linux-kernel - Re: [RFC 0/12] introduce down_write_killable for rw

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Message-ID: <20160310102412.GA21593@gmail.com>
Date:	Thu, 10 Mar 2016 11:24:13 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"David S. Miller" <davem@...emloft.net>,
	Tony Luck <tony.luck@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chris Zankel <chris@...kel.net>,
	Max Filippov <jcmvbkbc@...il.com>, x86@...nel.org,
	linux-alpha@...r.kernel.org, linux-ia64@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
	sparclinux@...r.kernel.org, linux-xtensa@...ux-xtensa.org,
	linux-arch@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [RFC 0/12] introduce down_write_killable for rw_semaphore


* Michal Hocko <mhocko@...nel.org> wrote:

> > > Why? Each syscall already is killable as the task might be killed by the OOM 
> > > killer.
> > 
> > Not all syscalls are interruptible - for example sys_sync() isn't:
> 
> I guess we are talking past each other. [...]

Heh, you are being polite, I think what happened is that I was being dense and 
didn't understand your point:

> [...] What I meant was that while all syscalls are allowed to not return to the 
> userspace because the task might get killed but not all of them accept to get 
> interrupted by a signal and return with EINTR. None of the man page of mmap, 
> mremap, mlock, mprotect list EINTR as a possibility so I would be really afraid 
> of returning an unexpected error code.

Indeed.

> Does this make more sense now?

It does!

Thanks,

	Ingo