linux-toradex.git/kernel/workqueue.c, branch v6.7-rc4

Merge tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-11-03T06:53:31+00:00

Pull non-MM updates from Andrew Morton:
 "As usual, lots of singleton and doubleton patches all over the tree
  and there's little I can say which isn't in the individual changelogs.

  The lengthier patch series are

   - 'kdump: use generic functions to simplify crashkernel reservation
     in arch', from Baoquan He. This is mainly cleanups and
     consolidation of the 'crashkernel=' kernel parameter handling

   - After much discussion, David Laight's 'minmax: Relax type checks in
     min() and max()' is here. Hopefully reduces some typecasting and
     the use of min_t() and max_t()

   - A group of patches from Oleg Nesterov which clean up and slightly
     fix our handling of reads from /proc/PID/task/... and which remove
     task_struct.thread_group"

* tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (64 commits)
  scripts/gdb/vmalloc: disable on no-MMU
  scripts/gdb: fix usage of MOD_TEXT not defined when CONFIG_MODULES=n
  .mailmap: add address mapping for Tomeu Vizoso
  mailmap: update email address for Claudiu Beznea
  tools/testing/selftests/mm/run_vmtests.sh: lower the ptrace permissions
  .mailmap: map Benjamin Poirier's address
  scripts/gdb: add lx_current support for riscv
  ocfs2: fix a spelling typo in comment
  proc: test ProtectionKey in proc-empty-vm test
  proc: fix proc-empty-vm test with vsyscall
  fs/proc/base.c: remove unneeded semicolon
  do_io_accounting: use sig->stats_lock
  do_io_accounting: use __for_each_thread()
  ocfs2: replace BUG_ON() at ocfs2_num_free_extents() with ocfs2_error()
  ocfs2: fix a typo in a comment
  scripts/show_delta: add __main__ judgement before main code
  treewide: mark stuff as __ro_after_init
  fs: ocfs2: check status values
  proc: test /proc/${pid}/statm
  compiler.h: move __is_constexpr() to compiler.h
  ...

treewide: mark stuff as __ro_after_init

2023-10-18T21:43:23+00:00

__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton

workqueue: Provide one lock class key per work_on_cpu() callsite

2023-10-18T09:49:19+00:00

All callers of work_on_cpu() share the same lock class key for all the
functions queued. As a result the workqueue related locking scenario for
a function A may be spuriously accounted as an inversion against the
locking scenario of function B such as in the following model:

	long A(void *arg)
	{
		mutex_lock(&mutex);
		mutex_unlock(&mutex);
	}

	long B(void *arg)
	{
	}

	void launchA(void)
	{
		work_on_cpu(0, A, NULL);
	}

	void launchB(void)
	{
		mutex_lock(&mutex);
		work_on_cpu(1, B, NULL);
		mutex_unlock(&mutex);
	}

launchA and launchB running concurrently have no chance to deadlock.
However the above can be reported by lockdep as a possible locking
inversion because the works containing A() and B() are treated as
belonging to the same locking class.

The following shows an existing example of such a spurious lockdep splat:

	 ======================================================
	 WARNING: possible circular locking dependency detected
	 6.6.0-rc1-00065-g934ebd6e5359 #35409 Not tainted
	 ------------------------------------------------------
	 kworker/0:1/9 is trying to acquire lock:
	 ffffffff9bc72f30 (cpu_hotplug_lock){++++}-{0:0}, at: _cpu_down+0x57/0x2b0

	 but task is already holding lock:
	 ffff9e3bc0057e60 ((work_completion)(&wfc.work)){+.+.}-{0:0}, at: process_scheduled_works+0x216/0x500

	 which lock already depends on the new lock.

	 the existing dependency chain (in reverse order) is:

	 -> #2 ((work_completion)(&wfc.work)){+.+.}-{0:0}:
			__flush_work+0x83/0x4e0
			work_on_cpu+0x97/0xc0
			rcu_nocb_cpu_offload+0x62/0xb0
			rcu_nocb_toggle+0xd0/0x1d0
			kthread+0xe6/0x120
			ret_from_fork+0x2f/0x40
			ret_from_fork_asm+0x1b/0x30

	 -> #1 (rcu_state.barrier_mutex){+.+.}-{3:3}:
			__mutex_lock+0x81/0xc80
			rcu_nocb_cpu_deoffload+0x38/0xb0
			rcu_nocb_toggle+0x144/0x1d0
			kthread+0xe6/0x120
			ret_from_fork+0x2f/0x40
			ret_from_fork_asm+0x1b/0x30

