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Date: Thu, 4 Oct 2018 09:22:17 +0200
From: Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH v2 2/3] mm/vmstat: skip NR_TLB_REMOTE_FLUSH* properly
Message-ID: <20181004072217.GB22233@dhcp22.suse.cz>
References: <20181001143138.95119-1-jannh@google.com>
 <20181001143138.95119-2-jannh@google.com>
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Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Jann Horn <jannh@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org, Davidlohr Bueso <dave@stgolabs.net>, Oleg Nesterov <oleg@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>, Christoph Lameter <clameter@sgi.com>, Roman Gushchin <guro@fb.com>, Kemi Wang <kemi.wang@intel.com>, Kees Cook <keescook@chromium.org>, Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>

On Mon 01-10-18 16:31:37, Jann Horn wrote:
> commit 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.
> 
> Fixes: 5dd0b16cdaff ("mm/vmstat: Make NR_TLB_REMOTE_FLUSH_RECEIVED available even on UP")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jann Horn <jannh@google.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/vmstat.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 4cea7b8f519d..7878da76abf2 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1275,6 +1275,9 @@ 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",
> -- 
> 2.19.0.605.g01d371f741-goog

-- 
Michal Hocko
SUSE Labs