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Michal Hocko dd33ad7b25 memory_hotplug: cond_resched in __remove_pages
We have received a bug report that unbinding a large pmem (>1TB) can
result in a soft lockup:

  NMI watchdog: BUG: soft lockup - CPU#9 stuck for 23s! [ndctl:4365]
  [...]
  Supported: Yes
  CPU: 9 PID: 4365 Comm: ndctl Not tainted 4.12.14-94.40-default #1 SLE12-SP4
  Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5C620.86B.01.00.0833.051120182255 05/11/2018
  task: ffff9cce7d4410c0 task.stack: ffffbe9eb1bc4000
  RIP: 0010:__put_page+0x62/0x80
  Call Trace:
   devm_memremap_pages_release+0x152/0x260
   release_nodes+0x18d/0x1d0
   device_release_driver_internal+0x160/0x210
   unbind_store+0xb3/0xe0
   kernfs_fop_write+0x102/0x180
   __vfs_write+0x26/0x150
   vfs_write+0xad/0x1a0
   SyS_write+0x42/0x90
   do_syscall_64+0x74/0x150
   entry_SYSCALL_64_after_hwframe+0x3d/0xa2
  RIP: 0033:0x7fd13166b3d0

It has been reported on an older (4.12) kernel but the current upstream
code doesn't cond_resched in the hot remove code at all and the given
range to remove might be really large.  Fix the issue by calling
cond_resched once per memory section.

Link: http://lkml.kernel.org/r/20181031125840.23982-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Dan Williams <dan.j.williams@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-11-03 10:09:38 -07:00
Documentation for-linus-20181102 2018-11-02 11:25:48 -07:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
arch powerpc fixes for 4.20 #2 2018-11-02 09:19:35 -07:00
block for-linus-20181102 2018-11-02 11:25:48 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto KEYS: asym_tpm: Add support for the sign operation [ver #2] 2018-10-26 09:30:47 +01:00
drivers for-linus-20181102 2018-11-02 11:25:48 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs bfs: add sanity check at bfs_fill_super() 2018-11-03 10:09:38 -07:00
include mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask 2018-11-03 10:09:37 -07:00
init memblock: stop using implicit alignment to SMP_CACHE_BYTES 2018-10-31 08:54:16 -07:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel kernel/sysctl.c: remove duplicated include 2018-11-03 10:09:37 -07:00
lib Merge branch 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-11-01 19:58:52 -07:00
mm memory_hotplug: cond_resched in __remove_pages 2018-11-03 10:09:38 -07:00
net Merge branch 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-11-01 19:58:52 -07:00
samples VFIO updates for v4.20 2018-10-31 11:01:38 -07:00
scripts The Compiler Attributes series 2018-11-01 18:34:46 -07:00
security + Features/Improvements 2018-11-02 10:04:26 -07:00
sound sound fixes for 4.20-rc1 2018-11-02 11:02:52 -07:00
tools powerpc fixes for 4.20 #2 2018-11-02 09:19:35 -07:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks" 2018-10-26 16:25:19 -07:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.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 .mailmap: add Oleksij Rempel 2018-10-31 08:54:12 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS The Compiler Attributes series 2018-11-01 18:34:46 -07:00
Makefile Globally warn on VLA use 2018-10-28 13:26:45 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.