From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rn-out-0910.google.com with SMTP id j71so1963425rne.4 for ; Mon, 24 Nov 2008 12:55:21 -0800 (PST) Message-ID: <84144f020811241255v2d4de38j59ceeb967227489@mail.gmail.com> Date: Mon, 24 Nov 2008 22:55:20 +0200 From: "Pekka Enberg" Subject: Re: [PATCH][V3]Make get_user_pages interruptible In-Reply-To: <6599ad830811241202o74312a18m84ed86a5f4393086@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <604427e00811211731l40898486r1a58e4940f3859e9@mail.gmail.com> <6599ad830811241202o74312a18m84ed86a5f4393086@mail.gmail.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Paul Menage Cc: Ying Han , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm , David Rientjes , Rohit Seth List-ID: Hi Paul, On Fri, Nov 21, 2008 at 5:31 PM, Ying Han wrote: >> */ >> - if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE))) >> - return i ? i : -ENOMEM; >> + if (unlikely(sigkill_pending(tsk))) >> + return i ? i : -ERESTARTSYS; On Mon, Nov 24, 2008 at 10:02 PM, Paul Menage wrote: > You've changed the check from sigkill_pending(current) to sigkill_pending(tsk). > > I originally made that sigkill_pending(current) since we want to avoid > tasks entering an unkillable state just because they're doing > get_user_pages() on a system that's short of memory. Admittedly for > the main case that we care about, mlock() (or an mmap() with > MCL_FUTURE set) then tsk==current, but philosophically it seems to me > to be more correct to do the check against current than tsk, since > current is the thing that's actually allocating the memory. But maybe > it would be better to check both? Well, most callers seem to pass 'current' to get_user_pages() but for the out-of-tree revoke patches, for example, you certainly want to check sigkill_pending(current) as well; otherwise the revoke operation is unkillable while in get_user_pages(). Not that revoke() is going to hit mainline any time soon but it does serve as an argument for checking both. Pekka -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org