RAS/CEC: Reduce offline page threshold for Intel systems

A large scale study of memory errors on Intel systems in data centers
showed that aggressively taking pages with corrected errors offline is
the best strategy of using corrected errors as a predictor of future
uncorrected errors.

Set the threshold to "2" on Intel systems. AMD guidance is that this is
not necessary for their systems.

Signed-off-by: Tony Luck <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Yazen Ghannam <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/YulOZ/[email protected]

Author: aegl

drivers/ras/cec.c

@@ -556,6 +556,14 @@ static int __init cec_init(void)
 	if (ce_arr.disabled)
 		return -ENODEV;
 
+	/*
+	 * Intel systems may avoid uncorrectable errors
+	 * if pages with corrected errors are aggressively
+	 * taken offline.
+	 */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+		action_threshold = 2;
+
 	ce_arr.array = (void *)get_zeroed_page(GFP_KERNEL);
 	if (!ce_arr.array) {
 		pr_err("Error allocating CE array page!\n");