Re: [PATCH] make lockdep happy with r/o bind mounts
On Mon, 24 Sep 2007 10:46:58 -0700 Dave Hansen <[EMAIL PROTECTED]>
wrote:
>
> With the r/o bind mount patches, we can have as many
> spinlocks nested as there are CPUs on the system.
> Lockdep freaks out after 8.
>
> So, create a new lockdep class of locks for the
> mnt_writer spinlocks, and initialize each of the
> cpu locks to be in a different class.
>
> It should shut up warnings like this, while still
> allowing some of the lockdep goodness to remain:
>
> =
> [ INFO: possible recursive locking detected ]
> 2.6.23-rc6 #6
> -
> swapper/1 is trying to acquire lock:
> (>lock){--..}, at: []
> lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
>
> but task is already holding lock:
> (>lock){--..}, at: []
> lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
>
> other info that might help us debug this:
> 1 lock held by swapper/1:
> #0: (>lock){--..}, at: []
> lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
>
> stack backtrace:
> [] show_trace_log_lvl+0x19/0x2e
> [] show_trace+0x12/0x14
> [] dump_stack+0x14/0x16
> [] print_deadlock_bug+0xb7/0xc1
> [] check_deadlock+0x40/0x54
> [] validate_chain+0x26e/0x319
> [] __lock_acquire+0x6c4/0x731
> [] lock_acquire+0x7a/0x94
> [] _spin_lock+0x38/0x62
> [] lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
> [] mntput_no_expire+0x38/0xad
> [] path_release_on_umount+0x15/0x18
> [] sys_umount+0x67/0x6f
> [] name_to_dev_t+0x22a/0x24c
> [] prepare_namespace+0x89/0x187
> [] kernel_init+0x9a/0xa3
> [] kernel_thread_helper+0x7/0x10
> ===
>
> Signed-off-by: Dave Hansen <[EMAIL PROTECTED]>
Acked-by: Peter Zijlstra <[EMAIL PROTECTED]>
> ---
>
> lxc-dave/fs/namespace.c |2 ++
> 1 file changed, 2 insertions(+)
>
> diff -puN fs/namespace.c~make-lockdep-happy-with-ro-bind-mounts fs/namespace.c
> --- lxc/fs/namespace.c~make-lockdep-happy-with-ro-bind-mounts 2007-09-24
> 10:32:23.0 -0700
> +++ lxc-dave/fs/namespace.c 2007-09-24 10:41:37.0 -0700
> @@ -116,6 +116,7 @@ struct mnt_writer {
>* must be ordered by cpu number.
>*/
> spinlock_t lock;
> + struct lock_class_key lock_class; /* compiles out with !lockdep */
> unsigned long count;
> struct vfsmount *mnt;
> } cacheline_aligned_in_smp;
> @@ -127,6 +128,7 @@ static int __init init_mnt_writers(void)
> for_each_possible_cpu(cpu) {
> struct mnt_writer *writer = _cpu(mnt_writers, cpu);
> spin_lock_init(>lock);
> + lockdep_set_class(>lock, >lock_class);
> writer->count = 0;
> }
> return 0;
> diff -puN include/linux/lockdep.h~make-lockdep-happy-with-ro-bind-mounts
> include/linux/lockdep.h
> _
-
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Re: [PATCH] make lockdep happy with r/o bind mounts
On Mon, 24 Sep 2007 10:46:58 -0700 Dave Hansen <[EMAIL PROTECTED]> wrote: > > With the r/o bind mount patches, we can have as many > spinlocks nested as there are CPUs on the system. > Lockdep freaks out after 8. The patch implements the right solution for this "invent your own lock" situation... Acked-by: Arjan van de Ven <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] make lockdep happy with r/o bind mounts
On Mon, 24 Sep 2007 10:46:58 -0700 Dave Hansen [EMAIL PROTECTED] wrote: With the r/o bind mount patches, we can have as many spinlocks nested as there are CPUs on the system. Lockdep freaks out after 8. The patch implements the right solution for this invent your own lock situation... Acked-by: Arjan van de Ven [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] make lockdep happy with r/o bind mounts
On Mon, 24 Sep 2007 10:46:58 -0700 Dave Hansen [EMAIL PROTECTED]
wrote:
With the r/o bind mount patches, we can have as many
spinlocks nested as there are CPUs on the system.
Lockdep freaks out after 8.
So, create a new lockdep class of locks for the
mnt_writer spinlocks, and initialize each of the
cpu locks to be in a different class.
It should shut up warnings like this, while still
allowing some of the lockdep goodness to remain:
=
[ INFO: possible recursive locking detected ]
2.6.23-rc6 #6
-
swapper/1 is trying to acquire lock:
(writer-lock){--..}, at: [c016c094]
lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
but task is already holding lock:
(writer-lock){--..}, at: [c016c094]
lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
other info that might help us debug this:
1 lock held by swapper/1:
#0: (writer-lock){--..}, at: [c016c094]
lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
stack backtrace:
[c01034ab] show_trace_log_lvl+0x19/0x2e
[c01034d2] show_trace+0x12/0x14
[c01035be] dump_stack+0x14/0x16
[c0130ab2] print_deadlock_bug+0xb7/0xc1
[c0130afc] check_deadlock+0x40/0x54
[c013100a] validate_chain+0x26e/0x319
[c0132cca] __lock_acquire+0x6c4/0x731
[c01332da] lock_acquire+0x7a/0x94
[c031bb01] _spin_lock+0x38/0x62
[c016c094] lock_and_coalesce_cpu_mnt_writer_counts+0x29/0x5c
[c016c5f8] mntput_no_expire+0x38/0xad
[c015fbed] path_release_on_umount+0x15/0x18
[c016cc76] sys_umount+0x67/0x6f
[c010058a] name_to_dev_t+0x22a/0x24c
[c0427207] prepare_namespace+0x89/0x187
[c0426cdd] kernel_init+0x9a/0xa3
[c010336f] kernel_thread_helper+0x7/0x10
===
Signed-off-by: Dave Hansen [EMAIL PROTECTED]
Acked-by: Peter Zijlstra [EMAIL PROTECTED]
---
lxc-dave/fs/namespace.c |2 ++
1 file changed, 2 insertions(+)
diff -puN fs/namespace.c~make-lockdep-happy-with-ro-bind-mounts fs/namespace.c
--- lxc/fs/namespace.c~make-lockdep-happy-with-ro-bind-mounts 2007-09-24
10:32:23.0 -0700
+++ lxc-dave/fs/namespace.c 2007-09-24 10:41:37.0 -0700
@@ -116,6 +116,7 @@ struct mnt_writer {
* must be ordered by cpu number.
*/
spinlock_t lock;
+ struct lock_class_key lock_class; /* compiles out with !lockdep */
unsigned long count;
struct vfsmount *mnt;
} cacheline_aligned_in_smp;
@@ -127,6 +128,7 @@ static int __init init_mnt_writers(void)
for_each_possible_cpu(cpu) {
struct mnt_writer *writer = per_cpu(mnt_writers, cpu);
spin_lock_init(writer-lock);
+ lockdep_set_class(writer-lock, writer-lock_class);
writer-count = 0;
}
return 0;
diff -puN include/linux/lockdep.h~make-lockdep-happy-with-ro-bind-mounts
include/linux/lockdep.h
_
-
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