linux-stable.git/arch/sh, branch v5.13.2

sched/core: Initialize the idle task with preemption disabled

2021-07-14T15:06:21+00:00

[ Upstream commit f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674 ]

As pointed out by commit

  de9b8f5dcbd9 ("sched: Fix crash trying to dequeue/enqueue the idle thread")

init_idle() can and will be invoked more than once on the same idle
task. At boot time, it is invoked for the boot CPU thread by
sched_init(). Then smp_init() creates the threads for all the secondary
CPUs and invokes init_idle() on them.

As the hotplug machinery brings the secondaries to life, it will issue
calls to idle_thread_get(), which itself invokes init_idle() yet again.
In this case it's invoked twice more per secondary: at _cpu_up(), and at
bringup_cpu().

Given smp_init() already initializes the idle tasks for all *possible*
CPUs, no further initialization should be required. Now, removing
init_idle() from idle_thread_get() exposes some interesting expectations
with regards to the idle task's preempt_count: the secondary startup always
issues a preempt_disable(), requiring some reset of the preempt count to 0
between hot-unplug and hotplug, which is currently served by
idle_thread_get() -> idle_init().

Given the idle task is supposed to have preemption disabled once and never
see it re-enabled, it seems that what we actually want is to initialize its
preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove
init_idle() from idle_thread_get().

Secondary startups were patched via coccinelle:

  @begone@
  @@

  -preempt_disable();
  ...
  cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

Signed-off-by: Valentin Schneider 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com
Signed-off-by: Sasha Levin

Merge tag 'quota_for_v5.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2021-05-20T16:20:15+00:00

Pull quota fixes from Jan Kara:
 "The most important part in the pull is disablement of the new syscall
  quotactl_path() which was added in rc1.

  The reason is some people at LWN discussion pointed out dirfd would be
  useful for this path based syscall and Christian Brauner agreed.

  Without dirfd it may be indeed problematic for containers. So let's
  just disable the syscall for now when it doesn't have users yet so
  that we have more time to mull over how to best specify the filesystem
  we want to work on"

* tag 'quota_for_v5.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  quota: Disable quotactl_path syscall
  quota: Use 'hlist_for_each_entry' to simplify code

quota: Disable quotactl_path syscall

2021-05-17T12:39:56+00:00

In commit fa8b90070a80 ("quota: wire up quotactl_path") we have wired up
new quotactl_path syscall. However some people in LWN discussion have
objected that the path based syscall is missing dirfd and flags argument
which is mostly standard for contemporary path based syscalls. Indeed
they have a point and after a discussion with Christian Brauner and
Sascha Hauer I've decided to disable the syscall for now and update its
API. Since there is no userspace currently using that syscall and it
hasn't been released in any major release, we should be fine.

CC: Christian Brauner 
CC: Sascha Hauer 
Link: https://lore.kernel.org/lkml/20210512153621.n5u43jsytbik4yze@wittgenstein
Signed-off-by: Jan Kara

sh: Remove unused variable

2021-05-10T21:23:04+00:00

Removes this annoying warning:

arch/sh/kernel/traps.c: In function ‘nmi_trap_handler’:
arch/sh/kernel/traps.c:183:15: warning: unused variable ‘cpu’ [-Wunused-variable]
  183 |  unsigned int cpu = smp_processor_id();

Fixes: fe3f1d5d7cd3 ("sh: Get rid of nmi_count()")
Signed-off-by: Eric Dumazet 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210414170517.1205430-1-eric.dumazet@gmail.com

Merge tag 'kbuild-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2021-05-08T17:00:11+00:00

Pull more Kbuild updates from Masahiro Yamada:

 - Convert sh and sparc to use generic shell scripts to generate the
   syscall headers

 - refactor .gitignore files

 - Update kernel/config_data.gz only when the content of the .config
   is really changed, which avoids the unneeded re-link of vmlinux

 - move "remove stale files" workarounds to scripts/remove-stale-files

 - suppress unused-but-set-variable warnings by default for Clang
   as well

 - fix locale setting LANG=C to LC_ALL=C

 - improve 'make distclean'

