From: Zachary Amsden <zach@vmware.com>
Date: Sun, 8 Apr 2007 23:04:01 +0000 (-0700)
Subject: [PATCH] Proper fix for highmem kmap_atomic functions for VMI for 2.6.21
X-Git-Tag: v2.6.21-rc7~38
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=49f19710512c825aaea73b9207b3a848027cda1d;p=pandora-kernel.git

[PATCH] Proper fix for highmem kmap_atomic functions for VMI for 2.6.21

Since lazy MMU batching mode still allows interrupts to enter, it is
possible for interrupt handlers to try to use kmap_atomic, which fails when
lazy mode is active, since the PTE update to highmem will be delayed.  The
best workaround is to issue an explicit flush in kmap_atomic_functions
case; this is the only way nested PTE updates can happen in the interrupt
handler.

Thanks to Jeremy Fitzhardinge for noting the bug and suggestions on a fix.

This patch gets reverted again when we start 2.6.22 and the bug gets fixed
differently.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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