From: Greg KH <greg@kroah.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Felix Kuehling <Felix.Kuehling@amd.com>,
Alex Deucher <alexander.deucher@amd.com>,
Zhenyu Wang <zhenyuw@linux.intel.com>,
Zhi Wang <zhi.a.wang@intel.com>, Felipe Balbi <balbi@kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>, Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org,
intel-gfx@lists.freedesktop.org, linux-usb@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 3/3] kernel: set USER_DS in kthread_use_mm
Date: Thu, 16 Apr 2020 08:43:11 +0200 [thread overview]
Message-ID: <20200416064311.GA300290@kroah.com> (raw)
In-Reply-To: <20200416053158.586887-4-hch@lst.de>
On Thu, Apr 16, 2020 at 07:31:58AM +0200, Christoph Hellwig wrote:
> Some architectures like arm64 and s390 require USER_DS to be set for
> kernel threads to access user address space, which is the whole purpose
> of kthread_use_mm, but other like x86 don't. That has lead to a huge
> mess where some callers are fixed up once they are tested on said
> architectures, while others linger around and yet other like io_uring
> try to do "clever" optimizations for what usually is just a trivial
> asignment to a member in the thread_struct for most architectures.
>
> Make kthread_use_mm set USER_DS, and kthread_unuse_mm restore to the
> previous value instead.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Acked-by: Michael S. Tsirkin <mst@redhat.com> [vhost]
> ---
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [usb]
next prev parent reply other threads:[~2020-04-16 6:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 5:31 improve use_mm / unuse_mm v2 Christoph Hellwig
2020-04-16 5:31 ` [PATCH 1/3] kernel: move use_mm/unuse_mm to kthread.c Christoph Hellwig
2020-04-16 5:31 ` [PATCH 2/3] kernel: better document the use_mm/unuse_mm API contract Christoph Hellwig
2020-04-16 6:43 ` Greg KH
2020-04-16 5:31 ` [PATCH 3/3] kernel: set USER_DS in kthread_use_mm Christoph Hellwig
2020-04-16 6:43 ` Greg KH [this message]
2020-04-17 3:17 ` improve use_mm / unuse_mm v2 Matthew Wilcox
2020-04-17 6:31 ` Christoph Hellwig
2020-04-17 14:25 ` Jens Axboe
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