	 -> #0 (cpu_hotplug_lock){++++}-{0:0}:
			__lock_acquire+0x1538/0x2500
			lock_acquire+0xbf/0x2a0
			percpu_down_write+0x31/0x200
			_cpu_down+0x57/0x2b0
			__cpu_down_maps_locked+0x10/0x20
			work_for_cpu_fn+0x15/0x20
			process_scheduled_works+0x2a7/0x500
			worker_thread+0x173/0x330
			kthread+0xe6/0x120
			ret_from_fork+0x2f/0x40
			ret_from_fork_asm+0x1b/0x30

	 other info that might help us debug this:

	 Chain exists of:
	   cpu_hotplug_lock --> rcu_state.barrier_mutex --> (work_completion)(&wfc.work)

	  Possible unsafe locking scenario:

			CPU0                    CPU1
			----                    ----
	   lock((work_completion)(&wfc.work));
									lock(rcu_state.barrier_mutex);
									lock((work_completion)(&wfc.work));
	   lock(cpu_hotplug_lock);

	  *** DEADLOCK ***

	 2 locks held by kworker/0:1/9:
	  #0: ffff900481068b38 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x212/0x500
	  #1: ffff9e3bc0057e60 ((work_completion)(&wfc.work)){+.+.}-{0:0}, at: process_scheduled_works+0x216/0x500

	 stack backtrace:
	 CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.6.0-rc1-00065-g934ebd6e5359 #35409
	 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
	 Workqueue: events work_for_cpu_fn
	 Call Trace:
	 rcu-torture: rcu_torture_read_exit: Start of episode
	  
	  dump_stack_lvl+0x4a/0x80
	  check_noncircular+0x132/0x150
	  __lock_acquire+0x1538/0x2500
	  lock_acquire+0xbf/0x2a0
	  ? _cpu_down+0x57/0x2b0
	  percpu_down_write+0x31/0x200
	  ? _cpu_down+0x57/0x2b0
	  _cpu_down+0x57/0x2b0
	  __cpu_down_maps_locked+0x10/0x20
	  work_for_cpu_fn+0x15/0x20
	  process_scheduled_works+0x2a7/0x500
	  worker_thread+0x173/0x330
	  ? __pfx_worker_thread+0x10/0x10
	  kthread+0xe6/0x120
	  ? __pfx_kthread+0x10/0x10
	  ret_from_fork+0x2f/0x40
	  ? __pfx_kthread+0x10/0x10
	  ret_from_fork_asm+0x1b/0x30
	  
Signed-off-by: Frederic Weisbecker 
Signed-off-by: Tejun Heo

workqueue: fix -Wformat-truncation in create_worker

2023-10-12T19:53:40+00:00

Compiling with W=1 emitted the following warning
(Compiler: gcc (x86-64, ver. 13.2.1, .config: result of make allyesconfig,
"Treat warnings as errors" turned off):

kernel/workqueue.c:2188:54: warning: ‘%d’ directive output may be
	truncated writing between 1 and 10 bytes into a region of size
	between 5 and 14 [-Wformat-truncation=]
kernel/workqueue.c:2188:50: note: directive argument in the range
	[0, 2147483647]
kernel/workqueue.c:2188:17: note: ‘snprintf’ output between 4 and 23 bytes
	into a destination of size 16

setting "id_buf" to size 23 will silence the warning, since GCC
determines snprintf's output to be max. 23 bytes in line 2188.

Please let me know if there are any mistakes in my patch!

Signed-off-by: Lucy Mielke 
Signed-off-by: Tejun Heo

workqueue: Override implicit ordered attribute in workqueue_apply_unbound_cpumask()

2023-10-12T19:52:15+00:00

Commit 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1
to be ordered") enabled implicit ordered attribute to be added to
WQ_UNBOUND workqueues with max_active of 1. This prevented the changing
of attributes to these workqueues leading to fix commit 0a94efb5acbb
("workqueue: implicit ordered attribute should be overridable").

However, workqueue_apply_unbound_cpumask() was not updated at that time.
So sysfs changes to wq_unbound_cpumask has no effect on WQ_UNBOUND
workqueues with implicit ordered attribute. Since not all WQ_UNBOUND
workqueues are visible on sysfs, we are not able to make all the
necessary cpumask changes even if we iterates all the workqueue cpumasks
in sysfs and changing them one by one.

Fix this problem by applying the corresponding change made
to apply_workqueue_attrs_locked() in the fix commit to
workqueue_apply_unbound_cpumask().

Fixes: 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered")
Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo

workqueue: Use the kmem_cache_free() instead of kfree() to release pwq

2023-10-12T17:34:07+00:00

Currently, the kfree() be used for pwq objects allocated with
kmem_cache_alloc() in alloc_and_link_pwqs(), this isn't wrong.
but usually, use "trace_kmem_cache_alloc/trace_kmem_cache_free"
to track memory allocation and free. this commit therefore use
kmem_cache_free() instead of kfree() in alloc_and_link_pwqs()
and also consistent with release of the pwq in rcu_free_pwq().

