Merge branch 'perf/urgent' into perf/core

Merge this branch to pick up a fixlet and to update to a more recent base.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

21 files changed, 136 insertions, 63 deletions

diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
index be6d9e365a8..3470624d783 100644
--- a/arch/x86/crypto/aesni-intel_asm.S
+++ b/arch/x86/crypto/aesni-intel_asm.S
@@ -2460,10 +2460,12 @@ ENTRY(aesni_cbc_dec)
 	pxor IN3, STATE4
 	movaps IN4, IV
 #else
-	pxor (INP), STATE2
-	pxor 0x10(INP), STATE3
 	pxor IN1, STATE4
 	movaps IN2, IV
+	movups (INP), IN1
+	pxor IN1, STATE2
+	movups 0x10(INP), IN2
+	pxor IN2, STATE3
 #endif
 	movups STATE1, (OUTP)
 	movups STATE2, 0x10(OUTP)
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index daeca56211e..673ac9b63d6 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -38,7 +38,7 @@
 int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
 {
 	int err = 0;
-	bool ia32 = is_ia32_task();
+	bool ia32 = test_thread_flag(TIF_IA32);
 
 	if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
 		return -EFAULT;
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 340ee49961a..f91e80f4f18 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -176,7 +176,7 @@
 #define X86_FEATURE_XSAVEOPT	(7*32+ 4) /* Optimized Xsave */
 #define X86_FEATURE_PLN		(7*32+ 5) /* Intel Power Limit Notification */
 #define X86_FEATURE_PTS		(7*32+ 6) /* Intel Package Thermal Status */
-#define X86_FEATURE_DTS		(7*32+ 7) /* Digital Thermal Sensor */
+#define X86_FEATURE_DTHERM	(7*32+ 7) /* Digital Thermal Sensor */
 #define X86_FEATURE_HW_PSTATE	(7*32+ 8) /* AMD HW-PState */
 
 /* Virtualization flags: Linux defined, word 8 */
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index 43876f16caf..cb00ccc7d57 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -47,16 +47,26 @@ static inline void native_set_pte(pte_t *ptep, pte_t pte)
  * they can run pmd_offset_map_lock or pmd_trans_huge or other pmd
  * operations.
  *
- * Without THP if the mmap_sem is hold for reading, the
- * pmd can only transition from null to not null while pmd_read_atomic runs.
- * So there's no need of literally reading it atomically.
+ * Without THP if the mmap_sem is hold for reading, the pmd can only
+ * transition from null to not null while pmd_read_atomic runs. So
+ * we can always return atomic pmd values with this function.
  *
  * With THP if the mmap_sem is hold for reading, the pmd can become
- * THP or null or point to a pte (and in turn become "stable") at any
- * time under pmd_read_atomic, so it's mandatory to read it atomically
- * with cmpxchg8b.
+ * trans_huge or none or point to a pte (and in turn become "stable")
+ * at any time under pmd_read_atomic. We could read it really
+ * atomically here with a atomic64_read for the THP enabled case (and
+ * it would be a whole lot simpler), but to avoid using cmpxchg8b we
+ * only return an atomic pmdval if the low part of the pmdval is later
+ * found stable (i.e. pointing to a pte). And we're returning a none
+ * pmdval if the low part of the pmd is none. In some cases the high
+ * and low part of the pmdval returned may not be consistent if THP is
+ * enabled (the low part may point to previously mapped hugepage,
+ * while the high part may point to a more recently mapped hugepage),
+ * but pmd_none_or_trans_huge_or_clear_bad() only needs the low part
+ * of the pmd to be read atomically to decide if the pmd is unstable
+ * or not, with the only exception of when the low part of the pmd is
+ * zero in which case we return a none pmd.
  */
-#ifndef CONFIG_TRANSPARENT_HUGEPAGE
 static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 {
 	pmdval_t ret;
@@ -74,12 +84,6 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
 
 	return (pmd_t) { ret };
 }
-#else /* CONFIG_TRANSPARENT_HUGEPAGE */
-static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
-{
-	return (pmd_t) { atomic64_read((atomic64_t *)pmdp) };
-}
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
 {
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 8afb6931981..b2297e58c6e 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -422,12 +422,14 @@ acpi_parse_int_src_ovr(struct acpi_subtable_header * header,
 		return 0;
 	}
 
