[patch, 2.6.17-mm2] fix acct_collect() siglock bug
From: Ingo Molnar
Date: Sat Jun 24 2006 - 17:52:37 EST
the patch below fixes a siglock usage bug introduced in -mm2. The lock
validator found it during bootup.
---------------
Subject: fix acct_collect() siglock bug
From: Ingo Molnar <mingo@xxxxxxx>
the lock validator noticed the following bug:
=========================================================
[ INFO: possible irq lock inversion dependency detected ]
---------------------------------------------------------
swapper/0 just changed the state of lock:
(tasklist_lock){..-?}, at: [<c01247c8>] send_group_sig_info+0xe/0x2f
but this lock took another, soft-irq-unsafe lock in the past:
(&sighand->siglock){--..}
and interrupts could create inverse lock ordering between them.
...
-> (init_sighand.siglock){....} ops: 18 {
...
hardirq-on-W at:
[<c0130577>] lock_acquire+0x56/0x73
[<c03ec59c>] _spin_lock+0x24/0x32
[<c01374bd>] acct_collect+0x81/0x115
[<c011b4fa>] do_exit+0x19a/0x7b3
[<c01273ce>] ____call_usermodehelper+0xdf/0xe1
[<c01007f1>] kernel_thread_helper+0x5/0xb
it turns out that acct_collect() takes current->sighand->siglock
with interrupts enabled - a big no-no. Fix it by disabling
interrupts.
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/acct.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux/kernel/acct.c
===================================================================
--- linux.orig/kernel/acct.c
+++ linux/kernel/acct.c
@@ -549,7 +549,7 @@ void acct_collect(long exitcode, int gro
up_read(¤t->mm->mmap_sem);
}
- spin_lock(¤t->sighand->siglock);
+ spin_lock_irq(¤t->sighand->siglock);
if (group_dead)
pacct->ac_mem = vsize / 1024;
if (thread_group_leader(current)) {
@@ -567,7 +567,7 @@ void acct_collect(long exitcode, int gro
pacct->ac_stime = cputime_add(pacct->ac_stime, current->stime);
pacct->ac_minflt += current->min_flt;
pacct->ac_majflt += current->maj_flt;
- spin_unlock(¤t->sighand->siglock);
+ spin_unlock_irq(¤t->sighand->siglock);
}
/**
-
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