Patch out the use of mutex's to protect the copy/clear user page
operations. These functions sleep, and therefore the mutex's cause
scheduling while atomic errors. Now this actually opens up the
possiblity of some corruption (not actually seen in practice, but
theoretically possible) and therefore is not the correct fix, but all
proposed replacements have so far been even more problematic.

diff --git a/arch/sh/mm/pg-sh4.c b/arch/sh/mm/pg-sh4.c
index df69da9..7bc36a4 100644
--- a/arch/sh/mm/pg-sh4.c
+++ b/arch/sh/mm/pg-sh4.c
@@ -37,7 +37,7 @@ void clear_user_page(void *to, unsigned 
 		unsigned long flags;
 
 		entry = pfn_pte(phys_addr >> PAGE_SHIFT, PAGE_KERNEL);
-		mutex_lock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
+//		mutex_lock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
 		set_pte(pte, entry);
 		local_irq_save(flags);
 		flush_tlb_one(get_asid(), p3_addr);
@@ -45,7 +45,7 @@ void clear_user_page(void *to, unsigned 
 		update_mmu_cache(NULL, p3_addr, entry);
 		__clear_user_page((void *)p3_addr, to);
 		pte_clear(&init_mm, p3_addr, pte);
-		mutex_unlock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
+//		mutex_unlock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
 	}
 }
 
@@ -73,7 +73,7 @@ void copy_user_page(void *to, void *from
 		unsigned long flags;
 
 		entry = pfn_pte(phys_addr >> PAGE_SHIFT, PAGE_KERNEL);
-		mutex_lock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
+//		mutex_lock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
 		set_pte(pte, entry);
 		local_irq_save(flags);
 		flush_tlb_one(get_asid(), p3_addr);
@@ -81,7 +81,7 @@ void copy_user_page(void *to, void *from
 		update_mmu_cache(NULL, p3_addr, entry);
 		__copy_user_page((void *)p3_addr, from, to);
 		pte_clear(&init_mm, p3_addr, pte);
-		mutex_unlock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
+//		mutex_unlock(&p3map_mutex[(address & CACHE_ALIAS)>>12]);
 	}
 }