From: Matthew Wilcox <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>,
Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>,
Al Viro <viro@zeniv.linux.org.uk>, Theodore Ts'o <tytso@mit.edu>,
adilger.kernel@dilger.ca, Jens Axboe <axboe@kernel.dk>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Eric Biggers <ebiggers@google.com>,
Philippe Ombredanne <pombredanne@nexb.com>,
Andreas Gruenbacher <agruenba@redhat.com>,
Greg KH <gregkh@linuxfoundation.org>,
kemi.wang@intel.com,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-nilfs <linux-nilfs@vger.kernel.org>
Subject: Re: [PATCH v2] fs: Convert return type int to vm_fault_t
Date: Mon, 3 Sep 2018 19:13:55 -0700 [thread overview]
Message-ID: <20180904021355.GA17153@bombadil.infradead.org> (raw)
In-Reply-To: <20180903172843.9bf312c738ce8a434dd9c242@linux-foundation.org>
On Mon, Sep 03, 2018 at 05:28:43PM -0700, Andrew Morton wrote:
> > > I'm beginning to feel vm_fault_t exhaustion. Please remind me what
> > > benefit we're going to get out of all this churn?
Hi Andrew,
The primary benefit is to help driver writers. At the moment, there
is nothing to stop them returning -ENOMEM instead of VM_FAULT_NOMEM.
There were one or two examples of this in the tree, but I think they're
all gone now.
Secondarily, there are a number of places which translate between error
codes and vm_fault codes. Those places are reduced as a result of these
patches, if not entirely eliminated yet. There was some pretty extreme
cargo-culting of errno to vm_fault switch statements, particularly in
the DRM drivers.
There were also several places which were just ignoring the return value
of vm_insert_foo(), and as a result of this audit, those have been fixed.
Those errors are going to be rare, but can cause inappropriate decisions
to be made by the OOM killer.
Now that I think about it, vmf_insert_foo() should probably get marked
with __must_check to prevent those kinds of errors from being introduced
again.
next prev parent reply other threads:[~2018-09-04 6:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-30 17:25 [PATCH v2] fs: Convert return type int to vm_fault_t Souptick Joarder
2018-08-30 23:33 ` Andrew Morton
2018-08-31 6:03 ` Souptick Joarder
2018-09-04 0:28 ` Andrew Morton
2018-09-04 2:13 ` Matthew Wilcox [this message]
2018-09-03 2:13 ` Ryusuke Konishi
2018-09-03 11:58 ` Souptick Joarder
2018-08-30 23:35 ` Andrew Morton
2018-08-31 16:58 ` Theodore Y. Ts'o
2018-09-01 16:21 ` Souptick Joarder
2018-09-03 4:49 ` Matthew Wilcox
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