From: "David Hildenbrand (Red Hat)" <david@kernel.org>
To: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Jeongjun Park <aha310510@gmail.com>
Cc: Harry Yoo <harry.yoo@oracle.com>,
Liam.Howlett@oracle.com, akpm@linux-foundation.org,
jannh@google.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, riel@surriel.com,
syzbot+b165fc2e11771c66d8ba@syzkaller.appspotmail.com,
syzkaller-bugs@googlegroups.com, vbabka@suse.cz
Subject: Re: [syzbot] [mm?] WARNING in folio_remove_rmap_ptes
Date: Thu, 1 Jan 2026 18:06:23 +0100 [thread overview]
Message-ID: <dd304877-1010-462d-bdf8-9d824250a05c@kernel.org> (raw)
In-Reply-To: <794095b5-e9ee-4fff-8e3a-1e6b98e670a2@lucifer.local>
On 1/1/26 17:32, Lorenzo Stoakes wrote:
> On Thu, Jan 01, 2026 at 11:30:52PM +0900, Jeongjun Park wrote:
>>
>> Based on my testing, I found that the WARNING starts from commit
>> d23cb648e365 ("mm/mremap: permit mremap() move of multiple VMAs"),
>> which is right after commit 2cf442d74216 ("mm/mremap: clean up mlock
>> populate behavior") in Lorenzo's mremap-related patch series.
>
> OK let me take a look.
Trying to make sense of the reproducer and how bpf comes into play ... I
assume BPF is only used to install a uprobe.
We seem to create a file0 and register a uprobe on it.
We then mmap() that file with PROT_NONE. We should end up in
uprobe_mmap() and trigger a COW fault -> allocate an anon_vma.
So likely the bpf magic is only there to allocate an anon_vma for a
PROT_NONE region.
But it's all a bit confusing ... :)
--
Cheers
David
next prev parent reply other threads:[~2026-01-01 17:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-23 5:23 syzbot
2025-12-23 8:24 ` David Hildenbrand (Red Hat)
2025-12-24 2:48 ` Hillf Danton
2025-12-24 5:35 ` Harry Yoo
2025-12-30 22:02 ` David Hildenbrand (Red Hat)
2025-12-31 6:59 ` Harry Yoo
2026-01-01 13:09 ` Jeongjun Park
2026-01-01 13:45 ` Harry Yoo
2026-01-01 14:30 ` Jeongjun Park
2026-01-01 16:32 ` Lorenzo Stoakes
2026-01-01 17:06 ` David Hildenbrand (Red Hat) [this message]
2026-01-01 21:28 ` Lorenzo Stoakes
2026-01-01 16:54 ` Lorenzo Stoakes
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