* [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 [-- Attachment #2: Digital signature --] [-- Type: application/pgp-signature, Size: 819 bytes --] ^ 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 [-- Attachment #2: Digital signature --] [-- 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 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 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 13:56 ` 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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