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authorDavid Rientjes <rientjes@google.com>2015-11-05 18:48:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-05 19:34:48 -0800
commitda39da3a54fed88e29024f2f1f6cd7357cd03a44 (patch)
treeca4bbdc90d4f7e3cf2e7258135380b6b4b0f5fc6 /mm/oom_kill.c
parent2d1e10412c2388ff9b6afc60536eaa195a419289 (diff)
downloadlinux-da39da3a54fed88e29024f2f1f6cd7357cd03a44.tar.bz2
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. 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 'mm/oom_kill.c')
-rw-r--r--mm/oom_kill.c8
1 files changed, 1 insertions, 7 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c170d9f0a158..58f3d2748ced 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -377,13 +377,11 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
static void dump_header(struct oom_control *oc, struct task_struct *p,
struct mem_cgroup *memcg)
{
- task_lock(current);
pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
"oom_score_adj=%hd\n",
current->comm, oc->gfp_mask, oc->order,
current->signal->oom_score_adj);
- cpuset_print_task_mems_allowed(current);
- task_unlock(current);
+ cpuset_print_current_mems_allowed();
dump_stack();
if (memcg)
mem_cgroup_print_oom_info(memcg, p);
@@ -509,10 +507,8 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
if (__ratelimit(&oom_rs))
dump_header(oc, p, memcg);
- task_lock(p);
pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
message, task_pid_nr(p), p->comm, points);
- task_unlock(p);
/*
* If any of p's children has a different mm and is eligible for kill,
@@ -586,10 +582,8 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
if (fatal_signal_pending(p))
continue;
- task_lock(p); /* Protect ->comm from prctl() */
pr_info("Kill process %d (%s) sharing same memory\n",
task_pid_nr(p), p->comm);
- task_unlock(p);
do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
}
rcu_read_unlock();