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Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0)

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  Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0) "Dr. David Alan Gilbert" <dave@treblig.org> - 2023-02-01 03:00 +0100
    Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0)) "Dr. David Alan Gilbert" <dave@treblig.org> - 2023-02-01 04:00 +0100
      Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0))) "Dr. David Alan Gilbert" <dave@treblig.org> - 2023-02-01 15:10 +0100
        Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0)))) "Dr. David Alan Gilbert" <dave@treblig.org> - 2023-02-01 19:00 +0100
          Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0)))) Diederik de Haas <didi.debian@cknow.org> - 2023-02-01 20:10 +0100
            Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0)))) "Dr. David Alan Gilbert" <dave@treblig.org> - 2023-02-04 02:10 +0100
              Bug#1029968: bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0 Diederik de Haas <didi.debian@cknow.org> - 2023-02-04 19:10 +0100
    Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0) Diederik de Haas <didi.debian@cknow.org> - 2023-02-01 07:30 +0100
      Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0) "Dr. David Alan Gilbert" <dave@treblig.org> - 2023-02-01 13:00 +0100

#78163 — Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0)

bisected:
GOOD [37fcacb50be7071d146144a6c5c5bf0194b9a1cf] phy: PHY_FSL_LYNX_28G should depend on ARCH_LAYERSCAPE
BAD [f5ff79fddf0efecca538046b5cc20fb3ded2ec4f] dma-mapping: remove CONFIG_DMA_REMAP
GOOD [e62c17f0455a74b182ce6373e2777817256afaa1] MAINTAINERS: update maintainer list of DMA MAPPING BENCHMARK
GOOD [0fb3436b4b36cf69f4544385aa2bb8c5a4913509] sparc: Remove usage of the deprecated "pci-dma-compat.h" API
GOOD [fba09099c6e506608e05e08ac717bf34501f821b] media: v4l2-pci-skeleton: Remove usage of the deprecated "pci-dma-compat.h" API

dg@major:~/kernel/kernel-clone$ git bisect good
f5ff79fddf0efecca538046b5cc20fb3ded2ec4f is the first bad commit
commit f5ff79fddf0efecca538046b5cc20fb3ded2ec4f
Author: Christoph Hellwig <hch@lst.de>
Date:   Sat Feb 26 16:40:21 2022 +0100

    dma-mapping: remove CONFIG_DMA_REMAP

That sounds like a believable cause given that it's IOMMU related
and device related.

-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

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#78164 — Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0))

Note that the oops at this bisect point is messier than on the newer
kernels; the newer kernels hit a WARN in __vmap_pages_range_noflush, where
as at this point it slams into a BUG, but the rest of the backtrace is similar;

