In commit dad1743e5993f19b3d7e7bd0fb35dc45b5326626
x86/mce: Only restart instruction after machine check recovery if it is safe
we fixed mce_notify_process() to force a signal to the current process
if it was not restartable (RIPV bit not set in MCG_STATUS). But doing
it here means that the process doesn't get told the virtual address of
the fault via siginfo_t->si_addr. This would prevent application level
recovery from the fault.
Make a new MF_MUST_KILL flag bit for memory_failure() et. al. to use
so that we will provide the right information with the signal.
Signed-off-by: Tony Luck <tony.l...@intel.com>
---
v2: Fix brainfart where I forgot to check mi->restartable to decide whether
to pass in the new MF_MUST_KILL bit [Thanks Boris for spotting this!]
Use same style syntax !!(flags & MF_MUST_KILL) [Also from Boris]
Faked tests with RIPV set and not set ... and found that we need one
more check on MF_MUST_KILL earlier in hwpoison_user_mappings() to
make sure it doesn't think the clean page case is recoverable.
arch/x86/kernel/cpu/mcheck/mce.c | 6 ++++--
include/linux/mm.h | 1 +
mm/memory-failure.c | 10 ++++++----
3 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index da27c5d..9f9ed4f 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1186,6 +1186,7 @@ void mce_notify_process(void)
{
unsigned long pfn;
struct mce_info *mi = mce_find_info();
+ int flags = MF_ACTION_REQUIRED;
if (!mi)
mce_panic("Lost physical address for unconsumed uncorrectable
error", NULL, NULL);
@@ -1200,8 +1201,9 @@ void mce_notify_process(void)
* doomed. We still need to mark the page as poisoned and alert any
* other users of the page.
*/
- if (memory_failure(pfn, MCE_VECTOR, MF_ACTION_REQUIRED) < 0 ||
- mi->restartable == 0) {
+ if (mi->restartable == 0)
+ flags |= MF_MUST_KILL;
+ if (memory_failure(pfn, MCE_VECTOR, flags) < 0) {
pr_err("Memory error not recovered");
force_sig(SIGBUS, current);
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b36d08c..f9f279c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1591,6 +1591,7 @@ void vmemmap_populate_print_last(void);
enum mf_flags {
MF_COUNT_INCREASED = 1 << 0,
MF_ACTION_REQUIRED = 1 << 1,
+ MF_MUST_KILL = 1 << 2,
};
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 ab1e714..83cc9ef 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -858,7 +858,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned
long pfn,
struct address_space *mapping;
LIST_HEAD(tokill);
int ret;
- int kill = 1;
+ int kill = 1, doit;
struct page *hpage = compound_head(p);
struct page *ppage;
@@ -888,7 +888,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned
long pfn,
* be called inside page lock (it's recommended but not enforced).
*/
mapping = page_mapping(hpage);
- if (!PageDirty(hpage) && mapping &&
+ if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
mapping_cap_writeback_dirty(mapping)) {
if (page_mkclean(hpage)) {
SetPageDirty(hpage);
@@ -965,12 +965,14 @@ static int hwpoison_user_mappings(struct page *p,
unsigned long pfn,
* Now that the dirty bit has been propagated to the
* struct page and all unmaps done we can decide if
* killing is needed or not. Only kill when the page
- * was dirty, otherwise the tokill list is merely
+ * was dirty or the process is not restartable,
+ * otherwise the tokill list is merely
* freed. When there was a problem unmapping earlier
* use a more force-full uncatchable kill to prevent
* any accesses to the poisoned memory.
*/
- kill_procs(&tokill, !!PageDirty(ppage), trapno,
+ doit = !!PageDirty(ppage) || !!(flags & MF_MUST_KILL);
+ kill_procs(&tokill, doit, trapno,
ret != SWAP_SUCCESS, p, pfn, flags);
return ret;
--
1.7.10.2.552.gaa3bb87
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
