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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 4/5] Add lock_page_killable
Date: Thu, 25 Oct 2007 14:13:57 +1000
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Cc: Matthew Wilcox <matthew@wil.cx>, torvalds@linux-foundation.org,
       linux-kernel@vger.kernel.org, Matthew Wilcox <willy@linux.intel.com>
References: <11932286982175-git-send-email-matthew@wil.cx> <11932286982653-git-send-email-matthew@wil.cx> <20071024211140.329fdd90.akpm@linux-foundation.org>
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On Thursday 25 October 2007 14:11, Andrew Morton wrote:
> On Wed, 24 Oct 2007 08:24:57 -0400 Matthew Wilcox <matthew@wil.cx> wrote:
> > and associated infrastructure such as sync_page_killable and
> > fatal_signal_pending.  Use lock_page_killable in
> > do_generic_mapping_read() to allow us to kill `cat' of a file on an
> > NFS-mounted filesystem.
>
> whoa, big change.
>
> What exactly are the semantics here?  If the process has actually been
> killed (ie: we know that userspace won't be running again) then we break
> out of a lock_page() and allow the process to exit?  ie: it's basically
> invisible to userspace?

The actual conversions should also be relatively useful groundwork
if we ever want to make more things become generally interruptible.


> If so, it sounds OK.  I guess.  We're still screwed if the process is doing
> a synchronous write and lots of other scenarios.

I don't think it will matter in too many situations. If the process is
doing a synchronous write, nothing is guaranteed until the syscall
returns success...
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