Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Jiri Slaby]

Hi,

after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu 
VMs started stalling (and the host at the same point too). It doesn't 
happen right after boot, maybe a suspend-resume cycle is needed (or 
longer uptime, or a couple of qemu VM starts, or ...). But when it 
happens, it happens all the time till the next reboot.

Older guest's kernels/distros are affected as well as Win10.

In guests, I see for example stalls in memset_orig or 
smp_call_function_many_cond -- traces below.

qemu-kvm-7.1.0-13.34.x86_64 from openSUSE.

It's quite interesting that:
   $ cat /proc/<PID_OF_QEMU>/cmdline
is stuck at read:

openat(AT_FDCWD, "/proc/12239/cmdline", O_RDONLY) = 3
newfstatat(3, "", {st_mode=S_IFREG|0444, st_size=0, ...}, AT_EMPTY_PATH) = 0
fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 
0) = 0x7f22f0487000
read(3, ^C^C^C^\^C

too. So I dumped blocked tasks (sysrq-w) on _host_ (see below) and 
everything seems to stall on mmap_read_lock() or 
mmap_write_lock_killable(). I don't see the hog (the one actually 
_having_ and sitting on the (presumably write) lock) in the dump though. 
I will perhaps boot a LOCKDEP-enabled kernel, so that I can do sysrq-d 
next time and see the holder.


There should be enough free memory (note caches at 8G):
                total        used        free      shared  buff/cache 
available
Mem:            15Gi        10Gi       400Mi       2,5Gi       8,0Gi 
   5,0Gi
Swap:             0B          0B          0B


I rmmoded kvm-intel now, so:
   qemu-kvm: failed to initialize kvm: No such file or directory
   qemu-kvm: falling back to tcg
and it behaves the same (more or less expected).

Is this known? Any idea how to debug this? Or maybe someone (I CCed a 
couple of guys who Acked mmap_*_lock() shuffling patches in 6.1) has a 
clue? Bisection is hard as it reproduces only under certain unknown 
circumstances.




Now the promised dumps:

 > sysrq: Show Blocked State
 > task:plasmashell     state:D stack:0     pid:2064  ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  down_read_killable+0x3d/0xa0
 >  __access_remote_vm+0x4c/0x370
 >  proc_pid_cmdline_read+0x17a/0x3c0
 >  vfs_read+0xa2/0x2c0
 >  ksys_read+0x63/0xe0
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7fda6b70795c
 > RSP: 002b:00007ffdd7b108b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fda6b70795c
 > RDX: 0000000000004000 RSI: 00007ffdd7b10a20 RDI: 0000000000000028
 > RBP: 000056536a70f610 R08: 0000000000000000 R09: 0000000000004000
 > R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000004000
 > R13: 0000000000004000 R14: 00007ffdd7b10a20 R15: 00007ffdd7b10a20
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12249 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  do_user_addr_fault+0x413/0x690
 >  exc_page_fault+0x66/0x150
 >  asm_exc_page_fault+0x22/0x30
 > RIP: 0033:0x55fc42ea2e9e
 > RSP: 002b:00007f054e5391c8 EFLAGS: 00010246
 > RAX: 00007f052aa01041 RBX: 0000000000000005 RCX: 0000000000000000
 > RDX: 00007f052aa01040 RSI: 000000000000008b RDI: 00007f0544000b70
 > RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000005
 > R10: 0000000000000003 R11: 0000000000000d60 R12: 00007f0544000b70
 > R13: fffffffffffffff0 R14: 000000000000000c R15: 00007f054400a510
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12251 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_write_slowpath+0x358/0x6a0
 >  down_write_killable+0x60/0x80
 >  do_mprotect_pkey+0xe9/0x430
 >  __x64_sys_mprotect+0x1b/0x30
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f05514a8ccb
 > RSP: 002b:00007f054d536fa8 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
 > RAX: ffffffffffffffda RBX: 00007f042c000030 RCX: 00007f05514a8ccb
 > RDX: 0000000000000003 RSI: 0000000000001000 RDI: 00007f042d304000
 > RBP: 0000000000000430 R08: 0000000001304000 R09: 0000000001305000
 > R10: 00007f042d303bf0 R11: 0000000000000206 R12: 0000000000000410
 > R13: 0000000000001000 R14: 0000000000000450 R15: 0000000000000000
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12252 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  do_user_addr_fault+0x413/0x690
 >  exc_page_fault+0x66/0x150
 >  asm_exc_page_fault+0x22/0x30
 > RIP: 0033:0x55fc42ea6217
 > RSP: 002b:00007f054cd361d0 EFLAGS: 00010246
 > RAX: 00007f052c593fff RBX: 00007f0500000018 RCX: 0000000000000000
 > RDX: 00007f052c593ffe RSI: 00000000000000e9 RDI: 00007f0430000b70
 > RBP: 00007f0430000b70 R08: 0000000000000000 R09: 0000000000000000
 > R10: 0000000000000000 R11: ffffffffd3a6c015 R12: 000000000000000c
 > R13: 0000000000000030 R14: 0000000000000080 R15: 00007f043000bad8
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12299 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  do_madvise.part.0+0xe2/0x2a0
 >  __x64_sys_madvise+0x5a/0x70
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f05514a8dab
 > RSP: 002b:00007f054f381758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
 > RAX: ffffffffffffffda RBX: 00007f054eb82000 RCX: 00007f05514a8dab
 > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f054eb82000
 > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
 > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
 > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f054eb82000
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12300 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  do_madvise.part.0+0xe2/0x2a0
 >  __x64_sys_madvise+0x5a/0x70
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f05514a8dab
 > RSP: 002b:00007f041b4b7758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
 > RAX: ffffffffffffffda RBX: 00007f041acb8000 RCX: 00007f05514a8dab
 > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041acb8000
 > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
 > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
 > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041acb8000
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12301 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  do_madvise.part.0+0xe2/0x2a0
 >  __x64_sys_madvise+0x5a/0x70
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f05514a8dab
 > RSP: 002b:00007f041acb6758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
 > RAX: ffffffffffffffda RBX: 00007f041a4b7000 RCX: 00007f05514a8dab
 > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041a4b7000
 > RBP: 0000000000801000 R08: 0000000000000005 R09: 0000000000001d4c
 > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
 > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041a4b7000
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12309 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  do_madvise.part.0+0xe2/0x2a0
 >  __x64_sys_madvise+0x5a/0x70
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f05514a8dab
 > RSP: 002b:00007f041a4b5758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
 > RAX: ffffffffffffffda RBX: 00007f0419cb6000 RCX: 00007f05514a8dab
 > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f0419cb6000
 > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
 > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
 > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f0419cb6000
 >  </TASK>
 > task:qemu-kvm        state:D stack:0     pid:12310 ppid:1905 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  do_madvise.part.0+0xe2/0x2a0
 >  __x64_sys_madvise+0x5a/0x70
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f05514a8dab
 > RSP: 002b:00007f04178b3758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
 > RAX: ffffffffffffffda RBX: 00007f04170b4000 RCX: 00007f05514a8dab
 > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f04170b4000
 > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
 > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
 > R13: 0000000000000000 R14: 00007f041a4b5300 R15: 00007f04170b4000
 >  </TASK>
 > task:ps              state:D stack:0     pid:12395 ppid:5727 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  down_read_killable+0x3d/0xa0
 >  __access_remote_vm+0x4c/0x370
 >  proc_pid_cmdline_read+0x17a/0x3c0
 >  vfs_read+0xa2/0x2c0
 >  ksys_read+0x63/0xe0
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f02fa455921
 > RSP: 002b:00007ffca71c5828 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
 > RAX: ffffffffffffffda RBX: 00007f02f9f53010 RCX: 00007f02fa455921
 > RDX: 0000000000020000 RSI: 00007f02f9f53010 RDI: 0000000000000006
 > RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000073
 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f02f9f53010
 > R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
 >  </TASK>
 > task:htop            state:D stack:0     pid:12400 ppid:4676 
flags:0x00000002
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  down_read_killable+0x3d/0xa0
 >  __access_remote_vm+0x4c/0x370
 >  proc_pid_cmdline_read+0x17a/0x3c0
 >  vfs_read+0xa2/0x2c0
 >  ksys_read+0x63/0xe0
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7f4284748921
 > RSP: 002b:00007ffc88c25398 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
 > RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007f4284748921
 > RDX: 0000000000001000 RSI: 00007ffc88c25490 RDI: 0000000000000007
 > RBP: 00007ffc88c25490 R08: 0000563dd4c68ab0 R09: 0000000000000000
 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
 > R13: 0000000000000007 R14: 00007ffc88c265a0 R15: 0000563dd4ca46c0
 >  </TASK>
 > task:htop            state:D stack:0     pid:12416 ppid:4595 
flags:0x00000006
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  down_read_killable+0x3d/0xa0
 >  __access_remote_vm+0x4c/0x370
 >  proc_pid_cmdline_read+0x17a/0x3c0
 >  vfs_read+0xa2/0x2c0
 >  ksys_read+0x63/0xe0
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7fe4d1b7f921
 > RSP: 002b:00007ffc8603e788 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
 > RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fe4d1b7f921
 > RDX: 0000000000001000 RSI: 00007ffc8603e880 RDI: 0000000000000007
 > RBP: 00007ffc8603e880 R08: 00005602572e7a20 R09: 0000000000000000
 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
 > R13: 0000000000000007 R14: 00007ffc8603f990 R15: 000056025735d540
 >  </TASK>
 > task:htop            state:D stack:0     pid:12464 ppid:12441 
flags:0x00000006
 > Call Trace:
 >  <TASK>
 >  __schedule+0x360/0x1350
 >  schedule+0x5a/0xd0
 >  rwsem_down_read_slowpath+0x272/0x4c0
 >  down_read_killable+0x3d/0xa0
 >  __access_remote_vm+0x4c/0x370
 >  proc_pid_cmdline_read+0x17a/0x3c0
 >  vfs_read+0xa2/0x2c0
 >  ksys_read+0x63/0xe0
 >  do_syscall_64+0x58/0x80
 >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7fb1e298f921
 > RSP: 002b:00007ffe419c8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
 > RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fb1e298f921
 > RDX: 0000000000001000 RSI: 00007ffe419c8d70 RDI: 0000000000000007
 > RBP: 00007ffe419c8d70 R08: 0000565345f95680 R09: 0000000000000000
 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
 > R13: 0000000000000007 R14: 00007ffe419c9e80 R15: 0000565345fd0470
 >  </TASK>









Guest lockups:



 > BUG: workqueue lockup - pool cpus=3 node=0 flags=0x0 nice=0 stuck for 
49s!
 > Showing busy workqueues and worker pools:
 > workqueue mm_percpu_wq: flags=0x8
 >   pwq 6: cpus=3 node=0 flags=0x0 nice=0 active=2/256 refcnt=4
 >     pending: vmstat_update, lru_add_drain_per_cpu BAR(49)
 > rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
 > watchdog: BUG: soft lockup - CPU#2 stuck for 211s! [jbd2/sda1-8:373]
 > Modules linked in: af_packet rfkill ...
 > CPU: 2 PID: 373 Comm: jbd2/sda1-8 Kdump: loaded Not tainted 
6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased) 
0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 > RIP: 0010:memset_orig+0x33/0xb0
 > Code: 01 01 01 01 01 01 01 01 48 0f af c1 41 89 f9 41 83 e1 07 75 74 
48 89 d1 48 c1 e9 06 74 39 66 0f 1f 84 00 00 00 00 00 48 ff c9 <48> 89 
07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
 > RSP: 0018:ffffbd1fc0487d08 EFLAGS: 00010216
 > RAX: 0000000000000000 RBX: ffff9fdb1b619138 RCX: 000000000000003f
 > RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff9fdb39f19000
 > RBP: ffff9fdb0054f000 R08: ffff9fdb0565cb00 R09: 0000000000000000
 > R10: ffff9fdb39f19000 R11: ffff9fdb442d71c0 R12: 0000000001000000
 > R13: ffff9fdb05079800 R14: ffff9fdb01658870 R15: ffff9fdb01658870
 > FS:  0000000000000000(0000) GS:ffff9fdb40d00000(0000) 
knlGS:0000000000000000
 > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 > CR2: 00005635dbce3fb8 CR3: 0000000103d54000 CR4: 00000000000006e0
 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 > Call Trace:
 >  <TASK>
 >  jbd2_journal_get_descriptor_buffer+0x88/0xf0 [jbd2 
3adb6041f8aa59fe471169b0e9945d8c67491cc7]
 >  jbd2_journal_commit_transaction+0x9e0/0x18b0 [jbd2 
3adb6041f8aa59fe471169b0e9945d8c67491cc7]
 >  kjournald2+0xa9/0x260 [jbd2 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
 >  kthread+0xda/0x100
 >  ret_from_fork+0x22/0x30
 >  </TASK>


