The patch titled
lockdep: fix delayacct locking bug
has been added to the -mm tree. Its filename is
lockdep-fix-delayacct-locking-bug.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: lockdep: fix delayacct locking bug
From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
======================================================
[ INFO: soft-safe -> soft-unsafe lock order detected ]
2.6.19-rc4 #1
------------------------------------------------------
mm_tester/1875 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
(&tsk->delays->lock){--..}, at: [<c0156652>] __delayacct_add_tsk+0x131/0x1d3
and this task is already holding:
(&sighand->siglock){.+..}, at: [<c0156b69>] taskstats_exit_send+0x52/0x3b2
which would create a new lock dependency:
(&sighand->siglock){.+..} -> (&tsk->delays->lock){--..}
but this new dependency connects a soft-irq-safe lock:
(&sighand->siglock){.+..}
... which became soft-irq-safe at:
[<c013d0da>] mark_lock+0x5c/0x38c
[<c013de51>] __lock_acquire+0x348/0x971
[<c013ea35>] lock_acquire+0x5c/0x77
[<c032132d>] _spin_lock_irqsave+0x3c/0x4b
[<c012fda9>] lock_task_sighand+0x1f/0x3c
[<c01309fd>] group_send_sig_info+0x25/0x56
[<c0130a4c>] send_group_sig_info+0x1e/0x30
[<c012a7c6>] it_real_fn+0x1d/0x5f
[<c013a453>] hrtimer_run_queues+0xf2/0x14a
[<c012e4fa>] run_timer_softirq+0x20/0x166
[<c012b307>] __do_softirq+0x6b/0xe6
[<c0106279>] do_softirq+0x61/0xd1
[<ffffffff>] 0xffffffff
to a soft-irq-unsafe lock:
(&tsk->delays->lock){--..}
... which became soft-irq-unsafe at:
... [<c013d0da>] mark_lock+0x5c/0x38c
[<c013deec>] __lock_acquire+0x3e3/0x971
[<c013ea35>] lock_acquire+0x5c/0x77
[<c032108a>] _spin_lock+0x33/0x3e
[<c015642b>] delayacct_end+0x58/0x7b
[<c015651e>] __delayacct_blkio_end+0x37/0x3a
[<c0157c0f>] sync_page+0x38/0x3b
[<c031f920>] __wait_on_bit_lock+0x2a/0x52
[<c0157bc9>] __lock_page+0x5b/0x61
[<c0159bc9>] read_cache_page+0xea/0x13a
[<c01abc05>] read_dev_sector+0x2e/0x84
[<c01ad364>] read_lba+0x5c/0xc0
[<c01ad602>] efi_partition+0x8f/0x6ed
[<c01abf3f>] rescan_partitions+0x106/0x20b
[<c019655b>] do_open+0x2aa/0x3ae
[<c01966b4>] blkdev_get+0x55/0x60
[<c01abdd7>] register_disk+0x17c/0x1de
[<c01e1810>] add_disk+0x36/0x41
[<c02775a7>] ide_disk_probe+0x8ef/0x918
[<c026b40f>] generic_ide_probe+0x1f/0x20
[<c02586a3>] really_probe+0x39/0xda
[<c02588cb>] __driver_attach+0x69/0xa1
[<c0257dbe>] bus_for_each_dev+0x3a/0x5c
[<c02585c3>] driver_attach+0x16/0x18
[<c0258092>] bus_add_driver+0x61/0x165
[<c010049b>] init+0x123/0x2d1
[<c0104be7>] kernel_thread_helper+0x7/0x10
[<ffffffff>] 0xffffffff
other info that might help us debug this:
<snip 607 lines of other output>
stack backtrace:
[<c0104eb6>] dump_trace+0x69/0x1b6
[<c010501b>] show_trace_log_lvl+0x18/0x2c
[<c010562e>] show_trace+0xf/0x11
[<c01056de>] dump_stack+0x15/0x17
[<c013d7f1>] check_usage+0x262/0x26c
[<c013e331>] __lock_acquire+0x828/0x971
[<c013ea35>] lock_acquire+0x5c/0x77
[<c032108a>] _spin_lock+0x33/0x3e
[<c0156652>] __delayacct_add_tsk+0x131/0x1d3
[<c0156b94>] taskstats_exit_send+0x7d/0x3b2
[<c01294ad>] do_exit+0x1f6/0x7f0
[<c0129b37>] complete_and_exit+0x0/0x13
[<c0103f5b>] syscall_call+0x7/0xb
DWARF2 unwinder stuck at syscall_call+0x7/0xb
Leftover inexact backtrace:
=======================
Make the delayacct lock irqsave; this avoids the possible deadlock where
an interrupt is taken while holding the delayacct lock which needs to take
