Patch "x86/mm: Remove the UP asm/tlbflush.h code, always use the (formerly) SMP code" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Dec 21, 2017

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2017-12-21 08:45 UTC #0 lore raw

This is a note to let you know that I've just added the patch titled

x86/mm: Remove the UP asm/tlbflush.h code, always use the (formerly) SMP code

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-mm-remove-the-up-asm-tlbflush.h-code-always-use-the-formerly-smp-code.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From ce4a4e565f5264909a18c733b864c3f74467f69e Mon Sep 17 00:00:00 2001

From: Andy Lutomirski <[email protected]>
Date: Sun, 28 May 2017 10:00:14 -0700
Subject: x86/mm: Remove the UP asm/tlbflush.h code, always use the (formerly) SMP code

From: Andy Lutomirski <[email protected]>

commit ce4a4e565f5264909a18c733b864c3f74467f69e upstream.

The UP asm/tlbflush.h generates somewhat nicer code than the SMP version. Aside from that, it's fallen quite a bit behind the SMP code:

- flush_tlb_mm_range() didn't flush individual pages if the range was small.

- The lazy TLB code was much weaker. This usually wouldn't matter, but, if a kernel thread flushed its lazy "active_mm" more than once (due to reclaim or similar), it wouldn't be unlazied and would instead pointlessly flush repeatedly.

- Tracepoints were missing.

Aside from that, simply having the UP code around was a maintanence burden, since it means that any change to the TLB flush code had to make sure not to break it.

Simplify everything by deleting the UP code.

Signed-off-by Andy Lutomirski <[email protected]>

Cc Andrew Morton <[email protected]>

Cc Arjan van de Ven <[email protected]>

Cc Borislav Petkov <[email protected]>

Cc Dave Hansen <[email protected]>

Cc Linus Torvalds <[email protected]>

Cc Mel Gorman <[email protected]>

Cc Michal Hocko <[email protected]>

Cc Nadav Amit <[email protected]>

Cc Peter Zijlstra <[email protected]>

Cc Rik van Riel <[email protected]>

Cc Thomas Gleixner <[email protected]>

Cc [email protected]

Signed-off-by Ingo Molnar <[email protected]>

Signed-off-by Eduardo Valentin <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 arch/x86/Kconfig                   |    2 
 arch/x86/include/asm/hardirq.h     |    2 
 arch/x86/include/asm/mmu.h         |    6 --
 arch/x86/include/asm/mmu_context.h |    2 
 arch/x86/include/asm/tlbbatch.h    |    2 
 arch/x86/include/asm/tlbflush.h    |   81 -------------------------------------
 arch/x86/mm/init.c                 |    2 
 arch/x86/mm/tlb.c                  |   17 -------
 8 files changed, 5 insertions(+), 109 deletions(-)

arch/x86/Kconfig +1 -1

@@ -45,7 +45,7 @@ config X86
 	select ARCH_USE_CMPXCHG_LOCKREF		if X86_64
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USE_QUEUED_SPINLOCKS
-	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
+	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_IPC_PARSE_VERSION	if X86_32

arch/x86/include/asm/hardirq.h +1 -1

@@ -22,8 +22,8 @@ typedef struct {
 #ifdef CONFIG_SMP
 	unsigned int irq_resched_count;
 	unsigned int irq_call_count;
-	unsigned int irq_tlb_count;
 #endif
+	unsigned int irq_tlb_count;
 #ifdef CONFIG_X86_THERMAL_VECTOR
 	unsigned int irq_thermal_count;
 #endif

arch/x86/include/asm/mmu.h +0 -6

@@ -33,12 +33,6 @@ typedef struct {
 #endif
 } mm_context_t;
 
-#ifdef CONFIG_SMP
 void leave_mm(int cpu);
-#else
-static inline void leave_mm(int cpu)
-{
-}
-#endif
 
 #endif /* _ASM_X86_MMU_H */

arch/x86/include/asm/mmu_context.h +0 -2

@@ -99,10 +99,8 @@ static inline void load_mm_ldt(struct mm
 
 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 {
-#ifdef CONFIG_SMP
 	if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
 		this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
-#endif
 }
 
 static inline int init_new_context(struct task_struct *tsk,

arch/x86/include/asm/tlbbatch.h +0 -2

@@ -3,7 +3,6 @@
 
 #include <linux/cpumask.h>
 
-#ifdef CONFIG_SMP
 struct arch_tlbflush_unmap_batch {
 	/*
 	 * Each bit set is a CPU that potentially has a TLB entry for one of

