From: Anton Blanchard <anton@samba.org>
To: linux-kernel@vger.kernel.org
Cc: wli@holomorphy.com, akpm@zip.com.au, torvalds@transmeta.com,
jsantos@austin.ibm.com
Subject: [PATCH] Missing memory barrier in pte_chain_unlock
Date: Thu, 25 Jul 2002 10:59:32 +1000 [thread overview]
Message-ID: <20020725005932.GA18140@krispykreme> (raw)
Hi,
On a ppc64 machine running 2.5.28 we were hitting this BUG in
__free_pages_ok:
BUG_ON(page->pte.chain != NULL);
In pte_chain_lock we use test_and_set_bit which implies a memory
barrier. In pte_chain_unlock we use clear_bit which has no memory
barriers so we need to add one.
Anton
===== include/linux/page-flags.h 1.12 vs edited =====
--- 1.12/include/linux/page-flags.h Wed Jul 17 07:46:30 2002
+++ edited/include/linux/page-flags.h Thu Jul 25 19:24:52 2002
@@ -249,6 +248,7 @@
static inline void pte_chain_unlock(struct page *page)
{
+ smp_mb__before_clear_bit();
clear_bit(PG_chainlock, &page->flags);
preempt_enable();
}
next reply other threads:[~2002-07-25 10:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-07-25 0:59 Anton Blanchard [this message]
2002-07-25 18:35 ` [PATCH] Missing memory barrier in pte_chain_unlock Andrew Morton
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