[   78.988024] BUG: unable to handle page fault for address: ffffbd7fc1100000
[   78.988033] #PF: supervisor write access in kernel mode
[   78.988036] #PF: error_code(0x000b) - reserved bit violation
[   78.988038] PGD 100000067 P4D 100000067 PUD 1001a6067 PMD 22b791067 PTE 8000270800cb9063
[   78.988046] Oops: 000b [#1] PREEMPT SMP PTI
[   78.988050] CPU: 7 PID: 879 Comm: cat Tainted: G          I       5.17.0-rc1dg+ #20
[   78.988054] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./P55M Pro, BIOS P1.50 09/10/2009
[   78.988056] RIP: 0010:__memset+0x24/0x30
[   78.988063] Code: cc cc cc cc cc cc 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 <f3> 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3
[   78.988067] RSP: 0018:ffffbd7fc0cc7d50 EFLAGS: 00010206
[   78.988071] RAX: 0000000000000000 RBX: ffff9679eb788a88 RCX: 0000000000002000
[   78.988073] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffbd7fc1100000
[   78.988076] RBP: 0000000080000000 R08: 0000000000000000 R09: ffffbd7fc1100000
[   78.988079] R10: 0000000000010000 R11: ffffbd7fc1100000 R12: 0000000000000010
[   78.988081] R13: 0000000000000010 R14: ffff9679ec8e4130 R15: 0000000000000010
[   78.988084] FS:  00007f91fb65a740(0000) GS:ffff9679efdc0000(0000) knlGS:0000000000000000
[   78.988087] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   78.988090] CR2: ffffbd7fc1100000 CR3: 000000022ce02000 CR4: 00000000000006e0
[   78.988093] Call Trace:
[   78.988096]  <TASK>
[   78.988100]  __videobuf_iolock+0x5cd/0x659 [videobuf_dma_sg]
[   78.988110]  vbi_buffer_prepare+0x1aa/0x2b0 [bttv]
[   78.988125]  __videobuf_read_start+0xb9/0x1d0 [videobuf_core]
[   78.988133]  videobuf_read_stream+0x2cb/0x330 [videobuf_core]
[   78.988140]  bttv_read+0xc5/0x1d0 [bttv]
[   78.988151]  v4l2_read+0x6b/0x80 [videodev]
[   78.988169]  vfs_read+0x97/0x190
[   78.988175]  ksys_read+0x63/0xe0
[   78.988179]  do_syscall_64+0x3a/0x80
[   78.988185]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   78.988191] RIP: 0033:0x7f91fb7550ed
[   78.988194] Code: 31 c0 e9 c6 fe ff ff 50 48 8d 3d f6 54 0a 00 e8 39 fe 01 00 66 0f 1f 84 00 00 00 00 00 80 3d f1 24 0e 00 00 74 17 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec
[   78.988198] RSP: 002b:00007ffdad058348 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   78.988202] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f91fb7550ed
[   78.988204] RDX: 0000000000020000 RSI: 00007f91fb350000 RDI: 0000000000000003
[   78.988207] RBP: 0000000000020000 R08: 00000000ffffffff R09: 0000000000000000
[   78.988209] R10: 00007f91fb66cb40 R11: 0000000000000246 R12: 00007f91fb350000
[   78.988212] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000000000
[   78.988216]  </TASK>
[   78.988218] Modules linked in: rfkill qrtr tuner_simple tuner_types intel_powerclamp coretemp tuner snd_hda_codec_via tda7432 kvm_intel snd_hda_codec_generic snd_hda_codec_hdmi tvaudio ledtrig_audio msp3400 snd_hda_intel kvm snd_intel_dspcfg bttv snd_intel_sdw_acpi snd_hda_codec irqbypass tea575x snd_hda_core tveeprom videobuf_dma_sg intel_cstate videobuf_core videodev snd_hwdep snd_bt87x intel_uncore snd_pcm serio_raw pcspkr iTCO_wdt i7core_edac mc joydev intel_pmc_bxt snd_timer iTCO_vendor_support snd watchdog soundcore sg evdev acpi_cpufreq firewire_sbp2 fuse msr configfs efi_pstore ip_tables x_tables autofs4 ext4 crc32c_generic crc16 mbcache jbd2 nouveau sd_mod t10_pi crc_t10dif crct10dif_generic ata_generic crct10dif_common hid_generic usbhid hid mxm_wmi wmi video i2c_algo_bit drm_ttm_helper ttm drm_kms_helper cec rc_core drm ahci libahci pata_via libata ehci_pci ehci_hcd psmouse r8169 usbcore scsi_mod crc32c_intel realtek i2c_i801 mdio_devres i2c_smbus libphy firewire_ohci
[   78.988301]  firewire_core lpc_ich usb_common scsi_common crc_itu_t button
[   78.988311] CR2: ffffbd7fc1100000
[   78.988314] ---[ end trace 0000000000000000 ]---
[   78.988316] RIP: 0010:__memset+0x24/0x30
[   78.988320] Code: cc cc cc cc cc cc 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 <f3> 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3
[   78.988324] RSP: 0018:ffffbd7fc0cc7d50 EFLAGS: 00010206
[   78.988327] RAX: 0000000000000000 RBX: ffff9679eb788a88 RCX: 0000000000002000
[   78.988329] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffbd7fc1100000
[   78.988332] RBP: 0000000080000000 R08: 0000000000000000 R09: ffffbd7fc1100000
[   78.988334] R10: 0000000000010000 R11: ffffbd7fc1100000 R12: 0000000000000010
[   78.988337] R13: 0000000000000010 R14: ffff9679ec8e4130 R15: 0000000000000010
[   78.988340] FS:  00007f91fb65a740(0000) GS:ffff9679efdc0000(0000) knlGS:0000000000000000
[   78.988343] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   78.988346] CR2: ffffbd7fc1100000 CR3: 000000022ce02000 CR4: 00000000000006e0

-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

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#78170 — Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0)))

Confirmed still happens on upstream 6.2.0-rc6
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

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#78172 — Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0))))

I sent this upstream report:
https://lore.kernel.org/linux-iommu/Y9qSwkLxeMpffZK%2F@gallifrey/T/#u
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

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#78174 — Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0))))

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Control: forwarded -1 https://lore.kernel.org/linux-iommu/Y9qSwkLxeMpffZK%2F@gallifrey/

On Wednesday, 1 February 2023 18:46:43 CET Dr. David Alan Gilbert wrote:
> I sent this upstream report:
> https://lore.kernel.org/linux-iommu/Y9qSwkLxeMpffZK%2F@gallifrey/T/#u

Thanks :-) Updated bug accordingly.

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#78184 — Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Info received (Bug#1029968: Acknowledgement (bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0))))

It's a bit messy...

a) The patch I bisected to is not the root cause of the bug; it just
triggers a ~9 year old bug in the v4l code - so this patch isn't going
to get changed.

b) The ~9 year old bug is in a particularly hairy piece of memory management
code  in v4l that I doubt anyone is going to fix.

c) The plan is all the drivers using that API are to either be retired
or rewritten using a new API; that's already been done for some of the
drivers and the bttv one is a few months out.  I'm not sure that's
any use to this version of Debian though.

d) The work arounds are:
  1) Disable iommu
  2) some v4l tools can use an mmap interface rather than the read(2)
interface; that seems to be OK.

