Panic when starting X with Intel KMS
Michael Butler
imb at protected-networks.net
Mon Jul 22 20:03:28 UTC 2013
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On 07/21/13 03:18, Konstantin Belousov wrote:
> On Sat, Jul 20, 2013 at 01:20:56PM +0200, Oliver Pinter wrote:
>> On 7/20/13, Gustau P?rez i Querol <gperez at entel.upc.edu> wrote:
>>> Reading the backtrace I see this:
>>>
>>> panic: pmap_release: pmap resident count -398580 != 0
>>>
>>> which comes from amd64/amd64/pmap.c:1936. I suspect that
>>> pmap->pm_stats.resident_count being negative is a bug.
>
> The issue happened somewhere before the process exit. Try the patch
> below, the idea is that your overflow count is really big, so the
> wrong-doer could cause underflow when acting.
>
> diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
> index 19be4e0..fcdc6af 100644
> --- a/sys/amd64/amd64/pmap.c
> +++ b/sys/amd64/amd64/pmap.c
> @@ -465,6 +465,9 @@ pmap_resident_count_dec(pmap_t pmap, int count)
> {
>
> PMAP_LOCK_ASSERT(pmap, MA_OWNED);
> + KASSERT(pmap->pm_stats.resident_count >= count,
> + ("pmap %p resident count underflow %ld %d", pmap,
> + pmap->pm_stats.resident_count, count));
> pmap->pm_stats.resident_count -= count;
> }
>
>
Post SVN r252653, I have experienced a similar problem but I'm not sure
it's related ..
root at toshi:/var/crash # less info.1
Dump header from device /dev/ada0s3b
Architecture: i386
Architecture Version: 2
Dump Length: 205541376B (196 MB)
Blocksize: 512
Dumptime: Sat Jul 20 15:21:39 2013
Hostname: toshi.auburn.protected-networks.net
Magic: FreeBSD Kernel Dump
Version String: FreeBSD 10.0-CURRENT #5 r253505M: Sat Jul 20 14:48:32
EDT 2013
imb at toshi.auburn.protected-networks.net:/usr/obj/usr/src/sys/TOSHI
Panic String: bad pte
Dump Parity: 854235148
Bounds: 1
Dump Status: good
root at toshi:/var/crash # kgdb /boot/kernel.old/kernel vmcore.1
[ snip ]
#0 0xc07b814c in doadump ()
(kgdb) bt
#0 0xc07b814c in doadump ()
#1 0xc07b86ec in kern_reboot ()
#2 0xc07b8b68 in panic ()
#3 0xc0b20b1d in pmap_remove_pages ()
#4 0xc0aa43dd in vmspace_exit ()
#5 0xc07814bf in exit1 ()
#6 0xc07ba5d5 in sigexit ()
#7 0xc07bd35f in postsig ()
#8 0xc0804e1b in ast ()
#9 0xc0b132b7 in doreti_ast ()
#10 0xf1633d08 in ?? ()
#11 0x2c00003b in ?? ()
#
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