On Wed, 2003-06-11 at 17:24, Andrew Morton wrote:
> Do you know what the actual oops is?
I got it all figured out now.
It is a divide by zero in update_write_batch() called from
as_completed_request().
> Odd that starting the X server triggers it. Be interesting if your patch
> fixes things for Brian.
I reproduced it without X.
The divide by zero is on line 959 with the divide by 'write_time'. It
can obviously be zero (see line 950). The divide by 'batch' on line 953
seems safe.
The correct patch is below.
Most important question: why are only some of us seeing this?
Robert Love
Fix as-iosched divide-by-zero bug.
drivers/block/as-iosched.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff -urN linux-2.5.70-mm8/drivers/block/as-iosched.c linux/drivers/block/as-iosched.c
--- linux-2.5.70-mm8/drivers/block/as-iosched.c 2003-06-11 17:12:02.000000000 -0700
+++ linux/drivers/block/as-iosched.c 2003-06-11 18:04:15.222619392 -0700
@@ -954,9 +954,9 @@
ad->write_batch_count /= 2;
else
ad->write_batch_count--;
-
+
} else if (write_time + 5 < batch && ad->current_write_count == 0) {
- if (batch / write_time > 2)
+ if (write_time && (batch / write_time > 2))
ad->write_batch_count *= 2;
else
ad->write_batch_count++;
-
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