Hello Bart,
Patch number 5 doesn't handle the case when device_for_each_child() is
called.
device_for_each_child() calls to target_unblock() that uses also
starget_for_each_device().
After applying also the following change the hang disappeared but it
didn't fix the warning.
Those fixes are not enough because if fast_io_fail_tmo is set to
infinity then the hang will remain,
because only __rport_fail_io_fast() calls to scsi_target_unblock() and
terminate_rport_io()
that free the sync cache command.
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e5d4b50..09f9566 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -3068,9 +3068,15 @@ void scsi_device_resume(struct scsi_device *sdev)
static int
target_unblock(struct device *dev, void *data)
{
- if (scsi_is_target_device(dev))
- starget_for_each_device(to_scsi_target(dev), data,
- device_unblock);
+ if (scsi_is_target_device(dev)) {
+ struct scsi_target *starget = to_scsi_target(dev);
+ struct Scsi_Host *shost = dev_to_shost(dev->parent);
+ unsigned long flags;
+
+ spin_lock_irqsave(shost->host_lock, flags);
+ __starget_for_each_device(starget, data, device_unblock);
+ spin_unlock_irqrestore(shost->host_lock, flags);
+ }
return 0;
}
--
1.8.4.3
Israel
On 3/14/2017 11:44 AM, Israel Rukshin wrote:
Hello Bart,
I applied and tested patches 3, 4 and 5.
I am sorry to tell you that it didn't work.
I saw the warning you added and the hang at device_del().
[ 333.696462] ------------[ cut here ]------------
[ 333.696471] WARNING: CPU: 11 PID: 321 at
drivers/scsi/scsi_sysfs.c:1280 __scsi_remove_device+0x106/0x110
[ 333.696472] Modules linked in: nfsv3 ib_srp(-) dm_service_time
scsi_transport_srp ib_uverbs ib_umad ib_ipoib ib_cm mlx4_ib ib_core
rpcsec_gss_krb5 nfsv4 dns_resolver nfs netconsole fscache dm_mirror
dm_region_hash dm_log sb_edac edac_core x86_pkg_temp_thermal
intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul
crc32_pclmul ghash_clmulni_intel iTCO_wdt pcbc iTCO_vendor_support
aesni_intel mei_me crypto_simd joydev input_leds ipmi_si ioatdma mei
glue_helper lpc_ich pcspkr cryptd ipmi_devintf shpchp ipmi_msghandler
sg i2c_i801 mfd_core dm_multipath dm_mod nfsd binfmt_misc auth_rpcgss
nfs_acl lockd grace sunrpc ip_tables ext4 jbd2 mbcache sd_mod mgag200
drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops isci igb
ttm ahci libsas ptp libahci scsi_transport_sas pps_core dca crc32c_intel
[ 333.696511] drm i2c_algo_bit libata mlx4_core fjes [last unloaded:
ib_srp]
[ 333.696516] CPU: 11 PID: 321 Comm: kworker/11:1 Not tainted
4.11.0-rc2+ #99
[ 333.696517] Hardware name: Supermicro X9DRFR/X9DRFR, BIOS 1.0a
09/11/2012
[ 333.696522] Workqueue: srp_remove srp_remove_work [ib_srp]
[ 333.696523] Call Trace:
[ 333.696530] dump_stack+0x63/0x90
[ 333.696534] __warn+0xcb/0xf0
[ 333.696536] warn_slowpath_null+0x1d/0x20
[ 333.696538] __scsi_remove_device+0x106/0x110
[ 333.696540] scsi_forget_host+0x60/0x70
[ 333.696545] scsi_remove_host+0x77/0x110
[ 333.696547] srp_remove_work+0x90/0x230 [ib_srp]
[ 333.696551] process_one_work+0x177/0x430
[ 333.696553] worker_thread+0x4e/0x4b0
[ 333.696555] kthread+0x101/0x140
[ 333.696556] ? process_one_work+0x430/0x430
[ 333.696558] ? kthread_create_on_node+0x60/0x60
[ 333.696563] ret_from_fork+0x2c/0x40
[ 333.696565] ---[ end trace b1edd584bf21aaba ]---
Israel.
On 3/14/2017 4:35 AM, Bart Van Assche wrote:
On Mon, 2017-03-13 at 14:55 -0700, James Bottomley wrote:
This is true, but I don't see how it can cause the host to be freed
before the sdev. The memory for struct Scsi_Host is freed in the
shost_gendev release routine, which should be pinned by the parent
traversal from sdev. So it should not be possible for
scsi_host_dev_release() to be called before
scsi_device_dev_release_usercontext() becase the latter has the final
put of the parent device.
Hello James,
I will run a bisect to see whether that provides more information about
what caused the change in the reference counting behavior.
Israel, since you did not hit the reference counting issue in your
tests,
can you repeat your test with patches 3, 4 and 5 applied?
Thanks,
Bart.