========================================


 > watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [kworker/2:2:134]
 > Modules linked in: af_packet rfkill ...
 > Supported: No, Unreleased kernel
 > CPU: 2 PID: 134 Comm: kworker/2:2 Not tainted 
5.14.21-150500.86.gca1fbb8-default #1 SLE15-SP5 (unreleased) 
f54a3c78ee6447e20bc183538de8800cbe783c87
 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 > Workqueue: events drm_fb_helper_damage_work [drm_kms_helper]
 > RIP: 0010:smp_call_function_many_cond+0x123/0x560
 > Code: ef e8 71 22 42 00 3b 05 2f 2c bd 01 89 c5 73 24 48 63 c5 49 8b 
7d 00 48 03 3c c5 a0 bb 42 b1 66 90 8b 47 08 a8 01 74 0a f3 90 <8b> 57 
08 83 e2 01 75 f6 eb c7 48 83 c4 48 5b 5d 41 5c 41 5d 41 5e
 > RSP: 0018:ffff9eff00227c68 EFLAGS: 00000202
 > RAX: 0000000000000011 RBX: 0000000000000001 RCX: 0000000000000000
 > RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff89a1c0dba8c0
 > RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
 > R10: 0000000000000003 R11: 0000000000000000 R12: ffff89a1c0d34b00
 > R13: ffff89a1c0d34b00 R14: 0000000000000000 R15: 0000000000000003
 > FS:  0000000000000000(0000) GS:ffff89a1c0d00000(0000) 
knlGS:0000000000000000
 > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 > CR2: 0000561f1be53000 CR3: 00000001024e6000 CR4: 00000000000006e0
 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 > Call Trace:
 >  <TASK>
 >  on_each_cpu_cond_mask+0x25/0x40
 >  __purge_vmap_area_lazy+0xba/0x6d0
 >  free_vmap_area_noflush+0x214/0x2f0
 >  remove_vm_area+0x80/0x90
 >  __vunmap+0x5e/0x260
 >  drm_gem_shmem_vunmap+0x6f/0x90 [drm_shmem_helper 
b732157accb2fabb75791e2dc3d5d21a30cf33cb]
 >  drm_gem_vunmap+0x24/0x50 [drm 14b5c4e21fb011b0159efe14dd82da3407d64716]
 >  drm_fb_helper_damage_work+0x16f/0x2f0 [drm_kms_helper 
b697aeb79f8910d3e952c8c60069f3e3382437ae]
 >  process_one_work+0x267/0x440
 >  worker_thread+0x2d/0x3d0
 >  kthread+0x156/0x180
 >  ret_from_fork+0x22/0x30
 >  </TASK>


========================================


 > watchdog: BUG: soft lockup - CPU#0 stuck for 319s! [watchdogd:57]
 > watchdog: BUG: soft lockup - CPU#3 stuck for 348s! [repo2solv:1139]
 > Modules linked in: af_packet rfkill nls_iso8859_1 nls_cp437 
snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg 
snd_intel_sdw_acpi snd_hda_codec snd_hda_core snd_hwdep vfat snd_pcm fat 
iTCO_wdt snd_timer ppdev virtio_net intel_pmc_bxt tiny_power_button 
i2c_i801 iTCO_vend>
 > CPU: 3 PID: 1139 Comm: repo2solv Kdump: loaded Not tainted 
6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased) 
0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 > RIP: 0010:clear_page_orig+0x12/0x40
 > Code: 5d c3 cc cc cc cc cc cc b9 00 02 00 00 31 c0 f3 48 ab c3 cc cc 
cc cc 90 31 c0 b9 40 00 00 00 66 0f 1f 84 00 00 00 00 00 ff c9 <48> 89 
07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
 > RSP: 0000:ffffb644c0da3be8 EFLAGS: 00010216
 > RAX: 0000000000000000 RBX: fffffccec4828000 RCX: 000000000000003f
 > RDX: fffffccec4828000 RSI: fffffccec4828040 RDI: ffffa04a20a00000
 > RBP: 0000000000000000 R08: ffffb644c0da3d10 R09: 0000000000028b29
 > R10: 0000000000000010 R11: ffffa04a441d51c0 R12: 0000000000140dca
 > R13: 0000000000000040 R14: 0000000000000001 R15: 0000000000000286
 > FS:  00007f91de710f80(0000) GS:ffffa04a40d80000(0000) 
knlGS:0000000000000000
 > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 > CR2: 00007f91de3d3000 CR3: 0000000101f86000 CR4: 00000000000006e0
 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 > Call Trace:
 >  <TASK>
 >  post_alloc_hook+0xa9/0xe0
 >  get_page_from_freelist+0x4d9/0x1590
 >  __alloc_pages+0xec/0x240
 >  __folio_alloc+0x17/0x50
 >  vma_alloc_folio+0x9c/0x370
 >  __handle_mm_fault+0x942/0xfe0
 >  handle_mm_fault+0xdb/0x2d0
 >  do_user_addr_fault+0x1ba/0x690
 >  exc_page_fault+0x66/0x150
 >  asm_exc_page_fault+0x22/0x30

thanks,
-- 
js
suse labs

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Vlastimil Babka]

On 1/11/23 09:00, Jiri Slaby wrote:
> Hi,
> 
> after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu 
> VMs started stalling (and the host at the same point too). It doesn't 
> happen right after boot, maybe a suspend-resume cycle is needed (or 
> longer uptime, or a couple of qemu VM starts, or ...). But when it 
> happens, it happens all the time till the next reboot.
> 
> Older guest's kernels/distros are affected as well as Win10.
> 
> In guests, I see for example stalls in memset_orig or 
> smp_call_function_many_cond -- traces below.
> 
> qemu-kvm-7.1.0-13.34.x86_64 from openSUSE.
> 
> It's quite interesting that:
>    $ cat /proc/<PID_OF_QEMU>/cmdline
> is stuck at read:
> 
> openat(AT_FDCWD, "/proc/12239/cmdline", O_RDONLY) = 3
> newfstatat(3, "", {st_mode=S_IFREG|0444, st_size=0, ...}, AT_EMPTY_PATH) = 0
> fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
> mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 
> 0) = 0x7f22f0487000
> read(3, ^C^C^C^\^C
> 
> too. So I dumped blocked tasks (sysrq-w) on _host_ (see below) and 
> everything seems to stall on mmap_read_lock() or 
> mmap_write_lock_killable(). I don't see the hog (the one actually 
> _having_ and sitting on the (presumably write) lock) in the dump though. 
> I will perhaps boot a LOCKDEP-enabled kernel, so that I can do sysrq-d 
> next time and see the holder.

How about setting up a kdump for the host, triggering a crash dump and
investigating that? If it's a write owner forgetting unlock, rw_semaphore
owner field could point to it. But it can also be that a down_write() is
pending, blocking further down_read()'s, while the current reader is missing
and not by design accurately tracked in the owner field.

Oh and it's also possible to enable the mmap_lock specific tracepoints and
analyze that.

