The patch titled
Subject: um: properly check all process' threads for a live mm
has been added to the -mm tree. Its filename is
um-properly-check-all-process-threads-for-a-live-mm.patch
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From: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx>
Subject: um: properly check all process' threads for a live mm
kill_off_processes() might miss a valid process, this is because checking
for process->mm is not enough. Process' main thread may exit or detach
its mm via use_mm(), but other threads may still have a valid mm.
To catch this we use find_lock_task_mm(), which walks up all threads and
returns an appropriate task (with task lock held).
Suggested-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/um/kernel/reboot.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff -puN arch/um/kernel/reboot.c~um-properly-check-all-process-threads-for-a-live-mm arch/um/kernel/reboot.c
--- a/arch/um/kernel/reboot.c~um-properly-check-all-process-threads-for-a-live-mm
+++ a/arch/um/kernel/reboot.c
@@ -6,6 +6,7 @@
#include "linux/sched.h"
#include "linux/spinlock.h"
#include "linux/slab.h"
+#include "linux/oom.h"
#include "kern_util.h"
#include "os.h"
#include "skas.h"
@@ -25,13 +26,13 @@ static void kill_off_processes(void)
read_lock(&tasklist_lock);
for_each_process(p) {
- task_lock(p);
- if (!p->mm) {
- task_unlock(p);
+ struct task_struct *t;
+
+ t = find_lock_task_mm(p);
+ if (!t)
continue;
- }
- pid = p->mm->context.id.u.pid;
- task_unlock(p);
+ pid = t->mm->context.id.u.pid;
+ task_unlock(t);
os_kill_ptraced_process(pid, 1);
}
read_unlock(&tasklist_lock);
_
Subject: Subject: um: properly check all process' threads for a live mm
Patches currently in -mm which might be from anton.vorontsov@xxxxxxxxxx are
cpu-introduce-clear_tasks_mm_cpumask-helper.patch
arm-use-clear_tasks_mm_cpumask.patch
powerpc-use-clear_tasks_mm_cpumask.patch
sh-use-clear_tasks_mm_cpumask.patch
blackfin-a-couple-of-task-mm-handling-fixes.patch
blackfin-fix-possible-deadlock-in-decode_address.patch
um-should-hold-tasklist_lock-while-traversing-processes.patch
um-fix-possible-race-on-task-mm.patch
um-properly-check-all-process-threads-for-a-live-mm.patch
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