From: "David Hildenbrand (arm)" <david@kernel.org>
To: Zi Yan <ziy@nvidia.com>
Cc: 是参差 <shicenci@gmail.com>,
linux-mm@kvack.org, linmiaohe@huawei.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
"Matthew Wilcox" <willy@infradead.org>
Subject: Re: WARNING in memory_failure() at include/linux/huge_mm.h:635 triggered
Date: Wed, 4 Feb 2026 20:18:14 +0100 [thread overview]
Message-ID: <e97d5c0c-b8ec-4da4-b838-7a308f8a6327@kernel.org> (raw)
In-Reply-To: <032058DC-CD8D-406A-B986-740E41C834B2@nvidia.com>
On 2/4/26 18:41, Zi Yan wrote:
> On 4 Feb 2026, at 12:34, Zi Yan wrote:
>
>> On 4 Feb 2026, at 12:23, Zi Yan wrote:
>>
>>>
>>>
>>> From the C repro above, syzbot opened a dev "/dev/sg#" and did mmap on it.
>>> Is it a device driver issue?
>>
>> OK, it is CONFIG_CHR_DEV_SG. And the driver allocates a compound page at[1].
>> Since we initialize folio fields in prep_compound_page(), it becomes a folio
>> when it is inserted into a VMA.
>
> More details:
> later at sg_vma_fault(), the driver just handles a page fault by supplying
> a subpage from a pre-allocated compound page[3]. We then get a large folio
> without !CONFIG_TRANSPARENT_HUGEPAGE.
We can identify such non-folio (but compound) things by looking at
PG_large_rmappable IIRC.
--
Cheers,
David
next prev parent reply other threads:[~2026-02-04 19:18 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-04 12:49 是参差
2026-02-04 17:12 ` David Hildenbrand (arm)
2026-02-04 17:15 ` David Hildenbrand (arm)
2026-02-04 17:23 ` Zi Yan
2026-02-04 17:34 ` Zi Yan
2026-02-04 17:41 ` Zi Yan
2026-02-04 19:18 ` David Hildenbrand (arm) [this message]
2026-02-04 19:48 ` Zi Yan
2026-02-04 19:55 ` David Hildenbrand (arm)
2026-02-04 20:13 ` Zi Yan
2026-02-04 20:31 ` David Hildenbrand (arm)
2026-02-04 20:45 ` Zi Yan
2026-02-04 21:14 ` David Hildenbrand (arm)
2026-02-04 21:08 ` Zi Yan
2026-02-04 21:37 ` David Hildenbrand (arm)
2026-02-04 21:41 ` Zi Yan
2026-02-05 2:00 ` jane.chu
2026-02-05 3:21 ` Miaohe Lin
2026-02-05 3:53 ` Zi Yan
2026-02-05 7:18 ` Miaohe Lin
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