x86/mm: remove vmalloc faulting

Remove fault handling on vmalloc areas, as the vmalloc code now takes
care of synchronizing changes to all page-tables in the system.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200515140023.25469-8-joro@8bytes.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 23 deletions

diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index 0e059b73437b..9f69cc497f4b 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -12,27 +12,6 @@ struct task_struct *__switch_to_asm(struct task_struct *prev,
 __visible struct task_struct *__switch_to(struct task_struct *prev,
 					  struct task_struct *next);
 
-/* This runs runs on the previous thread's stack. */
-static inline void prepare_switch_to(struct task_struct *next)
-{
-#ifdef CONFIG_VMAP_STACK
-	/*
-	 * If we switch to a stack that has a top-level paging entry
-	 * that is not present in the current mm, the resulting #PF will
-	 * will be promoted to a double-fault and we'll panic.  Probe
-	 * the new stack now so that vmalloc_fault can fix up the page
-	 * tables if needed.  This can only happen if we use a stack
-	 * in vmap space.
-	 *
-	 * We assume that the stack is aligned so that it never spans
-	 * more than one top-level paging entry.
-	 *
-	 * To minimize cache pollution, just follow the stack pointer.
-	 */
-	READ_ONCE(*(unsigned char *)next->thread.sp);
-#endif
-}
-
 asmlinkage void ret_from_fork(void);
 
 /*
@@ -67,8 +46,6 @@ struct fork_frame {
 
 #define switch_to(prev, next, last)					\
 do {									\
-	prepare_switch_to(next);					\
-									\
 	((last) = __switch_to_asm((prev), (next)));			\
 } while (0)