From a9dadc1c512807f955f0799e85830b420da47932 Mon Sep 17 00:00:00 2001 From: Cédric Le Goater Date: Tue, 8 Aug 2017 11:02:49 +0200 Subject: powerpc/xive: Fix the size of the cpumask used in xive_find_target_in_mask() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When called from xive_irq_startup(), the size of the cpumask can be larger than nr_cpu_ids. This can result in a WARN_ON such as: WARNING: CPU: 10 PID: 1 at ../arch/powerpc/sysdev/xive/common.c:476 xive_find_target_in_mask+0x110/0x2f0 ... NIP [c00000000008a310] xive_find_target_in_mask+0x110/0x2f0 LR [c00000000008a2e4] xive_find_target_in_mask+0xe4/0x2f0 Call Trace: xive_find_target_in_mask+0x74/0x2f0 (unreliable) xive_pick_irq_target.isra.1+0x200/0x230 xive_irq_startup+0x60/0x180 irq_startup+0x70/0xd0 __setup_irq+0x7bc/0x880 request_threaded_irq+0x14c/0x2c0 request_event_sources_irqs+0x100/0x180 __machine_initcall_pseries_init_ras_IRQ+0x104/0x134 do_one_initcall+0x68/0x1d0 kernel_init_freeable+0x290/0x374 kernel_init+0x24/0x170 ret_from_kernel_thread+0x5c/0x74 This happens because we're being called with our affinity mask set to irq_default_affinity. That in turn was populated using cpumask_setall(), which sets NR_CPUs worth of bits, not nr_cpu_ids worth. Finally cpumask_weight() will return > nr_cpu_ids when passed a mask which has > nr_cpu_ids bits set. Fix it by limiting the value returned by cpumask_weight(). Signed-off-by: Cédric Le Goater [mpe: Add change log details on actual cause] Signed-off-by: Michael Ellerman --- arch/powerpc/sysdev/xive/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/powerpc/sysdev/xive/common.c') diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c index 0db4c45bc561..558df6542b1a 100644 --- a/arch/powerpc/sysdev/xive/common.c +++ b/arch/powerpc/sysdev/xive/common.c @@ -447,7 +447,7 @@ static int xive_find_target_in_mask(const struct cpumask *mask, int cpu, first, num, i; /* Pick up a starting point CPU in the mask based on fuzz */ - num = cpumask_weight(mask); + num = min_t(int, cpumask_weight(mask), nr_cpu_ids); first = fuzz % num; /* Locate it */ -- cgit