[PATCH] ttm_get_pages() will OOPS with highmem allocation

[Jonathan Morton <jonathan.morton@movial.com>]

Reposting from this kernel bug:
https://bugzilla.kernel.org/show_bug.cgi?id=50241

I've tested the patch and it solves a highly repeatable OOPS with the
CedarView driver that I'm porting.


>From 3552913d3a1c2d3c4ce158e91dc18cd12b522cb2 Mon Sep 17 00:00:00 2001
From: Yakui Zhao <yakui.zhao@intel.com>
Date: Tue, 7 Feb 2012 15:33:13 -0500
Subject: [PATCH] Clear the ttm page allocated from high memory zone correctly

The TTM page can be allocated from high memory. In such case it is
wrong to use the page_address(page) as the virtual address for the high memory
page.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
---
 drivers/gpu/drm/ttm/ttm_page_alloc.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index d948575..df976d9 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -708,7 +708,10 @@ int ttm_get_pages(struct list_head *pages, int flags,
 	/* clear the pages coming from the pool if requested */
 	if (flags & TTM_PAGE_FLAG_ZERO_ALLOC) {
 		list_for_each_entry(p, pages, lru) {
-			clear_page(page_address(p));
+			if (PageHighMem(p))
+				clear_highpage(p);
+			else
+				clear_page(page_address(p));
 		}
 	}
 
-- 
1.7.7.6



-- 
From: Jonathan Morton
      jonathan.morton@movial.com