Merge tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull UML updates from Richard Weinberger:

 - Add support for rust (yay!)

 - Add support for LTO

 - Add platform bus support to virtio-pci

 - Various virtio fixes

 - Coding style, spelling cleanups

* tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (27 commits)
  Documentation: rust: Fix arch support table
  uml: vector: Remove unused definitions VECTOR_{WRITE,HEADERS}
  um: virt-pci: properly remove PCI device from bus
  um: virtio_uml: move device breaking into workqueue
  um: virtio_uml: mark device as unregistered when breaking it
  um: virtio_uml: free command if adding to virtqueue failed
  UML: define RUNTIME_DISCARD_EXIT
  virt-pci: add platform bus support
  um-virt-pci: Make max delay configurable
  um: virt-pci: implement pcibios_get_phb_of_node()
  um: Support LTO
  um: put power options in a menu
  um: Use CFLAGS_vmlinux
  um: Prevent building modules incompatible with MODVERSIONS
  um: Avoid pcap multiple definition errors
  um: Make the definition of cpu_data more compatible
  x86: um: vdso: Add '%rcx' and '%r11' to the syscall clobber list
  rust: arch/um: Add support for CONFIG_RUST under x86_64 UML
  rust: arch/um: Disable FP/SIMD instruction to match x86
  rust: arch/um: Use 'pie' relocation mode under UML
  ...

Documentation/rust/arch-support.rst

@@ -16,4 +16,6 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
 Architecture  Level of support  Constraints
 ============  ================  ==============================================
 ``x86``       Maintained        ``x86_64`` only.
+``um``        Maintained        ``x86_64`` only.
 ============  ================  ==============================================
+

arch/um/Kconfig

@@ -25,9 +25,12 @@ config UML
 	select GENERIC_IRQ_SHOW
 	select GENERIC_CPU_DEVICES
 	select HAVE_GCC_PLUGINS
+	select ARCH_SUPPORTS_LTO_CLANG
+	select ARCH_SUPPORTS_LTO_CLANG_THIN
 	select TRACE_IRQFLAGS_SUPPORT
 	select TTY # Needed for line.c
 	select HAVE_ARCH_VMAP_STACK
+	select HAVE_RUST			if X86_64
 
 config MMU
 	bool
@@ -242,4 +245,8 @@ source "arch/um/drivers/Kconfig"
 config ARCH_SUSPEND_POSSIBLE
 	def_bool y
 
+menu "Power management options"
+
 source "kernel/power/Kconfig"
+
+endmenu

arch/um/Makefile

@@ -68,6 +68,8 @@ KBUILD_CFLAGS += $(CFLAGS) $(CFLAGS-y) -D__arch_um__ \
 	-Din6addr_loopback=kernel_in6addr_loopback \
 	-Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr
 
+KBUILD_RUSTFLAGS += -Crelocation-model=pie
+
 KBUILD_AFLAGS += $(ARCH_INCLUDE)
 
 USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \
@@ -139,11 +141,10 @@ ifeq ($(CONFIG_LD_IS_BFD),y)
 LDFLAGS_EXECSTACK += $(call ld-option,--no-warn-rwx-segments)
 endif
 
-LD_FLAGS_CMDLINE = $(foreach opt,$(KBUILD_LDFLAGS),-Wl,$(opt))
+LD_FLAGS_CMDLINE = $(foreach opt,$(KBUILD_LDFLAGS) $(LDFLAGS_EXECSTACK),-Wl,$(opt))
 
 # Used by link-vmlinux.sh which has special support for um link
-export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE)
-export LDFLAGS_vmlinux := $(LDFLAGS_EXECSTACK)
+export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE) $(CC_FLAGS_LTO)
 
