diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h
index 939b1cff4a7b..0ba43d93414f 100644
--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -44,14 +44,27 @@ void clear_page_orig(void *page);
 void clear_page_rep(void *page);
 void clear_page_erms(void *page);
 
+/* This is an assembly header, avoid including too much of kmsan.h */
+#ifdef CONFIG_KMSAN
+void kmsan_clear_page(void *page_addr);
+#endif
+__no_sanitize_memory
 static inline void clear_page(void *page)
 {
+#ifdef CONFIG_KMSAN
+	/* alternative_call_2() changes |page|. */
+	void *page_copy = page;
+#endif
 	alternative_call_2(clear_page_orig,
 			   clear_page_rep, X86_FEATURE_REP_GOOD,
 			   clear_page_erms, X86_FEATURE_ERMS,
 			   "=D" (page),
 			   "0" (page)
 			   : "cc", "memory", "rax", "rcx");
+#ifdef CONFIG_KMSAN
+	/* Clear KMSAN shadow for the pages that have it. */
+	kmsan_clear_page(page_copy);
+#endif
 }
 
 void copy_page(void *to, void *from);
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index a39dcdb5ae34..fdb2abc11a82 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -7,6 +7,7 @@
  * (C) Copyright 1995 1996 Linus Torvalds
  */
 
+#include <linux/kmsan.h>
 #include <linux/memblock.h>
 #include <linux/init.h>
 #include <linux/io.h>
@@ -451,6 +452,8 @@ void iounmap(volatile void __iomem *addr)
 		return;
 	}
 
+	kmsan_iounmap_page_range((unsigned long)addr,
+		(unsigned long)addr + get_vm_area_size(p));
 	free_memtype(p->phys_addr, p->phys_addr + get_vm_area_size(p));
 
 	/* Finally remove it */
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 0eab79f82ce4..5bdb54d71c2e 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -8,6 +8,7 @@
 #include <linux/bitops.h>
 #include <linux/slab.h>
 #include <linux/log2.h>
+#include <linux/kmsan-checks.h>
 #include <linux/usb.h>
 #include <linux/wait.h>
 #include <linux/usb/hcd.h>
@@ -401,6 +402,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
 			URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
 			URB_DMA_SG_COMBINED);
 	urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
+	kmsan_handle_urb(urb, is_out);
 
 	if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
 			dev->state < USB_STATE_CONFIGURED)
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index ea5cdbd8c2c3..623b56f48685 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -5,6 +5,7 @@
 #include <linux/fs.h>
 #include <linux/kernel.h>
 #include <linux/bug.h>
+#include <linux/kmsan.h>
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
@@ -255,6 +256,8 @@ static inline void copy_user_highpage(struct page *to, struct page *from,
 	vfrom = kmap_atomic(from);
 	vto = kmap_atomic(to);
 	copy_user_page(vto, vfrom, vaddr, to);
+	/* User pages don't have shadow, just clear the destination. */
+	kmsan_clear_page(page_address(to));
 	kunmap_atomic(vto);
 	kunmap_atomic(vfrom);
 }
@@ -270,6 +273,7 @@ static inline void copy_highpage(struct page *to, struct page *from)
 	vfrom = kmap_atomic(from);
 	vto = kmap_atomic(to);
 	copy_page(vto, vfrom);
+	kmsan_copy_page_meta(to, from);
 	kunmap_atomic(vto);
 	kunmap_atomic(vfrom);
 }
diff --git a/kernel/exit.c b/kernel/exit.c
index a46a50d67002..9e3ce929110b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -60,6 +60,7 @@
 #include <linux/writeback.h>
 #include <linux/shm.h>
 #include <linux/kcov.h>
+#include <linux/kmsan.h>
 #include <linux/random.h>
 #include <linux/rcuwait.h>
 #include <linux/compat.h>
@@ -719,6 +720,7 @@ void __noreturn do_exit(long code)
 
 	profile_task_exit(tsk);
 	kcov_task_exit(tsk);
+	kmsan_task_exit(tsk);
 
 	WARN_ON(blk_needs_flush_plug(tsk));
 
diff --git a/kernel/fork.c b/kernel/fork.c
index bcdf53125210..0f08952a42dc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -37,6 +37,7 @@
 #include <linux/fdtable.h>
 #include <linux/iocontext.h>
 #include <linux/key.h>
+#include <linux/kmsan.h>
 #include <linux/binfmts.h>
 #include <linux/mman.h>
 #include <linux/mmu_notifier.h>
@@ -931,6 +932,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	account_kernel_stack(tsk, 1);
 
 	kcov_task_init(tsk);
+	kmsan_task_create(tsk);
 
