stm32mp1 rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:

[Ara.1]

Hi All,

with serial ttySTM2 9600 data exchange makes the cpu stall

:modified usart.c driver code to support schedule worker thread

i am getting a cpu0 and cpu 1 stall attached is the log

has any faced this rcp preempt issue

[Ara.1]

on running a load on serial sometime i see a cpu stall, what is the reason,

[ 2031.538785] I ttySTM2 69-0-69

[ 2031.540297] P 6 6

[ 2031.698787] I ttySTM2 69-0-69

[ 2031.700300] P 7 7

[ 2031.858788] I ttySTM2 69-0-69

[ 2031.860300] P 8 8

[ 2032.023702] I ttySTM2 69-0-69

[ 2032.025212] P 9 9

[ 2032.158679] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:

[ 2032.163348] rcu:   Tasks blocked on level-0 rcu_node (CPUs 0-1): P440

[ 2032.169707] rcu:   (detected by 1, t=2103 jiffies, g=334917, q=806593)

[ 2032.176164] apps.plugin   R running task    0  440  435 0x00000000

[ 2032.178779] I ttySTM2 69-0-69

[ 2032.183255] [<c0a28fa4>] (__schedule) from [<c0a29974>] (preempt_schedule_com                                            mon+0x20/0x98)

[ 2032.186186] P 10 10

[ 2032.194568] [<c0a29974>] (preempt_schedule_common) from [<c029330c>] (get_mem                                            _cgroup_from_mm.part.1+0x11c/0x120)

[ 2032.194589] [<c029330c>] (get_mem_cgroup_from_mm.part.1) from [<c02989e8>] (m                                            emcg_kmem_get_cache+0x88/0x3a8)

[ 2032.194607] [<c02989e8>] (memcg_kmem_get_cache) from [<c028b6f4>] (kmem_cache                                            _alloc+0x17c/0x280)

[ 2032.194626] [<c028b6f4>] (kmem_cache_alloc) from [<c02c6748>] (seq_open+0x30/                                            0x94)

[ 2032.194647] [<c02c6748>] (seq_open) from [<c02c6c1c>] (single_open+0x68/0x98)

[ 2032.240245] [<c02c6c1c>] (single_open) from [<c029d234>] (do_dentry_open+0x11                                            4/0x3b8)

[ 2032.248088] [<c029d234>] (do_dentry_open) from [<c02b029c>] (path_openat+0x2a                                            c/0x10fc)

[ 2032.256021] [<c02b029c>] (path_openat) from [<c02b2104>] (do_filp_open+0x74/0                                            xe4)

[ 2032.263518] [<c02b2104>] (do_filp_open) from [<c029e90c>] (do_sys_open+0x174/                                            0x1f8)

[ 2032.271192] [<c029e90c>] (do_sys_open) from [<c0101000>] (ret_fast_syscall+0x                                            0/0x54)

[ 2032.278941] Exception stack(0xebcb7fa8 to 0xebcb7ff0)

[ 2032.284004] 7fa0:          000a9b28 00089038 ffffff9c 00089038 00000                                            000 00000000

[ 2032.292200] 7fc0: 000a9b28 00089038 00000000 00000142 00068000 00000000 00000                                            062 00033428

[ 2032.300391] 7fe0: 00000142 be8b66d0 b6f35625 b6f37006

[ 2032.305448] apps.plugin   R running task    0  440  435 0x00000000

[ 2032.312525] [<c0a28fa4>] (__schedule) from [<c0a29974>] (preempt_schedule_com                                            mon+0x20/0x98)

[ 2032.320890] [<c0a29974>] (preempt_schedule_common) from [<c029330c>] (get_mem                                            _cgroup_from_mm.part.1+0x11c/0x120)

[ 2032.331085] [<c029330c>] (get_mem_cgroup_from_mm.part.1) from [<c02989e8>] (m                                            emcg_kmem_get_cache+0x88/0x3a8)

[ 2032.340931] [<c02989e8>] (memcg_kmem_get_cache) from [<c028b6f4>] (kmem_cache                                            _alloc+0x17c/0x280)

[ 2032.349738] [<c028b6f4>] (kmem_cache_alloc) from [<c02c6748>] (seq_open+0x30/                                            0x94)

[ 2032.357321] [<c02c6748>] (seq_open) from [<c02c6c1c>] (single_open+0x68/0x98)

[ 2032.364467] [<c02c6c1c>] (single_open) from [<c029d234>] (do_dentry_open+0x11                                            4/0x3b8)

[ 2032.372311] [<c029d234>] (do_dentry_open) from [<c02b029c>] (path_openat+0x2a                                            c/0x10fc)

[ 2032.380242] [<c02b029c>] (path_openat) from [<c02b2104>] (do_filp_open+0x74/0                                            xe4)

[ 2032.387740] [<c02b2104>] (do_filp_open) from [<c029e90c>] (do_sys_open+0x174/                                            0x1f8)

[ 2032.395411] [<c029e90c>] (do_sys_open) from [<c0101000>] (ret_fast_syscall+0x                                            0/0x54)