On Mon, Aug 17, 2020 at 05:04:41PM +0800, Libing Zhou wrote:
> In nmi_check_duration(), the 'whole_msecs' value should
> get from 'duration' to reflect actual time duration,
> but not 'action->max_duration'.
Fixes: 248ed51048c4 ("x86/nmi: Remove irq_work from the long duration NMI
handler")
> Signed-off-by: Libing Zhou <[email protected]>
> ---
> arch/x86/kernel/nmi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
> index 4fc9954a9560..c51ee659e520 100644
> --- a/arch/x86/kernel/nmi.c
> +++ b/arch/x86/kernel/nmi.c
> @@ -102,7 +102,7 @@ fs_initcall(nmi_warning_debugfs);
>
> static void nmi_check_duration(struct nmiaction *action, u64 duration)
> {
> - u64 whole_msecs = READ_ONCE(action->max_duration);
> + u64 whole_msecs = duration;
> int remainder_ns, decimal_msecs;
>
> if (duration < nmi_longest_ns || duration < action->max_duration)
The, IMO, saner solution is:
---
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 4fc9954a9560..47381666d6a5 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -102,7 +102,6 @@ fs_initcall(nmi_warning_debugfs);
static void nmi_check_duration(struct nmiaction *action, u64 duration)
{
- u64 whole_msecs = READ_ONCE(action->max_duration);
int remainder_ns, decimal_msecs;
if (duration < nmi_longest_ns || duration < action->max_duration)
@@ -110,12 +109,12 @@ static void nmi_check_duration(struct nmiaction *action,
u64 duration)
action->max_duration = duration;
- remainder_ns = do_div(whole_msecs, (1000 * 1000));
+ remainder_ns = do_div(duration, (1000 * 1000));
decimal_msecs = remainder_ns / 1000;
printk_ratelimited(KERN_INFO
"INFO: NMI handler (%ps) took too long to run: %lld.%03d
msecs\n",
- action->handler, whole_msecs, decimal_msecs);
+ action->handler, duration, decimal_msecs);
}
static int nmi_handle(unsigned int type, struct pt_regs *regs)
