From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Jenkins Subject: Re: s2disk hang update Date: Tue, 23 Feb 2010 14:24:25 +0000 Message-ID: <9b2b86521002230624g20661564mc35093ee0423ff77__41836.8818158799$1266935247$gmane$org@mail.gmail.com> References: <9b2b86521001020703v23152d0cy3ba2c08df88c0a79@mail.gmail.com> <201002212147.07987.rjw@sisk.pl> <4B82A440.6010701@googlemail.com> <201002222017.55588.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201002222017.55588.rjw@sisk.pl> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: "Rafael J. Wysocki" Cc: Mel Gorman , linux-kernel , hugh.dickins@tiscali.co.uk, pm list , Kernel Testers List List-Id: linux-pm@vger.kernel.org On 2/22/10, Rafael J. Wysocki wrote: > On Monday 22 February 2010, Alan Jenkins wrote: >> Rafael J. Wysocki wrote: >> > On Friday 19 February 2010, Alan Jenkins wrote: >> > >> >> On 2/18/10, Rafael J. Wysocki wrote: >> >> >> >>> On Thursday 18 February 2010, Alan Jenkins wrote: >> >>> >> >>>> On 2/17/10, Rafael J. Wysocki wrote: >> >>>> >> >>>>> On Wednesday 17 February 2010, Alan Jenkins wrote: >> >>>>> >> >>>>>> On 2/16/10, Rafael J. Wysocki wrote: >> >>>>>> >> >>>>>>> On Tuesday 16 February 2010, Alan Jenkins wrote: >> >>>>>>> >> >>>>>>>> On 2/16/10, Alan Jenkins wrote: >> >>>>>>>> >> >>>>>>>>> On 2/15/10, Rafael J. Wysocki wrote: >> >>>>>>>>> >> >>>>>>>>>> On Tuesday 09 February 2010, Alan Jenkins wrote: >> >>>>>>>>>> >> >>>>>>>>>>> Perhaps I spoke too soon. I see the same hang if I run too >> >>>>>>>>>>> many >> >>>>>>>>>>> applications. The first hibernation fails with "not enough >> >>>>>>>>>>> swap" >> >>>>>>>>>>> as >> >>>>>>>>>>> expected, but the second or third attempt hangs (with the same >> >>>>>>>>>>> backtrace >> >>>>>>>>>>> as before). >> >>>>>>>>>>> >> >>>>>>>>>>> The patch definitely helps though. Without the patch, I see a >> >>>>>>>>>>> hang >> >>>>>>>>>>> the >> >>>>>>>>>>> first time I try to hibernate with too many applications >> >>>>>>>>>>> running. >> >>>>>>>>>>> >> >>>>>>>>>> Well, I have an idea. >> >>>>>>>>>> >> >>>>>>>>>> Can you try to apply the appended patch in addition and see if >> >>>>>>>>>> that >> >>>>>>>>>> helps? >> >>>>>>>>>> >> >>>>>>>>>> Rafael >> >>>>>>>>>> >> >>>>>>>>> It doesn't seem to help. >> >>>>>>>>> >> >>>>>>>> To be clear: It doesn't stop the hang when I hibernate with too >> >>>>>>>> many >> >>>>>>>> applications. >> >>>>>>>> >> >>>>>>>> It does stop the same hang in a different case though. >> >>>>>>>> >> >>>>>>>> 1. boot with init=/bin/bash >> >>>>>>>> 2. run s2disk >> >>>>>>>> 3. cancel the s2disk >> >>>>>>>> 4. repeat steps 2&3 >> >>>>>>>> >> >>>>>>>> With the patch, I can run 10s of iterations, with no hang. >> >>>>>>>> Without the patch, it soon hangs, (in disable_nonboot_cpus(), as >> >>>>>>>> always). >> >>>>>>>> >> >>>>>>>> That's what happens on 2.6.33-rc7. On 2.6.30, there is no >> >>>>>>>> problem. >> >>>>>>>> On 2.6.31 and 2.6.32 I don't get a hang, but dmesg shows an >> >>>>>>>> allocation >> >>>>>>>> failure after a couple of iterations ("kthreadd: page allocation >> >>>>>>>> failure. order:1, mode:0xd0"). It looks like it