do_page_fault() in log reading process

[namiltd]

Sometimes logread hangs with log:

[23635.194051] do_page_fault(): sending SIGSEGV to logread for invalid write access to 00000000
[23635.202775] epc = 77e332c8 in libc.so[77da1000+b2000]
[23635.207966] ra  = 00401743 in logread-ubox[400000+3000]

Logread is run in cron every minute, the problem occurs several times a day.
Unfortunately I can't figure out the cause.

Tested on ramips/mt7620 TP-Link EC220-G5 v2

[namiltd]

On kernel 6.12 this causes a crash:

[  335.462668] CPU 0 Unable to handle kernel paging request at virtual address 702e1c60, epc == 702e1c60, ra == 80001db0
[  335.473640] Oops[#1]:
[  335.475973] CPU: 0 UID: 0 PID: 3559 Comm: logread Tainted: G           O       6.12.45 #0
[  335.484331] Tainted: [O]=OOT_MODULE
[  335.487887] Hardware name: TP-Link EC220-G5 v2
[  335.492685] $ 0   : 00000000 00000001 81b570e0 809a3cdc
[  335.498048] $ 4   : 00000cc0 00000001 00019e63 82b39300
[  335.503406] $ 8   : 00019e64 00000cc0 00000000 ffffffff
[  335.508763] $12   : 82bb9fa8 00000000 00000000 7ffcdfff
[  335.514121] $16   : 0000001b 77ec9000 77ee0000 68c6a69e
[  335.519479] $20   : 8383fbf8 00000000 55650000 77ee0000
[  335.524838] $24   : 00000003 807a0ea0                  
[  335.530194] $28   : 82e30000 82e31f28 00000000 80001db0
[  335.535553] Hi    : 00009700
[  335.538489] Lo    : 0000a69e
[  335.541426] epc   : 702e1c60 0x702e1c60
[  335.545349] ra    : 80001db0 work_notifysig+0x10/0x18
[  335.550519] Status: 1100f403	KERNEL EXL IE 
[  335.554804] Cause : 50800008 (ExcCode 02)
[  335.558895] BadVA : 702e1c60
[  335.561832] PrId  : 00019650 (MIPS 24KEc)
[  335.565922] Modules linked in: rt2800soc(O) rt2800mmio(O) rt2800lib(O) pppoe ppp_async nft_fib_inet nf_flow_table_inet rt2x00soc(O) rt2x00mmio(O) rt2x00lib(O) pppox ppp_generic nft_reject_ipv6 nft_reject_ipv4 nft_reject_inet nft_reject nft_redir nft_quota nft_numgen nft_nat nft_masq nft_log nft_limit nft_hash nft_flow_offload nft_fib_ipv6 nft_fib_ipv4 nft_fib nft_ct nft_chain_nat nf_tables nf_nat_tftp nf_nat_snmp_basic nf_nat_sip nf_nat_pptp nf_nat_irc nf_nat_h323 nf_nat_amanda nf_nat nf_flow_table nf_conntrack_tftp nf_conntrack_snmp nf_conntrack_sip nf_conntrack_sane nf_conntrack_pptp nf_conntrack_netbios_ns nf_conntrack_irc nf_conntrack_h323 nf_conntrack_broadcast nf_conntrack_amanda nf_conntrack mt76x2e(O) mt76x2_common(O) mt76x02_lib(O) mt76(O) mac80211(O) cfg80211(O) ts_kmp ts_fsm ts_bm slhc nfnetlink nf_reject_ipv6 nf_reject_ipv4 nf_log_syslog nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c crc_ccitt compat(O) asn1_decoder sit tunnel4 ip_tunnel sha512_generic seqiv sha3_generic jitterentropy_rng drbg hmac geniv rng cmac
[  335.566488]  leds_gpio rtl8367b rtl8366_smi gpio_button_hotplug(O) crc32c_generic
[  335.666103] Process logread (pid: 3559, threadinfo=aaef5cd3, task=99f56f6d, tls=77ee9dfc)
[  335.674461] Stack : 00000000 00000000 00000000 00000000 77ee8290 00420030 7fbdb308 00420030
[  335.683036]         00000000 00000001 00000000 00000048 77ec9000 0000001b 00000000 00000000
[  335.691606]         00000000 00000000 81d823d4 ffffffff 7fbdafe0 00000008 00401bc0 00000000
[  335.700178]         0000001b 77ec9000 77ee0000 68c6a69e 8383fbf8 00000000 55650000 77ee0000
[  335.708752]         00000000 77ea66d0 00000001 00000000 77ee8290 7fbdb070 00000000 77e70674
[  335.717324]         ...
[  335.719827] Call Trace:
[  335.719832] 
[  335.723906] 
[  335.725424] Code: (Bad address in epc)
[  335.725424] 
[  335.730755] 
[  335.732418] ---[ end trace 0000000000000000 ]---
[  335.737145] Kernel panic - not syncing: Fatal exception
[  335.742484] Rebooting in 3 seconds..

I noticed that the problem occurs when, in addition to logread run from cron, I display syslog in LuCI (multiple launches at the same time).

[namiltd]

Ping @guidosarducci