Messages in this thread Patch in this message | | | Subject | Re: [Alsa-devel] Re: 2.6.15-rt20, "bad page state", jackd (alsa 1.0.10 vs. recent kernels) | From | Fernando Lopez-Lezcano <> | Date | Sun, 12 Mar 2006 16:49:37 -0800 |
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On Sat, 2006-03-11 at 11:01 +1100, Nick Piggin wrote: > Fernando Lopez-Lezcano wrote: > > > Takashi and other gurus in alsa-devel, any comments on this? The > > original problem - not quoted in this email - is that when I stop jackd > > in the affected configurations I get errors similar to this one: > > > > > >>Bad page state at __free_pages_ok (in process 'jackd', page c1013ce0) > >>flags:0x00000414 mapping:00000000 mapcount:0 count:0 > >>Backtrace: > >> [<c015947d>] bad_page+0x7d/0xc0 (8) > >> [<c01598fd>] __free_pages_ok+0x9d/0x180 (36) > >> [<c015a5ac>] __pagevec_free+0x3c/0x50 (40) > >> [<c015db47>] release_pages+0x127/0x1a0 (16) > >> [<c016c93d>] free_pages_and_swap_cache+0x7d/0xc0 (80) > >> [<c01681ae>] unmap_region+0x13e/0x160 (28) > >> [<c0168461>] do_munmap+0xe1/0x120 (48) > >> [<c01684df>] sys_munmap+0x3f/0x60 (32) > >> [<c01034a1>] syscall_call+0x7/0xb (16) > >>Trying to fix it up, but a reboot is needed > > > > FWIW, this is a PageReserved page being freed. PageReserved does > anything, and you instead need to ensure the page count is incremented > in your ->nopage handler (ie. via get_page()). > > > > > One other thing occurred to me (not tested yet) > > > > - userspace regression in the module load code (so that in the end > > modules from the in kernel tree get mixed with modules coming from the > > externally compiled alsa tree). Very unlikely, I think, I could test for > > this by removing the in kernel modules temporarily. > > > > I have problems in both: > > snd-ice1712 (midiman delta 66) > > snd-hdsp (rme hdsp) > > but this seems to work fine: > > snd-echo3g (gina3g) > > > > The interesting thing is that the one that works (snd-echo3g) has no > > counterpat in the in kernel alsa tree - that is, only exists in the > > add-on modules compiled externally. Coincidence?
Well, I found it. Finally. I diffed memalloc.c in the alsa kernel tree with alsa stable 1.0.10 and googled for the obvious two chunks that stood out :-)
It's apparently an old issue, see here and follow the thread: http://lkml.org/lkml/2005/11/21/9 So, 1.0.10 obviously did not include these two patches:
======== --- linux-2.6.15-old/acore/memalloc.c 2006-03-10 15:13:36.636282832 -0800 +++ linux-2.6.15/sound/core/memalloc.c 2006-01-02 19:21:10.000000000 -0800 @@ -267,6 +197,7 @@
snd_assert(size > 0, return NULL); snd_assert(gfp_flags != 0, return NULL); + gfp_flags |= __GFP_COMP; /* compound page lets parts be mapped */ pg = get_order(size); if ((res = (void *) __get_free_pages(gfp_flags, pg)) != NULL) { mark_pages(virt_to_page(res), pg); @@ -311,6 +242,7 @@ snd_assert(dma != NULL, return NULL); pg = get_order(size); gfp_flags = GFP_KERNEL + | __GFP_COMP /* compound page lets parts be mapped */ | __GFP_NORETRY /* don't trigger OOM-killer */ | __GFP_NOWARN; /* no stack trace print - this call is non-critical */ res = dma_alloc_coherent(dev, PAGE_SIZE << pg, dma, gfp_flags); ======== With this in a short remote test 1.0.10 on top of 2.6.15-rt21 does not generate the bad page messages I originally reported. Woohoo!
And 1.0.11rc3 apparently only includes one of the two patches.
]# find . -type f -exec grep GFP_COMP {} \; -print #ifndef __GFP_COMP #define __GFP_COMP 0 ./include/adriver.h gfp_flags |= __GFP_COMP; /* compound page lets parts be mapped */ | __GFP_COMP /* compound page lets parts be mapped */ ./alsa-kernel/core/memalloc.c I'll test 1.0.11rc3 asap to confirm whether adding the missing bit makes a difference or not. I think I was getting the exact same error on 1.0.11rc3 but I have to make sure.
Thanks for all the help! -- Fernando
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