Merge tag 'v5.4-rc4' into docs-next

I need to pick up the independent changes made to
Documentation/core-api/memory-allocation.rst to be able to merge further
work without creating a total mess.

1 files changed, 21 insertions, 15 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 7ef849da8278..3151c87dff73 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -199,7 +199,6 @@ struct to_kill {
 	struct task_struct *tsk;
 	unsigned long addr;
 	short size_shift;
-	char addr_valid;
 };
 
 /*
@@ -324,22 +323,27 @@ static void add_to_kill(struct task_struct *tsk, struct page *p,
 		}
 	}
 	tk->addr = page_address_in_vma(p, vma);
-	tk->addr_valid = 1;
 	if (is_zone_device_page(p))
 		tk->size_shift = dev_pagemap_mapping_shift(p, vma);
 	else
 		tk->size_shift = compound_order(compound_head(p)) + PAGE_SHIFT;
 
 	/*
-	 * In theory we don't have to kill when the page was
-	 * munmaped. But it could be also a mremap. Since that's
-	 * likely very rare kill anyways just out of paranoia, but use
-	 * a SIGKILL because the error is not contained anymore.
+	 * Send SIGKILL if "tk->addr == -EFAULT". Also, as
+	 * "tk->size_shift" is always non-zero for !is_zone_device_page(),
+	 * so "tk->size_shift == 0" effectively checks no mapping on
+	 * ZONE_DEVICE. Indeed, when a devdax page is mmapped N times
+	 * to a process' address space, it's possible not all N VMAs
+	 * contain mappings for the page, but at least one VMA does.
+	 * Only deliver SIGBUS with payload derived from the VMA that
+	 * has a mapping for the page.
 	 */
-	if (tk->addr == -EFAULT || tk->size_shift == 0) {
+	if (tk->addr == -EFAULT) {
 		pr_info("Memory failure: Unable to find user space address %lx in %s\n",
 			page_to_pfn(p), tsk->comm);
-		tk->addr_valid = 0;
+	} else if (tk->size_shift == 0) {
+		kfree(tk);
+		return;
 	}
 	get_task_struct(tsk);
 	tk->tsk = tsk;
@@ -366,7 +370,7 @@ static void kill_procs(struct list_head *to_kill, int forcekill, bool fail,
 			 * make sure the process doesn't catch the
 			 * signal and then access the memory. Just kill it.
 			 */
-			if (fail || tk->addr_valid == 0) {
+			if (fail || tk->addr == -EFAULT) {
 				pr_err("Memory failure: %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
 				       pfn, tk->tsk->comm, tk->tsk->pid);
 				do_send_sig_info(SIGKILL, SEND_SIG_PRIV,
@@ -1253,17 +1257,19 @@ int memory_failure(unsigned long pfn, int flags)
 	if (!sysctl_memory_failure_recovery)
 		panic("Memory failure on page %lx", pfn);
 
-	if (!pfn_valid(pfn)) {
+	p = pfn_to_online_page(pfn);
+	if (!p) {
+		if (pfn_valid(pfn)) {
+			pgmap = get_dev_pagemap(pfn, NULL);
+			if (pgmap)
+				return memory_failure_dev_pagemap(pfn, flags,
+								  pgmap);
+		}
 		pr_err("Memory failure: %#lx: memory outside kernel control\n",
 			pfn);
 		return -ENXIO;
 	}
 
-	pgmap = get_dev_pagemap(pfn, NULL);
-	if (pgmap)
-		return memory_failure_dev_pagemap(pfn, flags, pgmap);
-
-	p = pfn_to_page(pfn);
 	if (PageHuge(p))
 		return memory_failure_hugetlb(pfn, flags);
 	if (TestSetPageHWPoison(p)) {