Linux: Fix broken mount enumeration on 6.13+

[Abyss-W4tcher]

Mount enumeration is currently broken on 6.13+ kernels. This is because "rb_node" entries are cast to "mount" entries using "mount.mnt_list" member instead of "mount.mnt_node".

The kernel's node_to_mount method uses "mnt_node":

• https://elixir.bootlin.com/linux/v6.9.12/source/fs/namespace.c#L1011

Enumeration did not break on samples ranging from 6.8 to 6.13 because "mnt_node" and "mnt_list" were under a common anonymous struct (at the same struct offset then), but a recent commit moved the "mnt_list" member out of it:

• torvalds/linux@344bac8#diff-2c08c5f537fd972c88159feea1a9cd61e283d628ae62914b1b6ee524204bef27L54

[ikelos]

Ok, one for the linux team to check and let me know if it's issue free to merge please @atcuno ... 5:)

[the-rectifier]

Hey all, just my two cents here.
I have been working with a Debian 6.12 sample where pagecache.Files was crashing the framework. So I checked linux.mountinfo and was empty as well. Applying this PR fixed both issues. So I guess some 6.12 kernels are affected as well

Linux version 6.12.48+deb13-amd64 ([email protected]) (x86_64-linux-gnu-gcc-14 (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44) # SMP PREEMPT_DYNAMIC Debian 6.12.48-1 (2025-09-20)

[Abyss-W4tcher]

Hey all, just my two cents here.
I have been working with a Debian 6.12 sample where pagecache.Files was crashing the framework. So I checked linux.mountinfo and was empty as well. Applying this PR fixed both issues. So I guess some 6.12 kernels are affected as well

Linux version 6.12.48+deb13-amd64 ([email protected]) (x86_64-linux-gnu-gcc-14 (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44) # SMP PREEMPT_DYNAMIC Debian 6.12.48-1 (2025-09-20)

I'm glad that it fixed the issue! Those changes can be backported to older kernel versions so that's not surprising 👍.