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b=mXa1p9OljcPPnHJe+S0GH8f6obYCNzxKYDdRO1my5cwauiSQ3W6HwFATHU6hTo3hF 21LYGc1ijTFwH0lWjVP6YdcPtcsA6JGnHW8g9LjMAkIEJmpDLWk3TKDD1TpL+mTZ7q tJ7MtxzA0aJpeJ6qgSQhZodFd66LDBIisBke4hwY= Date: Fri, 14 Jun 2024 11:21:48 -0700 From: Andrew Morton To: Christoph Hellwig Cc: Trond Myklebust , Anna Schumaker , Steve French , linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-mm@kvack.org, Barry Song , Ryan Roberts Subject: Re: [PATCH] nfs: fix nfs_swap_rw for large-folio swap Message-Id: <20240614112148.cd1961e84b736060c54bdf26@linux-foundation.org> In-Reply-To: <20240614100329.1203579-2-hch@lst.de> References: <20240614100329.1203579-1-hch@lst.de> <20240614100329.1203579-2-hch@lst.de> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: EF4711A0006 X-Stat-Signature: m38mq3xramxcgxjxco6pahzayku915jz X-Rspam-User: X-HE-Tag: 1718389312-546580 X-HE-Meta: U2FsdGVkX1/hTPUK8ijsIR9PTctLM3X2DlsJCP6B0agPapKuigixjUlpKYO0CKKy5G2D0vANHmwt4FSgfrluDNdMYjbDlnvfU11g4arpt3URKCODQJix7O/7fO7jg16YOlNLxWtVfsdodV/N/gUnnlQSA0AS9WdUISImzBhrylj1rEWt9eJ33wUipgBXBPdsBBGTjB5GKUMOQa1lWWqzcKfkSr2O1AHI19QVBoGUDoUODf5wRhKBkHhz8Yruq6wos1z2v9LNhD6UkLO1ePjIg0bOHIwtx0nom5U+u/efT47KY/aOToaMmgRjy3WrfqU9JDmm+k1dnqPzunJmHSQb0cu5IHpizTl106FYBGgbw3gk/MVcLYJd3ic8nz3QspnLs/4PMmnIQeKcV9z6E+3i7nEl03hQq+3RmlA1MAJtaeqfdzuSWMFUdGbqAWyLyxSUWVZ5GSUP0Dz8xDtaAgl+3jwF8BN4qrP40C3MImpFvRCV+Trzq3Vn2LhV6gzZIfPYGGypbVha3Ew2nPF8U62cCJOoJZlLpZJFDSuWHXoFyLx9QCaFmq6H4YJ+gpyiGdKvgnyYpE1QlfbwK9W/Hx18UEEsg9aszp1i3aFehlHYVIC4fivkMjBokDORoI7+qNg2CrvzNgFjdFtpes/fpFrQHm9qTaIaRbFLt/FW425cm+knzH0rU1vMeVlTeUYoJpJQ/fuwwE0GVonPWdIfGSueBUWbloz+HT/GimYOWZu9fM4yx5e4VgKXst9odl2KJTXK1oEegpTlWkqd7WRQKL43I8NR/xAYyFwwuw5/fYajAz5YZlp5RnrNehFr87klrSwuLZXHhn7OaWeQZB8Rc5RK0WoWg4rX77rrU51jGIVGKFL9HZ78lM3pyD2yCLapI5pxSZ4Hdd5si6KaTHdhrrzGqCJsif2GK08fz5+blrxKjoFAtpA86HUYL8OFFyPzOLfx771GI03Vc5klS7Dw2NQ lNClYzsa FVhf2JseIgryYuRAZyUSoGKg4W9O7E36vq/WnKvX+LU+MfOwTpota/FIjwvyMRC38xH0H3lcEhHZ3Tv1yyMS5cLy05gXoxBQfDYMAhgEAKQdaRALug6pjMbLOmhsxGfckBGCFHmBLh2zR1D8qsDFYbze/sfzhQQe17vS31y/RpOlwpMEydFKl+mBqaZ702I3Vge+yEElXBbRrlPa4YzjOX1K82tIj18LW/XZwPzCfw77mUen1lOXeBgo/XUrFRZlbzd1VJkJ9SmDB2ls= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 14 Jun 2024 12:03:25 +0200 Christoph Hellwig wrote: > As of Linux 6.10-rc the MM can swap out larger than page size chunks. > NFS has all code ready to handle this, but has a VM_BUG_ON that > triggers when this happens. Simply remove the VM_BUG_ON to fix this > use case. > > ... > > --- a/fs/nfs/direct.c > +++ b/fs/nfs/direct.c > @@ -141,8 +141,6 @@ int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter) > { > ssize_t ret; > > - VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE); > - > if (iov_iter_rw(iter) == READ) > ret = nfs_file_direct_read(iocb, iter, true); > else I'm thinking this should precede "mm: swap: entirely map large folios found in swapcache", or be a part of it. Barry/Chuanhua, any opinions?