 - always keep intermediate objects from scripts/link-vmlinux.sh

 - move IF_ENABLED out of  to make it self-contained

 - misc cleanups

* tag 'kbuild-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (25 commits)
  linux/kconfig.h: replace IF_ENABLED() with PTR_IF() in 
  kbuild: Don't remove link-vmlinux temporary files on exit/signal
  kbuild: remove the unneeded comments for external module builds
  kbuild: make distclean remove tag files in sub-directories
  kbuild: make distclean work against $(objtree) instead of $(srctree)
  kbuild: refactor modname-multi by using suffix-search
  kbuild: refactor fdtoverlay rule
  kbuild: parameterize the .o part of suffix-search
  arch: use cross_compiling to check whether it is a cross build or not
  kbuild: remove ARCH=sh64 support from top Makefile
  .gitignore: prefix local generated files with a slash
  kbuild: replace LANG=C with LC_ALL=C
  Makefile: Move -Wno-unused-but-set-variable out of GCC only block
  kbuild: add a script to remove stale generated files
  kbuild: update config_data.gz only when the content of .config is changed
  .gitignore: ignore only top-level modules.builtin
  .gitignore: move tags and TAGS close to other tag files
  kernel/.gitgnore: remove stale timeconst.h and hz.bc
  usr/include: refactor .gitignore
  genksyms: fix stale comment
  ...

Merge branch 'akpm' (patches from Andrew)

2021-05-07T07:34:51+00:00

Merge yet more updates from Andrew Morton:
 "This is everything else from -mm for this merge window.

  90 patches.

  Subsystems affected by this patch series: mm (cleanups and slub),
  alpha, procfs, sysctl, misc, core-kernel, bitmap, lib, compat,
  checkpatch, epoll, isofs, nilfs2, hpfs, exit, fork, kexec, gcov,
  panic, delayacct, gdb, resource, selftests, async, initramfs, ipc,
  drivers/char, and spelling"

* emailed patches from Andrew Morton : (90 commits)
  mm: fix typos in comments
  mm: fix typos in comments
  treewide: remove editor modelines and cruft
  ipc/sem.c: spelling fix
  fs: fat: fix spelling typo of values
  kernel/sys.c: fix typo
  kernel/up.c: fix typo
  kernel/user_namespace.c: fix typos
  kernel/umh.c: fix some spelling mistakes
  include/linux/pgtable.h: few spelling fixes
  mm/slab.c: fix spelling mistake "disired" -> "desired"
  scripts/spelling.txt: add "overflw"
  scripts/spelling.txt: Add "diabled" typo
  scripts/spelling.txt: add "overlfow"
  arm: print alloc free paths for address in registers
  mm/vmalloc: remove vwrite()
  mm: remove xlate_dev_kmem_ptr()
  drivers/char: remove /dev/kmem for good
  mm: fix some typos and code style problems
  ipc/sem.c: mundane typo fixes
  ...

mm: remove xlate_dev_kmem_ptr()

2021-05-07T07:26:34+00:00

Since /dev/kmem has been removed, let's remove the xlate_dev_kmem_ptr()
leftovers.

Link: https://lkml.kernel.org/r/20210324102351.6932-3-david@redhat.com
Signed-off-by: David Hildenbrand 
Acked-by: Geert Uytterhoeven 
Acked-by: Michal Hocko 
Cc: Linus Torvalds 
Cc: Greg Kroah-Hartman 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Russell King 
Cc: Brian Cain 
Cc: Geert Uytterhoeven 
Cc: Thomas Bogendoerfer 
Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: Yoshinori Sato 
Cc: Rich Felker 
Cc: "David S. Miller" 
Cc: Arnd Bergmann 
Cc: David Hildenbrand 
Cc: Krzysztof Kozlowski 
Cc: Mikulas Patocka 
Cc: Luc Van Oostenryck 
Cc: Mike Rapoport 
Cc: Palmer Dabbelt 
Cc: Luis Chamberlain 
Cc: Greentime Hu 
Cc: Sebastian Andrzej Siewior 
Cc: Randy Dunlap 
Cc: Jiaxun Yang 
Cc: "Peter Zijlstra (Intel)" 
Cc: Christophe Leroy 
Cc: Gerald Schaefer 
Cc: Niklas Schnelle 
Cc: Pierre Morel 
Cc: Ingo Molnar 
Cc: Kuninori Morimoto 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

drivers/char: remove /dev/kmem for good

2021-05-07T07:26:34+00:00

Patch series "drivers/char: remove /dev/kmem for good".

