On Tue, 24 Jul 2007, Oleg Nesterov wrote:
On 07/23, Jeremy Katz wrote:
On Fri, 20 Jul 2007, Oleg Nesterov wrote:
I still can't believe we have a double-free problem, this looks imposiible.
Do you see the
"idr_remove called for id=%d which is not allocated.\n"
in syslog?
No. I also added some accounting with atomic counters, and don't see
evidence of a second call to release_posix_timer.
Interesting. Could you show the patch? Where does sys_timer_create() set
counter == 1?
--- kernel/posix-timers.c.old 2007-07-24 11:21:29.000000000 -0700
+++ kernel/posix-timers.c 2007-07-20 15:49:51.000000000 -0700
@@ -409,13 +409,17 @@ static struct k_itimer * alloc_posix_tim
#define IT_ID_NOT_SET 0
static void release_posix_timer(struct k_itimer *tmr, int it_id_set)
{
+ atomic_inc(&tmr->freecount);
@@ -443,6 +447,7 @@ sys_timer_create(const clockid_t which_c
new_timer = alloc_posix_timer();
if (unlikely(!new_timer))
return -EAGAIN;
+ atomic_set(&new_timer->freecount, 0);
--- include/linux/posix-timers.h.old 2007-07-24 11:32:36.000000000 -0700
+++ include/linux/posix-timers.h 2007-07-20 15:15:44.000000000 -0700
@@ -62,6 +62,7 @@ struct k_itimer {
unsigned long expires;
} mmtimer;
} it;
+ atomic_t freecount;
};
struct k_clock {
Examination was done through a kgdb session when it caught the bug.
freecount always had the expected value, 1 during a delete operation,
and 0 otherwise.
Could you try the patch below? Perhaps we have some wierd problem with
->sigq corruption.
Tried, with apparent effect.
You mean, "null pointer dereference" in release_posix_timer() ? Or it was
BUG_ON(timr && !timr->sigq) in lock_timer() ?
Sorry. That should have been "without apparent effect".
I assume you didn't apply any other patches except Thomas's, yes?
Alone, as well as with Thomas' patch. Neither way changed the behavior.
Jeremy
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