On 04/21/2017 10:48 AM, Jens Axboe wrote:
> On 04/21/2017 10:40 AM, Bart Van Assche wrote:
>> On Fri, 2017-04-21 at 10:33 -0600, Jens Axboe wrote:
>>> On 04/21/2017 10:31 AM, Bart Van Assche wrote:
>>>> On Fri, 2017-04-21 at 10:25 -0600, Jens Axboe wrote:
>>>>> On 04/21/2017 09:32 AM, Bart Van Assche wrote:
>>>>>> Hello Jens,
>>>>>>
>>>>>> Since yesterday the following complaint is reported frequently after
>>>>>> having
>>>>>> installed the for-4.12/block branch on my test setup. Unless someone has
>>>>>> a
>>>>>> better proposal, I will run a bisect.
>>>>>>
>>>>>> BUG: sleeping function called from invalid context at
>>>>>> ./include/linux/buffer_head.h:349
>>>>>> in_atomic(): 1, irqs_disabled(): 0, pid: 8019, name: find
>>>>>> CPU: 10 PID: 8019 Comm: find Tainted: G W I 4.11.0-rc4-dbg+ #2
>>>>>> Call Trace:
>>>>>> dump_stack+0x68/0x93
>>>>>> ___might_sleep+0x16e/0x230
>>>>>> __might_sleep+0x4a/0x80
>>>>>> __ext4_get_inode_loc+0x1e0/0x4e0
>>>>>> ext4_iget+0x70/0xbc0
>>>>>> ext4_iget_normal+0x2f/0x40
>>>>>> ext4_lookup+0xb6/0x1f0
>>>>>> lookup_slow+0x104/0x1e0
>>>>>> walk_component+0x19a/0x330
>>>>>> path_lookupat+0x4b/0x100
>>>>>> filename_lookup+0x9a/0x110
>>>>>> user_path_at_empty+0x36/0x40
>>>>>> vfs_statx+0x67/0xc0
>>>>>> SYSC_newfstatat+0x20/0x40
>>>>>> SyS_newfstatat+0xe/0x10
>>>>>> entry_SYSCALL_64_fastpath+0x18/0xad
>>>>>
>>>>> How are you reproducing this? I've been running testing on the test box
>>>>> and I run it on my laptop as well, but I haven't seen anything odd.
>>>>
>>>> Hello Jens,
>>>>
>>>> All I have to do to reproduce this is to build, install and boot the
>>>> kernel.
>>>> Maybe we are using a different kernel config?
>>>
>>> I'd say odds are good we are not using an identical kernel config :-)
>>> What is your root device? Is it using mq and scheduling, or what's
>>> the config?
>>
>> Hello Jens,
>>
>> The boot device is a SATA disk:
>> # lsscsi
>> [0:0:0:0] disk ATA ST1000NM0033-9ZM GA67 /dev/sda
>>
>> SCSI-mq is enabled and the default I/O scheduler is the deadline scheduler.
>> From the kernel .config:
>> CONFIG_DEFAULT_IOSCHED="deadline"
>> CONFIG_SCSI_MQ_DEFAULT=y
>
> I wonder if it's an imbalance in the preempt count. Looking at it, it
> looks like we're not clearing the alloc data. But I would think that
> would potentially cause much worse problems, but maybe we got lucky?
>
> Let me generate a cleanup patch for that.
Something like the below.
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0b2f60407748..519e5a08c0c6 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -279,7 +279,7 @@ EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
unsigned int flags)
{
- struct blk_mq_alloc_data alloc_data = { .flags = flags };
+ struct blk_mq_alloc_data alloc_data;
struct request *rq;
int ret;
@@ -287,6 +287,7 @@ struct request *blk_mq_alloc_request(struct request_queue
*q, int rw,
if (ret)
return ERR_PTR(ret);
+ blk_mq_init_alloc_data(&alloc_data, flags);
rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
blk_mq_put_ctx(alloc_data.ctx);
@@ -305,7 +306,7 @@ EXPORT_SYMBOL(blk_mq_alloc_request);
struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
unsigned int flags, unsigned int hctx_idx)
{
- struct blk_mq_alloc_data alloc_data = { .flags = flags };
+ struct blk_mq_alloc_data alloc_data;
struct request *rq;
unsigned int cpu;
int ret;
@@ -326,6 +327,8 @@ struct request *blk_mq_alloc_request_hctx(struct
request_queue *q, int rw,
if (ret)
return ERR_PTR(ret);
+ blk_mq_init_alloc_data(&alloc_data, flags);
+
/*
* Check if the hardware context is actually mapped to anything.
* If not tell the caller that it should skip this queue.
@@ -1531,7 +1534,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue
*q, struct bio *bio)
{
const int is_sync = op_is_sync(bio->bi_opf);
const int is_flush_fua = op_is_flush(bio->bi_opf);
- struct blk_mq_alloc_data data = { .flags = 0 };
+ struct blk_mq_alloc_data data;
struct request *rq;
unsigned int request_count = 0;
struct blk_plug *plug;
@@ -1559,6 +1562,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue
*q, struct bio *bio)
trace_block_getrq(q, bio, bio->bi_opf);
+ blk_mq_init_alloc_data(&data, 0);
rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
if (unlikely(!rq)) {
__wbt_done(q->rq_wb, wb_acct);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 524f44742816..36cfc21c7cc6 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -148,6 +148,16 @@ struct blk_mq_alloc_data {
struct blk_mq_hw_ctx *hctx;
};
+static inline void blk_mq_init_alloc_data(struct blk_mq_alloc_data *data,
+ unsigned int flags)
+{
+ data->q = NULL;
+ data->flags = flags;
+ data->shallow_depth = 0;
+ data->ctx = NULL;
+ data->hctx = NULL;
+}
+
static inline struct blk_mq_tags *blk_mq_tags_from_data(struct
blk_mq_alloc_data *data)
{
if (data->flags & BLK_MQ_REQ_INTERNAL)
--
Jens Axboe
