New: BUG at swapops + rcu stall + soft lockup at running btrfs test suite (TEST=013\* ./misc-tests.sh)

https://bugzilla.kernel.org/show_bug.cgi?id=207873

            Bug ID: 207873
           Summary: BUG at swapops + rcu stall + soft lockup at running
                    btrfs test suite (TEST=013\* ./misc-tests.sh)
           Product: Platform Specific/Hardware
           Version: 2.5
    Kernel Version: 5.7-rc6
          Hardware: PPC-32
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: PPC-32
          Assignee: [email protected]
          Reporter: [email protected]
                CC: [email protected]
        Regression: No

Created attachment 289253
--> https://bugzilla.kernel.org/attachment.cgi?id=289253&action=edit
kernel .config (5.7-rc6, PowerMac G4 DP)

The bug is triggered by running "TEST=013\* ./misc-tests.sh" of btrfs-progs test suite, built from git master:

 # git clone https://github.com/kdave/btrfs-progs && cd btrfs-progs/
 # ./autogen.sh && ./configure --disable-documentation
 # make && make fssum
 # cd tests/
 # TEST=013\* ./misc-tests.sh

The G4 crashes and the reboot timer kicks in. Before it shows a series of stack traces, starting with the "kernel BUG at include/linux/swapops.h:197!"-part from bug #207221. After that I get an rcu stall and a soft lockup. For the full stacktrace have a look at the transcript of both screenshots.

[...]

rcu: INFO: rcu_sched self-detected stall on CPU

rcu: o1-....: (7799 ticks this GP) idle=a06/1/0x40000002 soft irq=11075/11075 fqs=2599
o(t=7804 jiffies g=21629 q=59)
Task dump for CPU 1:
dd R running task 0 2200 394 0x0000000c

Call Trace:
[f49fb458] [c00fcddc] sched_show_task+0x3bc/Ox3fe (unreliable)
[f49fb498] [c01c650c] rcu_dump_cpu_stacks+0x228/0x23c
[f49fb4e8] [c01c2e18] rcu_sched_clock_irq+0x81c/0x1360
[f49fb568] [c01d8940] update_process_times+0x2c/0x98
[f49fb588] [c02027d4] tick_sched_timer+0x128/0x1d8
[f49fb5a8] [c01dc49c] __hrtimer_run_queues+0x490/Oxae8
[f49fb698] [c01dd788] hrtimer_interrupt+0x278/0x520
[f49fb6f8] [c001710c] timer_interrupt+0x374/0xb4c
[f49fb738] [c002c5e4] ret_from_except+0x0/0x14
--- interrupt: 901 at do_raw_spin_lock+0x1c8/0x2cc
    LR = do_raw_spin_lock+0x1a4/0x2cc
[f49fb800] [c0180e0c] do_raw_spin_lock+0x188/0x2cc (unrelable)
[f49fb830] [c0428890] unmap_page_range+0x244/0xb08
[f49fb910] [c0429610] unmap_vmas+0x94/0xdc
[f49fb930] [c043c25c] exit_mmap+0x340/0x46c
[f49fba20] [c0078260] __mmput+0x78/0x360
[f49fba50] [c0090514] do_exit+0x9c4/0x21fc
[f49fbb20] [c0019d38] user_single_step_report+0x0/0x74
[f49fbb70] [c002c5e0] ret_from_except+0x0/0x4
--- interrupt: 700 at __migration_entry_wait+0x13c/0x198
    LR = __migration_entry_wait+0xf0/0x198
[f49fbc58] [c042c0f0] do_swap_page+0x1f0/0x198
[f49fbd28] [c042e7e4] handle_mm_fault+0x794/0x16f4
[f49fbe48] [c0039868] do_page_fault+0xf50/0x12f8
[f49fbf38] [c002c468] handle_page_fault+0x10/0x3c
--- interrupt: 301 at 0x87e378
    LR = 0x87e33c

[...]

I don't know wether this is a btrfs bug, or a bug only triggered by this specific test. So I am filing this as platform specific as I have not seen it on x86 yet.

Unlike bug #207221 KASAN is enabled here, so the stack trace looks slightly different.

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--- Comment #1 from Erhard F. ([email protected]) --- Created attachment 289255
--> https://bugzilla.kernel.org/attachment.cgi?id=289255&action=edit
kernel dmesg (5.7-rc6, PowerMac G4 DP)

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--- Comment #2 from Erhard F. ([email protected]) --- Created attachment 289257
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screenshot 01

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--- Comment #3 from Erhard F. ([email protected]) --- Created attachment 289259
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screenshot 02

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--- Comment #4 from Erhard F. ([email protected]) --- Created attachment 289261
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transcript of both screenshots

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Christophe Leroy ([email protected]) changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |[email protected]

--- Comment #5 from Christophe Leroy ([email protected]) --- Try
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=40bb0e904212cf7d6f041a98c58c8341b2016670

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Erhard F. ([email protected]) changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|NEW                         |RESOLVED
         Resolution|---                         |PATCH_ALREADY_AVAILABLE

--- Comment #6 from Erhard F. ([email protected]) --- (In reply to Christophe Leroy from comment #5)

Thanks for the hint! That patch did the trick. The btrfs test suite completes fine now and building larger projects works unremarkably.

Will close here as the fix seems to be going into -rc7.

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