> There should be enough free memory (note caches at 8G):
>                 total        used        free      shared  buff/cache 
> available
> Mem:            15Gi        10Gi       400Mi       2,5Gi       8,0Gi 
>    5,0Gi
> Swap:             0B          0B          0B
> 
> 
> I rmmoded kvm-intel now, so:
>    qemu-kvm: failed to initialize kvm: No such file or directory
>    qemu-kvm: falling back to tcg
> and it behaves the same (more or less expected).
> 
> Is this known? Any idea how to debug this? Or maybe someone (I CCed a 
> couple of guys who Acked mmap_*_lock() shuffling patches in 6.1) has a 
> clue? Bisection is hard as it reproduces only under certain unknown 
> circumstances.
> 
> 
> 
> 
> Now the promised dumps:
> 
>  > sysrq: Show Blocked State
>  > task:plasmashell     state:D stack:0     pid:2064  ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  down_read_killable+0x3d/0xa0
>  >  __access_remote_vm+0x4c/0x370
>  >  proc_pid_cmdline_read+0x17a/0x3c0
>  >  vfs_read+0xa2/0x2c0
>  >  ksys_read+0x63/0xe0
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7fda6b70795c
>  > RSP: 002b:00007ffdd7b108b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>  > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fda6b70795c
>  > RDX: 0000000000004000 RSI: 00007ffdd7b10a20 RDI: 0000000000000028
>  > RBP: 000056536a70f610 R08: 0000000000000000 R09: 0000000000004000
>  > R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000004000
>  > R13: 0000000000004000 R14: 00007ffdd7b10a20 R15: 00007ffdd7b10a20
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12249 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  do_user_addr_fault+0x413/0x690
>  >  exc_page_fault+0x66/0x150
>  >  asm_exc_page_fault+0x22/0x30
>  > RIP: 0033:0x55fc42ea2e9e
>  > RSP: 002b:00007f054e5391c8 EFLAGS: 00010246
>  > RAX: 00007f052aa01041 RBX: 0000000000000005 RCX: 0000000000000000
>  > RDX: 00007f052aa01040 RSI: 000000000000008b RDI: 00007f0544000b70
>  > RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000005
>  > R10: 0000000000000003 R11: 0000000000000d60 R12: 00007f0544000b70
>  > R13: fffffffffffffff0 R14: 000000000000000c R15: 00007f054400a510
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12251 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_write_slowpath+0x358/0x6a0
>  >  down_write_killable+0x60/0x80
>  >  do_mprotect_pkey+0xe9/0x430
>  >  __x64_sys_mprotect+0x1b/0x30
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f05514a8ccb
>  > RSP: 002b:00007f054d536fa8 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
>  > RAX: ffffffffffffffda RBX: 00007f042c000030 RCX: 00007f05514a8ccb
>  > RDX: 0000000000000003 RSI: 0000000000001000 RDI: 00007f042d304000
>  > RBP: 0000000000000430 R08: 0000000001304000 R09: 0000000001305000
>  > R10: 00007f042d303bf0 R11: 0000000000000206 R12: 0000000000000410
>  > R13: 0000000000001000 R14: 0000000000000450 R15: 0000000000000000
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12252 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  do_user_addr_fault+0x413/0x690
>  >  exc_page_fault+0x66/0x150
>  >  asm_exc_page_fault+0x22/0x30
>  > RIP: 0033:0x55fc42ea6217
>  > RSP: 002b:00007f054cd361d0 EFLAGS: 00010246
>  > RAX: 00007f052c593fff RBX: 00007f0500000018 RCX: 0000000000000000
>  > RDX: 00007f052c593ffe RSI: 00000000000000e9 RDI: 00007f0430000b70
>  > RBP: 00007f0430000b70 R08: 0000000000000000 R09: 0000000000000000
>  > R10: 0000000000000000 R11: ffffffffd3a6c015 R12: 000000000000000c
>  > R13: 0000000000000030 R14: 0000000000000080 R15: 00007f043000bad8
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12299 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  do_madvise.part.0+0xe2/0x2a0
>  >  __x64_sys_madvise+0x5a/0x70
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f05514a8dab
>  > RSP: 002b:00007f054f381758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>  > RAX: ffffffffffffffda RBX: 00007f054eb82000 RCX: 00007f05514a8dab
>  > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f054eb82000
>  > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>  > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>  > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f054eb82000
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12300 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  do_madvise.part.0+0xe2/0x2a0
>  >  __x64_sys_madvise+0x5a/0x70
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f05514a8dab
>  > RSP: 002b:00007f041b4b7758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>  > RAX: ffffffffffffffda RBX: 00007f041acb8000 RCX: 00007f05514a8dab
>  > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041acb8000
>  > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>  > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>  > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041acb8000
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12301 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  do_madvise.part.0+0xe2/0x2a0
>  >  __x64_sys_madvise+0x5a/0x70
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f05514a8dab
>  > RSP: 002b:00007f041acb6758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>  > RAX: ffffffffffffffda RBX: 00007f041a4b7000 RCX: 00007f05514a8dab
>  > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041a4b7000
>  > RBP: 0000000000801000 R08: 0000000000000005 R09: 0000000000001d4c
>  > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>  > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041a4b7000
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12309 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  do_madvise.part.0+0xe2/0x2a0
>  >  __x64_sys_madvise+0x5a/0x70
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f05514a8dab
>  > RSP: 002b:00007f041a4b5758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>  > RAX: ffffffffffffffda RBX: 00007f0419cb6000 RCX: 00007f05514a8dab
>  > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f0419cb6000
>  > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>  > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>  > R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f0419cb6000
>  >  </TASK>
>  > task:qemu-kvm        state:D stack:0     pid:12310 ppid:1905 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  do_madvise.part.0+0xe2/0x2a0
>  >  __x64_sys_madvise+0x5a/0x70
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f05514a8dab
>  > RSP: 002b:00007f04178b3758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>  > RAX: ffffffffffffffda RBX: 00007f04170b4000 RCX: 00007f05514a8dab
>  > RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f04170b4000
>  > RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>  > R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>  > R13: 0000000000000000 R14: 00007f041a4b5300 R15: 00007f04170b4000
>  >  </TASK>
>  > task:ps              state:D stack:0     pid:12395 ppid:5727 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  down_read_killable+0x3d/0xa0
>  >  __access_remote_vm+0x4c/0x370
>  >  proc_pid_cmdline_read+0x17a/0x3c0
>  >  vfs_read+0xa2/0x2c0
>  >  ksys_read+0x63/0xe0
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f02fa455921
>  > RSP: 002b:00007ffca71c5828 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>  > RAX: ffffffffffffffda RBX: 00007f02f9f53010 RCX: 00007f02fa455921
>  > RDX: 0000000000020000 RSI: 00007f02f9f53010 RDI: 0000000000000006
>  > RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000073
>  > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f02f9f53010
>  > R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
>  >  </TASK>
>  > task:htop            state:D stack:0     pid:12400 ppid:4676 
> flags:0x00000002
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  down_read_killable+0x3d/0xa0
>  >  __access_remote_vm+0x4c/0x370
>  >  proc_pid_cmdline_read+0x17a/0x3c0
>  >  vfs_read+0xa2/0x2c0
>  >  ksys_read+0x63/0xe0
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7f4284748921
>  > RSP: 002b:00007ffc88c25398 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>  > RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007f4284748921
>  > RDX: 0000000000001000 RSI: 00007ffc88c25490 RDI: 0000000000000007
>  > RBP: 00007ffc88c25490 R08: 0000563dd4c68ab0 R09: 0000000000000000
>  > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>  > R13: 0000000000000007 R14: 00007ffc88c265a0 R15: 0000563dd4ca46c0
>  >  </TASK>
>  > task:htop            state:D stack:0     pid:12416 ppid:4595 
> flags:0x00000006
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  down_read_killable+0x3d/0xa0
>  >  __access_remote_vm+0x4c/0x370
>  >  proc_pid_cmdline_read+0x17a/0x3c0
>  >  vfs_read+0xa2/0x2c0
>  >  ksys_read+0x63/0xe0
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7fe4d1b7f921
>  > RSP: 002b:00007ffc8603e788 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>  > RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fe4d1b7f921
>  > RDX: 0000000000001000 RSI: 00007ffc8603e880 RDI: 0000000000000007
>  > RBP: 00007ffc8603e880 R08: 00005602572e7a20 R09: 0000000000000000
>  > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>  > R13: 0000000000000007 R14: 00007ffc8603f990 R15: 000056025735d540
>  >  </TASK>
>  > task:htop            state:D stack:0     pid:12464 ppid:12441 
> flags:0x00000006
>  > Call Trace:
>  >  <TASK>
>  >  __schedule+0x360/0x1350
>  >  schedule+0x5a/0xd0
>  >  rwsem_down_read_slowpath+0x272/0x4c0
>  >  down_read_killable+0x3d/0xa0
>  >  __access_remote_vm+0x4c/0x370
>  >  proc_pid_cmdline_read+0x17a/0x3c0
>  >  vfs_read+0xa2/0x2c0
>  >  ksys_read+0x63/0xe0
>  >  do_syscall_64+0x58/0x80
>  >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>  > RIP: 0033:0x7fb1e298f921
>  > RSP: 002b:00007ffe419c8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>  > RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fb1e298f921
>  > RDX: 0000000000001000 RSI: 00007ffe419c8d70 RDI: 0000000000000007
>  > RBP: 00007ffe419c8d70 R08: 0000565345f95680 R09: 0000000000000000
>  > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>  > R13: 0000000000000007 R14: 00007ffe419c9e80 R15: 0000565345fd0470
>  >  </TASK>
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Guest lockups:
> 
> 
> 
>  > BUG: workqueue lockup - pool cpus=3 node=0 flags=0x0 nice=0 stuck for 
> 49s!
>  > Showing busy workqueues and worker pools:
>  > workqueue mm_percpu_wq: flags=0x8
>  >   pwq 6: cpus=3 node=0 flags=0x0 nice=0 active=2/256 refcnt=4
>  >     pending: vmstat_update, lru_add_drain_per_cpu BAR(49)
>  > rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
>  > watchdog: BUG: soft lockup - CPU#2 stuck for 211s! [jbd2/sda1-8:373]
>  > Modules linked in: af_packet rfkill ...
>  > CPU: 2 PID: 373 Comm: jbd2/sda1-8 Kdump: loaded Not tainted 
> 6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased) 
> 0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
>  > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>  > RIP: 0010:memset_orig+0x33/0xb0
>  > Code: 01 01 01 01 01 01 01 01 48 0f af c1 41 89 f9 41 83 e1 07 75 74 
> 48 89 d1 48 c1 e9 06 74 39 66 0f 1f 84 00 00 00 00 00 48 ff c9 <48> 89 
> 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
>  > RSP: 0018:ffffbd1fc0487d08 EFLAGS: 00010216
>  > RAX: 0000000000000000 RBX: ffff9fdb1b619138 RCX: 000000000000003f
>  > RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff9fdb39f19000
>  > RBP: ffff9fdb0054f000 R08: ffff9fdb0565cb00 R09: 0000000000000000
>  > R10: ffff9fdb39f19000 R11: ffff9fdb442d71c0 R12: 0000000001000000
>  > R13: ffff9fdb05079800 R14: ffff9fdb01658870 R15: ffff9fdb01658870
>  > FS:  0000000000000000(0000) GS:ffff9fdb40d00000(0000) 
> knlGS:0000000000000000
>  > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  > CR2: 00005635dbce3fb8 CR3: 0000000103d54000 CR4: 00000000000006e0
>  > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  > Call Trace:
>  >  <TASK>
>  >  jbd2_journal_get_descriptor_buffer+0x88/0xf0 [jbd2 
> 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>  >  jbd2_journal_commit_transaction+0x9e0/0x18b0 [jbd2 
> 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>  >  kjournald2+0xa9/0x260 [jbd2 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>  >  kthread+0xda/0x100
>  >  ret_from_fork+0x22/0x30
>  >  </TASK>
> 
> 
> ========================================
> 
> 
>  > watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [kworker/2:2:134]
>  > Modules linked in: af_packet rfkill ...
>  > Supported: No, Unreleased kernel
>  > CPU: 2 PID: 134 Comm: kworker/2:2 Not tainted 
> 5.14.21-150500.86.gca1fbb8-default #1 SLE15-SP5 (unreleased) 
> f54a3c78ee6447e20bc183538de8800cbe783c87
>  > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>  > Workqueue: events drm_fb_helper_damage_work [drm_kms_helper]
>  > RIP: 0010:smp_call_function_many_cond+0x123/0x560
>  > Code: ef e8 71 22 42 00 3b 05 2f 2c bd 01 89 c5 73 24 48 63 c5 49 8b 
> 7d 00 48 03 3c c5 a0 bb 42 b1 66 90 8b 47 08 a8 01 74 0a f3 90 <8b> 57 
> 08 83 e2 01 75 f6 eb c7 48 83 c4 48 5b 5d 41 5c 41 5d 41 5e
>  > RSP: 0018:ffff9eff00227c68 EFLAGS: 00000202
>  > RAX: 0000000000000011 RBX: 0000000000000001 RCX: 0000000000000000
>  > RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff89a1c0dba8c0
>  > RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
>  > R10: 0000000000000003 R11: 0000000000000000 R12: ffff89a1c0d34b00
>  > R13: ffff89a1c0d34b00 R14: 0000000000000000 R15: 0000000000000003
>  > FS:  0000000000000000(0000) GS:ffff89a1c0d00000(0000) 
> knlGS:0000000000000000
>  > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  > CR2: 0000561f1be53000 CR3: 00000001024e6000 CR4: 00000000000006e0
>  > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  > Call Trace:
>  >  <TASK>
>  >  on_each_cpu_cond_mask+0x25/0x40
>  >  __purge_vmap_area_lazy+0xba/0x6d0
>  >  free_vmap_area_noflush+0x214/0x2f0
>  >  remove_vm_area+0x80/0x90
>  >  __vunmap+0x5e/0x260
>  >  drm_gem_shmem_vunmap+0x6f/0x90 [drm_shmem_helper 
> b732157accb2fabb75791e2dc3d5d21a30cf33cb]
>  >  drm_gem_vunmap+0x24/0x50 [drm 14b5c4e21fb011b0159efe14dd82da3407d64716]
>  >  drm_fb_helper_damage_work+0x16f/0x2f0 [drm_kms_helper 
> b697aeb79f8910d3e952c8c60069f3e3382437ae]
>  >  process_one_work+0x267/0x440
>  >  worker_thread+0x2d/0x3d0
>  >  kthread+0x156/0x180
>  >  ret_from_fork+0x22/0x30
>  >  </TASK>
> 
> 
> ========================================
> 
> 
>  > watchdog: BUG: soft lockup - CPU#0 stuck for 319s! [watchdogd:57]
>  > watchdog: BUG: soft lockup - CPU#3 stuck for 348s! [repo2solv:1139]
>  > Modules linked in: af_packet rfkill nls_iso8859_1 nls_cp437 
> snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg 
> snd_intel_sdw_acpi snd_hda_codec snd_hda_core snd_hwdep vfat snd_pcm fat 
> iTCO_wdt snd_timer ppdev virtio_net intel_pmc_bxt tiny_power_button 
> i2c_i801 iTCO_vend>
>  > CPU: 3 PID: 1139 Comm: repo2solv Kdump: loaded Not tainted 
> 6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased) 
> 0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
>  > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>  > RIP: 0010:clear_page_orig+0x12/0x40
>  > Code: 5d c3 cc cc cc cc cc cc b9 00 02 00 00 31 c0 f3 48 ab c3 cc cc 
> cc cc 90 31 c0 b9 40 00 00 00 66 0f 1f 84 00 00 00 00 00 ff c9 <48> 89 
> 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
>  > RSP: 0000:ffffb644c0da3be8 EFLAGS: 00010216
>  > RAX: 0000000000000000 RBX: fffffccec4828000 RCX: 000000000000003f
>  > RDX: fffffccec4828000 RSI: fffffccec4828040 RDI: ffffa04a20a00000
>  > RBP: 0000000000000000 R08: ffffb644c0da3d10 R09: 0000000000028b29
>  > R10: 0000000000000010 R11: ffffa04a441d51c0 R12: 0000000000140dca
>  > R13: 0000000000000040 R14: 0000000000000001 R15: 0000000000000286
>  > FS:  00007f91de710f80(0000) GS:ffffa04a40d80000(0000) 
> knlGS:0000000000000000
>  > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  > CR2: 00007f91de3d3000 CR3: 0000000101f86000 CR4: 00000000000006e0
>  > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  > Call Trace:
>  >  <TASK>
>  >  post_alloc_hook+0xa9/0xe0
>  >  get_page_from_freelist+0x4d9/0x1590
>  >  __alloc_pages+0xec/0x240
>  >  __folio_alloc+0x17/0x50
>  >  vma_alloc_folio+0x9c/0x370
>  >  __handle_mm_fault+0x942/0xfe0
>  >  handle_mm_fault+0xdb/0x2d0
>  >  do_user_addr_fault+0x1ba/0x690
>  >  exc_page_fault+0x66/0x150
>  >  asm_exc_page_fault+0x22/0x30
> 
> thanks,

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Michal Hocko]

On Wed 11-01-23 09:00:04, Jiri Slaby wrote:
> Hi,
> 
> after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu VMs
> started stalling (and the host at the same point too). It doesn't happen
> right after boot, maybe a suspend-resume cycle is needed (or longer uptime,
> or a couple of qemu VM starts, or ...). But when it happens, it happens all
> the time till the next reboot.
> 
> Older guest's kernels/distros are affected as well as Win10.
> 
> In guests, I see for example stalls in memset_orig or
> smp_call_function_many_cond -- traces below.
> 
> qemu-kvm-7.1.0-13.34.x86_64 from openSUSE.
> 
> It's quite interesting that:
>   $ cat /proc/<PID_OF_QEMU>/cmdline
> is stuck at read:
> 
> openat(AT_FDCWD, "/proc/12239/cmdline", O_RDONLY) = 3
> newfstatat(3, "", {st_mode=S_IFREG|0444, st_size=0, ...}, AT_EMPTY_PATH) = 0
> fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
> mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
> 0x7f22f0487000
> read(3, ^C^C^C^\^C

This will require mmap_lock for read as well. And that is blocked
because there is a pending writer as well.
[...]
 