 # When cleaning we don't include .config, so we don't include
 # TT or skas makefiles and don't clean skas_ptregs.h.

arch/um/drivers/Kconfig

@@ -261,6 +261,7 @@ config UML_NET_VECTOR
 config UML_NET_VDE
 	bool "VDE transport (obsolete)"
 	depends on UML_NET
+	depends on !MODVERSIONS
 	select MAY_HAVE_RUNTIME_DEPS
 	help
 	  This User-Mode Linux network transport allows one or more running
@@ -309,6 +310,7 @@ config UML_NET_MCAST
 config UML_NET_PCAP
 	bool "pcap transport (obsolete)"
 	depends on UML_NET
+	depends on !MODVERSIONS
 	select MAY_HAVE_RUNTIME_DEPS
 	help
 	  The pcap transport makes a pcap packet stream on the host look

arch/um/drivers/pcap_kern.c

@@ -15,7 +15,7 @@ struct pcap_init {
 	char *filter;
 };
 
-void pcap_init(struct net_device *dev, void *data)
+void pcap_init_kern(struct net_device *dev, void *data)
 {
 	struct uml_net_private *pri;
 	struct pcap_data *ppri;
@@ -44,7 +44,7 @@ static int pcap_write(int fd, struct sk_buff *skb, struct uml_net_private *lp)
 }
 
 static const struct net_kern_info pcap_kern_info = {
-	.init			= pcap_init,
+	.init			= pcap_init_kern,
 	.protocol		= eth_protocol,
 	.read			= pcap_read,
 	.write			= pcap_write,

arch/um/drivers/vector_kern.c

@@ -767,6 +767,7 @@ static int vector_config(char *str, char **error_out)
 
 	if (parsed == NULL) {
 		*error_out = "vector_config failed to parse parameters";
+		kfree(params);
 		return -EINVAL;
 	}
 

arch/um/drivers/vector_user.h

@@ -68,8 +68,6 @@ struct vector_fds {
 };
 
 #define VECTOR_READ	1
-#define VECTOR_WRITE	(1 < 1)
-#define VECTOR_HEADERS	(1 < 2)
 
 extern struct arglist *uml_parse_vector_ifspec(char *arg);
 

arch/um/drivers/virt-pci.c

@@ -8,6 +8,7 @@
 #include <linux/virtio.h>
 #include <linux/virtio_config.h>
 #include <linux/logic_iomem.h>
+#include <linux/of_platform.h>
 #include <linux/irqdomain.h>
 #include <linux/virtio_pcidev.h>
 #include <linux/virtio-uml.h>
@@ -39,6 +40,8 @@ struct um_pci_device {
 	unsigned long status;
 
 	int irq;
+
+	bool platform;
 };
 
 struct um_pci_device_reg {
@@ -48,13 +51,15 @@ struct um_pci_device_reg {
 
 static struct pci_host_bridge *bridge;
 static DEFINE_MUTEX(um_pci_mtx);
+static struct um_pci_device *um_pci_platform_device;
 static struct um_pci_device_reg um_pci_devices[MAX_DEVICES];
 static struct fwnode_handle *um_pci_fwnode;
 static struct irq_domain *um_pci_inner_domain;
 static struct irq_domain *um_pci_msi_domain;
 static unsigned long um_pci_msi_used[BITS_TO_LONGS(MAX_MSI_VECTORS)];
 
-#define UM_VIRT_PCI_MAXDELAY 40000
+static unsigned int um_pci_max_delay_us = 40000;
+module_param_named(max_delay_us, um_pci_max_delay_us, uint, 0644);
 
 struct um_pci_message_buffer {
 	struct virtio_pcidev_msg hdr;
@@ -132,8 +137,11 @@ static int um_pci_send_cmd(struct um_pci_device *dev,
 				out ? 1 : 0,
 				posted ? cmd : HANDLE_NO_FREE(cmd),
 				GFP_ATOMIC);
-	if (ret)
+	if (ret) {
+		if (posted)
+			kfree(cmd);
 		goto out;
+	}
 
 	if (posted) {
 		virtqueue_kick(dev->cmd_vq);
@@ -155,7 +163,7 @@ static int um_pci_send_cmd(struct um_pci_device *dev,
 			kfree(completed);
 
 		if (WARN_ONCE(virtqueue_is_broken(dev->cmd_vq) ||
-			      ++delay_count > UM_VIRT_PCI_MAXDELAY,
+			      ++delay_count > um_pci_max_delay_us,
 			      "um virt-pci delay: %d", delay_count)) {
 			ret = -EIO;
 			break;
@@ -480,6 +488,9 @@ static void um_pci_handle_irq_message(struct virtqueue *vq,
 	struct virtio_device *vdev = vq->vdev;
 	struct um_pci_device *dev = vdev->priv;
 