-	if (intsrc->source_irq == 0 && intsrc->global_irq == 2) {
+	if (intsrc->source_irq == 0) {
 		if (acpi_skip_timer_override) {
-			printk(PREFIX "BIOS IRQ0 pin2 override ignored.\n");
+			printk(PREFIX "BIOS IRQ0 override ignored.\n");
 			return 0;
 		}
-		if (acpi_fix_pin2_polarity && (intsrc->inti_flags & ACPI_MADT_POLARITY_MASK)) {
+
+		if ((intsrc->global_irq == 2) && acpi_fix_pin2_polarity
+			&& (intsrc->inti_flags & ACPI_MADT_POLARITY_MASK)) {
 			intsrc->inti_flags &= ~ACPI_MADT_POLARITY_MASK;
 			printk(PREFIX "BIOS IRQ0 pin2 override: forcing polarity to high active.\n");
 		}
@@ -1334,17 +1336,12 @@ static int __init dmi_disable_acpi(const struct dmi_system_id *d)
 }
 
 /*
- * Force ignoring BIOS IRQ0 pin2 override
+ * Force ignoring BIOS IRQ0 override
  */
 static int __init dmi_ignore_irq0_timer_override(const struct dmi_system_id *d)
 {
-	/*
-	 * The ati_ixp4x0_rev() early PCI quirk should have set
-	 * the acpi_skip_timer_override flag already:
-	 */
 	if (!acpi_skip_timer_override) {
-		WARN(1, KERN_ERR "ati_ixp4x0 quirk not complete.\n");
-		pr_notice("%s detected: Ignoring BIOS IRQ0 pin2 override\n",
+		pr_notice("%s detected: Ignoring BIOS IRQ0 override\n",
 			d->ident);
 		acpi_skip_timer_override = 1;
 	}
@@ -1438,7 +1435,7 @@ static struct dmi_system_id __initdata acpi_dmi_table_late[] = {
 	 * is enabled.  This input is incorrectly designated the
 	 * ISA IRQ 0 via an interrupt source override even though
 	 * it is wired to the output of the master 8259A and INTIN0
-	 * is not connected at all.  Force ignoring BIOS IRQ0 pin2
+	 * is not connected at all.  Force ignoring BIOS IRQ0
 	 * override in that cases.
 	 */
 	{
@@ -1473,6 +1470,14 @@ static struct dmi_system_id __initdata acpi_dmi_table_late[] = {
 		     DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq 6715b"),
 		     },
 	 },
+	{
+	 .callback = dmi_ignore_irq0_timer_override,
+	 .ident = "FUJITSU SIEMENS",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "AMILO PRO V2030"),
+		     },
+	 },
 	{}
 };
 
diff --git a/arch/x86/kernel/cpu/mkcapflags.pl b/arch/x86/kernel/cpu/mkcapflags.pl
index dfea390e160..c7b3fe2d72e 100644
--- a/arch/x86/kernel/cpu/mkcapflags.pl
+++ b/arch/x86/kernel/cpu/mkcapflags.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/perl -w
 #
 # Generate the x86_cap_flags[] array from include/asm-x86/cpufeature.h
 #
@@ -11,22 +11,35 @@ open(OUT, "> $out\0") or die "$0: cannot create: $out: $!\n";
 print OUT "#include <asm/cpufeature.h>\n\n";
 print OUT "const char * const x86_cap_flags[NCAPINTS*32] = {\n";
 
+%features = ();
+$err = 0;
+
 while (defined($line = <IN>)) {
 	if ($line =~ /^\s*\#\s*define\s+(X86_FEATURE_(\S+))\s+(.*)$/) {
 		$macro = $1;
-		$feature = $2;
+		$feature = "\L$2";
 		$tail = $3;
 		if ($tail =~ /\/\*\s*\"([^"]*)\".*\*\//) {
-			$feature = $1;
+			$feature = "\L$1";
 		}
 