Exploring /dev/kmem and /dev/mem in the context of memory hot(un)plug and
memory ballooning, I started questioning the existence of /dev/kmem.

Comparing it with the /proc/kcore implementation, it does not seem to be
able to deal with things like

a) Pages unmapped from the direct mapping (e.g., to be used by secretmem)
  -> kern_addr_valid(). virt_addr_valid() is not sufficient.

b) Special cases like gart aperture memory that is not to be touched
  -> mem_pfn_is_ram()

Unless I am missing something, it's at least broken in some cases and might
fault/crash the machine.

Looks like its existence has been questioned before in 2005 and 2010 [1],
after ~11 additional years, it might make sense to revive the discussion.

CONFIG_DEVKMEM is only enabled in a single defconfig (on purpose or by
mistake?).  All distributions disable it: in Ubuntu it has been disabled
for more than 10 years, in Debian since 2.6.31, in Fedora at least
starting with FC3, in RHEL starting with RHEL4, in SUSE starting from
15sp2, and OpenSUSE has it disabled as well.

1) /dev/kmem was popular for rootkits [2] before it got disabled
   basically everywhere. Ubuntu documents [3] "There is no modern user of
   /dev/kmem any more beyond attackers using it to load kernel rootkits.".
   RHEL documents in a BZ [5] "it served no practical purpose other than to
   serve as a potential security problem or to enable binary module drivers
   to access structures/functions they shouldn't be touching"

2) /proc/kcore is a decent interface to have a controlled way to read
   kernel memory for debugging puposes. (will need some extensions to
   deal with memory offlining/unplug, memory ballooning, and poisoned
   pages, though)

3) It might be useful for corner case debugging [1]. KDB/KGDB might be a
   better fit, especially, to write random memory; harder to shoot
   yourself into the foot.

4) "Kernel Memory Editor" [4] hasn't seen any updates since 2000 and seems
   to be incompatible with 64bit [1]. For educational purposes,
   /proc/kcore might be used to monitor value updates -- or older
   kernels can be used.

5) It's broken on arm64, and therefore, completely disabled there.

Looks like it's essentially unused and has been replaced by better
suited interfaces for individual tasks (/proc/kcore, KDB/KGDB). Let's
just remove it.

[1] https://lwn.net/Articles/147901/
[2] https://www.linuxjournal.com/article/10505
[3] https://wiki.ubuntu.com/Security/Features#A.2Fdev.2Fkmem_disabled
[4] https://sourceforge.net/projects/kme/
[5] https://bugzilla.redhat.com/show_bug.cgi?id=154796

Link: https://lkml.kernel.org/r/20210324102351.6932-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210324102351.6932-2-david@redhat.com
Signed-off-by: David Hildenbrand 
Acked-by: Michal Hocko 
Acked-by: Kees Cook 
Cc: Linus Torvalds 
Cc: Greg Kroah-Hartman 
Cc: "Alexander A. Klimov" 
Cc: Alexander Viro 
Cc: Alexandre Belloni 
Cc: Andrew Lunn 
Cc: Andrey Zhizhikin 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Brian Cain 
Cc: Christian Borntraeger 
Cc: Christophe Leroy 
Cc: Chris Zankel 
Cc: Corentin Labbe 
Cc: "David S. Miller" 
Cc: "Eric W. Biederman" 
Cc: Geert Uytterhoeven 
Cc: Gerald Schaefer 
Cc: Greentime Hu 
Cc: Gregory Clement 
Cc: Heiko Carstens 
Cc: Helge Deller 
Cc: Hillf Danton 
Cc: huang ying 
Cc: Ingo Molnar 
Cc: Ivan Kokshaysky 
Cc: "James E.J. Bottomley" 
Cc: James Troup 
Cc: Jiaxun Yang 
Cc: Jonas Bonn 
Cc: Jonathan Corbet 
Cc: Kairui Song 
Cc: Krzysztof Kozlowski 
Cc: Kuninori Morimoto 
Cc: Liviu Dudau 
Cc: Lorenzo Pieralisi 
Cc: Luc Van Oostenryck 
Cc: Luis Chamberlain 
Cc: Matthew Wilcox 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Mike Rapoport 
Cc: Mikulas Patocka 
Cc: Minchan Kim 
Cc: Niklas Schnelle 
Cc: Oleksiy Avramchenko 
Cc: openrisc@lists.librecores.org
Cc: Palmer Dabbelt 
Cc: Paul Mackerras 
Cc: "Pavel Machek (CIP)" 
Cc: Pavel Machek 
Cc: "Peter Zijlstra (Intel)" 
Cc: Pierre Morel 
Cc: Randy Dunlap 
Cc: Richard Henderson 
Cc: Rich Felker 
Cc: Robert Richter 
Cc: Rob Herring 
Cc: Russell King 
Cc: Sam Ravnborg 
Cc: Sebastian Andrzej Siewior 
Cc: Sebastian Hesselbarth 
Cc: sparclinux@vger.kernel.org
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Steven Rostedt 
Cc: Sudeep Holla 
Cc: Theodore Dubois 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Viresh Kumar 
Cc: William Cohen 
Cc: Xiaoming Ni 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