+	if (!dev->irq)
+		return;
+
 	/* we should properly chain interrupts, but on ARCH=um we don't care */
 
 	switch (msg->op) {
@@ -533,6 +544,25 @@ static void um_pci_irq_vq_cb(struct virtqueue *vq)
 	}
 }
 
+/* Copied from arch/x86/kernel/devicetree.c */
+struct device_node *pcibios_get_phb_of_node(struct pci_bus *bus)
+{
+	struct device_node *np;
+
+	for_each_node_by_type(np, "pci") {
+		const void *prop;
+		unsigned int bus_min;
+
+		prop = of_get_property(np, "bus-range", NULL);
+		if (!prop)
+			continue;
+		bus_min = be32_to_cpup(prop);
+		if (bus->number == bus_min)
+			return np;
+	}
+	return NULL;
+}
+
 static int um_pci_init_vqs(struct um_pci_device *dev)
 {
 	struct virtqueue *vqs[2];
@@ -561,6 +591,55 @@ static int um_pci_init_vqs(struct um_pci_device *dev)
 	return 0;
 }
 
+static void __um_pci_virtio_platform_remove(struct virtio_device *vdev,
+					    struct um_pci_device *dev)
+{
+	virtio_reset_device(vdev);
+	vdev->config->del_vqs(vdev);
+
+	mutex_lock(&um_pci_mtx);
+	um_pci_platform_device = NULL;
+	mutex_unlock(&um_pci_mtx);
+
+	kfree(dev);
+}
+
+static int um_pci_virtio_platform_probe(struct virtio_device *vdev,
+					struct um_pci_device *dev)
+{
+	int ret;
+
+	dev->platform = true;
+
+	mutex_lock(&um_pci_mtx);
+
+	if (um_pci_platform_device) {
+		mutex_unlock(&um_pci_mtx);
+		ret = -EBUSY;
+		goto out_free;
+	}
+
+	ret = um_pci_init_vqs(dev);
+	if (ret) {
+		mutex_unlock(&um_pci_mtx);
+		goto out_free;
+	}
+
+	um_pci_platform_device = dev;
+
+	mutex_unlock(&um_pci_mtx);
+
+	ret = of_platform_default_populate(vdev->dev.of_node, NULL, &vdev->dev);
+	if (ret)
+		__um_pci_virtio_platform_remove(vdev, dev);
+
+	return ret;
+
+out_free:
+	kfree(dev);
+	return ret;
+}
+
 static int um_pci_virtio_probe(struct virtio_device *vdev)
 {
 	struct um_pci_device *dev;
@@ -574,6 +653,9 @@ static int um_pci_virtio_probe(struct virtio_device *vdev)
 	dev->vdev = vdev;
 	vdev->priv = dev;
 
+	if (of_device_is_compatible(vdev->dev.of_node, "simple-bus"))
+		return um_pci_virtio_platform_probe(vdev, dev);
+
 	mutex_lock(&um_pci_mtx);
 	for (i = 0; i < MAX_DEVICES; i++) {
 		if (um_pci_devices[i].dev)
@@ -623,9 +705,11 @@ static void um_pci_virtio_remove(struct virtio_device *vdev)
 	struct um_pci_device *dev = vdev->priv;
 	int i;
 
-        /* Stop all virtqueues */
-        virtio_reset_device(vdev);
-        vdev->config->del_vqs(vdev);
+	if (dev->platform) {
+		of_platform_depopulate(&vdev->dev);
+		__um_pci_virtio_platform_remove(vdev, dev);
+		return;
+	}
 
 	device_set_wakeup_enable(&vdev->dev, false);
 
@@ -633,12 +717,27 @@ static void um_pci_virtio_remove(struct virtio_device *vdev)
 	for (i = 0; i < MAX_DEVICES; i++) {
 		if (um_pci_devices[i].dev != dev)
 			continue;
+
 		um_pci_devices[i].dev = NULL;
 		irq_free_desc(dev->irq);
+
+		break;
 	}
 	mutex_unlock(&um_pci_mtx);
 