> Is this known? Any idea how to debug this?

I would recommend taking a crashdump when the host is in that state and
examine the state of the blocked lock. Dump will hopefully give you more
information about potential holder of the lock. If it is blocked on
writer then you should get the owner task. If it is in read mode then
this can get more tricky because the exact owner might be different from
the recorded one. Anyway the full list of tasks and their backtraces
could tell more.

HTH

-- 
Michal Hocko
SUSE Labs

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Linux kernel regression tracking (#adding)]

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 11.01.23 09:00, Jiri Slaby wrote:
> Hi,
> 
> after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu
> VMs started stalling (and the host at the same point too). It doesn't
> happen right after boot, maybe a suspend-resume cycle is needed (or
> longer uptime, or a couple of qemu VM starts, or ...). But when it
> happens, it happens all the time till the next reboot.

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced v6.0..v6.1
#regzbot title stalls in qemu with host running 6.1 (everything stuck at
mmap_read_lock())
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.

> Older guest's kernels/distros are affected as well as Win10.
> 
> In guests, I see for example stalls in memset_orig or
> smp_call_function_many_cond -- traces below.
> 
> qemu-kvm-7.1.0-13.34.x86_64 from openSUSE.
> 
> It's quite interesting that:
>   $ cat /proc/<PID_OF_QEMU>/cmdline
> is stuck at read:
> 
> openat(AT_FDCWD, "/proc/12239/cmdline", O_RDONLY) = 3
> newfstatat(3, "", {st_mode=S_IFREG|0444, st_size=0, ...}, AT_EMPTY_PATH)
> = 0
> fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
> mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
> 0) = 0x7f22f0487000
> read(3, ^C^C^C^\^C
> 
> too. So I dumped blocked tasks (sysrq-w) on _host_ (see below) and
> everything seems to stall on mmap_read_lock() or
> mmap_write_lock_killable(). I don't see the hog (the one actually
> _having_ and sitting on the (presumably write) lock) in the dump though.
> I will perhaps boot a LOCKDEP-enabled kernel, so that I can do sysrq-d
> next time and see the holder.
> 
> 
> There should be enough free memory (note caches at 8G):
>                total        used        free      shared  buff/cache
> available
> Mem:            15Gi        10Gi       400Mi       2,5Gi       8,0Gi  
> 5,0Gi
> Swap:             0B          0B          0B
> 
> 
> I rmmoded kvm-intel now, so:
>   qemu-kvm: failed to initialize kvm: No such file or directory
>   qemu-kvm: falling back to tcg
> and it behaves the same (more or less expected).
> 
> Is this known? Any idea how to debug this? Or maybe someone (I CCed a
> couple of guys who Acked mmap_*_lock() shuffling patches in 6.1) has a
> clue? Bisection is hard as it reproduces only under certain unknown
> circumstances.
> 
> 
> 
> 
> Now the promised dumps:
> 
>> sysrq: Show Blocked State
>> task:plasmashell     state:D stack:0     pid:2064  ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  down_read_killable+0x3d/0xa0
>>  __access_remote_vm+0x4c/0x370
>>  proc_pid_cmdline_read+0x17a/0x3c0
>>  vfs_read+0xa2/0x2c0
>>  ksys_read+0x63/0xe0
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7fda6b70795c
>> RSP: 002b:00007ffdd7b108b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fda6b70795c
>> RDX: 0000000000004000 RSI: 00007ffdd7b10a20 RDI: 0000000000000028
>> RBP: 000056536a70f610 R08: 0000000000000000 R09: 0000000000004000
>> R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000004000
>> R13: 0000000000004000 R14: 00007ffdd7b10a20 R15: 00007ffdd7b10a20
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12249 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  do_user_addr_fault+0x413/0x690
>>  exc_page_fault+0x66/0x150
>>  asm_exc_page_fault+0x22/0x30
>> RIP: 0033:0x55fc42ea2e9e
>> RSP: 002b:00007f054e5391c8 EFLAGS: 00010246
>> RAX: 00007f052aa01041 RBX: 0000000000000005 RCX: 0000000000000000
>> RDX: 00007f052aa01040 RSI: 000000000000008b RDI: 00007f0544000b70
>> RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000005
>> R10: 0000000000000003 R11: 0000000000000d60 R12: 00007f0544000b70
>> R13: fffffffffffffff0 R14: 000000000000000c R15: 00007f054400a510
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12251 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_write_slowpath+0x358/0x6a0
>>  down_write_killable+0x60/0x80
>>  do_mprotect_pkey+0xe9/0x430
>>  __x64_sys_mprotect+0x1b/0x30
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f05514a8ccb
>> RSP: 002b:00007f054d536fa8 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
>> RAX: ffffffffffffffda RBX: 00007f042c000030 RCX: 00007f05514a8ccb
>> RDX: 0000000000000003 RSI: 0000000000001000 RDI: 00007f042d304000
>> RBP: 0000000000000430 R08: 0000000001304000 R09: 0000000001305000
>> R10: 00007f042d303bf0 R11: 0000000000000206 R12: 0000000000000410
>> R13: 0000000000001000 R14: 0000000000000450 R15: 0000000000000000
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12252 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  do_user_addr_fault+0x413/0x690
>>  exc_page_fault+0x66/0x150
>>  asm_exc_page_fault+0x22/0x30
>> RIP: 0033:0x55fc42ea6217
>> RSP: 002b:00007f054cd361d0 EFLAGS: 00010246
>> RAX: 00007f052c593fff RBX: 00007f0500000018 RCX: 0000000000000000
>> RDX: 00007f052c593ffe RSI: 00000000000000e9 RDI: 00007f0430000b70
>> RBP: 00007f0430000b70 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: ffffffffd3a6c015 R12: 000000000000000c
>> R13: 0000000000000030 R14: 0000000000000080 R15: 00007f043000bad8
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12299 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  do_madvise.part.0+0xe2/0x2a0
>>  __x64_sys_madvise+0x5a/0x70
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f05514a8dab
>> RSP: 002b:00007f054f381758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>> RAX: ffffffffffffffda RBX: 00007f054eb82000 RCX: 00007f05514a8dab
>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f054eb82000
>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f054eb82000
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12300 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  do_madvise.part.0+0xe2/0x2a0
>>  __x64_sys_madvise+0x5a/0x70
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f05514a8dab
>> RSP: 002b:00007f041b4b7758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>> RAX: ffffffffffffffda RBX: 00007f041acb8000 RCX: 00007f05514a8dab
>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041acb8000
>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041acb8000
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12301 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  do_madvise.part.0+0xe2/0x2a0
>>  __x64_sys_madvise+0x5a/0x70
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f05514a8dab
>> RSP: 002b:00007f041acb6758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>> RAX: ffffffffffffffda RBX: 00007f041a4b7000 RCX: 00007f05514a8dab
>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041a4b7000
>> RBP: 0000000000801000 R08: 0000000000000005 R09: 0000000000001d4c
>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041a4b7000
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12309 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  do_madvise.part.0+0xe2/0x2a0
>>  __x64_sys_madvise+0x5a/0x70
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f05514a8dab
>> RSP: 002b:00007f041a4b5758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>> RAX: ffffffffffffffda RBX: 00007f0419cb6000 RCX: 00007f05514a8dab
>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f0419cb6000
>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f0419cb6000
>>  </TASK>
>> task:qemu-kvm        state:D stack:0     pid:12310 ppid:1905
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  do_madvise.part.0+0xe2/0x2a0
>>  __x64_sys_madvise+0x5a/0x70
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f05514a8dab
>> RSP: 002b:00007f04178b3758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>> RAX: ffffffffffffffda RBX: 00007f04170b4000 RCX: 00007f05514a8dab
>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f04170b4000
>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>> R13: 0000000000000000 R14: 00007f041a4b5300 R15: 00007f04170b4000
>>  </TASK>
>> task:ps              state:D stack:0     pid:12395 ppid:5727
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  down_read_killable+0x3d/0xa0
>>  __access_remote_vm+0x4c/0x370
>>  proc_pid_cmdline_read+0x17a/0x3c0
>>  vfs_read+0xa2/0x2c0
>>  ksys_read+0x63/0xe0
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f02fa455921
>> RSP: 002b:00007ffca71c5828 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>> RAX: ffffffffffffffda RBX: 00007f02f9f53010 RCX: 00007f02fa455921
>> RDX: 0000000000020000 RSI: 00007f02f9f53010 RDI: 0000000000000006
>> RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000073
>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f02f9f53010
>> R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
>>  </TASK>
>> task:htop            state:D stack:0     pid:12400 ppid:4676
> flags:0x00000002
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  down_read_killable+0x3d/0xa0
>>  __access_remote_vm+0x4c/0x370
>>  proc_pid_cmdline_read+0x17a/0x3c0
>>  vfs_read+0xa2/0x2c0
>>  ksys_read+0x63/0xe0
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7f4284748921
>> RSP: 002b:00007ffc88c25398 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>> RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007f4284748921
>> RDX: 0000000000001000 RSI: 00007ffc88c25490 RDI: 0000000000000007
>> RBP: 00007ffc88c25490 R08: 0000563dd4c68ab0 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 0000000000000007 R14: 00007ffc88c265a0 R15: 0000563dd4ca46c0
>>  </TASK>
>> task:htop            state:D stack:0     pid:12416 ppid:4595
> flags:0x00000006
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  down_read_killable+0x3d/0xa0
>>  __access_remote_vm+0x4c/0x370
>>  proc_pid_cmdline_read+0x17a/0x3c0
>>  vfs_read+0xa2/0x2c0
>>  ksys_read+0x63/0xe0
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7fe4d1b7f921
>> RSP: 002b:00007ffc8603e788 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>> RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fe4d1b7f921
>> RDX: 0000000000001000 RSI: 00007ffc8603e880 RDI: 0000000000000007
>> RBP: 00007ffc8603e880 R08: 00005602572e7a20 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 0000000000000007 R14: 00007ffc8603f990 R15: 000056025735d540
>>  </TASK>
>> task:htop            state:D stack:0     pid:12464 ppid:12441
> flags:0x00000006
>> Call Trace:
>>  <TASK>
>>  __schedule+0x360/0x1350
>>  schedule+0x5a/0xd0
>>  rwsem_down_read_slowpath+0x272/0x4c0
>>  down_read_killable+0x3d/0xa0
>>  __access_remote_vm+0x4c/0x370
>>  proc_pid_cmdline_read+0x17a/0x3c0
>>  vfs_read+0xa2/0x2c0
>>  ksys_read+0x63/0xe0
>>  do_syscall_64+0x58/0x80
>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>> RIP: 0033:0x7fb1e298f921
>> RSP: 002b:00007ffe419c8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>> RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fb1e298f921
>> RDX: 0000000000001000 RSI: 00007ffe419c8d70 RDI: 0000000000000007
>> RBP: 00007ffe419c8d70 R08: 0000565345f95680 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 0000000000000007 R14: 00007ffe419c9e80 R15: 0000565345fd0470
>>  </TASK>
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Guest lockups:
> 
> 
> 
>> BUG: workqueue lockup - pool cpus=3 node=0 flags=0x0 nice=0 stuck for
> 49s!
>> Showing busy workqueues and worker pools:
>> workqueue mm_percpu_wq: flags=0x8
>>   pwq 6: cpus=3 node=0 flags=0x0 nice=0 active=2/256 refcnt=4
>>     pending: vmstat_update, lru_add_drain_per_cpu BAR(49)
>> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
>> watchdog: BUG: soft lockup - CPU#2 stuck for 211s! [jbd2/sda1-8:373]
>> Modules linked in: af_packet rfkill ...
>> CPU: 2 PID: 373 Comm: jbd2/sda1-8 Kdump: loaded Not tainted
> 6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased)
> 0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>> RIP: 0010:memset_orig+0x33/0xb0
>> Code: 01 01 01 01 01 01 01 01 48 0f af c1 41 89 f9 41 83 e1 07 75 74
> 48 89 d1 48 c1 e9 06 74 39 66 0f 1f 84 00 00 00 00 00 48 ff c9 <48> 89
> 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
>> RSP: 0018:ffffbd1fc0487d08 EFLAGS: 00010216
>> RAX: 0000000000000000 RBX: ffff9fdb1b619138 RCX: 000000000000003f
>> RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff9fdb39f19000
>> RBP: ffff9fdb0054f000 R08: ffff9fdb0565cb00 R09: 0000000000000000
>> R10: ffff9fdb39f19000 R11: ffff9fdb442d71c0 R12: 0000000001000000
>> R13: ffff9fdb05079800 R14: ffff9fdb01658870 R15: ffff9fdb01658870
>> FS:  0000000000000000(0000) GS:ffff9fdb40d00000(0000)
> knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00005635dbce3fb8 CR3: 0000000103d54000 CR4: 00000000000006e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>  <TASK>
>>  jbd2_journal_get_descriptor_buffer+0x88/0xf0 [jbd2
> 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>>  jbd2_journal_commit_transaction+0x9e0/0x18b0 [jbd2
> 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>>  kjournald2+0xa9/0x260 [jbd2 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>>  kthread+0xda/0x100
>>  ret_from_fork+0x22/0x30
>>  </TASK>
> 
> 
> ========================================
> 
> 
>> watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [kworker/2:2:134]
>> Modules linked in: af_packet rfkill ...
>> Supported: No, Unreleased kernel
>> CPU: 2 PID: 134 Comm: kworker/2:2 Not tainted
> 5.14.21-150500.86.gca1fbb8-default #1 SLE15-SP5 (unreleased)
> f54a3c78ee6447e20bc183538de8800cbe783c87
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper]
>> RIP: 0010:smp_call_function_many_cond+0x123/0x560
>> Code: ef e8 71 22 42 00 3b 05 2f 2c bd 01 89 c5 73 24 48 63 c5 49 8b
> 7d 00 48 03 3c c5 a0 bb 42 b1 66 90 8b 47 08 a8 01 74 0a f3 90 <8b> 57
> 08 83 e2 01 75 f6 eb c7 48 83 c4 48 5b 5d 41 5c 41 5d 41 5e
>> RSP: 0018:ffff9eff00227c68 EFLAGS: 00000202
>> RAX: 0000000000000011 RBX: 0000000000000001 RCX: 0000000000000000
>> RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff89a1c0dba8c0
>> RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000003 R11: 0000000000000000 R12: ffff89a1c0d34b00
>> R13: ffff89a1c0d34b00 R14: 0000000000000000 R15: 0000000000000003
>> FS:  0000000000000000(0000) GS:ffff89a1c0d00000(0000)
> knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 0000561f1be53000 CR3: 00000001024e6000 CR4: 00000000000006e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>  <TASK>
>>  on_each_cpu_cond_mask+0x25/0x40
>>  __purge_vmap_area_lazy+0xba/0x6d0
>>  free_vmap_area_noflush+0x214/0x2f0
>>  remove_vm_area+0x80/0x90
>>  __vunmap+0x5e/0x260
>>  drm_gem_shmem_vunmap+0x6f/0x90 [drm_shmem_helper
> b732157accb2fabb75791e2dc3d5d21a30cf33cb]
>>  drm_gem_vunmap+0x24/0x50 [drm 14b5c4e21fb011b0159efe14dd82da3407d64716]
>>  drm_fb_helper_damage_work+0x16f/0x2f0 [drm_kms_helper
> b697aeb79f8910d3e952c8c60069f3e3382437ae]
>>  process_one_work+0x267/0x440
>>  worker_thread+0x2d/0x3d0
>>  kthread+0x156/0x180
>>  ret_from_fork+0x22/0x30
>>  </TASK>
> 
> 
> ========================================
> 
> 
>> watchdog: BUG: soft lockup - CPU#0 stuck for 319s! [watchdogd:57]
>> watchdog: BUG: soft lockup - CPU#3 stuck for 348s! [repo2solv:1139]
>> Modules linked in: af_packet rfkill nls_iso8859_1 nls_cp437
> snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg
> snd_intel_sdw_acpi snd_hda_codec snd_hda_core snd_hwdep vfat snd_pcm fat
> iTCO_wdt snd_timer ppdev virtio_net intel_pmc_bxt tiny_power_button
> i2c_i801 iTCO_vend>
>> CPU: 3 PID: 1139 Comm: repo2solv Kdump: loaded Not tainted
> 6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased)
> 0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>> RIP: 0010:clear_page_orig+0x12/0x40
>> Code: 5d c3 cc cc cc cc cc cc b9 00 02 00 00 31 c0 f3 48 ab c3 cc cc
> cc cc 90 31 c0 b9 40 00 00 00 66 0f 1f 84 00 00 00 00 00 ff c9 <48> 89
> 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
>> RSP: 0000:ffffb644c0da3be8 EFLAGS: 00010216
>> RAX: 0000000000000000 RBX: fffffccec4828000 RCX: 000000000000003f
>> RDX: fffffccec4828000 RSI: fffffccec4828040 RDI: ffffa04a20a00000
>> RBP: 0000000000000000 R08: ffffb644c0da3d10 R09: 0000000000028b29
>> R10: 0000000000000010 R11: ffffa04a441d51c0 R12: 0000000000140dca
>> R13: 0000000000000040 R14: 0000000000000001 R15: 0000000000000286
>> FS:  00007f91de710f80(0000) GS:ffffa04a40d80000(0000)
> knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007f91de3d3000 CR3: 0000000101f86000 CR4: 00000000000006e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>  <TASK>
>>  post_alloc_hook+0xa9/0xe0
>>  get_page_from_freelist+0x4d9/0x1590
>>  __alloc_pages+0xec/0x240
>>  __folio_alloc+0x17/0x50
>>  vma_alloc_folio+0x9c/0x370
>>  __handle_mm_fault+0x942/0xfe0
>>  handle_mm_fault+0xdb/0x2d0
>>  do_user_addr_fault+0x1ba/0x690
>>  exc_page_fault+0x66/0x150
>>  asm_exc_page_fault+0x22/0x30
> 
> thanks,

