man/man5/proc_pid.5: Clarify which user namespace affects permissions]

Hi Vivian,

Can you please confirm this is you? I received this patch from an address that doesn't match the one I see in your kernel commits, and when I replied to <[email protected]>, the message bounced. I'm just checking. See patch from the @live.com address below.

Have a lovely night!
Alex

----- Forwarded message from Vivian Wang <[email protected]> -----

Date: Mon, 16 Mar 2026 22:07:52 +0800
From: Vivian Wang <[email protected]>
To: Alejandro Colomar <[email protected]>
Cc: [email protected], Michael Kerrisk <[email protected]>
Subject: [PATCH] man/man5/proc_pid.5: Clarify which user namespace affects
permissions
Message-ID: <OSCPR01MB134682A1A80B8C9FB71CBA64DC640A@OSCPR01MB13468.jpnprd01.prod.outlook.com>
User-Agent: Mozilla Thunderbird

A more careful reading of fs/proc/base.c (since v4.11, as of v7.0-rc1) reveals that it is not task->cred->user_ns that is checked, but task->mm->user_ns, which is set during execve(2) (and copied over in fork(2) and so on) [1], and is the correct user namespace to check for ptrace-related purposes. Clarify the relevant text.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bfedb589252c01fa505ac9f6f2a3d5d68d707ef4

---
 man/man5/proc_pid.5 | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index eac97fa1d..2fe35bd09 100644
@@ -30,7 +30,9 @@ Before Linux 4.11,
 meant the "global" root user ID and group ID
 (i.e., UID 0 and GID 0 in the initial user namespace).
 Since Linux 4.11,
-if the process is in a noninitial user namespace that has a
+if when the last time the process called
+.BR execve (2),
+it was in a noninitial user namespace that has a
 valid mapping for user (group) ID 0 inside the namespace, then
 the user (group) ownership of the files under
 .IR /proc/ pid

2.53.0



----- End forwarded message -----

-- 
<https://www.alejandro-colomar.es>

Hi, Alejandro,

This is me.

Apologies for the confusion. My idea was to use my personal email ([email protected]) for dayjob-related stuff, and employer email (@iscas.ac.cn) for work-related stuff.

I've started signing off as "Vivian Wang <[email protected]>" in OpenSBI first, before being employed at ISCAS (see [1], firstly done in
[2] after someone complained about me just signing off as "dramforever <[email protected]>"). In June 2025 I was hired by ISCAS and started doing primarily kernel work, which was probably where you saw this.

I did not realize that apparently kernel.org mail bounces on my free Outlook email - I wasn't even getting it in my spam box. Unfortunately I don't think I have much control over the behavior of Microsoft's Outlook servers.

Next time I will use a different personal address - with a reply from my apparently more well known @iscas.ac.cn address vouching for its authenticity, to avoid confusion.

[1]: https://lore.kernel.org/opensbi/?q=f%3A%22Vivian+Wang+%3Cdramforever%22
[2]: https://lore.kernel.org/opensbi/TYYP286MB1439C5C64BCF8E9DB7883772C69F9@TYYP286MB1439.JPNP286.PROD.OUTLOOK.COM/

Thank you.

Vivian "dramforever" Wang

Hi Vivian,

Thanks for confirming! :)

No problem; I'm fine with your personal address. (At least, if it didn't bounce; that's a problem.)

So, I was saying I have applied the patch. Thanks! :-)

:)

Cheers,
Alex

<https://www.alejandro-colomar.es>