From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 6 Nov 2004 08:28:58 -0200 From: Marcelo Tosatti Subject: Re: [PATCH] Remove OOM killer from try_to_free_pages / all_unreclaimable braindamage Message-ID: <20041106102858.GC22514@logos.cnet> References: <20041105200118.GA20321@logos.cnet> <200411051532.51150.jbarnes@sgi.com> <20041106012018.GT8229@dualathlon.random> <1099706150.2810.147.camel@thomas> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1099706150.2810.147.camel@thomas> Sender: owner-linux-mm@kvack.org Return-Path: To: Thomas Gleixner Cc: Andrea Arcangeli , Jesse Barnes , Andrew Morton , Nick Piggin , LKML , linux-mm@kvack.org List-ID: On Sat, Nov 06, 2004 at 02:55:50AM +0100, Thomas Gleixner wrote: > On Sat, 2004-11-06 at 02:20 +0100, Andrea Arcangeli wrote: > > On Fri, Nov 05, 2004 at 03:32:50PM -0800, Jesse Barnes wrote: > > > On Friday, November 05, 2004 12:01 pm, Marcelo Tosatti wrote: > > > > In my opinion the correct approach is to trigger the OOM killer > > > > when kswapd is unable to free pages. Once that is done, the number > > > > of tasks inside page reclaim is irrelevant. > > > > > > That makes sense. > > > > I don't like it, kswapd may fail balancing because there's a GFP_DMA > > allocation that eat the last dma page, but we should not kill tasks if > > we fail to balance in kswapd, we should kill tasks only when no fail > > path exists (i.e. only during page faults, everything else in the kernel > > has a fail path and it should never trigger oom). > > > > If you move it in kswapd there's no way to prevent oom-killing from a > > syscall allocation (I guess even right now it would go wrong in this > > sense, but at least right now it's more fixable). I want to move the oom > > kill outside the alloc_page paths. The oom killing is all about the page > > faults not having a fail path, and in turn the oom killing should be > > moved in the page fault code, not in the allocator. Everything else > > should keep returning -ENOMEM to the caller. > > > > So to me moving the oom killer into kswapd looks a regression. > > My point is not where oom-killer is triggered. My point is the decision > criteria of oom-killer, when it is finally invoked, which process to > kill. That's kind of independend of your patch. Your patch corrects the > context in which oom-killer is called. My concern is that the decision > critrion which process should be killed is not sufficient. In my case it > kills sshd instead of a process which forks a bunch of child processes. > Thats just wrong, because it takes away the chance to log into the > machine remotely and fix the problem. Hi Thomas, Yes your patches are correct and needed independantly of where OOM killer is triggered from. -- 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: aart@kvack.org