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Subject[PATCH 3.4 10/43] mm/memory-failure.c-failure: send right signal code to correct thread
3.4-stable review patch.  If anyone has any objections, please let me know.


From: Tony Luck <>

commit a70ffcac741d31a406c1d2b832ae43d658e7e1cf upstream.

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).

Signed-off-by: Tony Luck <>
Signed-off-by: Naoya Horiguchi <>
Reported-by: Otto Bruggeman <>
Cc: Andi Kleen <>
Cc: Borislav Petkov <>
Cc: Chen Gong <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
Signed-off-by: Greg Kroah-Hartman <>

mm/memory-failure.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -208,9 +208,9 @@ static int kill_proc(struct task_struct
si.si_addr_lsb = compound_trans_order(compound_head(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

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