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From: Christoph Hellwig <hch@lst.de>
To: John Hubbard <jhubbard@nvidia.com>
Cc: "Christoph Hellwig" <hch@lst.de>,
	john.hubbard@gmail.com,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Boaz Harrosh" <boaz@plexistor.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Dave Chinner" <david@fromorbit.com>,
	"David Airlie" <airlied@linux.ie>,
	"David S . Miller" <davem@davemloft.net>,
	"Ilya Dryomov" <idryomov@gmail.com>, "Jan Kara" <jack@suse.cz>,
	"Jason Gunthorpe" <jgg@ziepe.ca>, "Jens Axboe" <axboe@kernel.dk>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Johannes Thumshirn" <jthumshirn@suse.de>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Miklos Szeredi" <miklos@szeredi.hu>,
	"Ming Lei" <ming.lei@redhat.com>, "Sage Weil" <sage@redhat.com>,
	"Santosh Shilimkar" <santosh.shilimkar@oracle.com>,
	"Yan Zheng" <zyan@redhat.com>,
	netdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-mm@kvack.org, linux-rdma@vger.kernel.org,
	bpf@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] mm/gup: introduce __put_user_pages()
Date: Tue, 23 Jul 2019 17:36:40 +0200	[thread overview]
Message-ID: <20190723153640.GB720@lst.de> (raw)
In-Reply-To: <8ab4899c-ec12-a713-cac2-d951fff2a347@nvidia.com>

On Mon, Jul 22, 2019 at 11:33:32PM -0700, John Hubbard wrote:
> I'm seeing about 18 places where set_page_dirty() is used, in the call site
> conversions so far, and about 20 places where set_page_dirty_lock() is
> used. So without knowing how many of the former (if any) represent bugs,
> you can see why the proposal here supports both DIRTY and DIRTY_LOCK.

Well, it should be fairly easy to audit.  set_page_dirty() is only
safe if we are dealing with a file backed page where we have reference
on the inode it hangs off.  Which should basically be never or almost
never.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: John Hubbard <jhubbard@nvidia.com>
Cc: "Christoph Hellwig" <hch@lst.de>,
	john.hubbard@gmail.com,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Boaz Harrosh" <boaz@plexistor.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Dave Chinner" <david@fromorbit.com>,
	"David Airlie" <airlied@linux.ie>,
	"David S . Miller" <davem@davemloft.net>,
	"Ilya Dryomov" <idryomov@gmail.com>, "Jan Kara" <jack@suse.cz>,
	"Jason Gunthorpe" <jgg@ziepe.ca>, "Jens Axboe" <axboe@kernel.dk>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Johannes Thumshirn" <jthumshirn@suse.de>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Miklos Szeredi" <miklos@szeredi.hu>
Subject: Re: [PATCH 1/3] mm/gup: introduce __put_user_pages()
Date: Tue, 23 Jul 2019 17:36:40 +0200	[thread overview]
Message-ID: <20190723153640.GB720@lst.de> (raw)
In-Reply-To: <8ab4899c-ec12-a713-cac2-d951fff2a347@nvidia.com>

On Mon, Jul 22, 2019 at 11:33:32PM -0700, John Hubbard wrote:
> I'm seeing about 18 places where set_page_dirty() is used, in the call site
> conversions so far, and about 20 places where set_page_dirty_lock() is
> used. So without knowing how many of the former (if any) represent bugs,
> you can see why the proposal here supports both DIRTY and DIRTY_LOCK.

Well, it should be fairly easy to audit.  set_page_dirty() is only
safe if we are dealing with a file backed page where we have reference
on the inode it hangs off.  Which should basically be never or almost
never.

  reply	other threads:[~2019-07-23 15:36 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-22 22:34 [PATCH 0/3] introduce __put_user_pages(), convert a few call sites john.hubbard
2019-07-22 22:34 ` john.hubbard
2019-07-22 22:34 ` [PATCH 1/3] mm/gup: introduce __put_user_pages() john.hubbard
2019-07-22 22:34   ` john.hubbard
2019-07-23  5:53   ` Christoph Hellwig
2019-07-23  6:33     ` John Hubbard
2019-07-23  6:33       ` John Hubbard
2019-07-23 15:36       ` Christoph Hellwig [this message]
2019-07-23 15:36         ` Christoph Hellwig
2019-07-22 22:34 ` [PATCH 2/3] drivers/gpu/drm/via: convert put_page() to put_user_page*() john.hubbard
2019-07-22 22:34   ` john.hubbard
2019-07-22 22:34 ` [PATCH 3/3] net/xdp: " john.hubbard
2019-07-22 22:34   ` john.hubbard
2019-07-23  0:25   ` Ira Weiny
2019-07-23  0:25     ` Ira Weiny
2019-07-23  4:41     ` John Hubbard
2019-07-23  4:41       ` John Hubbard
2019-07-23 12:47       ` Jason Gunthorpe
2019-07-23 12:47         ` Jason Gunthorpe
2019-07-23 18:06       ` Ira Weiny
2019-07-23 18:06         ` Ira Weiny
2019-07-23 23:24         ` John Hubbard
2019-07-23 23:24           ` John Hubbard

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