From: Matthew Wilcox <willy@infradead.org>
To: Jinjiang Tu <tujinjiang@huawei.com>
Cc: Rik van Riel <riel@surriel.com>,
ziy@nvidia.com, linux-kernel@vger.kernel.org,
kernel-team@meta.com, Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>, Hugh Dickins <hughd@kernel.org>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Liam R. Howlett" <liam@infradead.org>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: khugepaged: free xarray nodes left behind by failed collapse_file()
Date: Wed, 17 Jun 2026 03:18:21 +0100 [thread overview]
Message-ID: <ajID7ZpnBYOucAVz@casper.infradead.org> (raw)
In-Reply-To: <8a4caadc-f414-4874-97d4-2fbaebe2af39@huawei.com>
On Wed, Jun 17, 2026 at 10:00:59AM +0800, Jinjiang Tu wrote:
>
> 在 2026/6/16 23:29, Matthew Wilcox 写道:
> > On Tue, Jun 16, 2026 at 10:54:13AM -0400, Rik van Riel wrote:
> > > syzkaller reproduces it trivially with MADV_COLLAPSE on a sparse shmem
> > > mapping (collapse aborts with SCAN_TRUNCATED because the range is empty),
> > > and also via slab fault injection, which forces xas_create_range() down
> > > the xas_nomem() path before the same abort. kmemleak then reports the
> > > 576-byte struct xa_node objects allocated in xas_alloc()/xas_nomem().
> > I think the ways to produce this problem are sufficiently rare/unlikely
>
> I can reproduce it easily with following steps. [1]
> 1) create file /tmp/test_madvise_collapse and ftruncate to 4MB size, and
> then mmap the file
> 2) memset for the first 2MB
> 3) madvise(MADV_COLLAPSE) for the second 2MB
> 4) unlink the file
Yes, but is there a problem? That is, do we need to clear this up
before we get to clear_inode()?
next prev parent reply other threads:[~2026-06-17 2:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-16 14:54 Rik van Riel
2026-06-16 15:09 ` Zi Yan
2026-06-16 15:29 ` Matthew Wilcox
2026-06-17 2:00 ` Jinjiang Tu
2026-06-17 2:18 ` Matthew Wilcox [this message]
2026-06-17 7:33 ` Jinjiang Tu
2026-06-17 15:40 ` Rik van Riel
2026-06-17 18:05 ` Matthew Wilcox
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