Patch "x86/mm: Remove superfluous barriers" has been added to the 4.14-stable tree

Patch "x86/mm: Remove superfluous barriers" has been added to the 4.14-stable tree

[gregkh]

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

    x86/mm: Remove superfluous barriers

to the 4.14-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-superfluous-barriers.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b5fc6d943808b570bdfbec80f40c6b3855f1c48b Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 5 Dec 2017 13:34:46 +0100
Subject: x86/mm: Remove superfluous barriers

From: Peter Zijlstra <peterz@infradead.org>

commit b5fc6d943808b570bdfbec80f40c6b3855f1c48b upstream.

atomic64_inc_return() already implies smp_mb() before and after.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/include/asm/tlbflush.h |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -60,19 +60,13 @@ static inline void invpcid_flush_all_non
 
 static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
 {
-	u64 new_tlb_gen;
-
 	/*
 	 * Bump the generation count.  This also serves as a full barrier
 	 * that synchronizes with switch_mm(): callers are required to order
 	 * their read of mm_cpumask after their writes to the paging
 	 * structures.
 	 */
-	smp_mb__before_atomic();
-	new_tlb_gen = atomic64_inc_return(&mm->context.tlb_gen);
-	smp_mb__after_atomic();
-
-	return new_tlb_gen;
+	return atomic64_inc_return(&mm->context.tlb_gen);
 }
 
 #ifdef CONFIG_PARAVIRT


Patches currently in stable-queue which might be from peterz@infradead.org are

queue-4.14/x86-entry-rename-sysenter_stack-to-cpu_entry_area_entry_stack.patch
queue-4.14/x86-mm-put-mmu-to-hardware-asid-translation-in-one-place.patch
queue-4.14/x86-vsyscall-64-explicitly-set-_page_user-in-the-pagetable-hierarchy.patch
queue-4.14/x86-uv-use-the-right-tlb-flush-api.patch
queue-4.14/x86-decoder-fix-and-update-the-opcodes-map.patch
queue-4.14/x86-mm-dump_pagetables-check-page_present-for-real.patch
queue-4.14/x86-ldt-prevent-ldt-inheritance-on-exec.patch
queue-4.14/x86-microcode-dont-abuse-the-tlb-flush-interface.patch
queue-4.14/x86-doc-remove-obvious-weirdnesses-from-the-x86-mm-layout-documentation.patch
queue-4.14/init-invoke-init_espfix_bsp-from-mm_init.patch
queue-4.14/x86-cpu_entry_area-move-it-to-a-separate-unit.patch
queue-4.14/x86-vsyscall-64-warn-and-fail-vsyscall-emulation-in-native-mode.patch
queue-4.14/x86-mm-create-asm-invpcid.h.patch
queue-4.14/x86-mm-remove-superfluous-barriers.patch
queue-4.14/x86-ldt-rework-locking.patch
queue-4.14/arch-mm-allow-arch_dup_mmap-to-fail.patch
queue-4.14/x86-cpu_entry_area-move-it-out-of-the-fixmap.patch
queue-4.14/tools-headers-sync-objtool-uapi-header.patch
queue-4.14/x86-mm-remove-hard-coded-asid-limit-checks.patch
queue-4.14/x86-kconfig-limit-nr_cpus-on-32-bit-to-a-sane-amount.patch
queue-4.14/objtool-fix-64-bit-build-on-32-bit-host.patch
queue-4.14/x86-mm-add-comments-to-clarify-which-tlb-flush-functions-are-supposed-to-flush-what.patch
queue-4.14/x86-mm-move-the-cr3-construction-functions-to-tlbflush.h.patch
queue-4.14/x86-mm-dump_pagetables-make-the-address-hints-correct-and-readable.patch
queue-4.14/x86-insn-eval-add-utility-functions-to-get-segment-selector.patch
queue-4.14/objtool-move-synced-files-to-their-original-relative-locations.patch
queue-4.14/x86-mm-use-__flush_tlb_one-for-kernel-memory.patch
queue-4.14/objtool-move-kernel-headers-code-sync-check-to-a-script.patch
queue-4.14/x86-mm-64-improve-the-memory-map-documentation.patch
queue-4.14/objtool-fix-cross-build.patch