From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juha Aatrokoski Subject: Re: bcache hangs on writes, recovers after disabling discard on cache device Date: Thu, 18 Jul 2013 15:05:49 +0300 (EEST) Message-ID: References: <51C891C9.4060809@modelnine.org> <20130712011554.GA17799@kmo-pixel> <20130716210527.GC27000@kmo-pixel> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <20130716210527.GC27000@kmo-pixel> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kent Overstreet Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-bcache@vger.kernel.org On Tue, 16 Jul 2013, Kent Overstreet wrote: > On Tue, Jul 16, 2013 at 09:14:09PM +0300, Juha Aatrokoski wrote: >> On Fri, 12 Jul 2013, Juha Aatrokoski wrote: >>>> Can you give this patch a try? It's on top of the current >>>> bcache-for-3.11 branch >>> >>> OK, now running the same kernel with this patch applied and >>> discard enabled. However, it has previously taken my system 2-4 >>> days to trigger this bug, so I'd say at least two weeks before I >>> can say the patch (may have) fixed the issue. >> >> No such luck, hit the bug after four days of uptime. Disabling >> discard fixed the problem so at least it's not any worse than >> before. > > Argh, damn peculiar bug... and the fact that it takes so long to trigger > is frustrating. I'm honestly at a loss at this point as to what that IO > actually is. One thing I noticed is that your patch only affects the allocator, the journal still does discards the old way. Perhaps it's worth a try to apply a similar change to the journal discards? > I should've thought of this sooner, but if there's any way you could > capture some blktrace output while it's doing its spinning thing that > could be very helpful. OK, I will attempt to reproduce the bug again after the weekend and I'll try to remember to use blktrace.