Dave

-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

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#78185 — Bug#1029968: bttv/v4l: WARNING: CPU: 6 PID: 6164 at mm/vmalloc.c:487 __vmap_pages_range_noflush+0x3e0/0x4d0

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On Saturday, 4 February 2023 02:06:02 CET Dr. David Alan Gilbert wrote:
> a) The patch I bisected to is not the root cause of the bug; it just
> triggers a ~9 year old bug in the v4l code - so this patch isn't going
> to get changed.
> 
> b) The ~9 year old bug is in a particularly hairy piece of memory management
> code  in v4l that I doubt anyone is going to fix.
> 
> c) The plan is all the drivers using that API are to either be retired
> or rewritten using a new API; that's already been done for some of the
> drivers and the bttv one is a few months out.  I'm not sure that's
> any use to this version of Debian though.
> 
> d) The work arounds are:
>   1) Disable iommu
>   2) some v4l tools can use an mmap interface rather than the read(2)
> interface; that seems to be OK.

Also reading the upstream conversation, that seems like a good summary :)

I could be wrong (ofc), but I doubt this issue will be fixed in kernel 6.1 
which is planned to be Bookworm's kernel.

What you could do is test any patch(es) they put out and provide feedback on 
those and if you find that the patch(es) fixes the/your issue, you could 
consider providing a "Tested-By: yourname <your.email>" which can have a 
positive effect on the maintainer accepting the patch from which it then can 
procede further up the chain to Linus.
When it does end up in Linus' tree and it would need to have a new Kconfig 
option enabled in Debian's kernel, feel free to request that.

I think IOMMU is a really good thing, so disabling that does not sound ideal, 
but it could be an acceptable workaround (for now).
If you want to run Bookworm on your system, you'd probably have to wait till a 
suitable Backports kernel becomes available. If you go for Trixie, you should 
get (in time) the proper fix by just upgrading.

Thanks for all the investigative work and bringing it to upstream :-)

Cheers,
  Diederik

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#78165

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On Wednesday, 1 February 2023 02:52:13 CET Dr. David Alan Gilbert wrote:
> bisected:
> GOOD [37fcacb50be7071d146144a6c5c5bf0194b9a1cf] phy: PHY_FSL_LYNX_28G should
> depend on ARCH_LAYERSCAPE BAD [f5ff79fddf0efecca538046b5cc20fb3ded2ec4f]
> dma-mapping: remove CONFIG_DMA_REMAP GOOD
> [e62c17f0455a74b182ce6373e2777817256afaa1] MAINTAINERS: update maintainer
> list of DMA MAPPING BENCHMARK GOOD
> [0fb3436b4b36cf69f4544385aa2bb8c5a4913509] sparc: Remove usage of the
> deprecated "pci-dma-compat.h" API GOOD
> [fba09099c6e506608e05e08ac717bf34501f821b] media: v4l2-pci-skeleton: Remove
> usage of the deprecated "pci-dma-compat.h" API
> 
> dg@major:~/kernel/kernel-clone$ git bisect good
> f5ff79fddf0efecca538046b5cc20fb3ded2ec4f is the first bad commit
> commit f5ff79fddf0efecca538046b5cc20fb3ded2ec4f
> Author: Christoph Hellwig <hch@lst.de>
> Date:   Sat Feb 26 16:40:21 2022 +0100
> 
>     dma-mapping: remove CONFIG_DMA_REMAP
> 
> That sounds like a believable cause given that it's IOMMU related
> and device related.

Thanks for that thorough analyses!
If you're 'penguin42' on IRC, then I'd suggest to present your findings to
iommu@lists.linux.dev as both the author and the reviewer are highly likely 
subscribed to that list.

scripts/get_maintainer.pl drivers/iommu/dma-iommu.c
scripts/get_maintainer.pl kernel/dma/Makefile

list them both and both results have also that ML in their result.

HTH

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#78167

* Diederik de Haas (didi.debian@cknow.org) wrote:

> Thanks for that thorough analyses!

Thanks for the reply,

> If you're 'penguin42' on IRC,

Yep, that's me.

> then I'd suggest to present your findings to
> iommu@lists.linux.dev as both the author and the reviewer are highly likely 
> subscribed to that list.
> 
> scripts/get_maintainer.pl drivers/iommu/dma-iommu.c
> scripts/get_maintainer.pl kernel/dma/Makefile
> 
> list them both and both results have also that ML in their result.

Yep, will do; I'm just going to try a 6.2rc as well just in case it's
got fixed very recently, and have a poke about in case I can see
any obvious cause now I know the change that triggered it.
I'll include the linux-media list as well since it's just as likely
that it's a fault on the v4l/bttv driver.

Dave

> HTH


-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

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