答复: INFO: [BISECTED] Regression: A Problem with /sys/kernel/debug/kmemleak output: backtrace not printed since 6.2.0-rc1

黄朝阳 (Zhaoyang Huang)
2023-01-13T01:47:16Z

>On 12. 01. 2023. 20:50, Mirsad Todorovac wrote:
>> Hi all,
>>
>> there seems to be a problem with the output of
>/sys/kernel/debug/kmemleak:
>>
>> [root@pc-mtodorov ~]# cat /sys/kernel/debug/kmemleak unreferenced
>> object 0xffff951c118568b0 (size 16):
>> comm "kworker/u12:2", pid 56, jiffies 4294893952 (age 4356.548s)
>> hex dump (first 16 bytes):
>> 6d 65 6d 73 74 69 63 6b 30 00 00 00 00 00 00 00 memstick0.......
>> backtrace:
>> [root@pc-mtodorov ~]#
>>
>> Apparently, backtrace of called functions on the stack is no longer printed
>with the list of memory leaks.
>>
>> This appeared on Lenovo desktop 10TX000VCR, with AlmaLinux 8.7 and
>> BIOS version M22KT49A (11/10/2022) and 6.2-rc1 and 6.2-rc2 builds.
>>
>> This worked on 6.1 with the same CONFIG_KMEMLEAK=y and MGLRU
>enabled
>> on a vanilla mainstream kernel from Mr. Torvalds' tree. I don't know if this is
>deliberate feature for some reason or a bug.
>>
>> Please find attached the config, lshw and kmemleak output.
>>
>> The bisection gave this commit as the culprit for the severed stack
>> backtrace print in /sys/kernel/debug/kmemleak:
>>
>> mtodorov@domac:~/linux/kernel/linux_torvalds$ git bisect good
>> 56a61617dd2276cbc56a6c868599716386d70041 is the first bad commit
>> commit 56a61617dd2276cbc56a6c868599716386d70041
>> Author: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
>> Date: Thu Oct 27 17:50:24 2022 +0800
>>
>> mm: use stack_depot for recording kmemleak's backtrace
>>
>> Using stack_depot to record kmemleak's backtrace which has been
>> implemented on slub for reducing redundant information.
>>
>> The complete bisect log is:
>>
>> mtodorov@domac:~/linux/kernel/linux_torvalds$ git bisect log git
>> bisect start '--' 'mm'
>> # good: [830b3c68c1fb1e9176028d02ef86f3cf76aa2476] Linux 6.1 git
>> bisect good 830b3c68c1fb1e9176028d02ef86f3cf76aa2476
>> # bad: [1b929c02afd37871d5afb9d498426f83432e71c2] Linux 6.2-rc1 git
>> bisect bad 1b929c02afd37871d5afb9d498426f83432e71c2
>> # good: [8b9ed79c2d587bec5f603d66801478a5af9af842] Merge tag
>> 'x86_asm_for_v6.2' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
>> git bisect good 8b9ed79c2d587bec5f603d66801478a5af9af842
>> # good: [e83b39d6bbdb6d25bd6f5c258832774635d29b47] mm: make
>> drop_caches keep reclaiming on all nodes git bisect good
>> e83b39d6bbdb6d25bd6f5c258832774635d29b47
>> # good: [9997bc017549acd6425e32300eff28424ffeeb6b] zsmalloc:
>implement
>> writeback mechanism for zsmalloc git bisect good
>> 9997bc017549acd6425e32300eff28424ffeeb6b
>> # good: [6287b7dae80944bfa37784a8f9d6861a4facaa6e] mm,thp,rmap: fix
>> races between updates of subpages_mapcount git bisect good
>> 6287b7dae80944bfa37784a8f9d6861a4facaa6e
>> # good: [8fa590bf344816c925810331eea8387627bbeb40] Merge tag
>> 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
>> git bisect good 8fa590bf344816c925810331eea8387627bbeb40
>> # good: [4f292c4de4f6fb83776c0ff22674121eb6ddfa2f] Merge tag
>> 'x86_mm_for_6.2_v2' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
>> git bisect good 4f292c4de4f6fb83776c0ff22674121eb6ddfa2f
>> # bad: [1ea9d333ba475041efe43d9d9bc32e64aea2ea2b] Merge tag
>> 'mm-stable-2022-12-17-2' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
