[Bug 222094] New: sched_setattr: bug in `ERRORS` section w.r.t. `attr.sched_flags contains a flag other than SCHED_FLAG_RESET_ON_FORK`

[Bug 222094] New: sched_setattr: bug in `ERRORS` section w.r.t. `attr.sched_flags contains a flag other than SCHED_FLAG_RESET_ON_FORK`

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222094

            Bug ID: 222094
           Summary: sched_setattr: bug in `ERRORS` section w.r.t.
                    `attr.sched_flags contains a flag other than
                    SCHED_FLAG_RESET_ON_FORK`
           Product: Documentation
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: man-pages
          Assignee: documentation_man-pages@kernel-bugs.osdl.org
          Reporter: yaneurabeya@gmail.com
        Regression: No

Per https://www.man7.org/linux/man-pages/man2/sched_getattr.2.html:

This scenario documented in the manpage implies that `attr.sched_flags` must be
set to `SCHED_FLAG_RESET_ON_FORK`:

>       EINVAL attr.sched_flags contains a flag other than
>       SCHED_FLAG_RESET_ON_FORK.

The second scenario implies that `attr.sched_flags` is a bitmask which can
contain `SCHED_FLAG_UTIL_CLAMP_MIN` or `SCHED_FLAG_UTIL_CLAMP_MAX`:

>       EINVAL attr.sched_flags contains SCHED_FLAG_UTIL_CLAMP_MIN or
>       SCHED_FLAG_UTIL_CLAMP_MAX, and attr.sched_util_min or
>       attr.sched_util_max are out of bounds.

The first case contradicts the second case.

Doing some digging in the kernel source code [1], I couldn't find an obvious
spot where the first scenario was actually implemented -> **I think the
`SCHED_FLAG_RESET_ON_FORK ` scenario is a documentation bug.**

1.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/sched/syscalls.c?id=786244f70322e41c937e69f0f935bfd11a9611bf

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[Bug 222094] sched_setattr: bug in `ERRORS` section w.r.t. `attr.sched_flags contains a flag other than SCHED_FLAG_RESET_ON_FORK`

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222094

--- Comment #1 from Alejandro Colomar (alx@kernel.org) ---
Hello,

> Date: 2026-10-05 15:31:25+0000
> From: bugzilla-daemon@kernel.org
>
> https://bugzilla.kernel.org/show_bug.cgi?id=222094
> 
[...]
> 
> Per https://www.man7.org/linux/man-pages/man2/sched_getattr.2.html:
> 
> This scenario documented in the manpage implies that `attr.sched_flags` must
> be
> set to `SCHED_FLAG_RESET_ON_FORK`:
> 
> >       EINVAL attr.sched_flags contains a flag other than
> >       SCHED_FLAG_RESET_ON_FORK.
> 
> The second scenario implies that `attr.sched_flags` is a bitmask which can
> contain `SCHED_FLAG_UTIL_CLAMP_MIN` or `SCHED_FLAG_UTIL_CLAMP_MAX`:
> 
> >       EINVAL attr.sched_flags contains SCHED_FLAG_UTIL_CLAMP_MIN or
> >       SCHED_FLAG_UTIL_CLAMP_MAX, and attr.sched_util_min or
> >       attr.sched_util_max are out of bounds.
> 
> The first case contradicts the second case.
> 
> Doing some digging in the kernel source code [1], I couldn't find an obvious
> spot where the first scenario was actually implemented -> **I think the
> `SCHED_FLAG_RESET_ON_FORK ` scenario is a documentation bug.**
> 
> 1.
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/sched/syscalls.c?id=786244f70322e41c937e69f0f935bfd11a9611bf

Would you want to send a patch?  If so, please have a look at
<https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTIN>.


Have a lovely day!
Alex

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[Bug 222094] sched_setattr: bug in `ERRORS` section w.r.t. `attr.sched_flags contains a flag other than SCHED_FLAG_RESET_ON_FORK`

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222094

--- Comment #2 from Enji Cooper (yaneurabeya@gmail.com) ---
Created attachment 311258
  --> https://bugzilla.kernel.org/attachment.cgi?id=311258&action=edit
Patch

I've honestly never submitted a patch to the Linux mailing lists. There are a
lot of hoops to jump through in order to make a contribution... I'll try, but
please bear with me (I'll probably get something wrong).

