From: David Hildenbrand <david@redhat.com>
To: Max Kellermann <max.kellermann@ionos.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
lorenzo.stoakes@oracle.com, ziy@nvidia.com,
baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com,
npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com,
baohua@kernel.org, shikemeng@huaweicloud.com, kasong@tencent.com,
nphamcs@gmail.com, bhe@redhat.com, chrisl@kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] huge_mm.h: is_huge_zero_folio(NULL) should return false
Date: Wed, 27 Aug 2025 13:56:09 +0200 [thread overview]
Message-ID: <11a5d391-3a13-4376-98f1-34b529d3c583@redhat.com> (raw)
In-Reply-To: <CAKPOu+_8_gfko=Sh-YKpbgcMy0aJB=m9yrC5JJKEZm=yeYPOgA@mail.gmail.com>
On 27.08.25 12:13, Max Kellermann wrote:
> On Wed, Aug 27, 2025 at 11:36 AM David Hildenbrand <david@redhat.com> wrote:
>> Why should it be allowed to pass in garbage (folio == NULL) into a
>> function that operates on valid folios?
>
> This patch isn't about the function parameter but about the global
> variable being NULL.
> (Don't mix up with my other patch.)
Huh?
"Calling is_huge_zero_folio(NULL) should not be legal - it makes no
sense, and a different (theoretical) implementation may dereference
the pointer."
And then
"But currently, lacking any explicit documentation, this
call is legal."
No. It isn't. It never was.
--
Cheers
David / dhildenb
next prev parent reply other threads:[~2025-08-27 11:56 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-26 23:16 [PATCH 1/2] huge_mm.h: is_huge_zero_folio(NULL) should return false Max Kellermann
2025-08-26 23:16 ` [PATCH 2/2] mm/swap: add BUG_ON(folio==NULL) to folios_put_refs() Max Kellermann
2025-08-27 1:42 ` Zi Yan
2025-08-27 2:12 ` Chris Li
2025-08-27 9:38 ` David Hildenbrand
2025-08-27 1:19 ` [PATCH 1/2] huge_mm.h: is_huge_zero_folio(NULL) should return false Zi Yan
2025-08-27 1:55 ` Andrew Morton
2025-08-27 4:39 ` Max Kellermann
2025-08-27 9:36 ` David Hildenbrand
2025-08-27 10:13 ` Max Kellermann
2025-08-27 11:56 ` David Hildenbrand [this message]
2025-08-27 13:06 ` Max Kellermann
2025-08-27 14:34 ` David Hildenbrand
2025-08-27 15:03 ` [PATCH v2] huge_mm.h: disallow is_huge_zero_folio(NULL) Max Kellermann
2025-08-27 15:16 ` Lorenzo Stoakes
2025-08-27 15:38 ` Max Kellermann
2025-08-27 20:01 ` David Hildenbrand
2025-08-27 20:26 ` David Hildenbrand
2025-08-27 20:44 ` Lorenzo Stoakes
2025-08-28 8:48 ` [PATCH v3] " Max Kellermann
2025-08-28 9:35 ` Lorenzo Stoakes
2025-08-29 1:25 ` Zi Yan
2025-08-27 23:53 ` [PATCH v2] " Andrew Morton
2025-08-28 5:17 ` Max Kellermann
2025-08-28 7:57 ` David Hildenbrand
2025-08-27 15:05 ` [PATCH 1/2] huge_mm.h: is_huge_zero_folio(NULL) should return false Max Kellermann
2025-08-27 9:35 ` David Hildenbrand
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