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Paolo Bonzini]

On 1/11/23 09:00, Jiri Slaby wrote:
> 
> 
> I rmmoded kvm-intel now, so:
>    qemu-kvm: failed to initialize kvm: No such file or directory
>    qemu-kvm: falling back to tcg
> and it behaves the same (more or less expected).

Not entirely expected, but at least it throws the ball to mm camp and 
excludes any bug involving KVM mmu notifiers.

Paolo

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Pedro Falcato]

On Wed, Jan 11, 2023 at 8:00 AM Jiri Slaby <jirislaby@kernel.org> wrote:
>
> Hi,
>
> after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu
> VMs started stalling (and the host at the same point too). It doesn't
> happen right after boot, maybe a suspend-resume cycle is needed (or
> longer uptime, or a couple of qemu VM starts, or ...). But when it
> happens, it happens all the time till the next reboot.
>
> Older guest's kernels/distros are affected as well as Win10.
>
> In guests, I see for example stalls in memset_orig or
> smp_call_function_many_cond -- traces below.
>
> qemu-kvm-7.1.0-13.34.x86_64 from openSUSE.
>
> It's quite interesting that:
>    $ cat /proc/<PID_OF_QEMU>/cmdline
> is stuck at read:
>
> openat(AT_FDCWD, "/proc/12239/cmdline", O_RDONLY) = 3
> newfstatat(3, "", {st_mode=S_IFREG|0444, st_size=0, ...}, AT_EMPTY_PATH) = 0
> fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
> mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
> 0) = 0x7f22f0487000
> read(3, ^C^C^C^\^C
>
> too. So I dumped blocked tasks (sysrq-w) on _host_ (see below) and
> everything seems to stall on mmap_read_lock() or
> mmap_write_lock_killable(). I don't see the hog (the one actually
> _having_ and sitting on the (presumably write) lock) in the dump though.
> I will perhaps boot a LOCKDEP-enabled kernel, so that I can do sysrq-d
> next time and see the holder.
>
>
> There should be enough free memory (note caches at 8G):
>                 total        used        free      shared  buff/cache
> available
> Mem:            15Gi        10Gi       400Mi       2,5Gi       8,0Gi
>    5,0Gi
> Swap:             0B          0B          0B
>
>
> I rmmoded kvm-intel now, so:
>    qemu-kvm: failed to initialize kvm: No such file or directory
>    qemu-kvm: falling back to tcg
> and it behaves the same (more or less expected).
>
> Is this known? Any idea how to debug this? Or maybe someone (I CCed a
> couple of guys who Acked mmap_*_lock() shuffling patches in 6.1) has a
> clue? Bisection is hard as it reproduces only under certain unknown
> circumstances.

Hi,

I just want to chime in and say that I've also hit this regression
right as I (Arch) updated to 6.1 a few weeks ago.
This completely ruined my qemu workflow such that I had to fallback to
using an LTS kernel.

Some data I've gathered:
1) It seems to not happen right after booting - I'm unsure if this is
due to memory pressure or less CPU load or any other factor
2) It seems to intensify after swapping a fair amount? At least this
has been my experience.
3) The largest slowdown seems to be when qemu is booting the guest,
possibly during heavy memory allocation - problems range from "takes
tens of seconds to boot" to "qemu is completely blocked and needs a
SIGKILL spam".
4) While traditional process monitoring tools break (likely due to
mmap_lock getting hogged), I can (empirically, using /bin/free) tell
that the system seems to be swapping in/out quite a fair bit

My 4) is particularly confusing to me as I had originally blamed the
problem on the MGLRU changes, while you don't seem to be swapping at
all.
Could this be related to the maple tree patches? Should we CC both the
MGLRU folks and the maple folks?

I have little insight into what the kernel's state actually is apart
from this - perf seems to break, and I have no kernel debugger as this
is my live personal machine :/
I would love it if someone hinted to possible things I/we could try in
order to track this down. Is this not git-bisectable at all?

Thanks,
Pedro

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Jiri Slaby]

Hi,

On 12. 01. 23, 1:37, Pedro Falcato wrote:
> I just want to chime in and say that I've also hit this regression
> right as I (Arch) updated to 6.1 a few weeks ago.
> This completely ruined my qemu workflow such that I had to fallback to
> using an LTS kernel.
> 
> Some data I've gathered:
> 1) It seems to not happen right after booting - I'm unsure if this is
> due to memory pressure or less CPU load or any other factor

+1 as I wrote.

> 2) It seems to intensify after swapping a fair amount? At least this
> has been my experience.

I have no swap.

> 3) The largest slowdown seems to be when qemu is booting the guest,
> possibly during heavy memory allocation - problems range from "takes
> tens of seconds to boot" to "qemu is completely blocked and needs a
> SIGKILL spam".

+1

> 4) While traditional process monitoring tools break (likely due to
> mmap_lock getting hogged), I can (empirically, using /bin/free) tell
> that the system seems to be swapping in/out quite a fair bit

Yes, htop/top/ps and such are stuck at the read of /proc/<pid>/cmdline 
as I wrote (waiting for the mmap lock).

> My 4) is particularly confusing to me as I had originally blamed the
> problem on the MGLRU changes, while you don't seem to be swapping at
> all.
> Could this be related to the maple tree patches? Should we CC both the
> MGLRU folks and the maple folks?
> 
> I have little insight into what the kernel's state actually is apart
> from this - perf seems to break, and I have no kernel debugger as this
> is my live personal machine :/
> I would love it if someone hinted to possible things I/we could try in
> order to track this down. Is this not git-bisectable at all?

