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From: Barry Song <21cnbao@gmail.com>
Date: Sun, 16 Jun 2024 18:23:16 +0800
Message-ID: <CAGsJ_4ytrnXJbfVi=PpTw34iBDqEoAm3b16oZr2VQpVWLmh5zA@mail.gmail.com>
Subject: Re: [PATCH] nfs: fix nfs_swap_rw for large-folio swap
To: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>, Trond Myklebust <trondmy@kernel.org>, 
	Anna Schumaker <anna@kernel.org>, Steve French <sfrench@samba.org>, linux-nfs@vger.kernel.org, 
	linux-cifs@vger.kernel.org, linux-mm@kvack.org, 
	Barry Song <v-songbaohua@oppo.com>, Ryan Roberts <ryan.roberts@arm.com>
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On Sun, Jun 16, 2024 at 4:54=E2=80=AFPM Christoph Hellwig <hch@lst.de> wrot=
e:
>
> On Sun, Jun 16, 2024 at 12:16:10PM +1200, Barry Song wrote:
> > As I understand it, this isn't happening because we don't support
> > mTHP swapping out to a swapfile, whether it's on NFS or any
> > other filesystem.
>
> It does happen.  The reason why I sent this patch is becaue I observed
> the BUG_ON trigger on a trivial swap generation workload (usemem.c from
> xfstests).

This is quite unusual. Could you share your setup and backtrace? I'd
like to reproduce the issue, as the mm code only supports mTHP
swapout on block devices. What is your swap device or swap file?
Additionally, on what kind of filesystem is the executable file built
from usemem.c located?

>