[PATCH] scsi: target: tcmu: Use GFP_NOIO while handling cmds or holding cmdr_lock

[PATCH] scsi: target: tcmu: Use GFP_NOIO while handling cmds or holding cmdr_lock

[Bodo Stroesser]

Especially when using tcmu with tcm_loop, memory allocations with
GFP_KERNEL for a LUN can cause write back to the same LUN.

So we have to use GFP_NOIO when allocation is done while handling
commands or while holding cmdr_lock.

Signed-off-by: Bodo Stroesser <bostroesser@gmail.com>
---

This patch is based on Martin's for-next branch plus my short
series "scsi: target: tcmu: Replace IDR and radix_tree with XArray"
See:
 https://lore.kernel.org/linux-scsi/20210224185335.13844-1-bostroesser@gmail.com/

 drivers/target/target_core_user.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index ada3ef982969..9e1b115cb032 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -518,7 +518,7 @@ static inline int tcmu_get_empty_block(struct tcmu_dev *udev,
 		if (!page)
 			goto err_alloc;
 
-		if (xa_store(&udev->data_blocks, dbi, page, GFP_KERNEL))
+		if (xa_store(&udev->data_blocks, dbi, page, GFP_NOIO))
 			goto err_insert;
 	}
 
@@ -1272,7 +1272,7 @@ tcmu_tmr_notify(struct se_device *se_dev, enum tcm_tmreq_table tmf,
 	pr_debug("TMR event %d on dev %s, aborted cmds %d, afflicted cmd_ids %d\n",
 		 tcmu_tmr_type(tmf), udev->name, i, cmd_cnt);
 
-	tmr = kmalloc(sizeof(*tmr) + cmd_cnt * sizeof(*cmd_ids), GFP_KERNEL);
+	tmr = kmalloc(sizeof(*tmr) + cmd_cnt * sizeof(*cmd_ids), GFP_NOIO);
 	if (!tmr)
 		goto unlock;
 
-- 
2.12.3

Re: [PATCH] scsi: target: tcmu: Use GFP_NOIO while handling cmds or holding cmdr_lock

[michael.christie]

On 3/5/21 1:00 PM, Bodo Stroesser wrote:
> Especially when using tcmu with tcm_loop, memory allocations with
> GFP_KERNEL for a LUN can cause write back to the same LUN.
> 
> So we have to use GFP_NOIO when allocation is done while handling
> commands or while holding cmdr_lock.
> 
> Signed-off-by: Bodo Stroesser <bostroesser@gmail.com>

Reviewed-by: Mike Christie <michael.christie@oracle.com>

Re: [PATCH] scsi: target: tcmu: Use GFP_NOIO while handling cmds or holding cmdr_lock

[Martin K. Petersen]

Bodo,

> Especially when using tcmu with tcm_loop, memory allocations with
> GFP_KERNEL for a LUN can cause write back to the same LUN.

Applied to 5.13/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH] scsi: target: tcmu: Use GFP_NOIO while handling cmds or holding cmdr_lock

[Martin K. Petersen]

On Fri, 5 Mar 2021 20:00:09 +0100, Bodo Stroesser wrote:

> Especially when using tcmu with tcm_loop, memory allocations with
> GFP_KERNEL for a LUN can cause write back to the same LUN.
> 
> So we have to use GFP_NOIO when allocation is done while handling
> commands or while holding cmdr_lock.

Applied to 5.13/scsi-queue, thanks!

[1/1] scsi: target: tcmu: Use GFP_NOIO while handling cmds or holding cmdr_lock
      https://git.kernel.org/mkp/scsi/c/1080782f13e3

-- 
Martin K. Petersen	Oracle Linux Engineering