Messages in this thread Patch in this message | | | Date | Sat, 24 Jun 2006 23:48:53 +0200 | From | Ingo Molnar <> | Subject | [patch, 2.6.17-mm2] fix acct_collect() siglock bug |
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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@elte.hu>
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@elte.hu> --- 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); } /** - 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/
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