2022-01-21 16:57:24

by CGEL

Subject: [PATCH] drivers/scsi/csiostor: do not sleep with a spin lock held

From: Minghao Chi <[email protected]>

The might_sleep_if function in the mempool_alloc
may cause a sleep lock.We can't mempool_alloc()
with a spin lock held, so bring it up front.

Reported-by: Zeal Robot <[email protected]>
Signed-off-by: Minghao Chi <[email protected]>
Signed-off-by: CGEL ZTE <[email protected]>
---
drivers/scsi/csiostor/csio_attr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/csiostor/csio_attr.c b/drivers/scsi/csiostor/csio_attr.c
index 200e50089711..3d4ab439c756 100644
--- a/drivers/scsi/csiostor/csio_attr.c
+++ b/drivers/scsi/csiostor/csio_attr.c
@@ -424,8 +424,8 @@ csio_fcoe_alloc_vnp(struct csio_hw *hw, struct csio_lnode *ln)

/* Issue VNP cmd to alloc vport */
/* Allocate Mbox request */
- spin_lock_irq(&hw->lock);
mbp = mempool_alloc(hw->mb_mempool, GFP_ATOMIC);
+ spin_lock_irq(&hw->lock);
if (!mbp) {
CSIO_INC_STATS(hw, n_err_nomem);
ret = -ENOMEM;
@@ -505,8 +505,8 @@ csio_fcoe_free_vnp(struct csio_hw *hw, struct csio_lnode *ln)
/* Issue VNP cmd to free vport */
/* Allocate Mbox request */

- spin_lock_irq(&hw->lock);
mbp = mempool_alloc(hw->mb_mempool, GFP_ATOMIC);
+ spin_lock_irq(&hw->lock);
if (!mbp) {
CSIO_INC_STATS(hw, n_err_nomem);
ret = -ENOMEM;
--
2.25.1

2022-01-21 18:59:44

by Damien Le Moal

Subject: Re: [PATCH] drivers/scsi/csiostor: do not sleep with a spin lock held

On 1/19/22 14:59, [email protected] wrote:
> From: Minghao Chi <[email protected]>
>
> The might_sleep_if function in the mempool_alloc
> may cause a sleep lock.We can't mempool_alloc()
> with a spin lock held, so bring it up front.

But the allocation is GFP_ATOMIC, which does not have
__GFP_DIRECT_RECLAIM, so how come mempool_alloc() triggers the
might_sleep() warning ?

>
> Reported-by: Zeal Robot <[email protected]>
> Signed-off-by: Minghao Chi <[email protected]>
> Signed-off-by: CGEL ZTE <[email protected]>
> ---
> drivers/scsi/csiostor/csio_attr.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/csiostor/csio_attr.c b/drivers/scsi/csiostor/csio_attr.c
> index 200e50089711..3d4ab439c756 100644
> --- a/drivers/scsi/csiostor/csio_attr.c
> +++ b/drivers/scsi/csiostor/csio_attr.c
> @@ -424,8 +424,8 @@ csio_fcoe_alloc_vnp(struct csio_hw *hw, struct csio_lnode *ln)
>
> /* Issue VNP cmd to alloc vport */
> /* Allocate Mbox request */
> - spin_lock_irq(&hw->lock);
> mbp = mempool_alloc(hw->mb_mempool, GFP_ATOMIC);
> + spin_lock_irq(&hw->lock);
> if (!mbp) {
> CSIO_INC_STATS(hw, n_err_nomem);
> ret = -ENOMEM;
> @@ -505,8 +505,8 @@ csio_fcoe_free_vnp(struct csio_hw *hw, struct csio_lnode *ln)
> /* Issue VNP cmd to free vport */
> /* Allocate Mbox request */
>
> - spin_lock_irq(&hw->lock);
> mbp = mempool_alloc(hw->mb_mempool, GFP_ATOMIC);
> + spin_lock_irq(&hw->lock);
> if (!mbp) {
> CSIO_INC_STATS(hw, n_err_nomem);
> ret = -ENOMEM;


--
Damien Le Moal
Western Digital Research

2022-01-21 19:02:17

by Damien Le Moal

Subject: Re: [PATCH] drivers/scsi/csiostor: do not sleep with a spin lock held

On 1/19/22 17:57, [email protected] wrote:
>
> The might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM) in the
> mempool_alloc function uses __GFP_DIRECT_RECLAIM.

But the call to mempool_alloc() specifies GFP_ATOMIC, which does not
have __GFP_DIRECT_RECLAIM, so "gfp_mask & __GFP_DIRECT_RECLAIM" should
be false, and the might_sleep_if() not triggering. How can you see the
might sleep warning ?

--
Damien Le Moal
Western Digital Research

2022-01-21 19:02:18

by CGEL

Subject: Re: [PATCH] drivers/scsi/csiostor: do not sleep with a spin lock held

The might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM) in the
mempool_alloc function uses __GFP_DIRECT_RECLAIM.

2022-01-21 19:03:44

by CGEL

Subject: Re: [PATCH] drivers/scsi/csiostor: do not sleep with a spin lock held

Sorry, GFP_ATOMIC&__GFP_DIRECT_RECLAIM are indeed false