arch: rearrange headers inclusion order in asm/bitops for m68k, sh and h8300

2021-05-07T02:24:11+00:00

m68k and sh include bitmap/{find,le}.h prior to ffs/fls headers.  New
fast-path implementation in find.h requires ffs/fls.  Reordering the
headers inclusion sequence helps to prevent compile-time implicit function
declaration error.

[yury.norov@gmail.com: h8300: rearrange headers inclusion order in asm/bitops]
  Link: https://lkml.kernel.org/r/20210406183625.794227-1-yury.norov@gmail.com

Link: https://lkml.kernel.org/r/20210401003153.97325-5-yury.norov@gmail.com
Signed-off-by: Yury Norov 
Acked-by: Geert Uytterhoeven 
Acked-by: Rasmus Villemoes 
Reviewed-by: Andy Shevchenko 
Tested-by: Guenter Roeck 
Cc: Alexey Klimov 
Cc: Arnd Bergmann 
Cc: David Sterba 
Cc: Dennis Zhou 
Cc: Jianpeng Ma 
Cc: Joe Perches 
Cc: John Paul Adrian Glaubitz 
Cc: Josh Poimboeuf 
Cc: Rich Felker 
Cc: Stefano Brivio 
Cc: Wei Yang 
Cc: Wolfram Sang 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2021-05-05T20:50:15+00:00

Merge more updates from Andrew Morton:
 "The remainder of the main mm/ queue.

  143 patches.

  Subsystems affected by this patch series (all mm): pagecache, hugetlb,
  userfaultfd, vmscan, compaction, migration, cma, ksm, vmstat, mmap,
  kconfig, util, memory-hotplug, zswap, zsmalloc, highmem, cleanups, and
  kfence"

* emailed patches from Andrew Morton : (143 commits)
  kfence: use power-efficient work queue to run delayed work
  kfence: maximize allocation wait timeout duration
  kfence: await for allocation using wait_event
  kfence: zero guard page after out-of-bounds access
  mm/process_vm_access.c: remove duplicate include
  mm/mempool: minor coding style tweaks
  mm/highmem.c: fix coding style issue
  btrfs: use memzero_page() instead of open coded kmap pattern
  iov_iter: lift memzero_page() to highmem.h
  mm/zsmalloc: use BUG_ON instead of if condition followed by BUG.
  mm/zswap.c: switch from strlcpy to strscpy
  arm64/Kconfig: introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
  x86/Kconfig: introduce ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
  mm,memory_hotplug: add kernel boot option to enable memmap_on_memory
  acpi,memhotplug: enable MHP_MEMMAP_ON_MEMORY when supported
  mm,memory_hotplug: allocate memmap from the added memory range
  mm,memory_hotplug: factor out adjusting present pages into adjust_present_page_count()
  mm,memory_hotplug: relax fully spanned sections check
  drivers/base/memory: introduce memory_block_{online,offline}
  mm/memory_hotplug: remove broken locking of zone PCP structures during hot remove
  ...