mm: add new mmgrab() helper

Apart from adding the helper function itself, the rest of the kernel is
converted mechanically using:

  git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)->mm_count);/mmgrab\(\1\);/'
  git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)\.mm_count);/mmgrab\(\&\1\);/'

This is needed for a later patch that hooks into the helper, but might
be a worthwhile cleanup on its own.

(Michal Hocko provided most of the kerneldoc comment.)

Link: http://lkml.kernel.org/r/20161218123229.22952-1-vegard.nossum@oracle.com
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vegard Nossum 2017-02-27 14:30:07 -08:00 committed by Linus Torvalds
parent 522b837c67
commit f1f1007644
40 changed files with 65 additions and 43 deletions

View file

@ -653,7 +653,7 @@ static void mark_oom_victim(struct task_struct *tsk)
/* oom_mm is bound to the signal struct life time. */
if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm))
atomic_inc(&tsk->signal->oom_mm->mm_count);
mmgrab(tsk->signal->oom_mm);
/*
* Make sure that the task is woken up from uninterruptible sleep
@ -870,7 +870,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
/* Get a reference to safely compare mm after task_unlock(victim) */
mm = victim->mm;
atomic_inc(&mm->mm_count);
mmgrab(mm);
/*
* We should send SIGKILL before setting TIF_MEMDIE in order to prevent
* the OOM victim from depleting the memory reserves from the user