From bc88ef663265676419555df2dc469a471c0add31 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Sat, 21 Jan 2023 19:53:52 +1000 Subject: [PATCH] powerpc/64s: Fix local irq disable when PMIs are disabled When PMI interrupts are soft-masked, local_irq_save() will clear the PMI mask bit, allowing PMIs in and causing a race condition. This causes a deadlock in native_hpte_insert via hash_preload, which depends on PMIs being disabled since commit 8b91cee5eadd ("powerpc/64s/hash: Make hash faults work in NMI context"). native_hpte_insert calls local_irq_save(). It's possible the lpar hash code is also affected when tracing is enabled because __trace_hcall_entry() calls local_irq_save(). Fix this by making arch_local_irq_save() _or_ the IRQS_DISABLED bit into the mask. This was found with the stress_hpt option with a kbuild workload running together with `perf record -g`. Fixes: f442d004806e ("powerpc/64s: Add support to mask perf interrupts and replay them") Fixes: 8b91cee5eadd ("powerpc/64s/hash: Make hash faults work in NMI context") Signed-off-by: Nicholas Piggin [mpe: Just take the fix without the new warning] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230121095352.2823517-1-npiggin@gmail.com --- arch/powerpc/include/asm/hw_irq.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h index 77fa88c..0b7d01d 100644 --- a/arch/powerpc/include/asm/hw_irq.h +++ b/arch/powerpc/include/asm/hw_irq.h @@ -192,7 +192,7 @@ static inline void arch_local_irq_enable(void) static inline unsigned long arch_local_irq_save(void) { - return irq_soft_mask_set_return(IRQS_DISABLED); + return irq_soft_mask_or_return(IRQS_DISABLED); } static inline bool arch_irqs_disabled_flags(unsigned long flags) -- 2.7.4