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Brian King c03ecc192c scsi: ibmvfc: Set default timeout to avoid crash during migration
[ Upstream commit 764907293edc1af7ac857389af9dc858944f53dc ]

While testing live partition mobility, we have observed occasional crashes
of the Linux partition. What we've seen is that during the live migration,
for specific configurations with large amounts of memory, slow network
links, and workloads that are changing memory a lot, the partition can end
up being suspended for 30 seconds or longer. This resulted in the following
scenario:

CPU 0                          CPU 1
-------------------------------  ----------------------------------
scsi_queue_rq                    migration_store
 -> blk_mq_start_request          -> rtas_ibm_suspend_me
  -> blk_add_timer                 -> on_each_cpu(rtas_percpu_suspend_me
              _______________________________________V
             |
             V
    -> IPI from CPU 1
     -> rtas_percpu_suspend_me
                                     -> __rtas_suspend_last_cpu

-- Linux partition suspended for > 30 seconds --
                                      -> for_each_online_cpu(cpu)
                                           plpar_hcall_norets(H_PROD
 -> scsi_dispatch_cmd
                                      -> scsi_times_out
                                       -> scsi_abort_command
                                        -> queue_delayed_work
  -> ibmvfc_queuecommand_lck
   -> ibmvfc_send_event
    -> ibmvfc_send_crq
     - returns H_CLOSED
   <- returns SCSI_MLQUEUE_HOST_BUSY
-> __blk_mq_requeue_request

                                      -> scmd_eh_abort_handler
                                       -> scsi_try_to_abort_cmd
                                         - returns SUCCESS
                                       -> scsi_queue_insert

Normally, the SCMD_STATE_COMPLETE bit would protect against the command
completion and the timeout, but that doesn't work here, since we don't
check that at all in the SCSI_MLQUEUE_HOST_BUSY path.

In this case we end up calling scsi_queue_insert on a request that has
already been queued, or possibly even freed, and we crash.

The patch below simply increases the default I/O timeout to avoid this race
condition. This is also the timeout value that nearly all IBM SAN storage
recommends setting as the default value.

Link: https://lore.kernel.org/r/1610463998-19791-1-git-send-email-brking@linux.vnet.ibm.com
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-07 15:35:48 +01:00
arch x86: __always_inline __{rd,wr}msr() 2021-02-07 15:35:48 +01:00
block Revert "Revert "block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT"" 2021-02-07 15:35:47 +01:00
certs
crypto crypto: asym_tpm: correct zero out potential secrets 2021-01-12 20:16:17 +01:00
Documentation KVM: Forbid the use of tagged userspace addresses for memslots 2021-02-03 23:25:57 +01:00
drivers scsi: ibmvfc: Set default timeout to avoid crash during migration 2021-02-07 15:35:48 +01:00
fs btrfs: backref, use correct count to resolve normal data refs 2021-02-07 15:35:47 +01:00
include tcp: make TCP_USER_TIMEOUT accurate for zero window probes 2021-02-07 15:35:47 +01:00
init exec: Transform exec_update_mutex into a rw_semaphore 2021-01-09 13:44:55 +01:00
ipc
kernel PM: hibernate: flush swap writer after marking 2021-02-03 23:25:57 +01:00
lib lib/raid6: Let $(UNROLL) rules work with macOS userland 2021-01-19 18:26:15 +01:00
LICENSES
mm Revert "mm/slub: fix a memory leak in sysfs_slab_add()" 2021-01-30 13:54:09 +01:00
net mac80211: fix fast-rx encryption check 2021-02-07 15:35:48 +01:00
samples samples: bpf: Fix lwt_len_hist reusing previous BPF map 2020-12-30 11:51:12 +01:00
scripts depmod: handle the case of /sbin/depmod without /sbin in PATH 2021-01-12 20:16:10 +01:00
security dump_common_audit_data(): fix racy accesses to ->d_name 2021-01-19 18:26:16 +01:00
sound ASoC: SOF: Intel: hda: Resume codec to do jack detection 2021-02-07 15:35:48 +01:00
tools selftests: forwarding: Specify interface when invoking mausezahn 2021-02-03 23:26:01 +01:00
usr
virt KVM: Forbid the use of tagged userspace addresses for memslots 2021-02-03 23:25:57 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.95 2021-02-03 23:26:02 +01:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.