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Date: Sun, 31 Mar 2013 00:04:40 +0000 (UTC)
From: Paul Walmsley <paul@...an.com>
To: Mandeep Singh Baines <msb@...omium.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
cc: linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
Jeff Layton <jlayton@...hat.com>,
Shawn Guo <shawn.guo@...aro.org>, maciej.rutecki@...il.com,
Fengguang Wu <fengguang.wu@...el.com>,
Trond Myklebust <Trond.Myklebust@...app.com>,
Ingo Molnar <mingo@...hat.com>,
Ben Chan <benchan@...omium.org>,
Oleg Nesterov <oleg@...hat.com>, Tejun Heo <tj@...nel.org>,
"Rafael J. Wysocki" <rjw@...k.pl>
Subject: [PATCH] Revert "lockdep: check that no locks held at freeze time"
This reverts commit 6aa9707099c4b25700940eb3d016f16c4434360d.
Commit 6aa970 causes problems with NFS root filesystems. The failures
were noticed on OMAP2 and 3 boards during kernel init:
[ 5.508148] [ BUG: swapper/0/1 still has locks held! ]
[ 5.513610] 3.9.0-rc3-00344-ga937536 #1 Not tainted
[ 5.518798] -------------------------------------
[ 5.523773] 1 lock held by swapper/0/1:
[ 5.527893] #0: (&type->s_umount_key#13/1){+.+.+.}, at: [<c011e84c>] sget+0x248/0x574
[ 5.536437]
[ 5.536437] stack backtrace:
[ 5.541107] [<c001bba8>] (unwind_backtrace+0x0/0xf0) from [<c05304bc>] (rpc_wait_bit_killable+0x98/0xcc)
[ 5.551208] [<c05304bc>] (rpc_wait_bit_killable+0x98/0xcc) from [<c0551600>] (__wait_on_bit+0x74/0xb8)
[ 5.561096] [<c0551600>] (__wait_on_bit+0x74/0xb8) from [<c05516b0>] (out_of_line_wait_on_bit+0x6c/0x78)
[ 5.571166] [<c05516b0>] (out_of_line_wait_on_bit+0x6c/0x78) from [<c0530a0c>] (__rpc_execute+0xf0/0x360)
[ 5.581329] [<c0530a0c>] (__rpc_execute+0xf0/0x360) from [<c052a254>] (rpc_run_task+0x98/0xa4)
[ 5.590515] [<c052a254>] (rpc_run_task+0x98/0xa4) from [<c052a374>] (rpc_call_sync+0x48/0xb4)
[ 5.599578] [<c052a374>] (rpc_call_sync+0x48/0xb4) from [<c0234964>] (nfs_proc_get_root+0x48/0x124)
[ 5.609191] [<c0234964>] (nfs_proc_get_root+0x48/0x124) from [<c0227300>] (nfs_get_root+0x58/0x190)
[ 5.618804] [<c0227300>] (nfs_get_root+0x58/0x190) from [<c022abbc>] (nfs_fs_mount_common+0x98/0x158)
[ 5.628601] [<c022abbc>] (nfs_fs_mount_common+0x98/0x158) from [<c022b440>] (nfs_try_mount+0x144/0x214)
[ 5.638580] [<c022b440>] (nfs_try_mount+0x144/0x214) from [<c022c4e0>] (nfs_fs_mount+0x178/0x850)
[ 5.648010] [<c022c4e0>] (nfs_fs_mount+0x178/0x850) from [<c011f6e8>] (mount_fs+0x44/0x184)
[ 5.656860] [<c011f6e8>] (mount_fs+0x44/0x184) from [<c01384c4>] (vfs_kern_mount+0x4c/0xc0)
[ 5.665740] [<c01384c4>] (vfs_kern_mount+0x4c/0xc0) from [<c013a6d4>] (do_mount+0x6d0/0x858)
[ 5.674682] [<c013a6d4>] (do_mount+0x6d0/0x858) from [<c013a8e0>] (sys_mount+0x84/0xb8)
[ 5.683197] [<c013a8e0>] (sys_mount+0x84/0xb8) from [<c075faf0>] (do_mount_root+0x24/0xb0)
[ 5.691986] [<c075faf0>] (do_mount_root+0x24/0xb0) from [<c075fee4>] (mount_root+0x50/0xf8)
[ 5.700866] [<c075fee4>] (mount_root+0x50/0xf8) from [<c07600ec>] (prepare_namespace+0x160/0x1c4)
[ 5.710296] [<c07600ec>] (prepare_namespace+0x160/0x1c4) from [<c075f978>] (kernel_init_freeable+0x17c/0x1c4)
[ 5.720825] [<c075f978>] (kernel_init_freeable+0x17c/0x1c4) from [<c054b6c4>] (kernel_init+0x8/0xe4)
[ 5.730529] [<c054b6c4>] (kernel_init+0x8/0xe4) from [<c0013d90>] (ret_from_fork+0x14/0x24)
Although the rootfs mounts, the system is unstable. Here's a transcript from
a PM test:
http://www.pwsan.com/omap/testlogs/test_v3.9-rc3/20130317194234/pm/37xxevm/37xxevm_log.txt
Here's what the test log should look like:
http://www.pwsan.com/omap/testlogs/test_v3.8/20130218214403/pm/37xxevm/37xxevm_log.txt
Mailing list discussion is here:
http://lkml.org/lkml/2013/3/4/221
Deal with this for v3.9 by reverting the problem commit, until folks can
figure out the right long-term course of action.
