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John Pittman 784c9a29e9 dm kcopyd: avoid softlockup in run_complete_job
It was reported that softlockups occur when using dm-snapshot ontop of
slow (rbd) storage.  E.g.:

[ 4047.990647] watchdog: BUG: soft lockup - CPU#10 stuck for 22s! [kworker/10:23:26177]
...
[ 4048.034151] Workqueue: kcopyd do_work [dm_mod]
[ 4048.034156] RIP: 0010:copy_callback+0x41/0x160 [dm_snapshot]
...
[ 4048.034190] Call Trace:
[ 4048.034196]  ? __chunk_is_tracked+0x70/0x70 [dm_snapshot]
[ 4048.034200]  run_complete_job+0x5f/0xb0 [dm_mod]
[ 4048.034205]  process_jobs+0x91/0x220 [dm_mod]
[ 4048.034210]  ? kcopyd_put_pages+0x40/0x40 [dm_mod]
[ 4048.034214]  do_work+0x46/0xa0 [dm_mod]
[ 4048.034219]  process_one_work+0x171/0x370
[ 4048.034221]  worker_thread+0x1fc/0x3f0
[ 4048.034224]  kthread+0xf8/0x130
[ 4048.034226]  ? max_active_store+0x80/0x80
[ 4048.034227]  ? kthread_bind+0x10/0x10
[ 4048.034231]  ret_from_fork+0x35/0x40
[ 4048.034233] Kernel panic - not syncing: softlockup: hung tasks

Fix this by calling cond_resched() after run_complete_job()'s callout to
the dm_kcopyd_notify_fn (which is dm-snap.c:copy_callback in the above
trace).

Signed-off-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-08-08 09:16:24 -04:00
arch alpha: fix osf_wait4() breakage 2018-07-22 11:51:30 -07:00
block for-linus-20180713 2018-07-14 12:28:00 -07:00
certs certs/blacklist: fix const confusion 2018-06-26 09:43:03 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-07-19 07:32:44 -07:00
Documentation dm thin: include metadata_low_watermark threshold in pool status 2018-07-30 11:49:08 -04:00
drivers dm kcopyd: avoid softlockup in run_complete_job 2018-08-08 09:16:24 -04:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-07-22 12:04:51 -07:00
include dm kcopyd: return void from dm_kcopyd_copy() 2018-07-31 17:33:21 -04:00
init Kbuild fixes for v4.18 2018-06-30 13:05:30 -07:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-21 17:21:34 -07:00
lib Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-21 16:52:08 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm mm: make vm_area_alloc() initialize core fields 2018-07-21 15:24:03 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
security selinux/stable-4.18 PR 20180629 2018-06-30 11:15:12 -07:00
sound ALSA: hda/realtek - Yet another Clevo P950 quirk entry 2018-07-18 12:17:46 +02:00
tools Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-07-21 16:52:08 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt Miscellaneous bugfixes, plus a small patchlet related to Spectre v2. 2018-07-18 11:08:44 -07:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS MAINTAINERS: Peter has moved 2018-07-21 12:50:46 -07:00
Makefile Linux 4.18-rc6 2018-07-22 14:12:20 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.