-		if ($feature ne '') {
-			printf OUT "\t%-32s = \"%s\",\n",
-				"[$macro]", "\L$feature";
+		next if ($feature eq '');
+
+		if ($features{$feature}++) {
+			print STDERR "$in: duplicate feature name: $feature\n";
+			$err++;
 		}
+		printf OUT "\t%-32s = \"%s\",\n", "[$macro]", $feature;
 	}
 }
 print OUT "};\n";
 
 close(IN);
 close(OUT);
+
+if ($err) {
+	unlink($out);
+	exit(1);
+}
+
+exit(0);
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 6d32aefc9db..69d5feadab2 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1859,7 +1859,7 @@ unsigned long perf_misc_flags(struct pt_regs *regs)
 		else
 			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
 	} else {
-		if (user_mode(regs))
+		if (!kernel_ip(regs->ip))
 			misc |= PERF_RECORD_MISC_USER;
 		else
 			misc |= PERF_RECORD_MISC_KERNEL;
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index addf9e82a7f..ee8e9abc859 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -31,7 +31,7 @@ void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c)
 	const struct cpuid_bit *cb;
 
 	static const struct cpuid_bit __cpuinitconst cpuid_bits[] = {
-		{ X86_FEATURE_DTS,		CR_EAX, 0, 0x00000006, 0 },
+		{ X86_FEATURE_DTHERM,		CR_EAX, 0, 0x00000006, 0 },
 		{ X86_FEATURE_IDA,		CR_EAX, 1, 0x00000006, 0 },
 		{ X86_FEATURE_ARAT,		CR_EAX, 2, 0x00000006, 0 },
 		{ X86_FEATURE_PLN,		CR_EAX, 4, 0x00000006, 0 },
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8bfb6146f75..3f61904365c 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -444,12 +444,12 @@ void kgdb_roundup_cpus(unsigned long flags)
 
 /**
  *	kgdb_arch_handle_exception - Handle architecture specific GDB packets.
- *	@vector: The error vector of the exception that happened.
+ *	@e_vector: The error vector of the exception that happened.
  *	@signo: The signal number of the exception that happened.
  *	@err_code: The error code of the exception that happened.
- *	@remcom_in_buffer: The buffer of the packet we have read.
- *	@remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
- *	@regs: The &struct pt_regs of the current process.
+ *	@remcomInBuffer: The buffer of the packet we have read.
+ *	@remcomOutBuffer: The buffer of %BUFMAX bytes to write a packet into.
+ *	@linux_regs: The &struct pt_regs of the current process.
  *
  *	This function MUST handle the 'c' and 's' command packets,
  *	as well packets to set / remove a hardware breakpoint, if used.
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 086eb58c6e8..f1b42b3a186 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -120,11 +120,6 @@ bool kvm_check_and_clear_guest_paused(void)
 	bool ret = false;
 	struct pvclock_vcpu_time_info *src;
 
-	/*
-	 * per_cpu() is safe here because this function is only called from
-	 * timer functions where preemption is already disabled.
-	 */
-	WARN_ON(!in_atomic());
 	src = &__get_cpu_var(hv_clock);
 	if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
 		__this_cpu_and(hv_clock.flags, ~PVCLOCK_GUEST_STOPPED);
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 62c9457ccd2..c0f420f76cd 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -100,7 +100,7 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 				 struct dma_attrs *attrs)
 {
 	unsigned long dma_mask;
-	struct page *page = NULL;
+	struct page *page;
 	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	dma_addr_t addr;
 
@@ -108,6 +108,7 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 
 	flag |= __GFP_ZERO;
 again:
+	page = NULL;
 	if (!(flag & GFP_ATOMIC))
 		page = dma_alloc_from_contiguous(dev, count, get_order(size));
 	if (!page)
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 25b48edb847..5de92f1abd7 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -451,6 +451,14 @@ static struct dmi_system_id __initdata reboot_dmi_table[] = {
 			DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 990"),
 		},
 	},
+	{	/* Handle problems with rebooting on the Precision M6600. */
+		.callback = set_pci_reboot,
+		.ident = "Dell OptiPlex 990",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Precision M6600"),
+		},
+	},
 	{ }
 };
 
