Merge branch 'x86-mce-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull MCE changes from Ingo Molnar.

* 'x86-mce-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Fix return value of mce_chrdev_read() when erst is disabled
  x86/mce: Convert static array of pointers to per-cpu variables
  x86/mce: Replace hard coded hex constants with symbolic defines
  x86/mce: Recognise machine check bank signature for data path error
  x86/mce: Handle "action required" errors
  x86/mce: Add mechanism to safely save information in MCE handler
  x86/mce: Create helper function to save addr/misc when needed
  HWPOISON: Add code to handle "action required" errors.
  HWPOISON: Clean up memory_failure() vs. __memory_failure()

3 files changed, 53 insertions, 49 deletions

diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index c7fc7fd00e32..cc448bb983ba 100644
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -45,7 +45,7 @@ static int hwpoison_inject(void *data, u64 val)
 	 * do a racy check with elevated page count, to make sure PG_hwpoison
 	 * will only be set for the targeted owner (or on a free page).
 	 * We temporarily take page lock for try_get_mem_cgroup_from_page().
-	 * __memory_failure() will redo the check reliably inside page lock.
+	 * memory_failure() will redo the check reliably inside page lock.
 	 */
 	lock_page(hpage);
 	err = hwpoison_filter(hpage);
@@ -55,7 +55,7 @@ static int hwpoison_inject(void *data, u64 val)
 
 inject:
 	printk(KERN_INFO "Injecting memory failure at pfn %lx\n", pfn);
-	return __memory_failure(pfn, 18, MF_COUNT_INCREASED);
+	return memory_failure(pfn, 18, MF_COUNT_INCREASED);
 }
 
 static int hwpoison_unpoison(void *data, u64 val)
diff --git a/mm/madvise.c b/mm/madvise.c
index 74bf193eff04..f5ab745672b7 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -251,7 +251,7 @@ static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
 		printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n",
 		       page_to_pfn(p), start);
 		/* Ignore return value for now */
-		__memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
+		memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
 	}
 	return ret;
 }
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index c22076ffdd44..97cc2733551a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -187,33 +187,40 @@ int hwpoison_filter(struct page *p)
 EXPORT_SYMBOL_GPL(hwpoison_filter);
 
 /*
- * Send all the processes who have the page mapped an ``action optional''
- * signal.
+ * Send all the processes who have the page mapped a signal.
+ * ``action optional'' if they are not immediately affected by the error
+ * ``action required'' if error happened in current execution context
  */
-static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
-			unsigned long pfn, struct page *page)
+static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
+			unsigned long pfn, struct page *page, int flags)
 {
 	struct siginfo si;
 	int ret;
 
 	printk(KERN_ERR
-		"MCE %#lx: Killing %s:%d early due to hardware memory corruption\n",
+		"MCE %#lx: Killing %s:%d due to hardware memory corruption\n",
 		pfn, t->comm, t->pid);
 	si.si_signo = SIGBUS;
 	si.si_errno = 0;
-	si.si_code = BUS_MCEERR_AO;
 	si.si_addr = (void *)addr;
 #ifdef __ARCH_SI_TRAPNO
 	si.si_trapno = trapno;
 #endif
 	si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT;
-	/*
-	 * Don't use force here, it's convenient if the signal
-	 * can be temporarily blocked.
-	 * This could cause a loop when the user sets SIGBUS
-	 * to SIG_IGN, but hopefully no one will do that?
-	 */
-	ret = send_sig_info(SIGBUS, &si, t);  /* synchronous? */
+
+	if ((flags & MF_ACTION_REQUIRED) && t == current) {
+		si.si_code = BUS_MCEERR_AR;
+		ret = force_sig_info(SIGBUS, &si, t);
+	} else {
+		/*
+		 * Don't use force here, it's convenient if the signal
+		 * can be temporarily blocked.
+		 * This could cause a loop when the user sets SIGBUS
+		 * to SIG_IGN, but hopefully no one will do that?
+		 */
+		si.si_code = BUS_MCEERR_AO;
+		ret = send_sig_info(SIGBUS, &si, t);  /* synchronous? */
+	}
 	if (ret < 0)
 		printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n",
 		       t->comm, t->pid, ret);
@@ -338,8 +345,9 @@ static void add_to_kill(struct task_struct *tsk, struct page *p,
  * Also when FAIL is set do a force kill because something went
  * wrong earlier.
  */
-static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
-			  int fail, struct page *page, unsigned long pfn)
+static void kill_procs(struct list_head *to_kill, int doit, int trapno,
+			  int fail, struct page *page, unsigned long pfn,
+			  int flags)
 {
 	struct to_kill *tk, *next;
 
