Merge branch 'for-4.4/hotplug' into libnvdimm-for-next

60 files changed, 346 insertions, 194 deletions

diff --git a/arch/alpha/include/asm/word-at-a-time.h b/arch/alpha/include/asm/word-at-a-time.h
index 6b340d0f1521..902e6ab00a06 100644
--- a/arch/alpha/include/asm/word-at-a-time.h
+++ b/arch/alpha/include/asm/word-at-a-time.h
@@ -52,4 +52,6 @@ static inline unsigned long find_zero(unsigned long bits)
 #endif
 }
 
+#define zero_bytemask(mask) ((2ul << (find_zero(mask) * 8)) - 1)
+
 #endif /* _ASM_WORD_AT_A_TIME_H */
diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
index 233159d2eaab..bb8fa023d574 100644
--- a/arch/arm/boot/dts/Makefile
+++ b/arch/arm/boot/dts/Makefile
@@ -578,7 +578,7 @@ dtb-$(CONFIG_MACH_SUN4I) += \
 	sun4i-a10-hackberry.dtb \
 	sun4i-a10-hyundai-a7hd.dtb \
 	sun4i-a10-inet97fv2.dtb \
-	sun4i-a10-itead-iteaduino-plus.dts \
+	sun4i-a10-itead-iteaduino-plus.dtb \
 	sun4i-a10-jesurun-q5.dtb \
 	sun4i-a10-marsboard.dtb \
 	sun4i-a10-mini-xplus.dtb \
diff --git a/arch/arm/boot/dts/exynos4412.dtsi b/arch/arm/boot/dts/exynos4412.dtsi
index ca0e3c15977f..294cfe40388d 100644
--- a/arch/arm/boot/dts/exynos4412.dtsi
+++ b/arch/arm/boot/dts/exynos4412.dtsi
@@ -98,6 +98,7 @@
 			opp-hz = /bits/ 64 <800000000>;
 			opp-microvolt = <1000000>;
 			clock-latency-ns = <200000>;
+			opp-suspend;
 		};
 		opp07 {
 			opp-hz = /bits/ 64 <900000000>;
diff --git a/arch/arm/boot/dts/exynos5250-smdk5250.dts b/arch/arm/boot/dts/exynos5250-smdk5250.dts
index 15aea760c1da..c625e71217aa 100644
--- a/arch/arm/boot/dts/exynos5250-smdk5250.dts
+++ b/arch/arm/boot/dts/exynos5250-smdk5250.dts
@@ -197,6 +197,7 @@
 				regulator-name = "P1.8V_LDO_OUT10";
 				regulator-min-microvolt = <1800000>;
 				regulator-max-microvolt = <1800000>;
+				regulator-always-on;
 			};
 
 			ldo11_reg: LDO11 {
diff --git a/arch/arm/boot/dts/exynos5420.dtsi b/arch/arm/boot/dts/exynos5420.dtsi
index df9aee92ecf4..1b3d6c769a3c 100644
--- a/arch/arm/boot/dts/exynos5420.dtsi
+++ b/arch/arm/boot/dts/exynos5420.dtsi
@@ -1117,7 +1117,7 @@
 		interrupt-parent = <&combiner>;
 		interrupts = <3 0>;
 		clock-names = "sysmmu", "master";
-		clocks = <&clock CLK_SMMU_FIMD1M0>, <&clock CLK_FIMD1>;
+		clocks = <&clock CLK_SMMU_FIMD1M1>, <&clock CLK_FIMD1>;
 		power-domains = <&disp_pd>;
 		#iommu-cells = <0>;
 	};
diff --git a/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
index 79ffdfe712aa..3b43e57845ae 100644
--- a/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
+++ b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
@@ -472,7 +472,6 @@
 	 */
 	pinctrl-0 = <&pwm0_out &pwm1_out &pwm2_out &pwm3_out>;
 	pinctrl-names = "default";
-	samsung,pwm-outputs = <0>;
 	status = "okay";
 };
 