-	um_pci_rescan();
+	if (i < MAX_DEVICES) {
+		struct pci_dev *pci_dev;
+
+		pci_dev = pci_get_slot(bridge->bus, i);
+		if (pci_dev)
+			pci_stop_and_remove_bus_device_locked(pci_dev);
+	}
+
+	/* Stop all virtqueues */
+	virtio_reset_device(vdev);
+	dev->cmd_vq = NULL;
+	dev->irq_vq = NULL;
+	vdev->config->del_vqs(vdev);
 
 	kfree(dev);
 }
@@ -860,6 +959,30 @@ void *pci_root_bus_fwnode(struct pci_bus *bus)
 	return um_pci_fwnode;
 }
 
+static long um_pci_map_platform(unsigned long offset, size_t size,
+				const struct logic_iomem_ops **ops,
+				void **priv)
+{
+	if (!um_pci_platform_device)
+		return -ENOENT;
+
+	*ops = &um_pci_device_bar_ops;
+	*priv = &um_pci_platform_device->resptr[0];
+
+	return 0;
+}
+
+static const struct logic_iomem_region_ops um_pci_platform_ops = {
+	.map = um_pci_map_platform,
+};
+
+static struct resource virt_platform_resource = {
+	.name = "platform",
+	.start = 0x10000000,
+	.end = 0x1fffffff,
+	.flags = IORESOURCE_MEM,
+};
+
 static int __init um_pci_init(void)
 {
 	int err, i;
@@ -868,6 +991,8 @@ static int __init um_pci_init(void)
 				       &um_pci_cfgspace_ops));
 	WARN_ON(logic_iomem_add_region(&virt_iomem_resource,
 				       &um_pci_iomem_ops));
+	WARN_ON(logic_iomem_add_region(&virt_platform_resource,
+				       &um_pci_platform_ops));
 
 	if (WARN(CONFIG_UML_PCI_OVER_VIRTIO_DEVICE_ID < 0,
 		 "No virtio device ID configured for PCI - no PCI support\n"))

arch/um/drivers/virtio_uml.c

@@ -168,7 +168,8 @@ static void vhost_user_check_reset(struct virtio_uml_device *vu_dev,
 	if (!vu_dev->registered)
 		return;
 
-	virtio_break_device(&vu_dev->vdev);
+	vu_dev->registered = 0;
+
 	schedule_work(&pdata->conn_broken_wk);
 }
 
@@ -412,7 +413,7 @@ static irqreturn_t vu_req_read_message(struct virtio_uml_device *vu_dev,
 		if (msg.msg.header.flags & VHOST_USER_FLAG_NEED_REPLY)
 			vhost_user_reply(vu_dev, &msg.msg, response);
 		irq_rc = IRQ_HANDLED;
-	};
+	}
 	/* mask EAGAIN as we try non-blocking read until socket is empty */
 	vu_dev->recv_rc = (rc == -EAGAIN) ? 0 : rc;
 	return irq_rc;
@@ -1136,6 +1137,15 @@ void virtio_uml_set_no_vq_suspend(struct virtio_device *vdev,
 
 static void vu_of_conn_broken(struct work_struct *wk)
 {
+	struct virtio_uml_platform_data *pdata;
+	struct virtio_uml_device *vu_dev;
+
+	pdata = container_of(wk, struct virtio_uml_platform_data, conn_broken_wk);
+
+	vu_dev = platform_get_drvdata(pdata->pdev);
+
+	virtio_break_device(&vu_dev->vdev);
+
 	/*
 	 * We can't remove the device from the devicetree so the only thing we
 	 * can do is warn.
@@ -1266,8 +1276,14 @@ static int vu_unregister_cmdline_device(struct device *dev, void *data)
 static void vu_conn_broken(struct work_struct *wk)
 {
 	struct virtio_uml_platform_data *pdata;
+	struct virtio_uml_device *vu_dev;
 
 	pdata = container_of(wk, struct virtio_uml_platform_data, conn_broken_wk);
+
+	vu_dev = platform_get_drvdata(pdata->pdev);
+
+	virtio_break_device(&vu_dev->vdev);
+
 	vu_unregister_cmdline_device(&pdata->pdev->dev, NULL);
 }
 

arch/um/include/asm/processor-generic.h

@@ -91,7 +91,7 @@ struct cpuinfo_um {
 
 extern struct cpuinfo_um boot_cpu_data;
 
