linux-kernel - Fwd: Memleaks in offset

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Message-ID: <429b452c-2211-436a-9af7-21332f68db7d@gmail.com>
Date:   Tue, 24 Oct 2023 14:55:27 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Linux Filesystem Development <linux-fsdevel@...r.kernel.org>,
        Linux Regressions <regressions@...ts.linux.dev>
Cc:     Chuck Lever <chuck.lever@...cle.com>,
        Christian Brauner <brauner@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>, vladbu@...dia.com
Subject: Fwd: Memleaks in offset_ctx->xa (shmem)

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

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