[PATCH AUTOSEL 4.9 27/87] scsi: core: replace GFP_ATOMIC with GFP_KERNEL in scsi_scan.c

Sasha Levin
2019-03-27T18:21:35Z

From: Benjamin Block <bblock@linux.ibm.com>

[ Upstream commit 1749ef00f7312679f76d5e9104c5d1e22a829038 ]

We had a test-report where, under memory pressure, adding LUNs to the
systems would fail (the tests add LUNs strictly in sequence):

[ 5525.853432] scsi 0:0:1:1088045124: Direct-Access IBM 2107900 .148 PQ: 0 ANSI: 5
[ 5525.853826] scsi 0:0:1:1088045124: alua: supports implicit TPGS
[ 5525.853830] scsi 0:0:1:1088045124: alua: device naa.6005076303ffd32700000000000044da port group 0 rel port 43
[ 5525.853931] sd 0:0:1:1088045124: Attached scsi generic sg10 type 0
[ 5525.854075] sd 0:0:1:1088045124: [sdk] Disabling DIF Type 1 protection
[ 5525.855495] sd 0:0:1:1088045124: [sdk] 2097152 512-byte logical blocks: (1.07 GB/1.00 GiB)
[ 5525.855606] sd 0:0:1:1088045124: [sdk] Write Protect is off
[ 5525.855609] sd 0:0:1:1088045124: [sdk] Mode Sense: ed 00 00 08
[ 5525.855795] sd 0:0:1:1088045124: [sdk] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 5525.857838] sdk: sdk1
[ 5525.859468] sd 0:0:1:1088045124: [sdk] Attached SCSI disk
[ 5525.865073] sd 0:0:1:1088045124: alua: transition timeout set to 60 seconds
[ 5525.865078] sd 0:0:1:1088045124: alua: port group 00 state A preferred supports tolusnA
[ 5526.015070] sd 0:0:1:1088045124: alua: port group 00 state A preferred supports tolusnA
[ 5526.015213] sd 0:0:1:1088045124: alua: port group 00 state A preferred supports tolusnA
[ 5526.587439] scsi_alloc_sdev: Allocation failure during SCSI scanning, some SCSI devices might not be configured
[ 5526.588562] scsi_alloc_sdev: Allocation failure during SCSI scanning, some SCSI devices might not be configured

Looking at the code of scsi_alloc_sdev(), and all the calling contexts,
there seems to be no reason to use GFP_ATMOIC here. All the different
call-contexts use a mutex at some point, and nothing in between that
requires no sleeping, as far as I could see. Additionally, the code that
later allocates the block queue for the device (scsi_mq_alloc_queue())
already uses GFP_KERNEL.

There are similar allocations in two other functions:
scsi_probe_and_add_lun(), and scsi_add_lun(),; that can also be done with
GFP_KERNEL.

Here is the contexts for the three functions so far:

scsi_alloc_sdev()
scsi_probe_and_add_lun()
scsi_sequential_lun_scan()
__scsi_scan_target()
scsi_scan_target()
mutex_lock()
scsi_scan_channel()
scsi_scan_host_selected()
mutex_lock()
scsi_report_lun_scan()
__scsi_scan_target()
...
__scsi_add_device()
mutex_lock()
__scsi_scan_target()
...
scsi_report_lun_scan()
...
scsi_get_host_dev()
mutex_lock()

scsi_probe_and_add_lun()
...

scsi_add_lun()
scsi_probe_and_add_lun()
...

So replace all these, and give them a bit of a better chance to succeed,
with more chances of reclaim.

Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/scsi_scan.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 27a6d3c6cb7c..67f6f134abc4 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -219,7 +219,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);

sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
- GFP_ATOMIC);
+ GFP_KERNEL);
if (!sdev)
goto out;

@@ -796,7 +796,7 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
*/
sdev->inquiry = kmemdup(inq_result,
max_t(size_t, sdev->inquiry_len, 36),
- GFP_ATOMIC);
+ GFP_KERNEL);
if (sdev->inquiry == NULL)
return SCSI_SCAN_NO_RESPONSE;

@@ -1095,7 +1095,7 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
if (!sdev)
goto out;

- result = kmalloc(result_len, GFP_ATOMIC |
+ result = kmalloc(result_len, GFP_KERNEL |
((shost->unchecked_isa_dma) ? __GFP_DMA : 0));
if (!result)
goto out_free_sdev;
--
2.19.1