On Jan 22, 2014, at 10:29 AM, Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote:
>
> On Jan 22, 2014, at 7:19, Weston Andros Adamson <dros@xxxxxxxxxxxxxxx> wrote:
>
>> This might actually need a CC stable, although I’m not sure of the scope. It seems like it’s been this way for a while.
>>
>
> I’m assuming that if/when people hit it, they will ping us and ask for a push to stable: I’m just not sure how many people are hitting it at this point.
Agreed.
-drosf
>
> Cheers
> Trond
>
>> -dros
>>
>> On Jan 21, 2014, at 3:21 PM, Weston Andros Adamson <dros@xxxxxxxxxxxxxxx> wrote:
>>
>>> cond_resched_lock(cinfo->lock) is called everywhere else while holding
>>> the cinfo->lock spinlock. Not holding this lock while calling
>>> transfer_commit_list in filelayout_recover_commit_reqs causes the BUG
>>> below.
>>>
>>> It's true that we can't hold this lock while calling pnfs_put_lseg,
>>> because that might try to lock the inode lock - which might be the
>>> same lock as cinfo->lock.
>>>
>>> To reproduce, mount a 2 DS pynfs server and run an O_DIRECT command
>>> that crosses a stripe boundary and is not page aligned, such as:
>>>
>>> dd if=/dev/zero of=/mnt/f bs=17000 count=1 oflag=direct
>>>
>>> BUG: sleeping function called from invalid context at linux/fs/nfs/nfs4filelayout.c:1161
>>> in_atomic(): 0, irqs_disabled(): 0, pid: 27, name: kworker/0:1
>>> 2 locks held by kworker/0:1/27:
>>> #0: (events){.+.+.+}, at: [<ffffffff810501d7>] process_one_work+0x175/0x3a5
>>> #1: ((&dreq->work)){+.+...}, at: [<ffffffff810501d7>] process_one_work+0x175/0x3a5
>>> CPU: 0 PID: 27 Comm: kworker/0:1 Not tainted 3.13.0-rc3-branch-dros_testing+ #21
>>> Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
>>> Workqueue: events nfs_direct_write_schedule_work [nfs]
>>> 0000000000000000 ffff88007a39bbb8 ffffffff81491256 ffff88007b87a130 ffff88007a39bbd8 ffffffff8105f103 ffff880079614000 ffff880079617d40 ffff88007a39bc20 ffffffffa011603e ffff880078988b98 0000000000000000
>>> Call Trace:
>>> [<ffffffff81491256>] dump_stack+0x4d/0x66
>>> [<ffffffff8105f103>] __might_sleep+0x100/0x105
>>> [<ffffffffa011603e>] transfer_commit_list+0x94/0xf1 [nfs_layout_nfsv41_files]
>>> [<ffffffffa01160d6>] filelayout_recover_commit_reqs+0x3b/0x68 [nfs_layout_nfsv41_files]
>>> [<ffffffffa00ba53a>] nfs_direct_write_reschedule+0x9f/0x1d6 [nfs]
>>> [<ffffffff810705df>] ? mark_lock+0x1df/0x224
>>> [<ffffffff8106e617>] ? trace_hardirqs_off_caller+0x37/0xa4
>>> [<ffffffff8106e691>] ? trace_hardirqs_off+0xd/0xf
>>> [<ffffffffa00ba8f8>] nfs_direct_write_schedule_work+0x9d/0xb7 [nfs]
>>> [<ffffffff810501d7>] ? process_one_work+0x175/0x3a5
>>> [<ffffffff81050258>] process_one_work+0x1f6/0x3a5
>>> [<ffffffff810501d7>] ? process_one_work+0x175/0x3a5
>>> [<ffffffff8105187e>] worker_thread+0x149/0x1f5
>>> [<ffffffff81051735>] ? rescuer_thread+0x28d/0x28d
>>> [<ffffffff81056d74>] kthread+0xd2/0xda
>>> [<ffffffff81056ca2>] ? __kthread_parkme+0x61/0x61
>>> [<ffffffff8149e66c>] ret_from_fork+0x7c/0xb0
>>> [<ffffffff81056ca2>] ? __kthread_parkme+0x61/0x61
>>>
>>> Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
>>> ---
>>>
>>> I'm pretty sure this is the correct approach - it certainly fixes the BUG
>>> for me.
>>>
>>> fs/nfs/nfs4filelayout.c | 8 ++++----
>>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
>>> index 0a93e79..03fd8be 100644
>>> --- a/fs/nfs/nfs4filelayout.c
>>> +++ b/fs/nfs/nfs4filelayout.c
>>> @@ -1216,17 +1216,17 @@ static void filelayout_recover_commit_reqs(struct list_head *dst,
>>> struct pnfs_commit_bucket *b;
>>> int i;
>>>
>>> - /* NOTE cinfo->lock is NOT held, relying on fact that this is
>>> - * only called on single thread per dreq.
>>> - * Can't take the lock because need to do pnfs_put_lseg
>>> - */
>>> + spin_lock(cinfo->lock);
>>> for (i = 0, b = cinfo->ds->buckets; i < cinfo->ds->nbuckets; i++, b++) {
>>> if (transfer_commit_list(&b->written, dst, cinfo, 0)) {
>>> + spin_unlock(cinfo->lock);
>>> pnfs_put_lseg(b->wlseg);
>>> b->wlseg = NULL;
>>> + spin_lock(cinfo->lock);
>>> }
>>> }
>>> cinfo->ds->nwritten = 0;
>>> + spin_unlock(cinfo->lock);
>>> }
>>>
>>> static unsigned int
>>> --
>>> 1.8.3.4 (Apple Git-47)
>>>
>>> --
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>>
>
> --
> Trond Myklebust
> Linux NFS client maintainer
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