From: Tony Luck <tony.luck@xxxxxxxxx>
When a thread in a multi-threaded application hits a machine
check because of an uncorrectable error in memory - we want to
send the SIGBUS with si.si_code = BUS_MCEERR_AR to that thread.
Currently we fail to do that if the active thread is not the
primary thread in the process. collect_procs() just finds primary
threads and this test:
if ((flags & MF_ACTION_REQUIRED) && t == current) {
will see that the thread we found isn't the current thread
and so send a si.si_code = BUS_MCEERR_AO to the primary
(and nothing to the active thread at this time).
We can fix this by checking whether "current" shares the same
mm with the process that collect_procs() said owned the page.
If so, we send the SIGBUS to current (with code BUS_MCEERR_AR).
Reported-by: Otto Bruggeman <otto.g.bruggeman@xxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Chen Gong <gong.chen@xxxxxxxxxxxxxxxxxx>
Acked-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
mm/memory-failure.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git mmotm-2014-05-21-16-57.orig/mm/memory-failure.c mmotm-2014-05-21-16-57/mm/memory-failure.c
index e3154d99b87f..b73098ee91e6 100644
--- mmotm-2014-05-21-16-57.orig/mm/memory-failure.c
+++ mmotm-2014-05-21-16-57/mm/memory-failure.c
@@ -204,9 +204,9 @@ static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
#endif
si.si_addr_lsb = page_size_order(page) + PAGE_SHIFT;
- if ((flags & MF_ACTION_REQUIRED) && t == current) {
+ if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
si.si_code = BUS_MCEERR_AR;
- ret = force_sig_info(SIGBUS, &si, t);
+ ret = force_sig_info(SIGBUS, &si, current);
} else {
/*
* Don't use force here, it's convenient if the signal
--
1.9.3
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