Re: Abnormal values show up in /proc/allocinfo

[David Wang]

Hi, 

Some update

I reproduce the abnormal values of "func:compaction_alloc" today, just once. But I have not found a deterministic procedure yet.
Seems to me, it happens when kcompactd starts to work

    ret_from_fork(100.000% 57/57)
        kthread(100.000% 57/57)
            kcompactd(100.000% 57/57)
                compact_node(100.000% 57/57)
                    compact_zone(100.000% 57/57)
                        migrate_pages(100.000% 57/57)
                            migrate_pages_batch(100.000% 57/57)
                                compaction_alloc(100.000% 57/57)


Maybe, kcompactd mess up information needed by memory tracking? Just a wild guess.
And those negative signed values, and underflowed unsigned values could also be the side-effect of memory compaction.
A wilder guess....



FYI
David




At 2024-11-25 08:35:54, "Suren Baghdasaryan" <surenb@xxxxxxxxxx> wrote:
>On Sat, Nov 23, 2024 at 11:43 PM David Wang <00107082@xxxxxxx> wrote:
>>
>> Hi,
>>
>> I am running 6.12.0 for a week, and today I notice several strange
>> items in /proc/allocinfo:
>>
>>        -4096 18446744073709551615 mm/filemap.c:3787 func:do_read_cache_folio
>>  -1946730496 18446744073709076340 mm/filemap.c:1952 func:__filemap_get_folio
>>   -903294976 18446744073709331085 mm/readahead.c:263 func:page_cache_ra_unbounded
>>   -353054720 18446744073709465421 mm/shmem.c:1769 func:shmem_alloc_folio
>>  10547565210        0 mm/compaction.c:1880 func:compaction_alloc
>>   -156487680 18446744073709513411 mm/memory.c:1064 func:folio_prealloc
>>  -2422685696 18446744073708960140 mm/memory.c:1062 func:folio_prealloc
>>  -2332479488 18446744073708982163 fs/btrfs/extent_io.c:635 [btrfs] func:btrfs_alloc_page_array
>>
>> some values are way too large, seems like corrupted/uninitialized, and values for compaction_alloc
>> are inconsistent: non-zero size with zero count.
>>
>> I do not know when those data became this strange, and I have not reboot my system yet.
>> Do you guys need extra information before I reboot my system and started to try reproducing?
>
>Hi David,
>Thanks for reporting. Can you share your .config file? Also, do you
>see these abnormal values shortly after boot or does it take time for
>them to get into abnormal state?
>I'll take a look on Monday and see if there is an obvious issue and if
>I can reproduce this.
>Thanks,
>Suren.
>
>>
>>
>> Thanks
>> David
>>
>>
>>
>>