diff options
| author | David Rientjes <rientjes@google.com> | 2015-11-05 18:48:05 -0800 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2019-07-08 14:08:55 +0200 |
| commit | 173048a77ade2e0a276ba52ebf5e9ead5f4091d3 (patch) | |
| tree | 2b5fc3e96a25133ec716eba4c5361c0be31eb608 /kernel/cpuset.c | |
| parent | 3feac374ea522799fa5470b4f6d8d577b5490974 (diff) | |
mm, oom: remove task_lock protecting comm printing
The oom killer takes task_lock() in a couple of places solely to protect
printing the task's comm.
A process's comm, including current's comm, may change due to
/proc/pid/comm or PR_SET_NAME.
The comm will always be NULL-terminated, so the worst race scenario would
only be during update. We can tolerate a comm being printed that is in
the middle of an update to avoid taking the lock.
Other locations in the kernel have already dropped task_lock() when
printing comm, so this is consistent.
Change-Id: I89f64666a1db5d414aa53862fd6b665bbb8125bc
Signed-off-by: David Rientjes <rientjes@google.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index ab0be4565..f3a417c1d 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2601,28 +2601,26 @@ int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, #define CPUSET_NODELIST_LEN (256) /** - * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed - * @task: pointer to task_struct of some task. + * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed * - * Description: Prints @task's name, cpuset name, and cached copy of its - * mems_allowed to the kernel log. Must hold task_lock(task) to allow - * dereferencing task_cs(task). + * Description: Prints current's name, cpuset name, and cached copy of its + * mems_allowed to the kernel log. */ -void cpuset_print_task_mems_allowed(struct task_struct *tsk) +void cpuset_print_current_mems_allowed(void) { /* Statically allocated to prevent using excess stack. */ static char cpuset_nodelist[CPUSET_NODELIST_LEN]; static DEFINE_SPINLOCK(cpuset_buffer_lock); - struct cgroup *cgrp = task_cs(tsk)->css.cgroup; + struct cgroup *cgrp = task_cs(current)->css.cgroup; rcu_read_lock(); spin_lock(&cpuset_buffer_lock); nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, - tsk->mems_allowed); - printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", - tsk->comm, cgroup_name(cgrp), cpuset_nodelist); + current->mems_allowed); + pr_info("%s cpuset=%s mems_allowed=%s\n", + current->comm, cgroup_name(cgrp), cpuset_nodelist); spin_unlock(&cpuset_buffer_lock); rcu_read_unlock(); |