diff --git a/arch/arm/boot/dts/imx53-qsrb.dts b/arch/arm/boot/dts/imx53-qsrb.dts
index 66e47de5e826..96d7eede412e 100644
--- a/arch/arm/boot/dts/imx53-qsrb.dts
+++ b/arch/arm/boot/dts/imx53-qsrb.dts
@@ -36,7 +36,7 @@
 		pinctrl-0 = <&pinctrl_pmic>;
 		reg = <0x08>;
 		interrupt-parent = <&gpio5>;
-		interrupts = <23 0x8>;
+		interrupts = <23 IRQ_TYPE_LEVEL_HIGH>;
 		regulators {
 			sw1_reg: sw1a {
 				regulator-name = "SW1";
diff --git a/arch/arm/boot/dts/imx53.dtsi b/arch/arm/boot/dts/imx53.dtsi
index c3e3ca9362fb..cd170376eaca 100644
--- a/arch/arm/boot/dts/imx53.dtsi
+++ b/arch/arm/boot/dts/imx53.dtsi
@@ -15,6 +15,7 @@
 #include <dt-bindings/clock/imx5-clock.h>
 #include <dt-bindings/gpio/gpio.h>
 #include <dt-bindings/input/input.h>
+#include <dt-bindings/interrupt-controller/irq.h>
 
 / {
 	aliases {
diff --git a/arch/arm/boot/dts/imx6qdl-rex.dtsi b/arch/arm/boot/dts/imx6qdl-rex.dtsi
index 3373fd958e95..a50356243888 100644
--- a/arch/arm/boot/dts/imx6qdl-rex.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-rex.dtsi
@@ -35,7 +35,6 @@
 			compatible = "regulator-fixed";
 			reg = <1>;
 			pinctrl-names = "default";
-			pinctrl-0 = <&pinctrl_usbh1>;
 			regulator-name = "usbh1_vbus";
 			regulator-min-microvolt = <5000000>;
 			regulator-max-microvolt = <5000000>;
@@ -47,7 +46,6 @@
 			compatible = "regulator-fixed";
 			reg = <2>;
 			pinctrl-names = "default";
-			pinctrl-0 = <&pinctrl_usbotg>;
 			regulator-name = "usb_otg_vbus";
 			regulator-min-microvolt = <5000000>;
 			regulator-max-microvolt = <5000000>;
diff --git a/arch/arm/boot/dts/r8a7790.dtsi b/arch/arm/boot/dts/r8a7790.dtsi
index a0b2a79cbfbd..4624d0f2a754 100644
--- a/arch/arm/boot/dts/r8a7790.dtsi
+++ b/arch/arm/boot/dts/r8a7790.dtsi
@@ -1627,6 +1627,7 @@
 				"mix.0", "mix.1",
 				"dvc.0", "dvc.1",
 				"clk_a", "clk_b", "clk_c", "clk_i";
+		power-domains = <&cpg_clocks>;
 
 		status = "disabled";
 
diff --git a/arch/arm/boot/dts/r8a7791.dtsi b/arch/arm/boot/dts/r8a7791.dtsi
index 831525dd39a6..1666c8a6b143 100644
--- a/arch/arm/boot/dts/r8a7791.dtsi
+++ b/arch/arm/boot/dts/r8a7791.dtsi
@@ -1677,6 +1677,7 @@
 				"mix.0", "mix.1",
 				"dvc.0", "dvc.1",
 				"clk_a", "clk_b", "clk_c", "clk_i";
+		power-domains = <&cpg_clocks>;
 
 		status = "disabled";
 
diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
index 2bebaa286f9a..391230c3dc93 100644
--- a/arch/arm/boot/dts/sun7i-a20.dtsi
+++ b/arch/arm/boot/dts/sun7i-a20.dtsi
@@ -107,7 +107,7 @@
 				720000	1200000
 				528000	1100000
 				312000	1000000
-				144000	900000
+				144000	1000000
 				>;
 			#cooling-cells = <2>;
 			cooling-min-level = <0>;
diff --git a/arch/arm/mach-exynos/mcpm-exynos.c b/arch/arm/mach-exynos/mcpm-exynos.c
index 9bdf54795f05..56978199c479 100644
--- a/arch/arm/mach-exynos/mcpm-exynos.c
+++ b/arch/arm/mach-exynos/mcpm-exynos.c
@@ -20,6 +20,7 @@
 #include <asm/cputype.h>
 #include <asm/cp15.h>
 #include <asm/mcpm.h>
+#include <asm/smp_plat.h>
 
 #include "regs-pmu.h"
 #include "common.h"
@@ -70,7 +71,31 @@ static int exynos_cpu_powerup(unsigned int cpu, unsigned int cluster)
 		cluster >= EXYNOS5420_NR_CLUSTERS)
 		return -EINVAL;
 
-	exynos_cpu_power_up(cpunr);
+	if (!exynos_cpu_power_state(cpunr)) {
+		exynos_cpu_power_up(cpunr);
+
+		/*
+		 * This assumes the cluster number of the big cores(Cortex A15)
+		 * is 0 and the Little cores(Cortex A7) is 1.
+		 * When the system was booted from the Little core,
+		 * they should be reset during power up cpu.
+		 */
+		if (cluster &&
+		    cluster == MPIDR_AFFINITY_LEVEL(cpu_logical_map(0), 1)) {
+			/*
+			 * Before we reset the Little cores, we should wait
+			 * the SPARE2 register is set to 1 because the init
+			 * codes of the iROM will set the register after
+			 * initialization.
+			 */
+			while (!pmu_raw_readl(S5P_PMU_SPARE2))
+				udelay(10);
+
+			pmu_raw_writel(EXYNOS5420_KFC_CORE_RESET(cpu),
+					EXYNOS_SWRESET);
+		}
+	}
+
 	return 0;
 }
 
diff --git a/arch/arm/mach-exynos/regs-pmu.h b/arch/arm/mach-exynos/regs-pmu.h
index b7614333d296..fba9068ed260 100644
--- a/arch/arm/mach-exynos/regs-pmu.h
+++ b/arch/arm/mach-exynos/regs-pmu.h
@@ -513,6 +513,12 @@ static inline unsigned int exynos_pmu_cpunr(unsigned int mpidr)
 #define SPREAD_ENABLE						0xF
 #define SPREAD_USE_STANDWFI					0xF
 
+#define EXYNOS5420_KFC_CORE_RESET0				BIT(8)
+#define EXYNOS5420_KFC_ETM_RESET0				BIT(20)
+
+#define EXYNOS5420_KFC_CORE_RESET(_nr)				\
+	((EXYNOS5420_KFC_CORE_RESET0 | EXYNOS5420_KFC_ETM_RESET0) << (_nr))
+
 #define EXYNOS5420_BB_CON1					0x0784
 #define EXYNOS5420_BB_SEL_EN					BIT(31)
 #define EXYNOS5420_BB_PMOS_EN					BIT(7)
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index f9914d7c1bb0..d10b5d483022 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -42,7 +42,7 @@ endif
 CHECKFLAGS	+= -D__aarch64__
 
 ifeq ($(CONFIG_ARM64_ERRATUM_843419), y)
-CFLAGS_MODULE	+= -mcmodel=large
+KBUILD_CFLAGS_MODULE	+= -mcmodel=large
 endif
 
 # Default value
diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index 3bc498c250dc..41e58fe3c041 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -44,7 +44,7 @@
 #define __ARM_NR_compat_cacheflush	(__ARM_NR_COMPAT_BASE+2)
 #define __ARM_NR_compat_set_tls		(__ARM_NR_COMPAT_BASE+5)
 