I have rebooted to a fresh kernel which 1) have lockdep enabled, and 2) 
I have debuginfo for. So next time this happens, I can print held locks 
and dump a kcore (kdump is set up).

regards,
-- 
js
suse labs

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Yu Zhao]

On Wed, Jan 11, 2023 at 5:37 PM Pedro Falcato <pedro.falcato@gmail.com> wrote:
>
> On Wed, Jan 11, 2023 at 8:00 AM Jiri Slaby <jirislaby@kernel.org> wrote:
> >
> > Hi,
> >
> > after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu
> > VMs started stalling (and the host at the same point too). It doesn't
> > happen right after boot, maybe a suspend-resume cycle is needed (or
> > longer uptime, or a couple of qemu VM starts, or ...). But when it
> > happens, it happens all the time till the next reboot.
> >
> > Older guest's kernels/distros are affected as well as Win10.
> >
> > In guests, I see for example stalls in memset_orig or
> > smp_call_function_many_cond -- traces below.
> >
> > qemu-kvm-7.1.0-13.34.x86_64 from openSUSE.
> >
> > It's quite interesting that:
> >    $ cat /proc/<PID_OF_QEMU>/cmdline
> > is stuck at read:
> >
> > openat(AT_FDCWD, "/proc/12239/cmdline", O_RDONLY) = 3
> > newfstatat(3, "", {st_mode=S_IFREG|0444, st_size=0, ...}, AT_EMPTY_PATH) = 0
> > fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
> > mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
> > 0) = 0x7f22f0487000
> > read(3, ^C^C^C^\^C
> >
> > too. So I dumped blocked tasks (sysrq-w) on _host_ (see below) and
> > everything seems to stall on mmap_read_lock() or
> > mmap_write_lock_killable(). I don't see the hog (the one actually
> > _having_ and sitting on the (presumably write) lock) in the dump though.
> > I will perhaps boot a LOCKDEP-enabled kernel, so that I can do sysrq-d
> > next time and see the holder.
> >
> >
> > There should be enough free memory (note caches at 8G):
> >                 total        used        free      shared  buff/cache
> > available
> > Mem:            15Gi        10Gi       400Mi       2,5Gi       8,0Gi
> >    5,0Gi
> > Swap:             0B          0B          0B
> >
> >
> > I rmmoded kvm-intel now, so:
> >    qemu-kvm: failed to initialize kvm: No such file or directory
> >    qemu-kvm: falling back to tcg
> > and it behaves the same (more or less expected).
> >
> > Is this known? Any idea how to debug this? Or maybe someone (I CCed a
> > couple of guys who Acked mmap_*_lock() shuffling patches in 6.1) has a
> > clue? Bisection is hard as it reproduces only under certain unknown
> > circumstances.
>
> Hi,
>
> I just want to chime in and say that I've also hit this regression
> right as I (Arch) updated to 6.1 a few weeks ago.
> This completely ruined my qemu workflow such that I had to fallback to
> using an LTS kernel.
>
> Some data I've gathered:
> 1) It seems to not happen right after booting - I'm unsure if this is
> due to memory pressure or less CPU load or any other factor
> 2) It seems to intensify after swapping a fair amount? At least this
> has been my experience.
> 3) The largest slowdown seems to be when qemu is booting the guest,
> possibly during heavy memory allocation - problems range from "takes
> tens of seconds to boot" to "qemu is completely blocked and needs a
> SIGKILL spam".
> 4) While traditional process monitoring tools break (likely due to
> mmap_lock getting hogged), I can (empirically, using /bin/free) tell
> that the system seems to be swapping in/out quite a fair bit
>
> My 4) is particularly confusing to me as I had originally blamed the
> problem on the MGLRU changes, while you don't seem to be swapping at
> all.
> Could this be related to the maple tree patches? Should we CC both the
> MGLRU folks and the maple folks?

I don't think it's MGLRU because the way it uses mmap_lock is very
simple. Also you could prevent MGLRU from taking mmap_lock by echo 3
>/sys/kernel/mm/lru_gen/enabled, or you could disable MGLRU entirely
by echoing 0 to the same file, or even at build time, to rule it out.
(I assume you
turned on MGLRU in the first place.)

Adding Liam. He can speak for the maple tree.

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Maxim Levitsky]

On Thu, 2023-01-12 at 07:07 +0100, Jiri Slaby wrote:
> Hi,
> 
> On 12. 01. 23, 1:37, Pedro Falcato wrote:
> > I just want to chime in and say that I've also hit this regression
> > right as I (Arch) updated to 6.1 a few weeks ago.
> > This completely ruined my qemu workflow such that I had to fallback to
> > using an LTS kernel.
> > 
> > Some data I've gathered:
> > 1) It seems to not happen right after booting - I'm unsure if this is
> > due to memory pressure or less CPU load or any other factor
> 
> +1 as I wrote.
> 
> > 2) It seems to intensify after swapping a fair amount? At least this
> > has been my experience.
> 
> I have no swap.
> 
> > 3) The largest slowdown seems to be when qemu is booting the guest,
> > possibly during heavy memory allocation - problems range from "takes
> > tens of seconds to boot" to "qemu is completely blocked and needs a
> > SIGKILL spam".
> 
> +1
> 
> > 4) While traditional process monitoring tools break (likely due to
> > mmap_lock getting hogged), I can (empirically, using /bin/free) tell
> > that the system seems to be swapping in/out quite a fair bit
> 
> Yes, htop/top/ps and such are stuck at the read of /proc/<pid>/cmdline 
> as I wrote (waiting for the mmap lock).
> 
> > My 4) is particularly confusing to me as I had originally blamed the
> > problem on the MGLRU changes, while you don't seem to be swapping at
> > all.
> > Could this be related to the maple tree patches? Should we CC both the
> > MGLRU folks and the maple folks?
> > 
> > I have little insight into what the kernel's state actually is apart
> > from this - perf seems to break, and I have no kernel debugger as this
> > is my live personal machine :/
> > I would love it if someone hinted to possible things I/we could try in
> > order to track this down. Is this not git-bisectable at all?
> 
> I have rebooted to a fresh kernel which 1) have lockdep enabled, and 2) 
> I have debuginfo for. So next time this happens, I can print held locks 
> and dump a kcore (kdump is set up).
> 
> regards,

It is also possible that I noticed something like that on 6.1:

For me it happens when my system (also no swap, 96G out which 48 are permanetly reserved as 1G hugepages,
and this happens with VMs which don't use this hugepage reserve) 
is somewhat low on memory and qemu tries to lock all memory (I use -overcommit mem-lock=on)

Like it usually happens when I start 32 GB VM while having lot of stuff open in background, but
still not nearly close to 16GB.
As a workaround I lowered the reserved area to 32G.

I also see indication that things like htop or even opening a new shell hang quite hard.

What almost instantly helps is 'echo 3 | sudo tee /proc/sys/vm/drop_caches'
e.g that makes the VM start booting, and unlocks everything.

Best regards,
	Maxim Levitsky

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Vlastimil Babka]

On 1/12/23 11:31, Maxim Levitsky wrote:
> On Thu, 2023-01-12 at 07:07 +0100, Jiri Slaby wrote:
>> 
>> I have rebooted to a fresh kernel which 1) have lockdep enabled, and 2) 
>> I have debuginfo for. So next time this happens, I can print held locks 
>> and dump a kcore (kdump is set up).
>> 
>> regards,
> 
> It is also possible that I noticed something like that on 6.1:
> 
> For me it happens when my system (also no swap, 96G out which 48 are permanetly reserved as 1G hugepages,
> and this happens with VMs which don't use this hugepage reserve) 
> is somewhat low on memory and qemu tries to lock all memory (I use -overcommit mem-lock=on)
> 
> Like it usually happens when I start 32 GB VM while having lot of stuff open in background, but
> still not nearly close to 16GB.
> As a workaround I lowered the reserved area to 32G.
> 
> I also see indication that things like htop or even opening a new shell hang quite hard.
> 
> What almost instantly helps is 'echo 3 | sudo tee /proc/sys/vm/drop_caches'
> e.g that makes the VM start booting, and unlocks everything.

Note it's possible that temporary+recoverable things like that have a
different cause caused by compaction caught in a loop, as discussed here:

https://lore.kernel.org/all/a032e3bf-8470-095a-2262-791f5678e590@suse.cz/

> Best regards,
> 	Maxim Levitsky
> 

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Jiri Slaby]

On 12. 01. 23, 7:07, Jiri Slaby wrote:
> I have rebooted to a fresh kernel which 1) have lockdep enabled, and 2) 
> I have debuginfo for. So next time this happens, I can print held locks 

For the time being:

 >  Showing all locks held in the system:
 >  1 lock held by rcu_tasks_kthre/11:
 >   #0: ffffffffb097a550 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: 
rcu_tasks_one_gp+0x2b/0x3d0
 >  1 lock held by rcu_tasks_rude_/12:
 >   #0: ffffffffb097a2d0 (rcu_tasks_rude.tasks_gp_mutex){+.+.}-{3:3}, 
at: rcu_tasks_one_gp+0x2b/0x3d0
 >  1 lock held by rcu_tasks_trace/13:
 >   #0: ffffffffb097a010 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, 
at: rcu_tasks_one_gp+0x2b/0x3d0
 >  1 lock held by in:imklog/1308:
 >   #0: ffff9538d81364e8 (&f->f_pos_lock){+.+.}-{3:3}, at: 
__fdget_pos+0x4c/0x60
 >  2 locks held by plasmashell/6865:
 >   #0: ffff95393f6092e8 (&f->f_pos_lock){+.+.}-{3:3}, at: 
__fdget_pos+0x4c/0x60
 >   #1: ffff9538dc2aa458 (&mm->mmap_lock#2){++++}-{3:3}, at: 
__access_remote_vm+0x4f/0x3c0
 >  1 lock held by fuse mainloop/9772:
 >   #0: ffff953a578a7468 (&pipe->mutex/1){+.+.}-{3:3}, at: 
splice_file_to_pipe+0x26/0xd0
 >  1 lock held by fuse mainloop/9773:
 >   #0: ffff953a578a7e68 (&pipe->mutex/1){+.+.}-{3:3}, at: 
splice_file_to_pipe+0x26/0xd0
 >  1 lock held by fuse mainloop/25378:
 >   #0: ffff9538d3d8c868 (&pipe->mutex/1){+.+.}-{3:3}, at: 
splice_file_to_pipe+0x26/0xd0
 >  1 lock held by qemu-kvm/31097:
 >  6 locks held by qemu-kvm/31098:
 >   #0: ffff953a062080b0 (&vcpu->mutex){+.+.}-{3:3}, at: 
kvm_vcpu_ioctl+0x77/0x6d0 [kvm]
 >   #1: ffff9538c6e838e8 (&serio->lock){-.-.}-{2:2}, at: 
serio_interrupt+0x24/0x90
 >   #2: ffff9538c6e80230 (&dev->event_lock){-.-.}-{2:2}, at: 
input_event+0x3c/0x80
 >   #3: ffffffffb097af60 (rcu_read_lock){....}-{1:2}, at: 
input_pass_values.part.0+0x5/0x270
 >   #4: ffffffffb097af60 (rcu_read_lock){....}-{1:2}, at: 
__handle_sysrq+0x5/0xa0
 >   #5: ffffffffb097af60 (rcu_read_lock){....}-{1:2}, at: 
debug_show_all_locks+0x15/0x16b
 >  1 lock held by qemu-kvm/31099:
 >  3 locks held by qemu-kvm/31100:
 >  1 lock held by qemu-kvm/31819:
 >   #0: ffff9538dc2aa458 (&mm->mmap_lock#2){++++}-{3:3}, at: 
__vm_munmap+0x95/0x170
 >  1 lock held by qemu-kvm/31935:
 >   #0: ffff9538dc2aa458 (&mm->mmap_lock#2){++++}-{3:3}, at: 
do_madvise.part.0+0xe8/0x2a0
 >  1 lock held by dmesg/31873:
 >   #0: ffff9538ef6000d0 (&user->lock){+.+.}-{3:3}, at: 
devkmsg_read+0x4b/0x230
 >  1 lock held by ps/31996:
 >   #0: ffff9538dc2aa458 (&mm->mmap_lock#2){++++}-{3:3}, at: 
__access_remote_vm+0x4f/0x3c0


> and dump a kcore (kdump is set up).

Going to trigger a dump now.

-- 
js
suse labs

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Jiri Slaby]

On 12. 01. 23, 16:43, Jiri Slaby wrote:
>> and dump a kcore (kdump is set up).
> 
> Going to trigger a dump now.

Hmm, crash doesn't seems to work for 6.1, apparently. Once it did 
nothing, second time, it dumped an empty dir...

