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From: David Gibson <david@gibson.dropbear.id.au>
To: Andrew Morton <akpm@digeo.com>
Cc: Anton Blanchard <anton@samba.org>,
	linuxppc64-dev@lists.linuxppc.org, linux-kernel@vger.kernel.org
Subject: [PPC64] Bug fix for hugepages on ppc64
Date: Tue, 20 Jan 2004 17:21:11 +1100	[thread overview]
Message-ID: <20040120062111.GG6455@zax> (raw)

Andrew, please apply.

Currently the flag indicating whether or not hugepages are allowed
below 4GB is not correctly propagated across fork(), which can lead to
oopses.  The patch below fixes this.

diff -urN ppc64-linux-2.5/include/asm-ppc64/mmu_context.h linux-gogogo/include/asm-ppc64/mmu_context.h
--- ppc64-linux-2.5/include/asm-ppc64/mmu_context.h	2003-12-18 09:29:18.000000000 +1100
+++ linux-gogogo/include/asm-ppc64/mmu_context.h	2004-01-19 15:36:43.518987021 +1100
@@ -81,6 +81,8 @@
 {
 	long head;
 	unsigned long flags;
+	/* This does the right thing across a fork (I hope) */
+	unsigned long low_hpages = mm->context & CONTEXT_LOW_HPAGES;
 
 	spin_lock_irqsave(&mmu_context_queue.lock, flags);
 
@@ -91,6 +93,7 @@
 
 	head = mmu_context_queue.head;
 	mm->context = mmu_context_queue.elements[head];
+	mm->context |= low_hpages;
 
 	head = (head < LAST_USER_CONTEXT-1) ? head+1 : 0;
 	mmu_context_queue.head = head;


-- 
David Gibson			| For every complex problem there is a
david AT gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson

                 reply	other threads:[~2004-01-20  6:21 UTC|newest]

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