-#define cpu_data (&boot_cpu_data)
+#define cpu_data(cpu)    boot_cpu_data
 #define current_cpu_data boot_cpu_data
 #define cache_line_size()	(boot_cpu_data.cache_alignment)
 

arch/um/kernel/exec.c

@@ -29,8 +29,8 @@ void flush_thread(void)
 
 	ret = unmap(&current->mm->context.id, 0, TASK_SIZE, 1, &data);
 	if (ret) {
-		printk(KERN_ERR "flush_thread - clearing address space failed, "
-		       "err = %d\n", ret);
+		printk(KERN_ERR "%s - clearing address space failed, err = %d\n",
+		       __func__, ret);
 		force_sig(SIGKILL);
 	}
 	get_safe_registers(current_pt_regs()->regs.gp,

arch/um/kernel/tlb.c

@@ -314,7 +314,7 @@ static inline int update_p4d_range(pgd_t *pgd, unsigned long addr,
 	return ret;
 }
 
-void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
+static void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 			     unsigned long end_addr, int force)
 {
 	pgd_t *pgd;
@@ -597,6 +597,8 @@ void force_flush_all(void)
 	struct vm_area_struct *vma;
 	VMA_ITERATOR(vmi, mm, 0);
 
+	mmap_read_lock(mm);
 	for_each_vma(vmi, vma)
 		fix_range(mm, vma->vm_start, vma->vm_end, 1);
+	mmap_read_unlock(mm);
 }

arch/um/kernel/um_arch.c

@@ -96,7 +96,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 
 static void *c_start(struct seq_file *m, loff_t *pos)
 {
-	return *pos < nr_cpu_ids ? cpu_data + *pos : NULL;
+	return *pos < nr_cpu_ids ? &boot_cpu_data + *pos : NULL;
 }
 
 static void *c_next(struct seq_file *m, void *v, loff_t *pos)

arch/um/kernel/vmlinux.lds.S

-
+#define RUNTIME_DISCARD_EXIT
 KERNEL_STACK_SIZE = 4096 * (1 << CONFIG_KERNEL_STACK_ORDER);
 
 #ifdef CONFIG_LD_SCRIPT_STATIC

arch/um/os-Linux/irq.c

@@ -127,12 +127,10 @@ int os_mod_epoll_fd(int events, int fd, void *data)
 int os_del_epoll_fd(int fd)
 {
 	struct epoll_event event;
-	int result;
 	/* This is quiet as we use this as IO ON/OFF - so it is often
 	 * invoked on a non-existent fd
 	 */
-	result = epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, &event);
-	return result;
+	return epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, &event);
 }
 
 void os_set_ioignore(void)

arch/um/os-Linux/skas/mem.c

@@ -60,8 +60,8 @@ static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
 		printk(UM_KERN_ERR "Registers - \n");
 		for (i = 0; i < MAX_REG_NR; i++)
 			printk(UM_KERN_ERR "\t%d\t0x%lx\n", i, syscall_regs[i]);
-		panic("do_syscall_stub : PTRACE_SETREGS failed, errno = %d\n",
-		      -n);
+		panic("%s : PTRACE_SETREGS failed, errno = %d\n",
+		      __func__, -n);
 	}
 
