linux-kernel - Re: [PATCH RESEND v2 1/2] ucount: Fix atomic_long_inc

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Message-ID: <CAFULd4bLXhnNzbitQ8mX8-L-3HhW1BAGN0hzCpbAu58cTcRS2w@mail.gmail.com>
Date: Tue, 22 Jul 2025 08:44:29 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, "Eric W. Biederman" <ebiederm@...ssion.com>, 
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>, "Paul E. McKenney" <paulmck@...nel.org>, 
	Alexey Gladkov <legion@...nel.org>, Roman Gushchin <roman.gushchin@...ux.dev>, 
	MengEn Sun <mengensun@...cent.com>, Thomas Weißschuh <linux@...ssschuh.net>
Subject: Re: [PATCH RESEND v2 1/2] ucount: Fix atomic_long_inc_below()
 argument type

On Tue, Jul 22, 2025 at 12:43 AM Andrew Morton
<akpm@...ux-foundation.org> wrote:
>
> On Mon, 21 Jul 2025 19:45:57 +0200 Uros Bizjak <ubizjak@...il.com> wrote:
>
> > The type of u argument of atomic_long_inc_below() should be long
> > to avoid unwanted truncation to int.
> >
> > Fixes: f9c82a4ea89c ("Increase size of ucounts to atomic_long_t")
>
> Please (always!) provide a description of the userspace-visible effects
> of the bug.  That way I (and others) can decide whether the fix should
> be backported.  And people will be able to determine whether this patch
> may fix problems which they are observing.  Thanks.

The patch fixes the wrong argument type of an internal function to
prevent unwanted argument truncation. It fixes an internal locking
primitive; it should not have any direct effect on userspace.

Uros.