs devcgroup_mutex. Looking at the log, the culprit seems to be
f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to
RCU_LOCKDEP_WARN()"). It missed the bang for the second test while
inverting it, so adding rcu_read_lock() isn't the right fix here.
Paul, can you please fix it?
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-02 16:24 ` Tejun Heo
@ 2015-09-03 0:14 ` Paul E. McKenney
2015-09-03 13:48 ` Serge E. Hallyn
2015-09-03 13:56 ` Josh Boyer
0 siblings, 2 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-09-03 0:14 UTC (permalink / raw)
To: Tejun Heo
Cc: Felipe Balbi, James Morris, serge, linux-security-module,
linux-kernel, Linux OMAP Mailing List
On Wed, Sep 02, 2015 at 12:24:50PM -0400, Tejun Heo wrote:
> cc'ing Paul.
>
> On Wed, Sep 02, 2015 at 08:12:28AM -0500, Felipe Balbi wrote:
> > while booting AM437x device, the following splat
> > triggered:
> >
> > [ 12.005238] ===============================
> > [ 12.009749] [ INFO: suspicious RCU usage. ]
> > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> > [ 12.019050] -------------------------------
> > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> ...
> > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
>
> This shouldn't be happening because devcgroup_access_write() always
> grabs devcgroup_mutex. Looking at the log, the culprit seems to be
> f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to
> RCU_LOCKDEP_WARN()"). It missed the bang for the second test while
> inverting it, so adding rcu_read_lock() isn't the right fix here.
>
> Paul, can you please fix it?
Gah! Please see below.
Thanx, Paul
------------------------------------------------------------------------
security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition
f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()")
introduced a bug by incorrectly inverting the condition when moving from
rcu_lockdep_assert() to RCU_LOCKDEP_WARN(). This commit therefore fixes
the inversion.
Reported-by: Felipe Balbi <balbi@ti.com>
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Serge Hallyn <serge@hallyn.com>
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 73455089feef..03c1652c9a1f 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -401,7 +401,7 @@ static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
bool match = false;
RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
- lockdep_is_held(&devcgroup_mutex),
+ !lockdep_is_held(&devcgroup_mutex),
"device_cgroup:verify_new_ex called without proper synchronization");
if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-03 0:14 ` Paul E. McKenney
@ 2015-09-03 13:48 ` Serge E. Hallyn
2015-09-04 1:14 ` Paul E. McKenney
2015-09-03 13:56 ` Josh Boyer
1 sibling, 1 reply; 13+ messages in thread
From: Serge E. Hallyn @ 2015-09-03 13:48 UTC (permalink / raw)
To: Paul E. McKenney
Cc: Tejun Heo, Felipe Balbi, James Morris, serge,
linux-security-module, linux-kernel, Linux OMAP Mailing List
On Wed, Sep 02, 2015 at 05:14:33PM -0700, Paul E. McKenney wrote:
> On Wed, Sep 02, 2015 at 12:24:50PM -0400, Tejun Heo wrote:
> > cc'ing Paul.
> >
> > On Wed, Sep 02, 2015 at 08:12:28AM -0500, Felipe Balbi wrote:
> > > while booting AM437x device, the following splat
> > > triggered:
> > >
> > > [ 12.005238] ===============================
> > > [ 12.009749] [ INFO: suspicious RCU usage. ]
> > > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> > > [ 12.019050] -------------------------------
> > > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> > ...
> > > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> > > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> > > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> > > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> > > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> > > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> > > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
> >
> > This shouldn't be happening because devcgroup_access_write() always
> > grabs devcgroup_mutex. Looking at the log, the culprit seems to be
> > f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to
> > RCU_LOCKDEP_WARN()"). It missed the bang for the second test while
> > inverting it, so adding rcu_read_lock() isn't the right fix here.
> >
> > Paul, can you please fix it?
>
> Gah! Please see below.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition
>
> f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()")
> introduced a bug by incorrectly inverting the condition when moving from
> rcu_lockdep_assert() to RCU_LOCKDEP_WARN(). This commit therefore fixes
> the inversion.
>
> Reported-by: Felipe Balbi <balbi@ti.com>
> Reported-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Serge Hallyn <serge@hallyn.com>
Oh, makes sense :) (didn't see the original patch when it came by, sorry)
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 73455089feef..03c1652c9a1f 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -401,7 +401,7 @@ static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
> bool match = false;
>
> RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
> - lockdep_is_held(&devcgroup_mutex),
> + !lockdep_is_held(&devcgroup_mutex),
> "device_cgroup:verify_new_ex called without proper synchronization");
>
> if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-03 0:14 ` Paul E. McKenney
2015-09-03 13:48 ` Serge E. Hallyn
@ 2015-09-03 13:56 ` Josh Boyer
2015-09-04 1:15 ` Paul E. McKenney
1 sibling, 1 reply; 13+ messages in thread
From: Josh Boyer @ 2015-09-03 13:56 UTC (permalink / raw)
To: Paul McKenney
Cc: Tejun Heo, Felipe Balbi, James Morris, Serge E. Hallyn,
linux-security-module, Linux-Kernel@Vger. Kernel. Org,
Linux OMAP Mailing List
On Wed, Sep 2, 2015 at 8:14 PM, Paul E. McKenney
<paulmck@linux.vnet.ibm.com> wrote:
> On Wed, Sep 02, 2015 at 12:24:50PM -0400, Tejun Heo wrote:
>> cc'ing Paul.
