Re: 2.4.21-pre2 stalls out when running unixbench

From: Joe Korty (jak@rudolph.ccur.com)
Date: Sat Jan 04 2003 - 21:58:33 EST


> 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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