Fwd: Memleaks in offset_ctx->xa (shmem)

Fwd: Memleaks in offset_ctx->xa (shmem)

[Bagas Sanjaya]

Hi,

I notice a regression report on Bugzilla [1]. Quoting from it:

> We have been getting memleaks in offset_ctx->xa in our networking tests:
> 
> unreferenced object 0xffff8881004cd080 (size 576):
>   comm "systemd", pid 1, jiffies 4294893373 (age 1992.864s)
>   hex dump (first 32 bytes):
>     00 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>     38 5c 7c 02 81 88 ff ff 98 d0 4c 00 81 88 ff ff  8\|.......L.....
>   backtrace:
>     [<000000000f554608>] xas_alloc+0x306/0x430
>     [<0000000075537d52>] xas_create+0x4b4/0xc80
>     [<00000000a927aab2>] xas_store+0x73/0x1680
>     [<0000000020a61203>] __xa_alloc+0x1d8/0x2d0
>     [<00000000ae300af2>] __xa_alloc_cyclic+0xf1/0x310
>     [<000000001032332c>] simple_offset_add+0xd8/0x170
>     [<0000000073229fad>] shmem_mknod+0xbf/0x180
>     [<00000000242520ce>] vfs_mknod+0x3b0/0x5c0
>     [<000000001ef218dd>] unix_bind+0x2c2/0xdb0
>     [<0000000009b9a8dd>] __sys_bind+0x127/0x1e0
>     [<000000003c949fbb>] __x64_sys_bind+0x6e/0xb0
>     [<00000000b8a767c7>] do_syscall_64+0x3d/0x90
>     [<000000006132ae0d>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> Memleak trace points to some syscall performed by systemd and none of our tests do anything more advanced with it than 'systemctl restart ovs-vswitchd'. Basically it is a setup with Fedora and an upstream kernel that executes bunch of network offload tests with Open vSwitch, iproute2 tc, Linux bridge, etc.
> 
> It looks like those may be caused by recent commit 6faddda69f62 ("libfs: Add directory operations for stable offsets") but we don't have a proper reproduction, just sometimes arbitrary getting the memleak complains during/after the regression run.

See Bugzilla for the full thread.

Anyway, I'm adding it to regzbot:

#regzbot introduced: 6faddda69f623d https://bugzilla.kernel.org/show_bug.cgi?id=218039
#regzbot title: stable offsets directory operation support triggers offset_ctx->xa memory leak

Thanks.

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=218039

-- 
An old man doll... just what I always wanted! - Clara

Re: Fwd: Memleaks in offset_ctx->xa (shmem)

[Linux regression tracking (Thorsten Leemhuis)]

On 24.10.23 09:55, Bagas Sanjaya wrote:
> 
> I notice a regression report on Bugzilla [1]. Quoting from it:
> 
>> We have been getting memleaks in offset_ctx->xa in our networking tests:
>>
>> unreferenced object 0xffff8881004cd080 (size 576):
> [...]
> #regzbot introduced: 6faddda69f623d https://bugzilla.kernel.org/show_bug.cgi?id=218039
> #regzbot title: stable offsets directory operation support triggers offset_ctx->xa memory leak

Thx for adding this to regzbot.

Bagas, FWIW, before doing so you in the future might want to search lore
for an abbreviated commit-id with a wildcard (e.g.
https://lore.kernel.org/all/?q=6faddda6* ) and the bugzilla url (e.g.
https://lore.kernel.org/all/?q=https%3A%2F%2Fbugzilla.kernel.org%2Fshow_bug.cgi%3Fid%3D218039).
Because then in this case you would have noticed that this was already
discussed on the lists and Chuck asked to bring it to bugzilla for
further tracking, so forwarding this likely was not worth it:
https://lore.kernel.org/all/87ttqhq0i7.fsf@nvidia.com/

OTOH I wonder if what Chuck asked for was wise: '''Looks like "Memory
Management / Other" is appropriate for shmem, and Hugh or Andrew can
re-assign ownership to me.'''

Not sure if Hugh or Andrew actually do anything like that. I doubt that,
but maybe I'm wrong. Ahh, the joys of our bugzilla instance that many
core developers avoid... (FWIW, I don't blame anyone for that, I
understand why it's like that; but it complicated things...).

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
If I did something stupid, please tell me, as explained on that page.

P.S., FWIW:

#regzbot monitor: https://lore.kernel.org/all/87y1g9xjre.fsf@nvidia.com/

Re: Fwd: Memleaks in offset_ctx->xa (shmem)

[Bagas Sanjaya]

On 24/10/2023 21:18, Linux regression tracking (Thorsten Leemhuis) wrote:
> Bagas, FWIW, before doing so you in the future might want to search lore
> for an abbreviated commit-id with a wildcard (e.g.
> https://lore.kernel.org/all/?q=6faddda6* ) and the bugzilla url (e.g.
> https://lore.kernel.org/all/?q=https%3A%2F%2Fbugzilla.kernel.org%2Fshow_bug.cgi%3Fid%3D218039).
> Because then in this case you would have noticed that this was already
> discussed on the lists and Chuck asked to bring it to bugzilla for
> further tracking, so forwarding this likely was not worth it:
> https://lore.kernel.org/all/87ttqhq0i7.fsf@nvidia.com/
> 

Thanks for the tip reminder! I always forget it then...

-- 
An old man doll... just what I always wanted! - Clara