might be the >> >>>>>>>> same >> >>>>>>>> stop_machine thread allocation failure that causes the hang. >> >>>>>>>> >> >>>>>>> Have you tested it alone or on top of the previous one? If you've >> >>>>>>> tested it >> >>>>>>> alone, please apply the appended one in addition to it and retest. >> >>>>>>> >> >>>>>>> Rafael >> >>>>>>> >> >>>>>> I did test with both patches applied together - >> >>>>>> >> >>>>>> 1. [Update] MM / PM: Force GFP_NOIO during suspend/hibernation and >> >>>>>> resume >> >>>>>> 2. "reducing the number of pages that we're going to keep >> >>>>>> preallocated >> >>>>>> by >> >>>>>> 20%" >> >>>>>> >> >>>>> In that case you can try to reduce the number of preallocated pages >> >>>>> even >> >>>>> more, >> >>>>> ie. change "/ 5" to "/ 2" (for example) in the second patch. >> >>>>> >> >>>> It still hangs if I try to hibernate a couple of times with too many >> >>>> applications. >> >>>> >> >>> Hmm. I guess I asked that before, but is this a 32-bit or 64-bit >> >>> system and >> >>> how much RAM is there in the box? >> >>> >> >>> Rafael >> >>> >> >> EeePC 701. 32 bit. 512Mb RAM. 350Mb swap file, on a "first-gen" SSD. >> >> >> > >> > Hmm. I'd try to make free_unnecessary_pages() free all of the >> > preallocated >> > pages and see what happens. >> > >> >> It still hangs in hibernation_snapshot() / disable_nonboot_cpus(). >> After apparently freeing over 400Mb / 100,000 pages of preallocated ram. >> >> >> >> There is a change which I missed before. When I applied your first >> patch ("Force GFP_NOIO during suspend" etc.), it did change the hung >> task backtraces a bit. I don't know if it tells us anything. >> >> Without the patch, there were two backtraces. The first backtrace >> suggested a problem allocating pages for a kernel thread (at >> copy_process() / try_to_free_pages()). The second showed that this >> problem was blocking s2disk (at hibernation_snapshot() / >> disable_nonboot_cpus() / stop_machine_create()). >> >> With the GFP_NOIO patch, I see only the s2disk backtrace. > > Can you please post this backtrace? Sure. It's rather like the one I posted before, except a) it only shows the one hung task (s2disk) b) this time I had lockdep enabled c) this time most of the lines don't have question marks. Kernel verson: - mainline v2.6.33-rc8-164-gaea187c, with the one patch "Force GFP_NOIO..." Image: http://picasaweb.google.com/lh/photo/f9KRZT2l9wCmVt-Jdggd9g?feat=directlink INFO: task s2disk:1916 blocked for more than 120 seconds ... Call Trace: ? _raw_spin_unlock schedule_timeout+0x22 (timer.c:1366) ? mark_held_locks ? _raw_spin_unlock_irq ? trace_hardirqs_on_caller ? trace_hardirqs_on wait_for_common+0xb8 (sched.c:5844) ? default_wake_function wait_for_completion+0x12 (sched.c:5879) kthread_create+0x75 (kthread.c:133) ? worker_thread+0x0 create_workqueue_thread+0x38 (workqueue.c:921) ? worker_thread+0x0 __create_workqueue_key+0x156 (workqueue.c:1006) stop_machine_create+0x32 (stop_machine.c:121) disable_nonboot_cpus+0xe (cpu.c:370) hibernation_snapshot+0x94 (hibernate.c:266) snapshot_ioctl+0x21b (user.c:256) ... sys_ioctl+0x41 (ioctl.c:624) Thanks Alan