-#define __NR_compat_syscalls		388
+#define __NR_compat_syscalls		390
 #endif
 
 #define __ARCH_WANT_SYS_CLONE
diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index cef934a90f17..5b925b761a2a 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -797,3 +797,12 @@ __SYSCALL(__NR_memfd_create, sys_memfd_create)
 __SYSCALL(__NR_bpf, sys_bpf)
 #define __NR_execveat 387
 __SYSCALL(__NR_execveat, compat_sys_execveat)
+#define __NR_userfaultfd 388
+__SYSCALL(__NR_userfaultfd, sys_userfaultfd)
+#define __NR_membarrier 389
+__SYSCALL(__NR_membarrier, sys_membarrier)
+
+/*
+ * Please add new compat syscalls above this comment and update
+ * __NR_compat_syscalls in asm/unistd.h.
+ */
diff --git a/arch/arm64/include/uapi/asm/signal.h b/arch/arm64/include/uapi/asm/signal.h
index 8d1e7236431b..991bf5db2ca1 100644
--- a/arch/arm64/include/uapi/asm/signal.h
+++ b/arch/arm64/include/uapi/asm/signal.h
@@ -19,6 +19,9 @@
 /* Required for AArch32 compatibility. */
 #define SA_RESTORER	0x04000000
 
+#define MINSIGSTKSZ 5120
+#define SIGSTKSZ    16384
+
 #include <asm-generic/signal.h>
 
 #endif
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index cebf78661a55..253021ef2769 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -201,7 +201,7 @@ void unregister_step_hook(struct step_hook *hook)
 }
 
 /*
- * Call registered single step handers
+ * Call registered single step handlers
  * There is no Syndrome info to check for determining the handler.
  * So we call all the registered handlers, until the right handler is
  * found which returns zero.
@@ -271,20 +271,21 @@ static int single_step_handler(unsigned long addr, unsigned int esr,
  * Use reader/writer locks instead of plain spinlock.
  */
 static LIST_HEAD(break_hook);
-static DEFINE_RWLOCK(break_hook_lock);
+static DEFINE_SPINLOCK(break_hook_lock);
 
 void register_break_hook(struct break_hook *hook)
 {
-	write_lock(&break_hook_lock);
-	list_add(&hook->node, &break_hook);
-	write_unlock(&break_hook_lock);
+	spin_lock(&break_hook_lock);
+	list_add_rcu(&hook->node, &break_hook);
+	spin_unlock(&break_hook_lock);
 }
 
 void unregister_break_hook(struct break_hook *hook)
 {
-	write_lock(&break_hook_lock);
-	list_del(&hook->node);
-	write_unlock(&break_hook_lock);
+	spin_lock(&break_hook_lock);
+	list_del_rcu(&hook->node);
+	spin_unlock(&break_hook_lock);
+	synchronize_rcu();
 }
 
 static int call_break_hook(struct pt_regs *regs, unsigned int esr)
@@ -292,11 +293,11 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr)
 	struct break_hook *hook;
 	int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL;
 
-	read_lock(&break_hook_lock);
-	list_for_each_entry(hook, &break_hook, node)
+	rcu_read_lock();
+	list_for_each_entry_rcu(hook, &break_hook, node)
 		if ((esr & hook->esr_mask) == hook->esr_val)
 			fn = hook->fn;
-	read_unlock(&break_hook_lock);
+	rcu_read_unlock();
 
 	return fn ? fn(regs, esr) : DBG_HOOK_ERROR;
 }
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index f341866aa810..c08b9ad6f429 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -85,7 +85,7 @@ bool aarch64_insn_is_branch_imm(u32 insn)
 		aarch64_insn_is_bcond(insn));
 }
 
-static DEFINE_SPINLOCK(patch_lock);
+static DEFINE_RAW_SPINLOCK(patch_lock);
 
 static void __kprobes *patch_map(void *addr, int fixmap)
 {
@@ -131,13 +131,13 @@ static int __kprobes __aarch64_insn_write(void *addr, u32 insn)
 	unsigned long flags = 0;
 	int ret;
 
