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100% iowait on one of cpus in current -git

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From: Maxim Levitsky
Subject: 100% iowait on one of cpus in current -git
Date: Sunday, October 21, 2007 - 11:22 pm

Hi,

I found a bug in current -git:

On my system on of cpus stays 100% in iowait mode (I have core 2 duo)
Otherwise the system works OK, no disk activity and/or slowdown.
Suspecting that this is a swap-related problem I tried to turn swap of, but it doesn't affect anything.
It is probably some accounting bug.

If I start with init=/bin/bash, then this disappears.
I tried then to start usual /etc/init.d scripts then, and first one to show this bug was gpm.
but then I rebooted the system to X without gpm, and I still see 100% iowait.

No additional messages in dmesg.

I tried to bisect this, but eventually I run into other bugs that cause system to oops early.


This is very rough estimate of the bug location:


HEAD
......
c8f30ae54714abf494d79826d90b5e4844fbf355 - has the above bug, but otherwise works properly
.....
5c8e191e8437616a498a8e1cc0af3dd0d32bbff2 - fails early
.....
f4a1c2bce002f683801bcdbbc9fd89804614fb6b - last known working revision


Best regards,
	Maxim Levitsky

PS: .config attached.
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Messages in current thread:
100% iowait on one of cpus in current -git, Maxim Levitsky, (Sun Oct 21, 11:22 pm)
Re: 100% iowait on one of cpus in current -git, Paolo Ornati, (Mon Oct 22, 2:11 am)
Re: 100% iowait on one of cpus in current -git, Peter Zijlstra, (Mon Oct 22, 2:41 am)
Re: 100% iowait on one of cpus in current -git, Maxim Levitsky, (Mon Oct 22, 2:43 am)
Re: 100% iowait on one of cpus in current -git, Maxim Levitsky, (Mon Oct 22, 2:59 am)
Re: 100% iowait on one of cpus in current -git, Peter Zijlstra, (Mon Oct 22, 3:22 am)
Re: 100% iowait on one of cpus in current -git, Maxim Levitsky, (Mon Oct 22, 3:40 am)
Re: 100% iowait on one of cpus in current -git, Fengguang Wu, (Mon Oct 22, 3:55 am)
Re: 100% iowait on one of cpus in current -git, Maxim Levitsky, (Mon Oct 22, 3:58 am)
Re: 100% iowait on one of cpus in current -git, Fengguang Wu, (Mon Oct 22, 4:19 am)
Re: 100% iowait on one of cpus in current -git, Maxim Levitsky, (Mon Oct 22, 5:21 am)
Re: 100% iowait on one of cpus in current -git, Fengguang Wu, (Mon Oct 22, 5:37 am)
Re: 100% iowait on one of cpus in current -git, Maxim Levitsky, (Mon Oct 22, 6:05 am)
Re: 100% iowait on one of cpus in current -git, Fengguang Wu, (Mon Oct 22, 6:10 am)
Re: 100% iowait on one of cpus in current -git, Maxim Levitsky, (Mon Oct 22, 6:28 am)
[PATCH] reiserfs: don't drop PG_dirty when releasing sub-p ..., Fengguang Wu, (Tue Oct 23, 12:55 am)
Re: [PATCH] reiserfs: don't drop PG_dirty when releasing s ..., Peter Zijlstra, (Tue Oct 23, 3:07 am)
Re: [PATCH] reiserfs: don't drop PG_dirty when releasing s ..., Maxim Levitsky, (Tue Oct 23, 3:17 am)
Re: [PATCH] reiserfs: don't drop PG_dirty when releasing s ..., Fengguang Wu, (Tue Oct 23, 4:56 am)
Re: [PATCH] reiserfs: don't drop PG_dirty when releasing s ..., Chris Mason, (Tue Oct 23, 7:10 am)
Re: [PATCH] reiserfs: don't drop PG_dirty when releasing s ..., Fengguang Wu, (Tue Oct 23, 7:40 am)
Re: [PATCH] reiserfs: don't drop PG_dirty when releasing s ..., Fengguang Wu, (Tue Oct 23, 7:41 am)