linux-kernel - [PATCH 3.16 301/328] mm/vmstat.c: skip NR_TLB_REMOTE

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Date:   Sun, 09 Dec 2018 21:50:33 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Oleg Nesterov" <oleg@...hat.com>,
        "Davidlohr Bueso" <dave@...olabs.net>,
        "Ingo Molnar" <mingo@...nel.org>,
        "Kemi Wang" <kemi.wang@...el.com>, "Jann Horn" <jannh@...gle.com>,
        "Christoph Lameter" <clameter@....com>,
        "Kees Cook" <keescook@...omium.org>,
        "Michal Hocko" <mhocko@...e.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Andy Lutomirski" <luto@...nel.org>, "Roman Gushchin" <guro@...com>
Subject: [PATCH 3.16 301/328] mm/vmstat.c: skip NR_TLB_REMOTE_FLUSH* properly

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jann Horn <jannh@...gle.com>

commit 58bc4c34d249bf1bc50730a9a209139347cfacfe upstream.

5dd0b16cdaff ("mm/vmstat: Make NR_TLB_REMOTE_FLUSH_RECEIVED available even
on UP") made the availability of the NR_TLB_REMOTE_FLUSH* counters inside
the kernel unconditional to reduce #ifdef soup, but (either to avoid
showing dummy zero counters to userspace, or because that code was missed)
didn't update the vmstat_array, meaning that all following counters would
be shown with incorrect values.

This only affects kernel builds with
CONFIG_VM_EVENT_COUNTERS=y && CONFIG_DEBUG_TLBFLUSH=y && CONFIG_SMP=n.

Link: http://lkml.kernel.org/r/20181001143138.95119-2-jannh@google.com
Fixes: 5dd0b16cdaff ("mm/vmstat: Make NR_TLB_REMOTE_FLUSH_RECEIVED available even on UP")
Signed-off-by: Jann Horn <jannh@...gle.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Acked-by: Michal Hocko <mhocko@...e.com>
Acked-by: Roman Gushchin <guro@...com>
Cc: Davidlohr Bueso <dave@...olabs.net>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Christoph Lameter <clameter@....com>
Cc: Kemi Wang <kemi.wang@...el.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 mm/vmstat.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -864,6 +864,9 @@ const char * const vmstat_text[] = {
 #ifdef CONFIG_SMP
 	"nr_tlb_remote_flush",
 	"nr_tlb_remote_flush_received",
+#else
+	"", /* nr_tlb_remote_flush */
+	"", /* nr_tlb_remote_flush_received */
 #endif /* CONFIG_SMP */
 	"nr_tlb_local_flush_all",
 	"nr_tlb_local_flush_one",