>> git bisect bad 1ea9d333ba475041efe43d9d9bc32e64aea2ea2b
>> # bad: [56a61617dd2276cbc56a6c868599716386d70041] mm: use
>stack_depot
>> for recording kmemleak's backtrace git bisect bad
>> 56a61617dd2276cbc56a6c868599716386d70041
>> # good: [61b963b52f59524e27692bc1c14bfb2459e32eb3] mm/gup_test:
>free
>> memory allocated via kvcalloc() using kvfree() git bisect good
>> 61b963b52f59524e27692bc1c14bfb2459e32eb3
>> # first bad commit: [56a61617dd2276cbc56a6c868599716386d70041] mm:
>use
>> stack_depot for recording kmemleak's backtrace # good:
>> [9102b78b6f6ae6af3557114c265c266b312c1319] maple_tree: update
>> copyright dates for test code git bisect good
>> 9102b78b6f6ae6af3557114c265c266b312c1319
>> # first bad commit: [56a61617dd2276cbc56a6c868599716386d70041] mm:
>use
>> stack_depot for recording kmemleak's backtrace You have mail in
>> /var/mail/mtodorov mtodorov@domac:~/linux/kernel/linux_torvalds$
>>
>> The platform is 10TX000VCR
>(LENOVO_MT_10TX_BU_Lenovo_FM_V530S-07ICB)
>> running AlmaLinux 8.7 (CentOS clone) and BIOS M22KT49A.
>>
>> GCC used was:
>>
>> mtodorov@domac:~/linux/kernel/linux_torvalds$ gcc --version gcc
>> (Debian 8.3.0-6) 8.3.0 Copyright (C) 2018 Free Software Foundation,
>> Inc.
>> This is free software; see the source for copying conditions. There
>> is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
>PARTICULAR PURPOSE.
>> mtodorov@domac:~/linux/kernel/linux_torvalds$
>>
>> Hope this helps.
>>
>> I lack the insight to pinpoint the exact fault in the patch.
>
>P.S.
>
>To further complicate things, on Ubuntu 22.10 Lenovo Ideapad 3 15ITL6 laptop
>the kmemleak stack backtrace is printed correctly with the same kernels
>(but .deb instead of .rpm for the same build):
>
>unreferenced object 0xffff94ca88e042d0 (size 80):
> comm "thermald", pid 768, jiffies 4294893592 (age 78581.504s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 0d 01 2d 00 00 00 00 00 ..........-.....
> af 07 01 80 fd ac ff ff 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<ffffffffa0dcb921>] slab_post_alloc_hook+0x91/0x320
> [<ffffffffa0dcfb79>] kmem_cache_alloc+0x169/0x2f0
> [<ffffffffa12b1def>] acpi_os_acquire_object+0x2c/0x32
> [<ffffffffa12b1ea2>] acpi_ps_alloc_op+0x4a/0x99
> [<ffffffffa12af5c8>] acpi_ps_get_next_arg+0x611/0x761
> [<ffffffffa12afbbc>] acpi_ps_parse_loop+0x494/0x8d7
> [<ffffffffa12b1434>] acpi_ps_parse_aml+0x1bb/0x561
> [<ffffffffa12b24c8>] acpi_ps_execute_method+0x20f/0x2d5
> [<ffffffffa12a7acf>] acpi_ns_evaluate+0x34d/0x4f3
> [<ffffffffa12ad6a3>] acpi_evaluate_object+0x180/0x3ae
> [<ffffffffa1269ca8>] acpi_run_osc+0x128/0x250
> [<ffffffffc0bbb14f>] int3400_thermal_run_osc+0x6f/0xc0
>[int3400_thermal]
> [<ffffffffc0bbb293>] current_uuid_store+0xe3/0x120 [int3400_thermal]
> [<ffffffffa13b8ed4>] dev_attr_store+0x14/0x30
> [<ffffffffa0ee0458>] sysfs_kf_write+0x38/0x50
> [<ffffffffa0edf516>] kernfs_fop_write_iter+0x146/0x1d0 You have new
>mail in /var/mail/root root@marvin-IdeaPad-3-15ITL6:/home/marvin#
>
>Regards,
>Mirsad

thanks for head up. Could you please help to check If CONFIG_STACKTRACE and CONFIG_STACKDEPOT is enabled on the fault kernel?
>
>--
>Mirsad Goran Todorovac
>Sistem inženjer
>Grafički fakultet | Akademija likovnih umjetnosti Sveučilište u Zagrebu
>
>System engineer
>Faculty of Graphic Arts | Academy of Fine Arts University of Zagreb, Republic of
>Croatia The European Union