-	spin_lock_irqsave(&patch_lock, flags);
+	raw_spin_lock_irqsave(&patch_lock, flags);
 	waddr = patch_map(addr, FIX_TEXT_POKE0);
 
 	ret = probe_kernel_write(waddr, &insn, AARCH64_INSN_SIZE);
 
 	patch_unmap(FIX_TEXT_POKE0);
-	spin_unlock_irqrestore(&patch_lock, flags);
+	raw_spin_unlock_irqrestore(&patch_lock, flags);
 
 	return ret;
 }
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 6bab21f84a9f..232247945b1c 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -364,6 +364,8 @@ static void __init relocate_initrd(void)
 		to_free = ram_end - orig_start;
 
 	size = orig_end - orig_start;
+	if (!size)
+		return;
 
 	/* initrd needs to be relocated completely inside linear mapping */
 	new_start = memblock_find_in_range(0, PFN_PHYS(max_pfn),
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index aba9ead1384c..9fadf6d7039b 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -287,6 +287,7 @@ retry:
 			 * starvation.
 			 */
 			mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
+			mm_flags |= FAULT_FLAG_TRIED;
 			goto retry;
 		}
 	}
diff --git a/arch/h8300/include/asm/Kbuild b/arch/h8300/include/asm/Kbuild
index 70e6ae1e7006..373cb23301e3 100644
--- a/arch/h8300/include/asm/Kbuild
+++ b/arch/h8300/include/asm/Kbuild
@@ -73,4 +73,5 @@ generic-y += uaccess.h
 generic-y += ucontext.h
 generic-y += unaligned.h
 generic-y += vga.h
+generic-y += word-at-a-time.h
 generic-y += xor.h
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 9e777cd42b67..d10fd80dbb7e 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -256,6 +256,7 @@ static inline void __iomem * __ioremap_mode(phys_addr_t offset, unsigned long si
  */
 #define ioremap_nocache(offset, size)					\
 	__ioremap_mode((offset), (size), _CACHE_UNCACHED)
+#define ioremap_uc ioremap_nocache
 
 /*
  * ioremap_cachable -	map bus memory into CPU space
diff --git a/arch/mips/include/uapi/asm/swab.h b/arch/mips/include/uapi/asm/swab.h
index c4ddc4f0d2dc..23cd9b118c9e 100644
--- a/arch/mips/include/uapi/asm/swab.h
+++ b/arch/mips/include/uapi/asm/swab.h
@@ -13,16 +13,15 @@
 
 #define __SWAB_64_THRU_32__
 
-#if (defined(__mips_isa_rev) && (__mips_isa_rev >= 2)) ||		\
-    defined(_MIPS_ARCH_LOONGSON3A)
+#if !defined(__mips16) &&					\
+	((defined(__mips_isa_rev) && (__mips_isa_rev >= 2)) ||	\
+	 defined(_MIPS_ARCH_LOONGSON3A))
 
-static inline __attribute__((nomips16)) __attribute_const__
-		__u16 __arch_swab16(__u16 x)
+static inline __attribute_const__ __u16 __arch_swab16(__u16 x)
 {
 	__asm__(
 	"	.set	push			\n"
 	"	.set	arch=mips32r2		\n"
-	"	.set	nomips16		\n"
 	"	wsbh	%0, %1			\n"
 	"	.set	pop			\n"
 	: "=r" (x)
@@ -32,13 +31,11 @@ static inline __attribute__((nomips16)) __attribute_const__
 }
 #define __arch_swab16 __arch_swab16
 
