Date:   Fri, 13 Jan 2023 09:41:05 +0100
From:   Mirsad Goran Todorovac <mirsad.todorovac@....unizg.hr>
To:     黄朝阳 (Zhaoyang Huang) 
        <zhaoyang.huang@...soc.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        王科 (Ke Wang) <Ke.Wang@...soc.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Thorsten Leemhuis <regressions@...mhuis.info>
Subject: Re: 答复: INFO: [BISECTED] Regression: A Problem with /sys/kernel/debug/kmemleak output: backtrace not printed since 6.2.0-rc1

On 13.1.2023. 7:20, 黄朝阳 (Zhaoyang Huang) wrote:
>> /sys/kernel/debug/kmemleak output: backtrace not printed since 6.2.0-rc1
>>
>>
>>> 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@...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@...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@...ac:~/linux/kernel/linux_torvalds$ git bisect good
>>>> 56a61617dd2276cbc56a6c868599716386d70041 is the first bad commit
>>>> commit 56a61617dd2276cbc56a6c868599716386d70041
>>>> Author: Zhaoyang Huang <zhaoyang.huang@...soc.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@...ac:~/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@...ac:~/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@...ac:~/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@...ac:~/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@...vin-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?
> Please try the patch below if the configs are right. I think it should be caused by the late ready for kmemleak
> 
> commit 556eb1927da99ab366e370d593fc32da946768c3
> Author: Zhaoyang Huang <zhaoyang.huang@...soc.com>
> Date:   Fri Jan 13 14:13:39 2023 +0800
> 
>      mm: instroduce a flag to indicate stack_depot's ready
>      
>      try to solve the kmemleak's late ready issue.
> 
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 762b91f..7eb24bc 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -216,6 +216,7 @@ struct kmemleak_object {  static int kmemleak_warning;
>   /* set if a fatal kmemleak error has occurred */  static int kmemleak_error;
> +static int kmemleak_stadep_initialized;
>   
>   /* minimum and maximum address that may be valid pointers */  static unsigned long min_addr = ULONG_MAX; @@ -601,7 +602,7 @@ static noinline depot_stack_handle_t set_track_prepare(void)
>          unsigned long entries[MAX_TRACE];
>          unsigned int nr_entries;
>   
> -       if (!kmemleak_initialized)
> +       if (!kmemleak_stadep_initialized)
>                  return 0;
>          nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
>          trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT); @@ -2110,6 +2111,7 @@ void __init kmemleak_init(void)
>                  create_object((unsigned long)__start_ro_after_init,
>                                __end_ro_after_init - __start_ro_after_init,
>                                KMEMLEAK_GREY, GFP_ATOMIC);
> +       kmemleak_stadep_initialized = 1;
>   }

Hi, Zhaoyang,

Sorry, applied the patch and rebuilt, but it didn't work for me:

[root@...mtodorov marvin]# uname -rms
Linux 6.2.0-rc3-mglru-kmemlk-patch-zhaoyang1+ x86_64
[root@...mtodorov marvin]# cat /sys/kernel/debug/kmemleak
[root@...mtodorov marvin]# echo scan | tee !$
echo scan | tee /sys/kernel/debug/kmemleak
scan
[root@...mtodorov marvin]# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff98938fed1ee0 (size 16):
   comm "kworker/u12:2", pid 57, jiffies 4294894053 (age 66.616s)
   hex dump (first 16 bytes):
     6d 65 6d 73 74 69 63 6b 30 00 00 00 00 00 00 00  memstick0.......
   backtrace:
[root@...mtodorov marvin]#

Still the stack backtrace list is severed.
CONFIG_STACKDEPOT and CONFIG_STACKTRACE are both "=y":

[root@...mtodorov marvin]# grep -E 'CONFIG_(STACKTRACE|STACKDEPOT)' /boot/config-6.2.0-rc3-mglru-kmemlk-patch-zhaoyang1+
CONFIG_STACKTRACE_SUPPORT=y
CONFIG_STACKDEPOT=y
# CONFIG_STACKTRACE_BUILD_ID is not set
CONFIG_STACKTRACE=y
[root@...mtodorov marvin]#

Your patch was successfully applied (after some tweaks):

mtodorov@...ac:~/linux/kernel/linux_torvalds$ git diff mm
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 92f670edbf51..78fd3b89b057 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -216,6 +216,7 @@ static int kmemleak_initialized;
  static int kmemleak_warning;
  /* set if a fatal kmemleak error has occurred */
  static int kmemleak_error;
+static int kmemleak_stadep_initialized;

  /* minimum and maximum address that may be valid pointers */
  static unsigned long min_addr = ULONG_MAX;
@@ -601,7 +602,7 @@ static noinline depot_stack_handle_t set_track_prepare(void)
         unsigned long entries[MAX_TRACE];
         unsigned int nr_entries;

-       if (!kmemleak_initialized)
+       if (!kmemleak_stadep_initialized)
                 return 0;
         nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
         trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
@@ -2110,6 +2111,7 @@ void __init kmemleak_init(void)
                 create_object((unsigned long)__start_ro_after_init,
                               __end_ro_after_init - __start_ro_after_init,
                               KMEMLEAK_GREY, GFP_ATOMIC);
+       kmemleak_stadep_initialized = 1;
  }

  /*
mtodorov@...ac:~/linux/kernel/linux_torvalds$

Please verify that the above is correct.

Regards,
Mirsad

-- 
Mirsad Todorovac
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb
Republic of Croatia, the European Union
--
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu

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