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. Thanks Alan