>>
>> On Wed, Sep 02, 2015 at 08:12:28AM -0500, Felipe Balbi wrote:
>> > while booting AM437x device, the following splat
>> > triggered:
>> >
>> > [ 12.005238] ===============================
>> > [ 12.009749] [ INFO: suspicious RCU usage. ]
>> > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
>> > [ 12.019050] -------------------------------
>> > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
>> ...
>> > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
>> > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
>> > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
>> > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
>> > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
>> > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
>> > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
>>
>> This shouldn't be happening because devcgroup_access_write() always
>> grabs devcgroup_mutex. Looking at the log, the culprit seems to be
>> f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to
>> RCU_LOCKDEP_WARN()"). It missed the bang for the second test while
>> inverting it, so adding rcu_read_lock() isn't the right fix here.
>>
>> Paul, can you please fix it?
>
> Gah! Please see below.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition
>
> f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()")
> introduced a bug by incorrectly inverting the condition when moving from
> rcu_lockdep_assert() to RCU_LOCKDEP_WARN(). This commit therefore fixes
> the inversion.
>
> Reported-by: Felipe Balbi <balbi@ti.com>
> Reported-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Serge Hallyn <serge@hallyn.com>
Just tested this patch without Felipe's previous version on all my
machines. The splat is indeed gone.
Tested-by: Josh Boyer <jwboyer@fedoraproject.org>
josh
>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 73455089feef..03c1652c9a1f 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -401,7 +401,7 @@ static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
> bool match = false;
>
> RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
> - lockdep_is_held(&devcgroup_mutex),
> + !lockdep_is_held(&devcgroup_mutex),
> "device_cgroup:verify_new_ex called without proper synchronization");
>
> if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-03 13:48 ` Serge E. Hallyn
@ 2015-09-04 1:14 ` Paul E. McKenney
0 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-09-04 1:14 UTC (permalink / raw)
To: Serge E. Hallyn
Cc: Tejun Heo, Felipe Balbi, James Morris, linux-security-module,
linux-kernel, Linux OMAP Mailing List
On Thu, Sep 03, 2015 at 08:48:39AM -0500, Serge E. Hallyn wrote:
> On Wed, Sep 02, 2015 at 05:14:33PM -0700, Paul E. McKenney wrote:
> > On Wed, Sep 02, 2015 at 12:24:50PM -0400, Tejun Heo wrote:
> > > cc'ing Paul.
> > >
> > > On Wed, Sep 02, 2015 at 08:12:28AM -0500, Felipe Balbi wrote:
> > > > while booting AM437x device, the following splat
> > > > triggered:
> > > >
> > > > [ 12.005238] ===============================
> > > > [ 12.009749] [ INFO: suspicious RCU usage. ]
> > > > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> > > > [ 12.019050] -------------------------------
> > > > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> > > ...
> > > > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> > > > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> > > > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> > > > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> > > > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> > > > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> > > > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
> > >
> > > This shouldn't be happening because devcgroup_access_write() always
> > > grabs devcgroup_mutex. Looking at the log, the culprit seems to be
> > > f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to
> > > RCU_LOCKDEP_WARN()"). It missed the bang for the second test while
> > > inverting it, so adding rcu_read_lock() isn't the right fix here.
> > >
> > > Paul, can you please fix it?
> >
> > Gah! Please see below.
> >
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition
> >
> > f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()")
> > introduced a bug by incorrectly inverting the condition when moving from
> > rcu_lockdep_assert() to RCU_LOCKDEP_WARN(). This commit therefore fixes
> > the inversion.
> >
> > Reported-by: Felipe Balbi <balbi@ti.com>
> > Reported-by: Tejun Heo <tj@kernel.org>
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > Cc: Serge Hallyn <serge@hallyn.com>
>
> Oh, makes sense :) (didn't see the original patch when it came by, sorry)
I should have CCed you, apologies for failing to do so.
> Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Added, thank you!
