linux.git/kernel/workqueue.c, branch v5.11-rc1

Merge branch 'akpm' (patches from Andrew)

2020-12-15T20:53:37+00:00

Merge misc updates from Andrew Morton:

 - a few random little subsystems

 - almost all of the MM patches which are staged ahead of linux-next
   material. I'll trickle to post-linux-next work in as the dependents
   get merged up.

Subsystems affected by this patch series: kthread, kbuild, ide, ntfs,
ocfs2, arch, and mm (slab-generic, slab, slub, dax, debug, pagecache,
gup, swap, shmem, memcg, pagemap, mremap, hmm, vmalloc, documentation,
kasan, pagealloc, memory-failure, hugetlb, vmscan, z3fold, compaction,
oom-kill, migration, cma, page-poison, userfaultfd, zswap, zsmalloc,
uaccess, zram, and cleanups).

* emailed patches from Andrew Morton : (200 commits)
  mm: cleanup kstrto*() usage
  mm: fix fall-through warnings for Clang
  mm: slub: convert sysfs sprintf family to sysfs_emit/sysfs_emit_at
  mm: shmem: convert shmem_enabled_show to use sysfs_emit_at
  mm:backing-dev: use sysfs_emit in macro defining functions
  mm: huge_memory: convert remaining use of sprintf to sysfs_emit and neatening
  mm: use sysfs_emit for struct kobject * uses
  mm: fix kernel-doc markups
  zram: break the strict dependency from lzo
  zram: add stat to gather incompressible pages since zram set up
  zram: support page writeback
  mm/process_vm_access: remove redundant initialization of iov_r
  mm/zsmalloc.c: rework the list_add code in insert_zspage()
  mm/zswap: move to use crypto_acomp API for hardware acceleration
  mm/zswap: fix passing zero to 'PTR_ERR' warning
  mm/zswap: make struct kernel_param_ops definitions const
  userfaultfd/selftests: hint the test runner on required privilege
  userfaultfd/selftests: fix retval check for userfaultfd_open()
  userfaultfd/selftests: always dump something in modes
  userfaultfd: selftests: make __{s,u}64 format specifiers portable
  ...

workqueue: kasan: record workqueue stack

2020-12-15T20:13:42+00:00

Patch series "kasan: add workqueue stack for generic KASAN", v5.

Syzbot reports many UAF issues for workqueue, see [1].

In some of these access/allocation happened in process_one_work(), we
see the free stack is useless in KASAN report, it doesn't help
programmers to solve UAF for workqueue issue.

This patchset improves KASAN reports by making them to have workqueue
queueing stack.  It is useful for programmers to solve use-after-free or
double-free memory issue.

Generic KASAN also records the last two workqueue stacks and prints them
in KASAN report.  It is only suitable for generic KASAN.

[1] https://groups.google.com/g/syzkaller-bugs/search?q=%22use-after-free%22+process_one_work
[2] https://bugzilla.kernel.org/show_bug.cgi?id=198437

This patch (of 4):

When analyzing use-after-free or double-free issue, recording the
enqueuing work stacks is helpful to preserve usage history which
potentially gives a hint about the affected code.

For workqueue it has turned out to be useful to record the enqueuing work
call stacks.  Because user can see KASAN report to determine whether it is
root cause.  They don't need to enable debugobjects, but they have a
chance to find out the root cause.

Link: https://lkml.kernel.org/r/20201203022148.29754-1-walter-zh.wu@mediatek.com
Link: https://lkml.kernel.org/r/20201203022442.30006-1-walter-zh.wu@mediatek.com
Signed-off-by: Walter Wu 
Suggested-by: Marco Elver 
Acked-by: Marco Elver 
Acked-by: Tejun Heo 
Reviewed-by: Dmitry Vyukov 
Reviewed-by: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Alexander Potapenko 
Cc: Lai Jiangshan 
Cc: Marco Elver 
Cc: Matthias Brugger 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

workqueue: Manually break affinity on hotplug

2020-11-10T17:38:58+00:00

Don't rely on the scheduler to force break affinity for us -- it will
stop doing that for per-cpu-kthreads.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Valentin Schneider 
Acked-by: Tejun Heo 
Reviewed-by: Daniel Bristot de Oliveira 
Link: https://lkml.kernel.org/r/20201023102346.464718669@infradead.org

workqueue: fix a kernel-doc warning

2020-10-16T05:28:20+00:00

As warned by Sphinx:

	./Documentation/core-api/workqueue:400: ./kernel/workqueue.c:1218: WARNING: Unexpected indentation.

the return code table is currently not recognized, as it lacks
markups.

Acked-by: Tejun Heo 
Signed-off-by: Mauro Carvalho Chehab

treewide: Make all debug_obj_descriptors const

2020-09-24T19:56:25+00:00

This should make it harder for the kernel to corrupt the debug object
descriptor, used to call functions to fixup state and track debug objects,
by moving the structure to read-only memory.

Signed-off-by: Stephen Boyd 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Kees Cook 
Link: https://lore.kernel.org/r/20200815004027.2046113-3-swboyd@chromium.org

maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

2020-06-17T17:57:41+00:00

Better describe what these functions do.

Suggested-by: Linus Torvalds 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

workqueue: use BUILD_BUG_ON() for compile time test instead of WARN_ON()

2020-06-01T15:02:42+00:00

Any runtime WARN_ON() has to be fixed, and BUILD_BUG_ON() can
help you nitice it earlier.

Signed-off-by: Lai Jiangshan 
Signed-off-by: Tejun Heo

workqueue: remove useless unlock() and lock() in series

2020-05-29T14:25:23+00:00

This is no point to unlock() and then lock() the same mutex
back to back.

Signed-off-by: Lai Jiangshan 
Signed-off-by: Tejun Heo

workqueue: void unneeded requeuing the pwq in rescuer thread

2020-05-29T14:22:10+00:00

008847f66c3 ("workqueue: allow rescuer thread to do more work.") made
the rescuer worker requeue the pwq immediately if there may be more
work items which need rescuing instead of waiting for the next mayday
timer expiration.  Unfortunately, it checks only whether the pool needs
help from rescuers, but it doesn't check whether the pwq has work items
in the pool (the real reason that this rescuer can help for the pool).

The patch adds the check and void unneeded requeuing.

Signed-off-by: Lai Jiangshan 
Signed-off-by: Tejun Heo

workqueue: Convert the pool::lock and wq_mayday_lock to raw_spinlock_t

2020-05-29T14:03:47+00:00

The workqueue code has it's internal spinlocks (pool::lock), which
are acquired on most workqueue operations. These spinlocks are
converted to 'sleeping' spinlocks on a RT-kernel.

Workqueue functions can be invoked from contexts which are truly atomic
even on a PREEMPT_RT enabled kernel. Taking sleeping locks from such
contexts is forbidden.

The pool::lock hold times are bound and the code sections are
relatively short, which allows to convert pool::lock and as a
consequence wq_mayday_lock to raw spinlocks which are truly spinning
locks even on a PREEMPT_RT kernel.

With the previous conversion of the manager waitqueue to a simple
waitqueue workqueues are now fully RT compliant.

Signed-off-by: Sebastian Andrzej Siewior 
Reviewed-by: Lai Jiangshan 
Signed-off-by: Tejun Heo