Re: 2.6.23.1: mdadm/raid5 hung/d-state

Chuck Ebbert
2007-11-07T16:40:00Z

On 11/05/2007 03:36 AM, BERTRAND Joël wrote:
> Neil Brown wrote:
>> On Sunday November 4, jpiszcz@lucidpixels.com wrote:
>>> # ps auxww | grep D
>>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
>>> root 273 0.0 0.0 0 0 ? D Oct21 14:40
>>> [pdflush]
>>> root 274 0.0 0.0 0 0 ? D Oct21 13:00
>>> [pdflush]
>>>
>>> After several days/weeks, this is the second time this has happened,
>>> while doing regular file I/O (decompressing a file), everything on
>>> the device went into D-state.
>>
>> At a guess (I haven't looked closely) I'd say it is the bug that was
>> meant to be fixed by
>>
>> commit 4ae3f847e49e3787eca91bced31f8fd328d50496
>>
>> except that patch applied badly and needed to be fixed with
>> the following patch (not in git yet).
>> These have been sent to stable@ and should be in the queue for 2.6.23.2
>
> My linux-2.6.23/drivers/md/raid5.c contains your patch for a long
> time :
>
> ...
> spin_lock(&sh->lock);
> clear_bit(STRIPE_HANDLE, &sh->state);
> clear_bit(STRIPE_DELAYED, &sh->state);
>
> s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
> s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
> s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
> /* Now to look around and see what can be done */
>
> /* clean-up completed biofill operations */
> if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
> clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
> clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
> clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
> }
>
> rcu_read_lock();
> for (i=disks; i--; ) {
> mdk_rdev_t *rdev;
> struct r5dev *dev = &sh->dev[i];
> ...
>
> but it doesn't fix this bug.
>

Did that chunk starting with "clean-up completed biofill operations" end
up where it belongs? The patch with the big context moves it to a different
place from where the original one puts it when applied to 2.6.23...

Lately I've seen several problems where the context isn't enough to make
a patch apply properly when some offsets have changed. In some cases a
patch won't apply at all because two nearly-identical areas are being
changed and the first chunk gets applied where the second one should,
leaving nowhere for the second chunk to apply.