@@ -11,6 +10,5 @@ struct arch_tlbflush_unmap_batch {
 	 */
 	struct cpumask cpumask;
 };
-#endif
 
 #endif /* _ARCH_X86_TLBBATCH_H */

arch/x86/include/asm/tlbflush.h +1 ~~-80~~

107 lines not on this page · raw message

arch/x86/mm/init.c +0 -2

@@ -764,10 +764,8 @@ void __init zone_sizes_init(void)
 }
 
 DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate) = {
-#ifdef CONFIG_SMP
 	.active_mm = &init_mm,
 	.state = 0,
-#endif
 	.cr4 = ~0UL,	/* fail hard if we screw up cr4 shadow initialization */
 };
 EXPORT_SYMBOL_GPL(cpu_tlbstate);

arch/x86/mm/tlb.c +2 ~~-15~~

@@ -15,7 +15,7 @@
 #include <linux/debugfs.h>
 
 /*
- *	Smarter SMP flushing macros.
+ *	TLB flushing, formerly SMP-only
  *		c/o Linus Torvalds.
  *
  *	These mean you can really definitely utterly forget about

@@ -28,8 +28,6 @@
  *	Implement flush IPI by CALL_FUNCTION_VECTOR, Alex Shi
  */
 
-#ifdef CONFIG_SMP
-
 /*
  * We cannot call mmdrop() because we are in interrupt context,
  * instead update mm->cpu_vm_mask.

@@ -53,8 +51,6 @@ void leave_mm(int cpu)
 }
 EXPORT_SYMBOL_GPL(leave_mm);
 
-#endif /* CONFIG_SMP */
-
 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	       struct task_struct *tsk)
 {

@@ -85,10 +81,8 @@ void switch_mm_irqs_off(struct mm_struct
 				set_pgd(pgd, init_mm.pgd[stack_pgd_index]);
 		}
 
-#ifdef CONFIG_SMP
 		this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
 		this_cpu_write(cpu_tlbstate.active_mm, next);
-#endif
 
 		cpumask_set_cpu(cpu, mm_cpumask(next));

@@ -146,9 +140,7 @@ void switch_mm_irqs_off(struct mm_struct
 		if (unlikely(prev->context.ldt != next->context.ldt))
 			load_mm_ldt(next);
 #endif
-	}
-#ifdef CONFIG_SMP
-	  else {
+	} else {
 		this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
 		BUG_ON(this_cpu_read(cpu_tlbstate.active_mm) != next);

@@ -175,11 +167,8 @@ void switch_mm_irqs_off(struct mm_struct
 			load_mm_ldt(next);
 		}
 	}
-#endif
 }
 
-#ifdef CONFIG_SMP
-
 /*
  * The flush IPI assumes that a thread switch happens in this order:
  * [cpu0: the cpu that switches]

@@ -459,5 +448,3 @@ static int __init create_tlb_single_page
 	return 0;
 }
 late_initcall(create_tlb_single_page_flush_ceiling);
-
-#endif /* CONFIG_SMP */

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/x86-mm-refactor-flush_tlb_mm_range-to-merge-local-and-remote-cases.patch queue-4.9/x86-mm-pass-flush_tlb_info-to-flush_tlb_others-etc.patch queue-4.9/x86-mm-rework-lazy-tlb-to-track-the-actual-loaded-mm.patch queue-4.9/x86-mm-kvm-teach-kvm-s-vmx-code-that-cr3-isn-t-a-constant.patch queue-4.9/x86-mm-use-new-merged-flush-logic-in-arch_tlbbatch_flush.patch queue-4.9/x86-kvm-vmx-simplify-segment_base.patch queue-4.9/x86-entry-unwind-create-stack-frames-for-saved-interrupt-registers.patch queue-4.9/x86-mm-reduce-indentation-in-flush_tlb_func.patch queue-4.9/x86-mm-remove-the-up-asm-tlbflush.h-code-always-use-the-formerly-smp-code.patch queue-4.9/x86-mm-reimplement-flush_tlb_page-using-flush_tlb_mm_range.patch queue-4.9/mm-x86-mm-make-the-batched-unmap-tlb-flush-api-more-generic.patch queue-4.9/x86-kvm-vmx-defer-tr-reload-after-vm-exit.patch queue-4.9/x86-mm-change-the-leave_mm-condition-for-local-tlb-flushes.patch queue-4.9/x86-mm-be-more-consistent-wrt-page_shift-vs-page_size-in-tlb-flush-code.patch