 	err = ptrace(PTRACE_CONT, pid, 0, 0);
@@ -81,20 +81,17 @@ static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
 	offset = *((unsigned long *) mm_idp->stack + 1);
 	if (offset) {
 		data = (unsigned long *)(mm_idp->stack + offset - STUB_DATA);
-		printk(UM_KERN_ERR "do_syscall_stub : ret = %ld, offset = %ld, "
-		       "data = %p\n", ret, offset, data);
+		printk(UM_KERN_ERR "%s : ret = %ld, offset = %ld, data = %p\n",
+		       __func__, ret, offset, data);
 		syscall = (unsigned long *)((unsigned long)data + data[0]);
-		printk(UM_KERN_ERR "do_syscall_stub: syscall %ld failed, "
-		       "return value = 0x%lx, expected return value = 0x%lx\n",
-		       syscall[0], ret, syscall[7]);
-		printk(UM_KERN_ERR "    syscall parameters: "
-		       "0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
+		printk(UM_KERN_ERR "%s: syscall %ld failed, return value = 0x%lx, expected return value = 0x%lx\n",
+		       __func__, syscall[0], ret, syscall[7]);
+		printk(UM_KERN_ERR "    syscall parameters: 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
 		       syscall[1], syscall[2], syscall[3],
 		       syscall[4], syscall[5], syscall[6]);
 		for (n = 1; n < data[0]/sizeof(long); n++) {
 			if (n == 1)
-				printk(UM_KERN_ERR "    additional syscall "
-				       "data:");
+				printk(UM_KERN_ERR "    additional syscall data:");
 			if (n % 4 == 1)
 				printk("\n" UM_KERN_ERR "      ");
 			printk("  0x%lx", data[n]);

arch/x86/Makefile.um

 # SPDX-License-Identifier: GPL-2.0
 core-y += arch/x86/crypto/
 
+#
+# Disable SSE and other FP/SIMD instructions to match normal x86
+#
+KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
+KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2
+
 ifeq ($(CONFIG_X86_32),y)
 START := 0x8048000
 

arch/x86/um/vdso/Makefile

@@ -61,7 +61,7 @@ CFLAGS_REMOVE_um_vdso.o = -pg -fprofile-arcs -ftest-coverage
 #
 quiet_cmd_vdso = VDSO    $@
       cmd_vdso = $(CC) -nostdlib -o $@ \
-		       $(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
+		       $(CC_FLAGS_LTO) $(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
 		       -Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \
 		 sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'
 

arch/x86/um/vdso/um_vdso.c

@@ -17,8 +17,10 @@ int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
 {
 	long ret;
 
-	asm("syscall" : "=a" (ret) :
-		"0" (__NR_clock_gettime), "D" (clock), "S" (ts) : "memory");
+	asm("syscall"
+		: "=a" (ret)
+		: "0" (__NR_clock_gettime), "D" (clock), "S" (ts)
+		: "rcx", "r11", "memory");
 
 	return ret;
 }
@@ -29,8 +31,10 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 {
 	long ret;
 
-	asm("syscall" : "=a" (ret) :
-		"0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");
+	asm("syscall"
+		: "=a" (ret)
+		: "0" (__NR_gettimeofday), "D" (tv), "S" (tz)
+		: "rcx", "r11", "memory");
 
 	return ret;
 }

fs/hostfs/hostfs_kern.c

@@ -412,7 +412,7 @@ static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
 	if (page->index >= end_index)
 		count = inode->i_size & (PAGE_SIZE-1);
 
-	buffer = kmap(page);
+	buffer = kmap_local_page(page);
 
 	err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
 	if (err != count) {
@@ -428,9 +428,9 @@ static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
 	err = 0;
 
  out:
-	kunmap(page);
-
+	kunmap_local(buffer);
 	unlock_page(page);
+
 	return err;
 }
 
@@ -441,7 +441,7 @@ static int hostfs_read_folio(struct file *file, struct folio *folio)
 	loff_t start = page_offset(page);
 	int bytes_read, ret = 0;
 
-	buffer = kmap(page);
+	buffer = kmap_local_page(page);
 	bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
 			PAGE_SIZE);
 	if (bytes_read < 0) {
@@ -458,8 +458,9 @@ static int hostfs_read_folio(struct file *file, struct folio *folio)
 
  out:
 	flush_dcache_page(page);
-	kunmap(page);
+	kunmap_local(buffer);
 	unlock_page(page);
+
 	return ret;
 }
 
@@ -484,9 +485,9 @@ static int hostfs_write_end(struct file *file, struct address_space *mapping,
 	unsigned from = pos & (PAGE_SIZE - 1);
 	int err;
 
-	buffer = kmap(page);
+	buffer = kmap_local_page(page);
 	err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
-	kunmap(page);
+	kunmap_local(buffer);
 
 	if (!PageUptodate(page) && err == PAGE_SIZE)
 		SetPageUptodate(page);