@@ -363,8 +371,8 @@ static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
 			 * check for that, but we need to tell the
 			 * process anyways.
 			 */
-			else if (kill_proc_ao(tk->tsk, tk->addr, trapno,
-					      pfn, page) < 0)
+			else if (kill_proc(tk->tsk, tk->addr, trapno,
+					      pfn, page, flags) < 0)
 				printk(KERN_ERR
 		"MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
 					pfn, tk->tsk->comm, tk->tsk->pid);
@@ -844,7 +852,7 @@ static int page_action(struct page_state *ps, struct page *p,
  * the pages and send SIGBUS to the processes if the data was dirty.
  */
 static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
-				  int trapno)
+				  int trapno, int flags)
 {
 	enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
 	struct address_space *mapping;
@@ -962,8 +970,8 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	 * use a more force-full uncatchable kill to prevent
 	 * any accesses to the poisoned memory.
 	 */
-	kill_procs_ao(&tokill, !!PageDirty(ppage), trapno,
-		      ret != SWAP_SUCCESS, p, pfn);
+	kill_procs(&tokill, !!PageDirty(ppage), trapno,
+		      ret != SWAP_SUCCESS, p, pfn, flags);
 
 	return ret;
 }
@@ -984,7 +992,25 @@ static void clear_page_hwpoison_huge_page(struct page *hpage)
 		ClearPageHWPoison(hpage + i);
 }
 
-int __memory_failure(unsigned long pfn, int trapno, int flags)
+/**
+ * memory_failure - Handle memory failure of a page.
+ * @pfn: Page Number of the corrupted page
+ * @trapno: Trap number reported in the signal to user space.
+ * @flags: fine tune action taken
+ *
+ * This function is called by the low level machine check code
+ * of an architecture when it detects hardware memory corruption
+ * of a page. It tries its best to recover, which includes
+ * dropping pages, killing processes etc.
+ *
+ * The function is primarily of use for corruptions that
+ * happen outside the current execution context (e.g. when
+ * detected by a background scrubber)
+ *
+ * Must run in process context (e.g. a work queue) with interrupts
+ * enabled and no spinlocks hold.
+ */
+int memory_failure(unsigned long pfn, int trapno, int flags)
 {
 	struct page_state *ps;
 	struct page *p;
@@ -1130,7 +1156,7 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
 	 * Now take care of user space mappings.
 	 * Abort on fail: __delete_from_page_cache() assumes unmapped page.
 	 */
-	if (hwpoison_user_mappings(p, pfn, trapno) != SWAP_SUCCESS) {
+	if (hwpoison_user_mappings(p, pfn, trapno, flags) != SWAP_SUCCESS) {
 		printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn);
 		res = -EBUSY;
 		goto out;
@@ -1156,29 +1182,7 @@ out:
 	unlock_page(hpage);
 	return res;
 }
-EXPORT_SYMBOL_GPL(__memory_failure);
-
-/**
- * memory_failure - Handle memory failure of a page.
- * @pfn: Page Number of the corrupted page
- * @trapno: Trap number reported in the signal to user space.
- *
- * This function is called by the low level machine check code
- * of an architecture when it detects hardware memory corruption
- * of a page. It tries its best to recover, which includes
- * dropping pages, killing processes etc.
- *
- * The function is primarily of use for corruptions that
- * happen outside the current execution context (e.g. when
- * detected by a background scrubber)
- *
- * Must run in process context (e.g. a work queue) with interrupts
- * enabled and no spinlocks hold.
- */
-void memory_failure(unsigned long pfn, int trapno)
-{
-	__memory_failure(pfn, trapno, 0);
-}
+EXPORT_SYMBOL_GPL(memory_failure);
 
 #define MEMORY_FAILURE_FIFO_ORDER	4
 #define MEMORY_FAILURE_FIFO_SIZE	(1 << MEMORY_FAILURE_FIFO_ORDER)
@@ -1251,7 +1255,7 @@ static void memory_failure_work_func(struct work_struct *work)
 		spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
 		if (!gotten)
 			break;
-		__memory_failure(entry.pfn, entry.trapno, entry.flags);
+		memory_failure(entry.pfn, entry.trapno, entry.flags);
 	}
 }