irqchip/gic-v3-its: Cap lpi_id_bits to reduce memory footprint

Jia He · KAGA-KOKO · commit 4cb205c0c50f · 2018-09-06T20:31:59.000+02:00
Commit fe8e935 ("irqchip/gic-v3-its: Use full range of LPIs"), removes the cap for lpi_id_bits, which causes the following warning to trigger on a QDF2400 server: WARNING: CPU: 0 PID: 0 at mm/page_alloc.c:4066 __alloc_pages_nodemask ... Call trace: __alloc_pages_nodemask+0x2d8/0x1188 alloc_pages_current+0x8c/0xd8 its_allocate_prop_table+0x5c/0xb8 its_init+0x220/0x3c0 gic_init_bases+0x250/0x380 gic_acpi_init+0x16c/0x2a4 In its_alloc_lpi_tables(), lpi_id_bits is 24 in QDF2400. The allocation in allocate_prop_table() tries therefore to allocate 16M (order 12 if pagesize=4k), which triggers the warning. As said by MarcL Capping lpi_id_bits at 16 (which is what we had before) is plenty, will save a some memory, and gives some margin before we need to push it up again. Bring the upper limit of lpi_id_bits back to prevent Fixes: fe8e935 ("irqchip/gic-v3-its: Use full range of LPIs") Suggested-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Jia He <jia.he@hxt-semitech.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Tested-by: Olof Johansson <olof@lixom.net> Cc: Jason Cooper <jason@lakedaemon.net> Cc: linux-arm-kernel@lists.infradead.org Link: https://lkml.kernel.org/r/1535432006-2304-1-git-send-email-jia.he@hxt-semitech.com
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
@@ -1439,6 +1439,7 @@ static struct irq_chip its_irq_chip = {
  * The consequence of the above is that allocation is cost is low, but
  * freeing is expensive. We assumes that freeing rarely occurs.
  */
+#define ITS_MAX_LPI_NRBITS	16 /* 64K LPIs */
 
 static DEFINE_MUTEX(lpi_range_lock);
 static LIST_HEAD(lpi_range_list);
@@ -1625,7 +1626,8 @@ static int __init its_alloc_lpi_tables(void)
 {
 	phys_addr_t paddr;
 
-	lpi_id_bits = GICD_TYPER_ID_BITS(gic_rdists->gicd_typer);
+	lpi_id_bits = min_t(u32, GICD_TYPER_ID_BITS(gic_rdists->gicd_typer),
+				ITS_MAX_LPI_NRBITS);
 	gic_rdists->prop_page = its_allocate_prop_table(GFP_NOWAIT);
 	if (!gic_rdists->prop_page) {
 		pr_err("Failed to allocate PROPBASE\n");