Thanx, Paul
> > diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> > index 73455089feef..03c1652c9a1f 100644
> > --- a/security/device_cgroup.c
> > +++ b/security/device_cgroup.c
> > @@ -401,7 +401,7 @@ static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
> > bool match = false;
> >
> > RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
> > - lockdep_is_held(&devcgroup_mutex),
> > + !lockdep_is_held(&devcgroup_mutex),
> > "device_cgroup:verify_new_ex called without proper synchronization");
> >
> > if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
>
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] security: device_cgroup: fix RCU lockdep splat
2015-09-03 13:56 ` Josh Boyer
@ 2015-09-04 1:15 ` Paul E. McKenney
0 siblings, 0 replies; 13+ messages in thread
From: Paul E. McKenney @ 2015-09-04 1:15 UTC (permalink / raw)
To: Josh Boyer
Cc: Tejun Heo, Felipe Balbi, James Morris, Serge E. Hallyn,
linux-security-module, Linux-Kernel@Vger. Kernel. Org,
Linux OMAP Mailing List
On Thu, Sep 03, 2015 at 09:56:05AM -0400, Josh Boyer wrote:
> On Wed, Sep 2, 2015 at 8:14 PM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
> > On Wed, Sep 02, 2015 at 12:24:50PM -0400, Tejun Heo wrote:
> >> cc'ing Paul.
> >>
> >> On Wed, Sep 02, 2015 at 08:12:28AM -0500, Felipe Balbi wrote:
> >> > while booting AM437x device, the following splat
> >> > triggered:
> >> >
> >> > [ 12.005238] ===============================
> >> > [ 12.009749] [ INFO: suspicious RCU usage. ]
> >> > [ 12.014116] 4.2.0-next-20150831 #1154 Not tainted
> >> > [ 12.019050] -------------------------------
> >> > [ 12.023408] security/device_cgroup.c:405 device_cgroup:verify_new_ex called without proper synchronization!
> >> ...
> >> > [ 12.128326] [<c0317a04>] (verify_new_ex) from [<c0317f50>] (devcgroup_access_write+0x374/0x658)
> >> > [ 12.137426] [<c0317f50>] (devcgroup_access_write) from [<c00d2800>] (cgroup_file_write+0x28/0x1bc)
> >> > [ 12.146796] [<c00d2800>] (cgroup_file_write) from [<c01f1670>] (kernfs_fop_write+0xc0/0x1b8)
> >> > [ 12.155620] [<c01f1670>] (kernfs_fop_write) from [<c0177c94>] (__vfs_write+0x1c/0xd8)
> >> > [ 12.163783] [<c0177c94>] (__vfs_write) from [<c0178594>] (vfs_write+0x90/0x16c)
> >> > [ 12.171426] [<c0178594>] (vfs_write) from [<c0178db4>] (SyS_write+0x44/0x9c)
> >> > [ 12.178806] [<c0178db4>] (SyS_write) from [<c000f680>] (ret_fast_syscall+0x0/0x1c)
> >>
> >> This shouldn't be happening because devcgroup_access_write() always
> >> grabs devcgroup_mutex. Looking at the log, the culprit seems to be
> >> f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to
> >> RCU_LOCKDEP_WARN()"). It missed the bang for the second test while
> >> inverting it, so adding rcu_read_lock() isn't the right fix here.
> >>
> >> Paul, can you please fix it?
> >
> > Gah! Please see below.
> >
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition
> >
> > f78f5b90c4ff ("rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()")
> > introduced a bug by incorrectly inverting the condition when moving from
> > rcu_lockdep_assert() to RCU_LOCKDEP_WARN(). This commit therefore fixes
> > the inversion.
> >
> > Reported-by: Felipe Balbi <balbi@ti.com>
> > Reported-by: Tejun Heo <tj@kernel.org>
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > Cc: Serge Hallyn <serge@hallyn.com>
>
> Just tested this patch without Felipe's previous version on all my
> machines. The splat is indeed gone.
>
> Tested-by: Josh Boyer <jwboyer@fedoraproject.org>
Thank you, added!
Thanx, Paul
> josh
>
> >
> > diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> > index 73455089feef..03c1652c9a1f 100644
> > --- a/security/device_cgroup.c
> > +++ b/security/device_cgroup.c
> > @@ -401,7 +401,7 @@ static bool verify_new_ex(struct dev_cgroup *dev_cgroup,
> > bool match = false;
> >
> > RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
> > - lockdep_is_held(&devcgroup_mutex),
> > + !lockdep_is_held(&devcgroup_mutex),
> > "device_cgroup:verify_new_ex called without proper synchronization");
> >
> > if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) {
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
>
^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2015-09-04 1:15 UTC | newest]
Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-08-31 20:40 [PATCH] security: device_cgroup: fix RCU lockdep splat Felipe Balbi
2015-09-01 9:12 ` Sebastian Ott
2015-09-01 13:08 ` Felipe Balbi
2015-09-02 12:29 ` Josh Boyer
2015-09-02 12:56 ` Felipe Balbi
2015-09-02 13:12 ` [PATCH v2] " Felipe Balbi
2015-09-02 15:27 ` Josh Boyer
2015-09-02 16:24 ` Tejun Heo
2015-09-03 0:14 ` Paul E. McKenney
2015-09-03 13:48 ` Serge E. Hallyn
2015-09-04 1:14 ` Paul E. McKenney
2015-09-03 13:56 ` Josh Boyer
2015-09-04 1:15 ` Paul E. McKenney
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