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3fab55bea29..7bd8a082365 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -349,9 +349,12 @@ static bool __cpuinit match_llc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
 
 static bool __cpuinit match_mc(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
 {
-	if (c->phys_proc_id == o->phys_proc_id)
-		return topology_sane(c, o, "mc");
+	if (c->phys_proc_id == o->phys_proc_id) {
+		if (cpu_has(c, X86_FEATURE_AMD_DCM))
+			return true;
 
+		return topology_sane(c, o, "mc");
+	}
 	return false;
 }
 
diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c
index 459b58a8a15..25b7ae8d058 100644
--- a/arch/x86/lib/csum-wrappers_64.c
+++ b/arch/x86/lib/csum-wrappers_64.c
@@ -115,7 +115,7 @@ EXPORT_SYMBOL(csum_partial_copy_to_user);
  * @src: source address
  * @dst: destination address
  * @len: number of bytes to be copied.
- * @isum: initial sum that is added into the result (32bit unfolded)
+ * @sum: initial sum that is added into the result (32bit unfolded)
  *
  * Returns an 32bit unfolded checksum of the buffer.
  */
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index be1ef574ce9..78fe3f1ac49 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -180,7 +180,7 @@ err_free_memtype:
 
 /**
  * ioremap_nocache     -   map bus memory into CPU space
- * @offset:    bus address of the memory
+ * @phys_addr:    bus address of the memory
  * @size:      size of the resource to map
  *
  * ioremap_nocache performs a platform specific sequence of operations to
@@ -217,7 +217,7 @@ EXPORT_SYMBOL(ioremap_nocache);
 
 /**
  * ioremap_wc	-	map memory into CPU space write combined
- * @offset:	bus address of the memory
+ * @phys_addr:	bus address of the memory
  * @size:	size of the resource to map
  *
  * This version of ioremap ensures that the memory is marked write combining.
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index e1ebde31521..a718e0d2350 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -122,7 +122,7 @@ within(unsigned long addr, unsigned long start, unsigned long end)
 
 /**
  * clflush_cache_range - flush a cache range with clflush
- * @addr:	virtual start address
+ * @vaddr:	virtual start address
  * @size:	number of bytes to flush
  *
  * clflush is an unordered instruction which needs fencing with mfence
diff --git a/arch/x86/platform/mrst/early_printk_mrst.c b/arch/x86/platform/mrst/early_printk_mrst.c
index 3c6e328483c..028454f0c3a 100644
--- a/arch/x86/platform/mrst/early_printk_mrst.c
+++ b/arch/x86/platform/mrst/early_printk_mrst.c
@@ -110,19 +110,16 @@ static struct kmsg_dumper dw_dumper;
 static int dumper_registered;
 
 static void dw_kmsg_dump(struct kmsg_dumper *dumper,
-			enum kmsg_dump_reason reason,
-			const char *s1, unsigned long l1,
-			const char *s2, unsigned long l2)
+			 enum kmsg_dump_reason reason)
 {
-	int i;
+	static char line[1024];
+	size_t len;
 
 	/* When run to this, we'd better re-init the HW */
 	mrst_early_console_init();
 
-	for (i = 0; i < l1; i++)
-		early_mrst_console.write(&early_mrst_console, s1 + i, 1);
-	for (i = 0; i < l2; i++)
-		early_mrst_console.write(&early_mrst_console, s2 + i, 1);
+	while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len))
+		early_mrst_console.write(&early_mrst_console, line, len);
 }
 
 /* Set the ratio rate to 115200, 8n1, IRQ disabled */
diff --git a/arch/x86/um/sys_call_table_32.c b/arch/x86/um/sys_call_table_32.c
index 416bd40c0eb..68d1dc91b37 100644
--- a/arch/x86/um/sys_call_table_32.c
+++ b/arch/x86/um/sys_call_table_32.c
@@ -39,9 +39,9 @@
 #undef __SYSCALL_I386
 #define __SYSCALL_I386(nr, sym, compat) [ nr ] = sym,
 