the delayacct lock.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Cc: Shailabh Nagar <nagar@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/delayacct.c | 15 +++++++++------
1 files changed, 9 insertions(+), 6 deletions(-)
diff -puN kernel/delayacct.c~lockdep-fix-delayacct-locking-bug kernel/delayacct.c
--- a/kernel/delayacct.c~lockdep-fix-delayacct-locking-bug
+++ a/kernel/delayacct.c
@@ -66,6 +66,7 @@ static void delayacct_end(struct timespe
{
struct timespec ts;
s64 ns;
+ unsigned long flags;
do_posix_clock_monotonic_gettime(end);
ts = timespec_sub(*end, *start);
@@ -73,10 +74,10 @@ static void delayacct_end(struct timespe
if (ns < 0)
return;
- spin_lock(¤t->delays->lock);
+ spin_lock_irqsave(¤t->delays->lock, flags);
*total += ns;
(*count)++;
- spin_unlock(¤t->delays->lock);
+ spin_unlock_irqrestore(¤t->delays->lock, flags);
}
void __delayacct_blkio_start(void)
@@ -104,6 +105,7 @@ int __delayacct_add_tsk(struct taskstats
s64 tmp;
struct timespec ts;
unsigned long t1,t2,t3;
+ unsigned long flags;
/* Though tsk->delays accessed later, early exit avoids
* unnecessary returning of other data
@@ -136,14 +138,14 @@ int __delayacct_add_tsk(struct taskstats
/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
- spin_lock(&tsk->delays->lock);
+ spin_lock_irqsave(&tsk->delays->lock, flags);
tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
d->blkio_count += tsk->delays->blkio_count;
d->swapin_count += tsk->delays->swapin_count;
- spin_unlock(&tsk->delays->lock);
+ spin_unlock_irqrestore(&tsk->delays->lock, flags);
done:
return 0;
@@ -152,11 +154,12 @@ done:
__u64 __delayacct_blkio_ticks(struct task_struct *tsk)
{
__u64 ret;
+ unsigned long flags;
- spin_lock(&tsk->delays->lock);
+ spin_lock_irqsave(&tsk->delays->lock, flags);
ret = nsec_to_clock_t(tsk->delays->blkio_delay +
tsk->delays->swapin_delay);
- spin_unlock(&tsk->delays->lock);
+ spin_unlock_irqrestore(&tsk->delays->lock, flags);
return ret;
}
_
Patches currently in -mm which might be from a.p.zijlstra@xxxxxxxxx are
nfs4-fix-for-recursive-locking-problem.patch
lockdep-fix-delayacct-locking-bug.patch
bonding-lockdep-annotation.patch
lockdep-annotate-sk_lock-nesting-in-af_bluetooth-v2.patch
grab-swap-token-reordered.patch
new-scheme-to-preempt-swap-token.patch
new-scheme-to-preempt-swap-token-tidy.patch
mm-arch-do_page_fault-vs-in_atomic.patch
mm-pagefault_disableenable.patch
mm-pagefault_disableenable-s390-fix.patch
mm-kummap_atomic-vs-in_atomic.patch
lockdep-annotate-nfs-nfsd-in-kernel-sockets.patch
lockdep-annotate-nfs-nfsd-in-kernel-sockets-tidy.patch
lockdep-fix-ide-proc-interaction.patch
lockdep-spin_lock_irqsave_nested.patch
lockdep-spin_lock_irqsave_nested-fix.patch
lockdep-spin_lock_irqsave_nested-fix-2.patch
lockdep-annotate-bcsp-driver.patch
tty-signal-tty-locking.patch
tty-signal-tty-locking-3270-fix.patch
do_task_stat-dont-take-tty_mutex.patch
do_acct_process-dont-take-tty_mutex.patch
sys_unshare-remove-a-broken-clone_sighand-code.patch
remove-the-old-bd_mutex-lockdep-annotation.patch
new-bd_mutex-lockdep-annotation.patch
remove-lock_key-approach-to-managing-nested-bd_mutex-locks.patch
simplify-some-aspects-of-bd_mutex-nesting.patch
use-mutex_lock_nested-for-bd_mutex-to-avoid-lockdep-warning.patch
avoid-lockdep-warning-in-md.patch
bdev-fix-bd_part_count-leak.patch
lockdep-annotate-nfsd4-recover-code.patch
-
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