 #ifdef CONFIG_FAULT_INJECTION
 	tsk->fail_nth = 0;
diff --git a/kernel/kthread.c b/kernel/kthread.c
index b262f47046ca..33ca743ca8b5 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -17,6 +17,7 @@
 #include <linux/unistd.h>
 #include <linux/file.h>
 #include <linux/export.h>
+#include <linux/kmsan.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/freezer.h>
@@ -350,6 +351,7 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
 		set_cpus_allowed_ptr(task, cpu_all_mask);
 	}
 	kfree(create);
+	kmsan_task_create(task);
 	return task;
 }
 
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ca65327a6de8..c9ef7fb0906f 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1915,6 +1915,12 @@ int vprintk_store(int facility, int level,
 	 * prefix which might be passed-in as a parameter.
 	 */
 	text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
+	/*
+	 * If any of vscnprintf() arguments is uninitialized, KMSAN will report
+	 * one or more errors and also probably mark text_len as uninitialized.
+	 * Initialize |text_len| to prevent the errors from spreading further.
+	 */
+	text_len = KMSAN_INIT_VALUE(text_len);
 
 	/* mark and strip a trailing newline */
 	if (text_len && text[text_len-1] == '\n') {
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 0427a86743a4..6d566dd68b35 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -11,6 +11,7 @@
 
 #include <linux/export.h>
 #include <linux/kernel_stat.h>
+#include <linux/kmsan.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
 #include <linux/mm.h>
@@ -370,7 +371,9 @@ static inline void invoke_softirq(void)
 		 * it is the irq stack, because it should be near empty
 		 * at this stage.
 		 */
+		kmsan_softirq_enter();
 		__do_softirq();
+		kmsan_softirq_exit();
 #else
 		/*
 		 * Otherwise, irq_exit() is called on the task stack that can
@@ -600,7 +603,9 @@ static void run_ksoftirqd(unsigned int cpu)
 		 * We can safely run softirq on inline stack, as we are not deep
 		 * in the task stack here.
 		 */
+		kmsan_softirq_enter();
 		__do_softirq();
+		kmsan_softirq_exit();
 		local_irq_enable();
 		cond_resched();
 		return;
diff --git a/lib/ioremap.c b/lib/ioremap.c
index 0a2ffadc6d71..5f830cee5bfc 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -6,6 +6,7 @@
  *
  * (C) Copyright 1995 1996 Linus Torvalds
  */
+#include <linux/kmsan.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
@@ -214,6 +215,8 @@ int ioremap_page_range(unsigned long addr,
 	unsigned long start;
 	unsigned long next;
 	int err;
+	unsigned long old_addr = addr;
+	phys_addr_t old_phys_addr = phys_addr;
 
 	might_sleep();
 	BUG_ON(addr >= end);
@@ -228,6 +231,8 @@ int ioremap_page_range(unsigned long addr,
 	} while (pgd++, phys_addr += (next - addr), addr = next, addr != end);
 
 	flush_cache_vmap(start, end);
+	if (!err)
+		kmsan_ioremap_page_range(old_addr, end, old_phys_addr, prot);
 
 	return err;
 }
diff --git a/mm/compaction.c b/mm/compaction.c
index 672d3c78c6ab..720a8a4dafec 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -84,6 +84,15 @@ static void split_map_pages(struct list_head *list)
 
 		for (i = 0; i < nr_pages; i++) {
 			list_add(&page->lru, &tmp_list);
+#ifdef CONFIG_KMSAN
+			/*
+			 * TODO(glider): we may lose the metadata when copying
+			 * something to these pages. Need to allocate shadow
+			 * and origin pages here instead.
+			 */
+			page->shadow = NULL;
+			page->origin = NULL;
+#endif
 			page++;
 		}
 	}
diff --git a/mm/gup.c b/mm/gup.c
index 8f236a335ae9..8f5f99772278 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -4,6 +4,7 @@
 #include <linux/err.h>
 #include <linux/spinlock.h>
 
+#include <linux/kmsan.h>
 #include <linux/mm.h>
 #include <linux/memremap.h>
 #include <linux/pagemap.h>
@@ -2349,6 +2350,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	    gup_fast_permitted(start, end)) {
 		local_irq_save(flags);
 		gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
+		kmsan_gup_pgd_range(pages, nr);
 		local_irq_restore(flags);
 	}
 
@@ -2418,6 +2420,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
 	    gup_fast_permitted(start, end)) {
 		local_irq_disable();
 		gup_pgd_range(addr, end, gup_flags, pages, &nr);
+		kmsan_gup_pgd_range(pages, nr);
 		local_irq_enable();
 		ret = nr;
 	}
diff --git a/mm/memory.c b/mm/memory.c
index b1ca51a079f2..48ceacc06e2d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -51,6 +51,7 @@
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
 #include <linux/memremap.h>
+#include <linux/kmsan.h>
 #include <linux/ksm.h>
 #include <linux/rmap.h>
 #include <linux/export.h>
@@ -2328,6 +2329,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		if (!new_page)
 			goto oom;
 		cow_user_page(new_page, old_page, vmf->address, vma);
+		kmsan_copy_page_meta(new_page, old_page);
 	}
 
 	if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ecc3dbad606b..c98e4441c7c0 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -26,6 +26,8 @@
 #include <linux/compiler.h>
 #include <linux/kernel.h>
 #include <linux/kasan.h>
+#include <linux/kmsan.h>
+#include <linux/kmsan-checks.h>
 #include <linux/module.h>
 #include <linux/suspend.h>
 #include <linux/pagevec.h>
@@ -1133,6 +1135,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
 	trace_mm_page_free(page, order);
+	kmsan_free_page(page, order);
 
