From: jak@rudolph.ccur.com (Joe Korty)
Message-Id: <200301050258.CAA01487@rudolph.ccur.com>
Subject: Re: 2.4.21-pre2 stalls out when running unixbench
To: akpm@digeo.com (Andrew Morton)
Date: Sat, 4 Jan 2003 21:58:33 -0500 (EST)
Cc: joe.korty@ccur.com (Joe Korty), sct@redhat.com, adilger@clusterfs.com,
       rusty@rustcorp.com.au, riel@conectiva.com.br,
       linux-kernel@vger.kernel.org, hch@sgi.com
Reply-To: joe.korty@ccur.com (Joe Korty)
In-Reply-To: <3E16C171.BFEA45AE@digeo.com> from "Andrew Morton" at Jan 04, 2003 03:11:45 AM
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> With respect to the lockup problem: it is due to a non-atomic __set_bit()
> in the new buffer_attached() implementation.
> 
> Sure, we don't need atomic semantics for the BH_Attached bit because
> it is always read and modified under a global spinlock.  But *other*
> users of buffer_head.b_state do not run under that lock so the nonatomic
> RMW will stomp on their changes.   2.4.20 does not have this bug.
> 
> Here is a patch:


Hi Andrew,
The patch works (been running the unixbench subset for an hour now).
Your time and effort and very clear explanations are much appreciated.
Thanks,
Joe
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