-static inline __attribute__((nomips16)) __attribute_const__
-		__u32 __arch_swab32(__u32 x)
+static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
 {
 	__asm__(
 	"	.set	push			\n"
 	"	.set	arch=mips32r2		\n"
-	"	.set	nomips16		\n"
 	"	wsbh	%0, %1			\n"
 	"	rotr	%0, %0, 16		\n"
 	"	.set	pop			\n"
@@ -54,13 +51,11 @@ static inline __attribute__((nomips16)) __attribute_const__
  * 64-bit kernel on r2 CPUs.
  */
 #ifdef __mips64
-static inline __attribute__((nomips16)) __attribute_const__
-		__u64 __arch_swab64(__u64 x)
+static inline __attribute_const__ __u64 __arch_swab64(__u64 x)
 {
 	__asm__(
 	"	.set	push			\n"
 	"	.set	arch=mips64r2		\n"
-	"	.set	nomips16		\n"
 	"	dsbh	%0, %1			\n"
 	"	dshd	%0, %0			\n"
 	"	.set	pop			\n"
@@ -71,5 +66,5 @@ static inline __attribute__((nomips16)) __attribute_const__
 }
 #define __arch_swab64 __arch_swab64
 #endif /* __mips64 */
-#endif /* MIPS R2 or newer or Loongson 3A */
+#endif /* (not __mips16) and (MIPS R2 or newer or Loongson 3A) */
 #endif /* _ASM_SWAB_H */
diff --git a/arch/powerpc/configs/ppc64_defconfig b/arch/powerpc/configs/ppc64_defconfig
index 6bc0ee4b1070..2c041b535a64 100644
--- a/arch/powerpc/configs/ppc64_defconfig
+++ b/arch/powerpc/configs/ppc64_defconfig
@@ -111,7 +111,7 @@ CONFIG_SCSI_QLA_FC=m
 CONFIG_SCSI_QLA_ISCSI=m
 CONFIG_SCSI_LPFC=m
 CONFIG_SCSI_VIRTIO=m
-CONFIG_SCSI_DH=m
+CONFIG_SCSI_DH=y
 CONFIG_SCSI_DH_RDAC=m
 CONFIG_SCSI_DH_ALUA=m
 CONFIG_ATA=y
diff --git a/arch/powerpc/configs/pseries_defconfig b/arch/powerpc/configs/pseries_defconfig
index 7991f37e5fe2..36871a4bfa54 100644
--- a/arch/powerpc/configs/pseries_defconfig
+++ b/arch/powerpc/configs/pseries_defconfig
@@ -114,7 +114,7 @@ CONFIG_SCSI_QLA_FC=m
 CONFIG_SCSI_QLA_ISCSI=m
 CONFIG_SCSI_LPFC=m
 CONFIG_SCSI_VIRTIO=m
-CONFIG_SCSI_DH=m
+CONFIG_SCSI_DH=y
 CONFIG_SCSI_DH_RDAC=m
 CONFIG_SCSI_DH_ALUA=m
 CONFIG_ATA=y
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index ac1662956e0c..ab9f4e0ed4cf 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -7,4 +7,3 @@ generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += rwsem.h
 generic-y += vtime.h
-generic-y += word-at-a-time.h
diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index cab6753f1be5..3f191f573d4f 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -61,8 +61,13 @@ struct machdep_calls {
 					       unsigned long addr,
 					       unsigned char *hpte_slot_array,
 					       int psize, int ssize, int local);
-	/* special for kexec, to be called in real mode, linear mapping is
-	 * destroyed as well */
+	/*
+	 * Special for kexec.
+	 * To be called in real mode with interrupts disabled. No locks are
+	 * taken as such, concurrent access on pre POWER5 hardware could result
+	 * in a deadlock.
+	 * The linear mapping is destroyed as well.
+	 */
 	void		(*hpte_clear_all)(void);
 
 	void __iomem *	(*ioremap)(phys_addr_t addr, unsigned long size,
diff --git a/arch/powerpc/include/asm/word-at-a-time.h b/arch/powerpc/include/asm/word-at-a-time.h
index 5b3a903adae6..e4396a7d0f7c 100644
--- a/arch/powerpc/include/asm/word-at-a-time.h
+++ b/arch/powerpc/include/asm/word-at-a-time.h