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[Bug 222094] sched_setattr: bug in `ERRORS` section w.r.t. `attr.sched_flags contains a flag other than SCHED_FLAG_RESET_ON_FORK`

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222094

--- Comment #3 from Alejandro Colomar (alx@kernel.org) ---
Hi,

> Date: 2026-10-23 18:47:22+0000
> From: bugzilla-daemon@kernel.org
>
> https://bugzilla.kernel.org/show_bug.cgi?id=222094
> 
> --- Comment #2 from Enji Cooper (yaneurabeya@gmail.com) ---
> Created attachment 311258
>   --> https://bugzilla.kernel.org/attachment.cgi?id=311258&action=edit
> Patch
> 
> I've honestly never submitted a patch to the Linux mailing lists. There are a
> lot of hoops to jump through in order to make a contribution... I'll try, but
> please bear with me (I'll probably get something wrong).

Sure!  You're welcome to try.  :-)

I've forwarded your patch to the mailing list in this email.


Have a lovely night!
Alex

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[Bug 222094] sched_setattr: bug in `ERRORS` section w.r.t. `attr.sched_flags contains a flag other than SCHED_FLAG_RESET_ON_FORK`

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222094

--- Comment #4 from Alejandro Colomar (alx@kernel.org) ---
Created attachment 311260
  --> https://bugzilla.kernel.org/attachment.cgi?id=311260&action=edit
signature.asc

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Re: [Bug 222094] sched_setattr: bug in `ERRORS` section w.r.t. `attr.sched_flags contains a flag other than SCHED_FLAG_RESET_ON_FORK`

[Alejandro Colomar]

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[moving discussion to the mailing list]

Hi Enji,

> Date: 2026-10-23 21:27:52+0200
> From: Alejandro Colomar <alx@kernel.org>
>
> Hi,
> 
> > Date: 2026-10-23 18:47:22+0000
> > From: bugzilla-daemon@kernel.org
> >
> > https://bugzilla.kernel.org/show_bug.cgi?id=222094
> > 
> > --- Comment #2 from Enji Cooper (yaneurabeya@gmail.com) ---
> > Created attachment 311258
> >   --> https://bugzilla.kernel.org/attachment.cgi?id=311258&action=edit
> > Patch
> > 
> > I've honestly never submitted a patch to the Linux mailing lists. There are a
> > lot of hoops to jump through in order to make a contribution... I'll try, but
> > please bear with me (I'll probably get something wrong).
> 
> Sure!  You're welcome to try.  :-)
> 
> I've forwarded your patch to the mailing list in this email.
> 
> 
> Have a lovely night!
> Alex
> 
> -- 
> <https://www.alejandro-colomar.es>

> From cfaef3da82a115fbce47dec58b458c6cfc439667 Mon Sep 17 00:00:00 2001
> Message-ID: <cfaef3da82a115fbce47dec58b458c6cfc439667.1792780609.git.yaneurabeya@gmail.com>
> From: Enji Cooper <yaneurabeya@gmail.com>
> Date: Fri, 23 Oct 2026 10:39:20 -0700
> Subject: [PATCH] man/man2/sched_setattr.2: update `EINVAL` case with
>  `.sched_flags`
> To: Alejandro Colomar <alx+linux-man@kernel.org>
> Cc: <linux-man@vger.kernel.org>
> 
> In more recent versions of the kernel, `.sched_flags` is a treated as a
> bitmask that supports values like `SCHED_FLAG_UTIL_CLAMP_MIN`, etc.
> 
> Account for the additional flags so the documentation is up to date with
> the kernel implementation of `sched_setattr`.
> 
> Ref: linux.git 480a6ca2dc6e ("sched/uclamp: Allow to reset a task uclamp constraint value")
> 
> Signed-off-by: Enji Cooper <yaneurabeya@gmail.com>
> ---
>  man/man2/sched_setattr.2 | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/man/man2/sched_setattr.2 b/man/man2/sched_setattr.2
> index 80a0ac726dcf..b163ba482390 100644
> --- a/man/man2/sched_setattr.2
> +++ b/man/man2/sched_setattr.2
> @@ -411,13 +411,16 @@ .SH ERRORS
>  .BR sched (7).
>  .TP
>  .B EINVAL
> -.I attr.sched_policy
> -is not one of the recognized policies.
> -.TP
> -.B EINVAL
>  .I attr.sched_flags
>  contains a flag other than
> -.BR SCHED_FLAG_RESET_ON_FORK .
> +.BR SCHED_FLAG_RESET_ON_FORK ,
> +.BR SCHED_FLAG_UTIL_CLAMP_MIN ,
> +or
> +.BR SCHED_FLAG_UTIL_CLAMP_MAX .
> +.TP
> +.B EINVAL
> +.I attr.sched_policy
> +is not one of the recognized policies.

I wonder why you moved this paragraph.  It doesn't seem to be necessary,
right?


Cheers,
Alex

>  .TP
>  .B EINVAL
>  .I attr.sched_priority
> -- 
> 2.50.1 (Apple Git-155)
> 




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