Signed-off-by: Zqiang 
Signed-off-by: Tejun Heo

workqueue: Fix UAF report by KASAN in pwq_release_workfn()

2023-10-04T19:06:26+00:00

Currently, for UNBOUND wq, if the apply_wqattrs_prepare() return error,
the apply_wqattr_cleanup() will be called and use the pwq_release_worker
kthread to release resources asynchronously. however, the kfree(wq) is
invoked directly in failure path of alloc_workqueue(), if the kfree(wq)
has been executed and when the pwq_release_workfn() accesses wq, this
leads to the following scenario:

BUG: KASAN: slab-use-after-free in pwq_release_workfn+0x339/0x380 kernel/workqueue.c:4124
Read of size 4 at addr ffff888027b831c0 by task pool_workqueue_/3

CPU: 0 PID: 3 Comm: pool_workqueue_ Not tainted 6.5.0-rc7-next-20230825-syzkaller #0
Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xc4/0x620 mm/kasan/report.c:475
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 pwq_release_workfn+0x339/0x380 kernel/workqueue.c:4124
 kthread_worker_fn+0x2fc/0xa80 kernel/kthread.c:823
 kthread+0x33a/0x430 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 

Allocated by task 5054:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:599 [inline]
 kzalloc include/linux/slab.h:720 [inline]
 alloc_workqueue+0x16f/0x1490 kernel/workqueue.c:4684
 kvm_mmu_init_tdp_mmu+0x23/0x100 arch/x86/kvm/mmu/tdp_mmu.c:19
 kvm_mmu_init_vm+0x248/0x2e0 arch/x86/kvm/mmu/mmu.c:6180
 kvm_arch_init_vm+0x39/0x720 arch/x86/kvm/x86.c:12311
 kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1222 [inline]
 kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:5089 [inline]
 kvm_dev_ioctl+0xa31/0x1c20 arch/x86/kvm/../../../virt/kvm/kvm_main.c:5131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5054:
 kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x15b/0x1b0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1800 [inline]
 slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826
 slab_free mm/slub.c:3809 [inline]
 __kmem_cache_free+0xb8/0x2f0 mm/slub.c:3822
 alloc_workqueue+0xe76/0x1490 kernel/workqueue.c:4746
 kvm_mmu_init_tdp_mmu+0x23/0x100 arch/x86/kvm/mmu/tdp_mmu.c:19
 kvm_mmu_init_vm+0x248/0x2e0 arch/x86/kvm/mmu/mmu.c:6180
 kvm_arch_init_vm+0x39/0x720 arch/x86/kvm/x86.c:12311
 kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1222 [inline]
 kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:5089 [inline]
 kvm_dev_ioctl+0xa31/0x1c20 arch/x86/kvm/../../../virt/kvm/kvm_main.c:5131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

This commit therefore flush pwq_release_worker in the alloc_and_link_pwqs()
before invoke kfree(wq).

Reported-by: syzbot+60db9f652c92d5bacba4@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=60db9f652c92d5bacba4
Signed-off-by: Zqiang 
Signed-off-by: Tejun Heo

workqueue: Fix missed pwq_release_worker creation in wq_cpu_intensive_thresh_init()

2023-09-18T18:50:31+00:00

Currently, if the wq_cpu_intensive_thresh_us is set to specific
value, will cause the wq_cpu_intensive_thresh_init() early exit
and missed creation of pwq_release_worker. this commit therefore
create the pwq_release_worker in advance before checking the
wq_cpu_intensive_thresh_us.

Signed-off-by: Zqiang 
Signed-off-by: Tejun Heo 
Fixes: 967b494e2fd1 ("workqueue: Use a kthread_worker to release pool_workqueues")

workqueue: Removed double allocation of wq_update_pod_attrs_buf

2023-09-18T18:35:25+00:00

First commit 2930155b2e272 ("workqueue: Initialize unbound CPU pods later in
the boot") added the initialization of wq_update_pod_attrs_buf to
workqueue_init_early(), and then latter on, commit 84193c07105c6
("workqueue: Generalize unbound CPU pods") added it as well. This appeared
in a kmemleak run where the second allocation made the first allocation
leak.

