Comment 0 for bug 1770003

Dear Canonical,

We found that the current Ubuntu kernel contains a problem related to qla2xxx driver which causes:

[ 66.295233] Unable to handle kernel paging request for data at address 0x8882f6ed90e9151a
[ 66.295297] Faulting instruction address: 0xc00000000038a110
cpu 0x50: Vector: 380 (Data Access Out of Range) at [c00000000692f650]
    pc: c00000000038a110: kmem_cache_alloc_node+0x2f0/0x350
    lr: c00000000038a0fc: kmem_cache_alloc_node+0x2dc/0x350
    sp: c00000000692f8d0
   msr: 9000000000009033
   dar: 8882f6ed90e9151a
  current = 0xc00000000698fd00
  paca = 0xc00000000fab7000 softe: 0 irq_happened: 0x01
    pid = 1762, comm = systemd-journal
Linux version 4.15.0-20-generic (buildd@bos02-ppc64el-002) (gcc version 7.3.0 (Ubuntu 7.3.0-14ubuntu1)) #16-Ubuntu SMP Wed Apr 4 13:57:51 UTC 2018 (Ubuntu 4.15.0-20.21-generic 4.15.20)
enter ? for help
[c00000000692f8d0] c000000000389fd4 kmem_cache_alloc_node+0x1b4/0x350 (unreliable)
[c00000000692f940] c000000000b2ec6c __alloc_skb+0x6c/0x220
[c00000000692f9a0] c000000000b30b6c alloc_skb_with_frags+0x7c/0x2e0
[c00000000692fa30] c000000000b247cc sock_alloc_send_pskb+0x29c/0x2c0
[c00000000692fae0] c000000000c5705c unix_dgram_sendmsg+0x15c/0x8f0
[c00000000692fbc0] c000000000b1ec64 sock_sendmsg+0x64/0x90
[c00000000692fbf0] c000000000b20abc ___sys_sendmsg+0x31c/0x390
[c00000000692fd90] c000000000b221ec __sys_sendmsg+0x5c/0xc0
[c00000000692fe30] c00000000000b184 system_call+0x58/0x6c
--- Exception: c00 (System Call) at 000074826f6fa9c4
SP (7ffff5dc5510) is in userspace

We were able to get rid of this problem cherry picking some of the upstream patches. Do you think they might fit in the SRU criteria?

The commit ids are below and they were easily cherry picked.

eaf75d1815dad230dac2f1e8f1dc0349b2d50071: scsi: qla2xxx: Fix double free bug after firmware timeout
6d67492764b39ad6efb6822816ad73dc141752f4: scsi: qla2xxx: Prevent relogin trigger from sending too many commands
7ac0c332f96bb9688560726f5e80c097ed8de59a: scsi: qla2xxx: Fix warning in qla2x00_async_iocb_timeout()
045d6ea200af794ba15515984cff63787a7fc3c0: scsi: qla2xxx: Don't call dma_free_coherent with IRQ disabled.
1ae634eb28533b82f9777a47c1ade44cb8c0182b: scsi: qla2xxx: Serialize session free in qlt_free_session_done
d8630bb95f46ea118dede63bd75533faa64f9612: scsi: qla2xxx: Serialize session deletion by using work_lock
        Requries: 1c6cacf4ea6c04a58a0e3057f5ed60c24a4ffeff ('scsi: qla2xxx: Fixup locking for session deletion')
94cff6e114df56d0df74cdabe3481df38d9b0c1e: scsi: qla2xxx: Remove unused argument from qlt_schedule_sess_for_dele?
9cd883f07a54e5301d51e259acd250bb035996be: scsi: qla2xxx: Fix session cleanup for N2N