From: Matthew Wilcox <willy@infradead.org>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
Souptick Joarder <jrdr.linux@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: Signal handling in a page fault handler
Date: Tue, 3 Apr 2018 06:48:54 -0700 [thread overview]
Message-ID: <20180403134854.GA28565@bombadil.infradead.org> (raw)
In-Reply-To: <152276164305.32747.4969221700358143640@mail.alporthouse.com>
On Tue, Apr 03, 2018 at 02:20:43PM +0100, Chris Wilson wrote:
> Quoting Matthew Wilcox (2018-04-03 14:10:25)
> > On Tue, Apr 03, 2018 at 01:33:15PM +0100, Chris Wilson wrote:
> > > Quoting Matthew Wilcox (2018-04-02 15:10:58)
> > > > I don't think the graphics drivers really want to be interrupted by
> > > > any signal.
> > >
> > > Assume the worst case and we may block for 10s. Even a 10ms delay may be
> > > unacceptable to some signal handlers (one presumes). For the number one
> > > ^C usecase, yes that may be reduced to only bother if it's killable, but
> > > I wonder if there are not timing loops (e.g. sigitimer in Xorg < 1.19)
> > > that want to be able to interrupt random blockages.
> >
> > Ah, setitimer / SIGALRM. So what do we want to have happen if that
> > signal handler touches the mmaped device memory?
>
> Burn in a great ball of fire :) Isn't that what usually happens if you
> do anything in a signal handler?
I don't know. My mummy and daddy don't let me play with sharp things
like signals.
> Hmm, if SIGBUS has a handler does that count as a killable signal? The
> ddx does have code to service SIGBUS emitted when accessing the mmapped
> pointer that may result from the page insertion failing with no memory
> (or other random error). There we stop accessing via the pointer and
> use another indirect method.
Any signal with a handler is non-fatal, and so a call to
mutex_lock_killable() would not return if SIGBUS was delivered to a thread
blocking in a page fault. mutex_lock_interruptible() would return -EINTR.
next prev parent reply other threads:[~2018-04-03 13:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-02 14:10 Signal handling in a page fault handler Matthew Wilcox
2018-04-03 12:33 ` Chris Wilson
2018-04-03 13:10 ` Matthew Wilcox
[not found] ` <152276164305.32747.4969221700358143640@mail.alporthouse.com>
2018-04-03 13:48 ` Matthew Wilcox [this message]
2018-04-03 13:12 ` Thomas Hellstrom
2018-04-03 14:48 ` Matthew Wilcox
2018-04-03 15:12 ` Daniel Vetter
2018-04-04 9:32 ` Daniel Vetter
2018-04-04 14:39 ` Matthew Wilcox
2018-04-04 15:15 ` Daniel Vetter
2018-04-04 16:24 ` Matthew Wilcox
2018-04-04 17:45 ` Daniel Vetter
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