Fixes: 84193c07105c6 ("workqueue: Generalize unbound CPU pods")
Signed-off-by: Steven Rostedt (Google) 
Reviewed-by: Geert Uytterhoeven 
Signed-off-by: Tejun Heo

workqueue: fix data race with the pwq->stats[] increment

2023-08-29T19:52:16+00:00

KCSAN has discovered a data race in kernel/workqueue.c:2598:

[ 1863.554079] ==================================================================
[ 1863.554118] BUG: KCSAN: data-race in process_one_work / process_one_work

[ 1863.554142] write to 0xffff963d99d79998 of 8 bytes by task 5394 on cpu 27:
[ 1863.554154] process_one_work (kernel/workqueue.c:2598)
[ 1863.554166] worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2752)
[ 1863.554177] kthread (kernel/kthread.c:389)
[ 1863.554186] ret_from_fork (arch/x86/kernel/process.c:145)
[ 1863.554197] ret_from_fork_asm (arch/x86/entry/entry_64.S:312)

[ 1863.554213] read to 0xffff963d99d79998 of 8 bytes by task 5450 on cpu 12:
[ 1863.554224] process_one_work (kernel/workqueue.c:2598)
[ 1863.554235] worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2752)
[ 1863.554247] kthread (kernel/kthread.c:389)
[ 1863.554255] ret_from_fork (arch/x86/kernel/process.c:145)
[ 1863.554266] ret_from_fork_asm (arch/x86/entry/entry_64.S:312)

[ 1863.554280] value changed: 0x0000000000001766 -> 0x000000000000176a

[ 1863.554295] Reported by Kernel Concurrency Sanitizer on:
[ 1863.554303] CPU: 12 PID: 5450 Comm: kworker/u64:1 Tainted: G             L     6.5.0-rc6+ #44
[ 1863.554314] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023
[ 1863.554322] Workqueue: btrfs-endio btrfs_end_bio_work [btrfs]
[ 1863.554941] ==================================================================

    lockdep_invariant_state(true);
→   pwq->stats[PWQ_STAT_STARTED]++;
    trace_workqueue_execute_start(work);
    worker->current_func(work);

Moving pwq->stats[PWQ_STAT_STARTED]++; before the line

    raw_spin_unlock_irq(&pool->lock);

resolves the data race without performance penalty.

KCSAN detected at least one additional data race:

[  157.834751] ==================================================================
[  157.834770] BUG: KCSAN: data-race in process_one_work / process_one_work

[  157.834793] write to 0xffff9934453f77a0 of 8 bytes by task 468 on cpu 29:
[  157.834804] process_one_work (/home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2606)
[  157.834815] worker_thread (/home/marvin/linux/kernel/linux_torvalds/./include/linux/list.h:292 /home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2752)
[  157.834826] kthread (/home/marvin/linux/kernel/linux_torvalds/kernel/kthread.c:389)
[  157.834834] ret_from_fork (/home/marvin/linux/kernel/linux_torvalds/arch/x86/kernel/process.c:145)
[  157.834845] ret_from_fork_asm (/home/marvin/linux/kernel/linux_torvalds/arch/x86/entry/entry_64.S:312)

[  157.834859] read to 0xffff9934453f77a0 of 8 bytes by task 214 on cpu 7:
[  157.834868] process_one_work (/home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2606)
[  157.834879] worker_thread (/home/marvin/linux/kernel/linux_torvalds/./include/linux/list.h:292 /home/marvin/linux/kernel/linux_torvalds/kernel/workqueue.c:2752)
[  157.834890] kthread (/home/marvin/linux/kernel/linux_torvalds/kernel/kthread.c:389)
[  157.834897] ret_from_fork (/home/marvin/linux/kernel/linux_torvalds/arch/x86/kernel/process.c:145)
[  157.834907] ret_from_fork_asm (/home/marvin/linux/kernel/linux_torvalds/arch/x86/entry/entry_64.S:312)

[  157.834920] value changed: 0x000000000000052a -> 0x0000000000000532

[  157.834933] Reported by Kernel Concurrency Sanitizer on:
[  157.834941] CPU: 7 PID: 214 Comm: kworker/u64:2 Tainted: G             L     6.5.0-rc7-kcsan-00169-g81eaf55a60fc #4
[  157.834951] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023
[  157.834958] Workqueue: btrfs-endio btrfs_end_bio_work [btrfs]
[  157.835567] ==================================================================

in code:

        trace_workqueue_execute_end(work, worker->current_func);
→       pwq->stats[PWQ_STAT_COMPLETED]++;
        lock_map_release(&lockdep_map);
        lock_map_release(&pwq->wq->lockdep_map);

which needs to be resolved separately.

Fixes: 725e8ec59c56c ("workqueue: Add pwq->stats[] and a monitoring script")
Cc: Tejun Heo 
Suggested-by: Lai Jiangshan 
Link: https://lore.kernel.org/lkml/20230818194448.29672-1-mirsad.todorovac@alu.unizg.hr/
Signed-off-by: Mirsad Goran Todorovac 
Signed-off-by: Tejun Heo