Messages in this thread |  | | Subject | Re: [PATCH] prevent timespec/timeval to ktime_t overflow | | From | Thomas Gleixner <> | | Date | Sat, 02 Sep 2006 20:41:33 +0200 |
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On Fri, 2006-09-01 at 20:13 -0700, Andrew Morton wrote: > > Fun, here is a version with a bigabyte blocker. > > Your patch triggers waaaaaaay early. > > netconsole: remote IP 192.168.2.33 > netconsole: remote ethernet address 00:0d:56:c6:c6:cc > Initializing CPU#0 > PID hash table entries: 4096 (order: 12, 32768 bytes) > time.c: Using 14.318180 MHz WALL HPET GTOD HPET/TSC timer. > time.c: Detected 3400.238 MHz processor. > ktime_set: -1157140842 : 0
-------------^ !!!!!!!
> BUG: warning at include/linux/ktime.h:84/ktime_set() > > Call Trace: > <IRQ> [<ffffffff80247021>] hrtimer_run_queues+0x10e/0x211
This seems to happen inside hrtimer_get_softirq_time(). wall_to_monotonic is negative.
Why does the check trigger ? We compare a "long", which contains a negative value against some positive constant.
ktime_t ktime_set(const long secs, const unsigned long nsecs) { if (unlikely(secs >= KTIME_SEC_MAX)) {
where KTIME_SEC_MAX is 0x7FFFFFFFFFFFFFFF / 1000 000 000 =
9223372036 == 0x225C17D04,
which is compared against
-1157140842 == 0xFFFFFFFFBB076E96
This smells like gcc magic. Can you please disassemble the code in question ?
> I wonder if this is related to the occasional hrtimr_run_queues() lockup > which Andi is encountering.
Hmm, not sure.
tglx
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