Re: Linux 6.3-rc2

[Guenter Roeck]

On Sun, Mar 12, 2023 at 04:45:57PM -0700, Linus Torvalds wrote:
> It's another Sunday afternoon. which must mean another rc release.
> 
> This one looks fairly normal, although if you look at the diffs, they
> are dominated by the removal of a staging driver (r8188eu) that has
> been superceded by a proper driver. That removal itself is 90% of the
> diffs.
> 
> But if you filter that out, it all looks normal. Still more than two
> thirds in drivers, but hey, that's pretty normal. It's mostly gpu and
> networking as usual, but there's various other driver fixes in there
> too.
> 
> Outside of that regular driver noise (and the unusual driver removal
> noise) it's a little bit of everything: core networking, arch fixes,
> documentation, filesystems (btrfs, xfs, and ext4, but also some core
> vfs fixes). And io_uring and some tooling.
> 
> The full shortlog is appended, for the adventurous souls that want to
> get that kind of details. The release feels fairly normal so far, but
> it's early days. Please keep testing and reporting any issues,
> 

Build results:
	total: 153 pass: 146 fail: 7
Failed builds:
	alpha:allmodconfig
	csky:allmodconfig
	m68k:allmodconfig
	openrisc:allmodconfig
	parisc:allmodconfig
	s390:allmodconfig
	sparc64:allmodconfig
Qemu test results:
	total: 517 pass: 517 fail: 0

---
Build failures:

alpha:allmodconfig
csky:allmodconfig
m68k:allmodconfig
openrisc:allmodconfig
parisc:allmodconfig
s390:allmodconfig
sparc64:allmodconfig

Tracked at https://linux-regtracking.leemhuis.info/regzbot/mainline.

- Build failures for sparc64:allmodconfig and parisc:allmodconfig with gcc 11.x
- Build error in drivers/media/i2c/imx290.c if PM support is disabled

Fixes pending.

===
Runtime:

Warning backtraces in calls from ct_nmi_enter(),
seen randomly.

   28.758119] ------------[ cut here ]------------
[   28.758418] WARNING: CPU: 0 PID: 301 at kernel/locking/lockdep.c:5527 check_flags+0x170/0x258
[   28.759084] DEBUG_LOCKS_WARN_ON(current->softirqs_enabled)
[   28.759127] Modules linked in:
[   28.759652] CPU: 0 PID: 301 Comm: run.sh Tainted: G                 N 6.2.0-13115-gee3f96b16468 #1
[   28.759959] Hardware name: Freescale i.MX7 Dual (Device Tree)
[   28.760324]  unwind_backtrace from show_stack+0x10/0x14
[   28.760567]  show_stack from dump_stack_lvl+0x68/0x90
[   28.760708]  dump_stack_lvl from __warn+0x70/0x1e0
[   28.760863]  __warn from warn_slowpath_fmt+0x118/0x230
[   28.761015]  warn_slowpath_fmt from check_flags+0x170/0x258
[   28.761179]  check_flags from lock_is_held_type+0x6c/0x308
[   28.761326]  lock_is_held_type from rcu_read_lock_sched_held+0x3c/0x70
[   28.761505]  rcu_read_lock_sched_held from trace_rcu_dyntick+0x7c/0x128
[   28.761698]  trace_rcu_dyntick from ct_nmi_enter+0x6c/0xe4
[   28.761857]  ct_nmi_enter from irq_enter+0x8/0x10
[   28.762021]  irq_enter from generic_handle_arch_irq+0xc/0x64
[   28.762187]  generic_handle_arch_irq from call_with_stack+0x18/0x20
[   28.762370]  call_with_stack from __irq_svc+0x9c/0xbc
[   28.762594] Exception stack(0xd1b15f60 to 0xd1b15fa8)
[   28.762849] 5f60: ecac8b10 40000000 b6ec9418 c1c2607c 00000000 40000000 c557b00b 00000001
[   28.763056] 5f80: 00000b00 c0101278 c557b0f0 00000000 00000051 d1b15fb0 c01011c4 c0103c00
[   28.763249] 5fa0: 40000013 ffffffff
[   28.763394]  __irq_svc from vfp_support_entry+0x1c/0x30
[   28.763659] irq event stamp: 6348
[   28.763783] hardirqs last  enabled at (6347): [<c010106c>] __und_usr+0x6c/0x98
[   28.764030] hardirqs last disabled at (6348): [<c0100bd4>] __irq_svc+0x54/0xbc
[   28.764232] softirqs last  enabled at (6328): [<c0103814>] vfp_sync_hwstate+0x48/0x8c
[   28.764453] softirqs last disabled at (6326): [<c01037cc>] vfp_sync_hwstate+0x0/0x8c
[   28.764665] ---[ end trace 0000000000000000 ]---
[   28.764907] irq event stamp: 6348
[   28.765018] hardirqs last  enabled at (6347): [<c010106c>] __und_usr+0x6c/0x98
[   28.765202] hardirqs last disabled at (6348): [<c0100bd4>] __irq_svc+0x54/0xbc
[   28.765386] softirqs last  enabled at (6328): [<c0103814>] vfp_sync_hwstate+0x48/0x8c
[   28.765575] softirqs last disabled at (6326): [<c01037cc>] vfp_sync_hwstate+0x0/0x8c

Sample decoded stack trace:

[   11.848957] unwind_backtrace from show_stack (arch/arm/kernel/traps.c:258)
[   11.848999] show_stack from dump_stack_lvl (lib/dump_stack.c:107 (discriminator 4))
[   11.849026] dump_stack_lvl from __warn (./include/linux/jump_label.h:260 ./include/linux/jump_label.h:270 ./include/trace/events/error_report.h:69 kernel/panic.c:681)
[   11.849053] __warn from warn_slowpath_fmt (./include/asm-generic/preempt.h:59 ./include/linux/context_tracking.h:154 kernel/panic.c:706)
[   11.849081] warn_slowpath_fmt from check_flags (kernel/locking/lockdep.c:5527 (discriminator 9))
[   11.849110] check_flags from lock_is_held_type (./arch/arm/include/asm/percpu.h:37 kernel/locking/lockdep.c:462 kernel/locking/lockdep.c:5711)
[   11.849138] lock_is_held_type from rcu_read_lock_sched_held (kernel/rcu/update.c:125)
[   11.849170] rcu_read_lock_sched_held from ct_nmi_enter (./include/trace/events/rcu.h:480 ./include/trace/events/rcu.h:480 kernel/context_tracking.c:297)
[   11.849202] ct_nmi_enter from irq_enter (kernel/softirq.c:625)
[   11.849227] irq_enter from generic_handle_arch_irq (kernel/irq/handle.c:238)
[   11.849256] generic_handle_arch_irq from call_with_stack (arch/arm/lib/call_with_stack.S:45)
[   11.849287] call_with_stack from __irq_svc (arch/arm/kernel/entry-armv.S:232)

Seen if CONFIG_DEBUG_LOCK_ALLOC=y and CONFIG_CONTEXT_TRACKING_IDLE=y.
It seems that rcu_read_lock_sched_held() can be true when entering an interrupt.

The problem is not seen in v6.2, but occurs randomly on ToT with various
arm emulations.
First time observed and reproduced with v6.2-5715-g0175ec3a28c6. Still trying
to track down further.

Guenter