 	/*
 	 * Check tail pages before head page information is cleared to
@@ -3121,6 +3124,7 @@ void split_page(struct page *page, unsigned int order)
 	VM_BUG_ON_PAGE(PageCompound(page), page);
 	VM_BUG_ON_PAGE(!page_count(page), page);
 
+	kmsan_split_page(page, order);
 	for (i = 1; i < (1 << order); i++)
 		set_page_refcounted(page + i);
 	split_page_owner(page, order);
@@ -3253,6 +3257,13 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
 /*
  * Allocate a page from the given zone. Use pcplists for order-0 allocations.
  */
+/*
+ * TODO(glider): rmqueue() may call __msan_poison_alloca() through a call to
+ * set_pfnblock_flags_mask(). If __msan_poison_alloca() attempts to allocate
+ * pages for the stack depot, it may call rmqueue() again, which will result
+ * in a deadlock.
+ */
+__no_sanitize_memory
 static inline
 struct page *rmqueue(struct zone *preferred_zone,
 			struct zone *zone, unsigned int order,
@@ -4781,6 +4792,11 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
 
 	trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
 
+	if (page)
+		if (kmsan_alloc_page(page, order, gfp_mask)) {
+			__free_pages(page, order);
+			page = NULL;
+		}
 	return page;
 }
 EXPORT_SYMBOL(__alloc_pages_nodemask);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a3c70e275f4e..bdf66ffcf02c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -29,6 +29,7 @@
 #include <linux/rcupdate.h>
 #include <linux/pfn.h>
 #include <linux/kmemleak.h>
+#include <linux/kmsan.h>
 #include <linux/atomic.h>
 #include <linux/compiler.h>
 #include <linux/llist.h>
@@ -119,7 +120,8 @@ static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end)
 	} while (p4d++, addr = next, addr != end);
 }
 
-static void vunmap_page_range(unsigned long addr, unsigned long end)
+/* Exported for KMSAN, visible in mm/kmsan/kmsan.h only. */
+void __vunmap_page_range(unsigned long addr, unsigned long end)
 {
 	pgd_t *pgd;
 	unsigned long next;
@@ -133,6 +135,12 @@ static void vunmap_page_range(unsigned long addr, unsigned long end)
 		vunmap_p4d_range(pgd, addr, next);
 	} while (pgd++, addr = next, addr != end);
 }
+EXPORT_SYMBOL(__vunmap_page_range);
+static void vunmap_page_range(unsigned long addr, unsigned long end)
+{
+	kmsan_vunmap_page_range(addr, end);
+	__vunmap_page_range(addr, end);
+}
 
 static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
 		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
@@ -216,8 +224,11 @@ static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
  * will have pfns corresponding to the "pages" array.
  *
  * Ie. pte at addr+N*PAGE_SIZE shall point to pfn corresponding to pages[N]
+ *
+ * This function is exported for use in KMSAN, but is only declared in KMSAN
+ * headers.
  */
-static int vmap_page_range_noflush(unsigned long start, unsigned long end,
+int __vmap_page_range_noflush(unsigned long start, unsigned long end,
 				   pgprot_t prot, struct page **pages)
 {
 	pgd_t *pgd;
@@ -237,6 +248,14 @@ static int vmap_page_range_noflush(unsigned long start, unsigned long end,
 
 	return nr;
 }
+EXPORT_SYMBOL(__vmap_page_range_noflush);
+
+static int vmap_page_range_noflush(unsigned long start, unsigned long end,
+				   pgprot_t prot, struct page **pages)
+{
+	kmsan_vmap_page_range_noflush(start, end, prot, pages);
+	return __vmap_page_range_noflush(start, end, prot, pages);
+}
 
 static int vmap_page_range(unsigned long start, unsigned long end,
 			   pgprot_t prot, struct page **pages)
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 17bd8f539bc7..fd22c4a4ba42 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
+#include <linux/kmsan-checks.h>
 #include <linux/sched.h>
 #include <linux/string.h>
 #include <linux/errno.h>
@@ -659,6 +660,7 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
 	} else {
 		qdisc->empty = true;
 	}
+	kmsan_check_skb(skb);
 
 	return skb;
 }