-typedef void (*sys_call_ptr_t)(void);
+typedef asmlinkage void (*sys_call_ptr_t)(void);
 
-extern void sys_ni_syscall(void);
+extern asmlinkage void sys_ni_syscall(void);
 
 const sys_call_ptr_t sys_call_table[] __cacheline_aligned = {
 	/*
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index e74df9548a0..ff962d4b821 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -209,6 +209,9 @@ static void __init xen_banner(void)
 	       xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
 }
 
+#define CPUID_THERM_POWER_LEAF 6
+#define APERFMPERF_PRESENT 0
+
 static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0;
 static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0;
 
@@ -242,6 +245,11 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 		*dx = cpuid_leaf5_edx_val;
 		return;
 
+	case CPUID_THERM_POWER_LEAF:
+		/* Disabling APERFMPERF for kernel usage */
+		maskecx = ~(1 << APERFMPERF_PRESENT);
+		break;
+
 	case 0xb:
 		/* Suppress extended topology stuff */
 		maskebx = 0;
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index ffd08c414e9..64effdc6da9 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -706,6 +706,7 @@ int m2p_add_override(unsigned long mfn, struct page *page,
 	unsigned long uninitialized_var(address);
 	unsigned level;
 	pte_t *ptep = NULL;
+	int ret = 0;
 
 	pfn = page_to_pfn(page);
 	if (!PageHighMem(page)) {
@@ -741,6 +742,24 @@ int m2p_add_override(unsigned long mfn, struct page *page,
 	list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
 	spin_unlock_irqrestore(&m2p_override_lock, flags);
 
+	/* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in
+	 * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other
+	 * pfn so that the following mfn_to_pfn(mfn) calls will return the
+	 * pfn from the m2p_override (the backend pfn) instead.
+	 * We need to do this because the pages shared by the frontend
+	 * (xen-blkfront) can be already locked (lock_page, called by
+	 * do_read_cache_page); when the userspace backend tries to use them
+	 * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
+	 * do_blockdev_direct_IO is going to try to lock the same pages
+	 * again resulting in a deadlock.
+	 * As a side effect get_user_pages_fast might not be safe on the
+	 * frontend pages while they are being shared with the backend,
+	 * because mfn_to_pfn (that ends up being called by GUPF) will
+	 * return the backend pfn rather than the frontend pfn. */
+	ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
+	if (ret == 0 && get_phys_to_machine(pfn) == mfn)
+		set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(m2p_add_override);
@@ -752,6 +771,7 @@ int m2p_remove_override(struct page *page, bool clear_pte)
 	unsigned long uninitialized_var(address);
 	unsigned level;
 	pte_t *ptep = NULL;
+	int ret = 0;
 
 	pfn = page_to_pfn(page);
 	mfn = get_phys_to_machine(pfn);
@@ -821,6 +841,22 @@ int m2p_remove_override(struct page *page, bool clear_pte)
 	} else
 		set_phys_to_machine(pfn, page->index);
 
+	/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
+	 * somewhere in this domain, even before being added to the
+	 * m2p_override (see comment above in m2p_add_override).
+	 * If there are no other entries in the m2p_override corresponding
+	 * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
+	 * the original pfn (the one shared by the frontend): the backend
+	 * cannot do any IO on this page anymore because it has been
+	 * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
+	 * the original pfn causes mfn_to_pfn(mfn) to return the frontend
+	 * pfn again. */
+	mfn &= ~FOREIGN_FRAME_BIT;
+	ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
+	if (ret == 0 && get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
+			m2p_find_override(mfn) == NULL)
+		set_phys_to_machine(pfn, mfn);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(m2p_remove_override);
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 3ebba0753d3..a4790bf22c5 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -371,7 +371,8 @@ char * __init xen_memory_setup(void)
 	populated = xen_populate_chunk(map, memmap.nr_entries,
 			max_pfn, &last_pfn, xen_released_pages);
 
-	extra_pages += (xen_released_pages - populated);
+	xen_released_pages -= populated;
+	extra_pages += xen_released_pages;
 
 	if (last_pfn > max_pfn) {
 		max_pfn = min(MAX_DOMAIN_PAGES, last_pfn);