So for now, only the lock dump is available. Next time, I will dump at 
least process states (sysrq-t).

thanks,
-- 
js
suse labs

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Liam Howlett]

* Jiri Slaby <jirislaby@kernel.org> [230112 11:57]:
> On 12. 01. 23, 16:43, Jiri Slaby wrote:
> > > and dump a kcore (kdump is set up).
> > 
> > Going to trigger a dump now.
> 
> Hmm, crash doesn't seems to work for 6.1, apparently. Once it did nothing,
> second time, it dumped an empty dir...

These was a patch added a few days ago to crash to support the maple
tree [1].  This might be why you are having issues?

1. https://www.mail-archive.com/crash-utility@redhat.com/msg09805.html

Thanks,
Liam

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Liam Howlett]

* Yu Zhao <yuzhao@google.com> [230112 03:23]:
> On Wed, Jan 11, 2023 at 5:37 PM Pedro Falcato <pedro.falcato@gmail.com> wrote:
> >
> > On Wed, Jan 11, 2023 at 8:00 AM Jiri Slaby <jirislaby@kernel.org> wrote:
> > >
> > > Hi,
> > >
> > > after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu
> > > VMs started stalling (and the host at the same point too). It doesn't
> > > happen right after boot, maybe a suspend-resume cycle is needed (or
> > > longer uptime, or a couple of qemu VM starts, or ...). But when it
> > > happens, it happens all the time till the next reboot.
> > >
> > > Older guest's kernels/distros are affected as well as Win10.

...

> > >
> > > There should be enough free memory (note caches at 8G):
> > >                 total        used        free      shared  buff/cache
> > > available
> > > Mem:            15Gi        10Gi       400Mi       2,5Gi       8,0Gi
> > >    5,0Gi
> > > Swap:             0B          0B          0B
> > >
> > >
> > > I rmmoded kvm-intel now, so:
> > >    qemu-kvm: failed to initialize kvm: No such file or directory
> > >    qemu-kvm: falling back to tcg
> > > and it behaves the same (more or less expected).
> > >
...

> > Some data I've gathered:
> > 1) It seems to not happen right after booting - I'm unsure if this is
> > due to memory pressure or less CPU load or any other factor
> > 2) It seems to intensify after swapping a fair amount? At least this
> > has been my experience.
> > 3) The largest slowdown seems to be when qemu is booting the guest,
> > possibly during heavy memory allocation - problems range from "takes
> > tens of seconds to boot" to "qemu is completely blocked and needs a
> > SIGKILL spam".
> > 4) While traditional process monitoring tools break (likely due to
> > mmap_lock getting hogged), I can (empirically, using /bin/free) tell
> > that the system seems to be swapping in/out quite a fair bit
> >
> > My 4) is particularly confusing to me as I had originally blamed the
> > problem on the MGLRU changes, while you don't seem to be swapping at
> > all.
> > Could this be related to the maple tree patches? Should we CC both the
> > MGLRU folks and the maple folks?

I think we all monitor the linux-mm list, but a direct CC would not
hurt.

> 
> I don't think it's MGLRU because the way it uses mmap_lock is very
> simple. Also you could prevent MGLRU from taking mmap_lock by echo 3
> >/sys/kernel/mm/lru_gen/enabled, or you could disable MGLRU entirely
> by echoing 0 to the same file, or even at build time, to rule it out.
> (I assume you
> turned on MGLRU in the first place.)
> 
> Adding Liam. He can speak for the maple tree.

Thanks Yu (and Vlastimil) for the Cc on this issue.  My changes to the
mmap_lock were certainly not trivial and so it could be something I've
done in regards to the maple tree or the changes to the mm code for the
maple tree..

There might be a relevant patch [1] in the mm-unstable (Cc'ed to stable)
which could affect to the maple tree while under memory pressure.

The bug [2] would manifest itself in returning a range below the
requested allocation window, or the incorrect return code.  This could
certainly cause applications to misbehave, although it is not obvious to
me why the mmap_lock would remain held if this is the issue.

1. https://lore.kernel.org/linux-mm/20230111200136.1851322-1-Liam.Howlett@oracle.com/
2. https://bugzilla.kernel.org/show_bug.cgi?id=216911

Thanks,
Liam

Re: Stalls in qemu with host running 6.1 (everything stuck at mmap_read_lock())

[Vlastimil Babka]

On 1/11/23 10:21, Linux kernel regression tracking (#adding) wrote:
> [CCing the regression list, as it should be in the loop for regressions:
> https://docs.kernel.org/admin-guide/reporting-regressions.html]
> 
> [TLDR: I'm adding this report to the list of tracked Linux kernel
> regressions; the text you find below is based on a few templates
> paragraphs you might have encountered already in similar form.
> See link in footer if these mails annoy you.]
> 
> On 11.01.23 09:00, Jiri Slaby wrote:
>> Hi,
>> 
>> after I updated the host from 6.0 to 6.1 (being at 6.1.4 ATM), my qemu
>> VMs started stalling (and the host at the same point too). It doesn't
>> happen right after boot, maybe a suspend-resume cycle is needed (or
>> longer uptime, or a couple of qemu VM starts, or ...). But when it
>> happens, it happens all the time till the next reboot.
> 
> Thanks for the report. To be sure the issue doesn't fall through the
> cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
> tracking bot:
> 
> #regzbot ^introduced v6.0..v6.1
> #regzbot title stalls in qemu with host running 6.1 (everything stuck at
> mmap_read_lock())
> #regzbot ignore-activity
> 
> This isn't a regression? This issue or a fix for it are already
> discussed somewhere else? It was fixed already? You want to clarify when
> the regression started to happen? Or point out I got the title or
> something else totally wrong? Then just reply and tell me -- ideally
> while also telling regzbot about it, as explained by the page listed in
> the footer of this mail.
> 
> Developers: When fixing the issue, remember to add 'Link:' tags pointing
> to the report (the parent of this mail). See page linked in footer for
> details.
> 
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)

FWIW, I consider this serious enough to be fixed in mainline+stable ASAP,
hopefully in rc5, as it does hurt people using 6.1. mm-fixes PR for rc5 was
sent 2 days ago [1] so please flag this in your regression report for Linus
etc. Thanks.

[1]
https://lore.kernel.org/all/20230116152712.612b60d26b497d1d5749f4dc@linux-foundation.org/

> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> That page also explains what to do if mails like this annoy you.
> 
>> Older guest's kernels/distros are affected as well as Win10.
>> 
>> In guests, I see for example stalls in memset_orig or
>> smp_call_function_many_cond -- traces below.
>> 
>> qemu-kvm-7.1.0-13.34.x86_64 from openSUSE.
>> 
>> It's quite interesting that:
>>   $ cat /proc/<PID_OF_QEMU>/cmdline
>> is stuck at read:
>> 
>> openat(AT_FDCWD, "/proc/12239/cmdline", O_RDONLY) = 3
>> newfstatat(3, "", {st_mode=S_IFREG|0444, st_size=0, ...}, AT_EMPTY_PATH)
>> = 0
>> fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
>> mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
>> 0) = 0x7f22f0487000
>> read(3, ^C^C^C^\^C
>> 
>> too. So I dumped blocked tasks (sysrq-w) on _host_ (see below) and
>> everything seems to stall on mmap_read_lock() or
>> mmap_write_lock_killable(). I don't see the hog (the one actually
>> _having_ and sitting on the (presumably write) lock) in the dump though.
>> I will perhaps boot a LOCKDEP-enabled kernel, so that I can do sysrq-d
>> next time and see the holder.
>> 
>> 
>> There should be enough free memory (note caches at 8G):
>>                total        used        free      shared  buff/cache
>> available
>> Mem:            15Gi        10Gi       400Mi       2,5Gi       8,0Gi  
>> 5,0Gi
>> Swap:             0B          0B          0B
>> 
>> 
>> I rmmoded kvm-intel now, so:
>>   qemu-kvm: failed to initialize kvm: No such file or directory
>>   qemu-kvm: falling back to tcg
>> and it behaves the same (more or less expected).
>> 
>> Is this known? Any idea how to debug this? Or maybe someone (I CCed a
>> couple of guys who Acked mmap_*_lock() shuffling patches in 6.1) has a
>> clue? Bisection is hard as it reproduces only under certain unknown
>> circumstances.
>> 
>> 
>> 
>> 
>> Now the promised dumps:
>> 
>>> sysrq: Show Blocked State
>>> task:plasmashell     state:D stack:0     pid:2064  ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  down_read_killable+0x3d/0xa0
>>>  __access_remote_vm+0x4c/0x370
>>>  proc_pid_cmdline_read+0x17a/0x3c0
>>>  vfs_read+0xa2/0x2c0
>>>  ksys_read+0x63/0xe0
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7fda6b70795c
>>> RSP: 002b:00007ffdd7b108b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fda6b70795c
>>> RDX: 0000000000004000 RSI: 00007ffdd7b10a20 RDI: 0000000000000028
>>> RBP: 000056536a70f610 R08: 0000000000000000 R09: 0000000000004000
>>> R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000004000
>>> R13: 0000000000004000 R14: 00007ffdd7b10a20 R15: 00007ffdd7b10a20
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12249 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  do_user_addr_fault+0x413/0x690
>>>  exc_page_fault+0x66/0x150
>>>  asm_exc_page_fault+0x22/0x30
>>> RIP: 0033:0x55fc42ea2e9e
>>> RSP: 002b:00007f054e5391c8 EFLAGS: 00010246
>>> RAX: 00007f052aa01041 RBX: 0000000000000005 RCX: 0000000000000000
>>> RDX: 00007f052aa01040 RSI: 000000000000008b RDI: 00007f0544000b70
>>> RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000005
>>> R10: 0000000000000003 R11: 0000000000000d60 R12: 00007f0544000b70
>>> R13: fffffffffffffff0 R14: 000000000000000c R15: 00007f054400a510
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12251 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_write_slowpath+0x358/0x6a0
>>>  down_write_killable+0x60/0x80
>>>  do_mprotect_pkey+0xe9/0x430
>>>  __x64_sys_mprotect+0x1b/0x30
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f05514a8ccb
>>> RSP: 002b:00007f054d536fa8 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
>>> RAX: ffffffffffffffda RBX: 00007f042c000030 RCX: 00007f05514a8ccb
>>> RDX: 0000000000000003 RSI: 0000000000001000 RDI: 00007f042d304000
>>> RBP: 0000000000000430 R08: 0000000001304000 R09: 0000000001305000
>>> R10: 00007f042d303bf0 R11: 0000000000000206 R12: 0000000000000410
>>> R13: 0000000000001000 R14: 0000000000000450 R15: 0000000000000000
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12252 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  do_user_addr_fault+0x413/0x690
>>>  exc_page_fault+0x66/0x150
>>>  asm_exc_page_fault+0x22/0x30
>>> RIP: 0033:0x55fc42ea6217
>>> RSP: 002b:00007f054cd361d0 EFLAGS: 00010246
>>> RAX: 00007f052c593fff RBX: 00007f0500000018 RCX: 0000000000000000
>>> RDX: 00007f052c593ffe RSI: 00000000000000e9 RDI: 00007f0430000b70
>>> RBP: 00007f0430000b70 R08: 0000000000000000 R09: 0000000000000000
>>> R10: 0000000000000000 R11: ffffffffd3a6c015 R12: 000000000000000c
>>> R13: 0000000000000030 R14: 0000000000000080 R15: 00007f043000bad8
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12299 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  do_madvise.part.0+0xe2/0x2a0
>>>  __x64_sys_madvise+0x5a/0x70
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f05514a8dab
>>> RSP: 002b:00007f054f381758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>>> RAX: ffffffffffffffda RBX: 00007f054eb82000 RCX: 00007f05514a8dab
>>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f054eb82000
>>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f054eb82000
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12300 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  do_madvise.part.0+0xe2/0x2a0
>>>  __x64_sys_madvise+0x5a/0x70
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f05514a8dab
>>> RSP: 002b:00007f041b4b7758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>>> RAX: ffffffffffffffda RBX: 00007f041acb8000 RCX: 00007f05514a8dab
>>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041acb8000
>>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041acb8000
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12301 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  do_madvise.part.0+0xe2/0x2a0
>>>  __x64_sys_madvise+0x5a/0x70
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f05514a8dab
>>> RSP: 002b:00007f041acb6758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>>> RAX: ffffffffffffffda RBX: 00007f041a4b7000 RCX: 00007f05514a8dab
>>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f041a4b7000
>>> RBP: 0000000000801000 R08: 0000000000000005 R09: 0000000000001d4c
>>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f041a4b7000
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12309 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  do_madvise.part.0+0xe2/0x2a0
>>>  __x64_sys_madvise+0x5a/0x70
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f05514a8dab
>>> RSP: 002b:00007f041a4b5758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>>> RAX: ffffffffffffffda RBX: 00007f0419cb6000 RCX: 00007f05514a8dab
>>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f0419cb6000
>>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>>> R13: 000000000000000b R14: 00007fff19b2efe0 R15: 00007f0419cb6000
>>>  </TASK>
>>> task:qemu-kvm        state:D stack:0     pid:12310 ppid:1905
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  do_madvise.part.0+0xe2/0x2a0
>>>  __x64_sys_madvise+0x5a/0x70
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f05514a8dab
>>> RSP: 002b:00007f04178b3758 EFLAGS: 00000206 ORIG_RAX: 000000000000001c
>>> RAX: ffffffffffffffda RBX: 00007f04170b4000 RCX: 00007f05514a8dab
>>> RDX: 0000000000000004 RSI: 00000000007fb000 RDI: 00007f04170b4000
>>> RBP: 0000000000801000 R08: 000055fc45749778 R09: 000055fc45749798
>>> R10: 0000000000000008 R11: 0000000000000206 R12: fffffffffffffb68
>>> R13: 0000000000000000 R14: 00007f041a4b5300 R15: 00007f04170b4000
>>>  </TASK>
>>> task:ps              state:D stack:0     pid:12395 ppid:5727
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  down_read_killable+0x3d/0xa0
>>>  __access_remote_vm+0x4c/0x370
>>>  proc_pid_cmdline_read+0x17a/0x3c0
>>>  vfs_read+0xa2/0x2c0
>>>  ksys_read+0x63/0xe0
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f02fa455921
>>> RSP: 002b:00007ffca71c5828 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>>> RAX: ffffffffffffffda RBX: 00007f02f9f53010 RCX: 00007f02fa455921
>>> RDX: 0000000000020000 RSI: 00007f02f9f53010 RDI: 0000000000000006
>>> RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000073
>>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f02f9f53010
>>> R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
>>>  </TASK>
>>> task:htop            state:D stack:0     pid:12400 ppid:4676
>> flags:0x00000002
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  down_read_killable+0x3d/0xa0
>>>  __access_remote_vm+0x4c/0x370
>>>  proc_pid_cmdline_read+0x17a/0x3c0
>>>  vfs_read+0xa2/0x2c0
>>>  ksys_read+0x63/0xe0
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7f4284748921
>>> RSP: 002b:00007ffc88c25398 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>>> RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007f4284748921
>>> RDX: 0000000000001000 RSI: 00007ffc88c25490 RDI: 0000000000000007
>>> RBP: 00007ffc88c25490 R08: 0000563dd4c68ab0 R09: 0000000000000000
>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>>> R13: 0000000000000007 R14: 00007ffc88c265a0 R15: 0000563dd4ca46c0
>>>  </TASK>
>>> task:htop            state:D stack:0     pid:12416 ppid:4595
>> flags:0x00000006
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  down_read_killable+0x3d/0xa0
>>>  __access_remote_vm+0x4c/0x370
>>>  proc_pid_cmdline_read+0x17a/0x3c0
>>>  vfs_read+0xa2/0x2c0
>>>  ksys_read+0x63/0xe0
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7fe4d1b7f921
>>> RSP: 002b:00007ffc8603e788 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>>> RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fe4d1b7f921
>>> RDX: 0000000000001000 RSI: 00007ffc8603e880 RDI: 0000000000000007
>>> RBP: 00007ffc8603e880 R08: 00005602572e7a20 R09: 0000000000000000
>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>>> R13: 0000000000000007 R14: 00007ffc8603f990 R15: 000056025735d540
>>>  </TASK>
>>> task:htop            state:D stack:0     pid:12464 ppid:12441
>> flags:0x00000006
>>> Call Trace:
>>>  <TASK>
>>>  __schedule+0x360/0x1350
>>>  schedule+0x5a/0xd0
>>>  rwsem_down_read_slowpath+0x272/0x4c0
>>>  down_read_killable+0x3d/0xa0
>>>  __access_remote_vm+0x4c/0x370
>>>  proc_pid_cmdline_read+0x17a/0x3c0
>>>  vfs_read+0xa2/0x2c0
>>>  ksys_read+0x63/0xe0
>>>  do_syscall_64+0x58/0x80
>>>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
>>> RIP: 0033:0x7fb1e298f921
>>> RSP: 002b:00007ffe419c8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>>> RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fb1e298f921
>>> RDX: 0000000000001000 RSI: 00007ffe419c8d70 RDI: 0000000000000007
>>> RBP: 00007ffe419c8d70 R08: 0000565345f95680 R09: 0000000000000000
>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>>> R13: 0000000000000007 R14: 00007ffe419c9e80 R15: 0000565345fd0470
>>>  </TASK>
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> Guest lockups:
>> 
>> 
>> 
>>> BUG: workqueue lockup - pool cpus=3 node=0 flags=0x0 nice=0 stuck for
>> 49s!
>>> Showing busy workqueues and worker pools:
>>> workqueue mm_percpu_wq: flags=0x8
>>>   pwq 6: cpus=3 node=0 flags=0x0 nice=0 active=2/256 refcnt=4
>>>     pending: vmstat_update, lru_add_drain_per_cpu BAR(49)
>>> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
>>> watchdog: BUG: soft lockup - CPU#2 stuck for 211s! [jbd2/sda1-8:373]
>>> Modules linked in: af_packet rfkill ...
>>> CPU: 2 PID: 373 Comm: jbd2/sda1-8 Kdump: loaded Not tainted
>> 6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased)
>> 0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
>>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>>> RIP: 0010:memset_orig+0x33/0xb0
>>> Code: 01 01 01 01 01 01 01 01 48 0f af c1 41 89 f9 41 83 e1 07 75 74
>> 48 89 d1 48 c1 e9 06 74 39 66 0f 1f 84 00 00 00 00 00 48 ff c9 <48> 89
>> 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
>>> RSP: 0018:ffffbd1fc0487d08 EFLAGS: 00010216
>>> RAX: 0000000000000000 RBX: ffff9fdb1b619138 RCX: 000000000000003f
>>> RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff9fdb39f19000
>>> RBP: ffff9fdb0054f000 R08: ffff9fdb0565cb00 R09: 0000000000000000
>>> R10: ffff9fdb39f19000 R11: ffff9fdb442d71c0 R12: 0000000001000000
>>> R13: ffff9fdb05079800 R14: ffff9fdb01658870 R15: ffff9fdb01658870
>>> FS:  0000000000000000(0000) GS:ffff9fdb40d00000(0000)
>> knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00005635dbce3fb8 CR3: 0000000103d54000 CR4: 00000000000006e0
>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>> Call Trace:
>>>  <TASK>
>>>  jbd2_journal_get_descriptor_buffer+0x88/0xf0 [jbd2
>> 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>>>  jbd2_journal_commit_transaction+0x9e0/0x18b0 [jbd2
>> 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>>>  kjournald2+0xa9/0x260 [jbd2 3adb6041f8aa59fe471169b0e9945d8c67491cc7]
>>>  kthread+0xda/0x100
>>>  ret_from_fork+0x22/0x30
>>>  </TASK>
>> 
>> 
>> ========================================
>> 
>> 
>>> watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [kworker/2:2:134]
>>> Modules linked in: af_packet rfkill ...
>>> Supported: No, Unreleased kernel
>>> CPU: 2 PID: 134 Comm: kworker/2:2 Not tainted
>> 5.14.21-150500.86.gca1fbb8-default #1 SLE15-SP5 (unreleased)
>> f54a3c78ee6447e20bc183538de8800cbe783c87
>>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>>> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper]
>>> RIP: 0010:smp_call_function_many_cond+0x123/0x560
>>> Code: ef e8 71 22 42 00 3b 05 2f 2c bd 01 89 c5 73 24 48 63 c5 49 8b
>> 7d 00 48 03 3c c5 a0 bb 42 b1 66 90 8b 47 08 a8 01 74 0a f3 90 <8b> 57
>> 08 83 e2 01 75 f6 eb c7 48 83 c4 48 5b 5d 41 5c 41 5d 41 5e
>>> RSP: 0018:ffff9eff00227c68 EFLAGS: 00000202
>>> RAX: 0000000000000011 RBX: 0000000000000001 RCX: 0000000000000000
>>> RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff89a1c0dba8c0
>>> RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
>>> R10: 0000000000000003 R11: 0000000000000000 R12: ffff89a1c0d34b00
>>> R13: ffff89a1c0d34b00 R14: 0000000000000000 R15: 0000000000000003
>>> FS:  0000000000000000(0000) GS:ffff89a1c0d00000(0000)
>> knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 0000561f1be53000 CR3: 00000001024e6000 CR4: 00000000000006e0
>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>> Call Trace:
>>>  <TASK>
>>>  on_each_cpu_cond_mask+0x25/0x40
>>>  __purge_vmap_area_lazy+0xba/0x6d0
>>>  free_vmap_area_noflush+0x214/0x2f0
>>>  remove_vm_area+0x80/0x90
>>>  __vunmap+0x5e/0x260
>>>  drm_gem_shmem_vunmap+0x6f/0x90 [drm_shmem_helper
>> b732157accb2fabb75791e2dc3d5d21a30cf33cb]
>>>  drm_gem_vunmap+0x24/0x50 [drm 14b5c4e21fb011b0159efe14dd82da3407d64716]
>>>  drm_fb_helper_damage_work+0x16f/0x2f0 [drm_kms_helper
>> b697aeb79f8910d3e952c8c60069f3e3382437ae]
>>>  process_one_work+0x267/0x440
>>>  worker_thread+0x2d/0x3d0
>>>  kthread+0x156/0x180
>>>  ret_from_fork+0x22/0x30
>>>  </TASK>
>> 
>> 
>> ========================================
>> 
>> 
>>> watchdog: BUG: soft lockup - CPU#0 stuck for 319s! [watchdogd:57]
>>> watchdog: BUG: soft lockup - CPU#3 stuck for 348s! [repo2solv:1139]
>>> Modules linked in: af_packet rfkill nls_iso8859_1 nls_cp437
>> snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg
>> snd_intel_sdw_acpi snd_hda_codec snd_hda_core snd_hwdep vfat snd_pcm fat
>> iTCO_wdt snd_timer ppdev virtio_net intel_pmc_bxt tiny_power_button
>> i2c_i801 iTCO_vend>
>>> CPU: 3 PID: 1139 Comm: repo2solv Kdump: loaded Not tainted
>> 6.1.4-rc1-1.gbc1c341-default #1 openSUSE Tumbleweed (unreleased)
>> 0c91ab593caf7d5045d7e3b6ff751ade7e57ec84
>>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>>> RIP: 0010:clear_page_orig+0x12/0x40
>>> Code: 5d c3 cc cc cc cc cc cc b9 00 02 00 00 31 c0 f3 48 ab c3 cc cc
>> cc cc 90 31 c0 b9 40 00 00 00 66 0f 1f 84 00 00 00 00 00 ff c9 <48> 89
>> 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
>>> RSP: 0000:ffffb644c0da3be8 EFLAGS: 00010216
>>> RAX: 0000000000000000 RBX: fffffccec4828000 RCX: 000000000000003f
>>> RDX: fffffccec4828000 RSI: fffffccec4828040 RDI: ffffa04a20a00000
>>> RBP: 0000000000000000 R08: ffffb644c0da3d10 R09: 0000000000028b29
>>> R10: 0000000000000010 R11: ffffa04a441d51c0 R12: 0000000000140dca
>>> R13: 0000000000000040 R14: 0000000000000001 R15: 0000000000000286
>>> FS:  00007f91de710f80(0000) GS:ffffa04a40d80000(0000)
>> knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00007f91de3d3000 CR3: 0000000101f86000 CR4: 00000000000006e0
>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>> Call Trace:
>>>  <TASK>
>>>  post_alloc_hook+0xa9/0xe0
>>>  get_page_from_freelist+0x4d9/0x1590
>>>  __alloc_pages+0xec/0x240
>>>  __folio_alloc+0x17/0x50
>>>  vma_alloc_folio+0x9c/0x370
>>>  __handle_mm_fault+0x942/0xfe0
>>>  handle_mm_fault+0xdb/0x2d0
>>>  do_user_addr_fault+0x1ba/0x690
>>>  exc_page_fault+0x66/0x150
>>>  asm_exc_page_fault+0x22/0x30
>> 
>> thanks,
>