arch, mm: Remove tlb_fast_mode()

Since the introduction of preemptible mmu_gather TLB fast mode has been
broken. TLB fast mode relies on there being absolutely no concurrency;
it frees pages first and invalidates TLBs later.

However now we can get concurrency and stuff goes *bang*.

This patch removes all tlb_fast_mode() code; it was found the better
option vs trying to patch the hole by entangling tlb invalidation with
the scheduler.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 16 deletions

diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index b1b1fa6..13821c3 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -97,11 +97,9 @@ struct mmu_gather {
 	unsigned long		start;
 	unsigned long		end;
 	unsigned int		need_flush : 1,	/* Did free PTEs */
-				fast_mode  : 1; /* No batching   */
-
 	/* we are in the middle of an operation to clear
 	 * a full mm and can make some optimizations */
-	unsigned int		fullmm : 1,
+				fullmm : 1,
 	/* we have performed an operation which
 	 * requires a complete flush of the tlb */
 				need_flush_all : 1;
@@ -114,19 +112,6 @@ struct mmu_gather {
 
 #define HAVE_GENERIC_MMU_GATHER
 
-static inline int tlb_fast_mode(struct mmu_gather *tlb)
-{
-#ifdef CONFIG_SMP
-	return tlb->fast_mode;
-#else
-	/*
-	 * For UP we don't need to worry about TLB flush
-	 * and page free order so much..
-	 */
-	return 1;
-#endif
-}
-
 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm);
 void tlb_flush_mmu(struct mmu_gather *tlb);
 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start,