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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2021-03-12 21:08:03 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-03-13 11:27:30 -0800 |
| commit | 149fc787353f65b7e72e05e7b75d34863266c3e2 (patch) | |
| tree | 9c1436d6fd11b3ba6e8151c707f11b8c5cfe788e | |
| parent | 0aa41cae92c1e2e61ae5b3a2dde8e674172e40ac (diff) | |
| download | linux-149fc787353f65b7e72e05e7b75d34863266c3e2.tar.bz2 | |
include/linux/sched/mm.h: use rcu_dereference in in_vfork()
Fix a sparse warning by using rcu_dereference(). Technically this is a
bug and a sufficiently aggressive compiler could reload the `real_parent'
pointer outside the protection of the rcu lock (and access freed memory),
but I think it's pretty unlikely to happen.
Link: https://lkml.kernel.org/r/20210221194207.1351703-1-willy@infradead.org
Fixes: b18dc5f291c0 ("mm, oom: skip vforked tasks from being selected")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/sched/mm.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 1ae08b8462a4..90b2a0bce11c 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -140,7 +140,8 @@ static inline bool in_vfork(struct task_struct *tsk) * another oom-unkillable task does this it should blame itself. */ rcu_read_lock(); - ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm; + ret = tsk->vfork_done && + rcu_dereference(tsk->real_parent)->mm == tsk->mm; rcu_read_unlock(); return ret; |