Signed-off-by: Paul Walmsley <paul@...an.com>
Cc: Mandeep Singh Baines <msb@...omium.org>
Cc: Jeff Layton <jlayton@...hat.com>
Cc: Shawn Guo <shawn.guo@...aro.org>
Cc: <maciej.rutecki@...il.com>
Cc: Fengguang Wu <fengguang.wu@...el.com>
Cc: Trond Myklebust <Trond.Myklebust@...app.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Ben Chan <benchan@...omium.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Rafael J. Wysocki <rjw@...k.pl>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
---
include/linux/debug_locks.h | 4 ++--
include/linux/freezer.h | 3 ---
kernel/exit.c | 2 +-
kernel/lockdep.c | 17 +++++++++--------
4 files changed, 12 insertions(+), 14 deletions(-)
diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index a975de1..3bd46f7 100644
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -51,7 +51,7 @@ struct task_struct;
extern void debug_show_all_locks(void);
extern void debug_show_held_locks(struct task_struct *task);
extern void debug_check_no_locks_freed(const void *from, unsigned long len);
-extern void debug_check_no_locks_held(void);
+extern void debug_check_no_locks_held(struct task_struct *task);
#else
static inline void debug_show_all_locks(void)
{
@@ -67,7 +67,7 @@ debug_check_no_locks_freed(const void *from, unsigned long len)
}
static inline void
-debug_check_no_locks_held(void)
+debug_check_no_locks_held(struct task_struct *task)
{
}
#endif
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 043a5cf..e70df40 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -3,7 +3,6 @@
#ifndef FREEZER_H_INCLUDED
#define FREEZER_H_INCLUDED
-#include <linux/debug_locks.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/atomic.h>
@@ -49,8 +48,6 @@ extern void thaw_kernel_threads(void);
static inline bool try_to_freeze(void)
{
- if (!(current->flags & PF_NOFREEZE))
- debug_check_no_locks_held();
might_sleep();
if (likely(!freezing(current)))
return false;
diff --git a/kernel/exit.c b/kernel/exit.c
index 51e485c..60bc027 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -835,7 +835,7 @@ void do_exit(long code)
/*
* Make sure we are holding no locks:
*/
- debug_check_no_locks_held();
+ debug_check_no_locks_held(tsk);
/*
* We can do this unlocked here. The futex code uses this flag
* just to verify whether the pi state cleanup has been done
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 259db20..8a0efac 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -4088,7 +4088,7 @@ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
}
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
-static void print_held_locks_bug(void)
+static void print_held_locks_bug(struct task_struct *curr)
{
if (!debug_locks_off())
return;
@@ -4097,21 +4097,22 @@ static void print_held_locks_bug(void)
printk("\n");
printk("=====================================\n");
- printk("[ BUG: %s/%d still has locks held! ]\n",
- current->comm, task_pid_nr(current));
+ printk("[ BUG: lock held at task exit time! ]\n");
print_kernel_ident();
printk("-------------------------------------\n");
- lockdep_print_held_locks(current);
+ printk("%s/%d is exiting with locks still held!\n",
+ curr->comm, task_pid_nr(curr));
+ lockdep_print_held_locks(curr);
+
printk("\nstack backtrace:\n");
dump_stack();
}
-void debug_check_no_locks_held(void)
+void debug_check_no_locks_held(struct task_struct *task)
{
- if (unlikely(current->lockdep_depth > 0))
- print_held_locks_bug();
+ if (unlikely(task->lockdep_depth > 0))
+ print_held_locks_bug(task);
}
-EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
void debug_show_all_locks(void)
{
--
1.7.10.4
--
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