HWPOISON: Add code to handle "action required" errors.

Add new flag bit "MF_ACTION_REQUIRED" to be used by machine check
code to force a signal with si_code = BUS_MCEERR_AR in the case
where the error occurs in processor execution context. Pass the
flags argument along call chain:
	memory_failure()
	  hwpoison_user_mappings()
	    kill_procs()
	      kill_proc()

Drop the "_ao" suffix from kill_procs_ao() and kill_proc_ao() since
they can now handle "action required" as well as "action optional" errors.

Acked-by: Borislav Petkov <bp@amd64.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index bcc5234747246b0be01128d7081e06e50dcff070..bf169ca698126efbcc393818ecaec74319d6d762 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1606,6 +1606,7 @@ void vmemmap_populate_print_last(void);
 
 enum mf_flags {
        MF_COUNT_INCREASED = 1 << 0,
+       MF_ACTION_REQUIRED = 1 << 1,
 };
 extern int memory_failure(unsigned long pfn, int trapno, int flags);
 extern void memory_failure_queue(unsigned long pfn, int trapno, int flags);

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ab259bb0adc5edde7dbae854d9209fa641001375..95fd307ebb3025580d94abe7e4a0a4ade3605ed3 100644 (file)
--- 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;
 }
@@ -1148,7 +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;