From: Michal Hocko <mhocko@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: Qian Cai <cai@lca.pw>, Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm v2] mm/page_isolation: fix potential warning from user
Date: Mon, 20 Jan 2020 16:43:15 +0100 [thread overview]
Message-ID: <20200120154315.GK18451@dhcp22.suse.cz> (raw)
In-Reply-To: <aa5f235e-6449-1531-1355-6974f3d38740@redhat.com>
On Mon 20-01-20 15:13:54, David Hildenbrand wrote:
> On 20.01.20 15:11, Qian Cai wrote:
> >> On Jan 20, 2020, at 9:01 AM, David Hildenbrand <david@redhat.com> wrote:
> >> On 20.01.20 14:56, Qian Cai wrote:
[...]
> >>>> FWIW, I'd prefer this change without any such cleanups (e.g., I don't
> >>>> like returning a bool from this function and the IS_ERR handling, makes
> >>>> the function harder to read than before)
> >>>
> >>> What is Michal or Andrew’s opinion? BTW, a bonus point to return a bool
> >>> is that it helps the code robustness in general, as UBSAN will be able to
> >>> catch any abuse.
> >>>
> >>
> >> A return type of bool on a function that does not test a property
> >> ("has_...", "is"...") is IMHO confusing.
> >
> > That is fine. It could be renamed to set_migratetype_is_isolate() or
> > is_set_migratetype_isolate() which seems pretty minor because we
> > have no consistency in the naming of this in linux kernel at all, i.e.,
> > many existing bool function names without those test of properties.
>
> It does not query a property, so "is_set_migratetype_isolate()" is plain
> wrong.
>
> Anyhow, Michal does not seem to care.
Well, TBH I have missed this change. My bad. I have mostly checked that
the WARN_ONCE is not gated by the check and didn't expect more changes.
But I have likely missed that change in the previous version already.
You guys are too quick with new version to my standard.
Anyway, I do agree that bool is clumsy here. Returning false on success
is just head scratching. Nobody really consumes the errno value but I
would just leave it that way or if there is a strong need to change then
do it in a separate patch.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-01-20 15:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-20 13:19 [PATCH -mm v2] mm/page_isolation: fix potential warning from user Qian Cai
2020-01-20 13:30 ` David Hildenbrand
2020-01-20 13:38 ` Qian Cai
2020-01-20 13:38 ` David Hildenbrand
2020-01-20 13:56 ` Qian Cai
2020-01-20 14:01 ` David Hildenbrand
2020-01-20 14:11 ` Qian Cai
2020-01-20 14:13 ` David Hildenbrand
2020-01-20 15:43 ` Michal Hocko [this message]
2020-01-20 14:07 ` Michal Hocko
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