From: Oleg Nesterov <oleg@redhat.com>
To: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: "Greg KH" <gregkh@linuxfoundation.org>,
"Arve Hjønnevåg" <arve@android.com>,
"KOSAKI Motohiro" <kosaki.motohiro@gmail.com>,
"San Mehat" <san@google.com>, "Colin Cross" <ccross@android.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
linux-kernel@vger.kernel.org, kernel-team@android.com,
linaro-kernel@lists.linaro.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH v3] staging: android/lowmemorykiller: Don't grab tasklist_lock
Date: Fri, 3 Feb 2012 17:36:51 +0100 [thread overview]
Message-ID: <20120203163651.GB4190@redhat.com> (raw)
In-Reply-To: <20120203000345.GA14338@oksana.dev.rtsoft.ru>
On 02/03, Anton Vorontsov wrote:
>
> @@ -132,7 +133,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
> }
> selected_oom_adj = min_adj;
>
> - read_lock(&tasklist_lock);
> + rcu_read_lock();
> for_each_process(p) {
> struct mm_struct *mm;
> struct signal_struct *sig;
> @@ -180,12 +181,12 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
> lowmem_deathpending = selected;
> task_handoff_register(&task_nb);
> #endif
> - force_sig(SIGKILL, selected);
> + send_sig(SIGKILL, selected, 0);
> rem -= selected_tasksize;
> }
> lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
> sc->nr_to_scan, sc->gfp_mask, rem);
> - read_unlock(&tasklist_lock);
> + rcu_read_unlock();
I think this is correct. As for ->mm check please look at
find_lock_task_mm().
You can also remove the !sig check.
And, forgot to mention. There is another reason why mm != NULL
check is wrong (send_sig_all too). A kernel thread can do use_mm().
You should also check PF_KTHREAD.
Oleg.
next prev parent reply other threads:[~2012-02-03 16:43 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 4:33 [PATCH] staging: android/lowmemorykiller: Don't grab tasklist_lock Anton Vorontsov
2012-02-02 12:54 ` Oleg Nesterov
2012-02-02 17:16 ` Anton Vorontsov
2012-02-03 0:03 ` [PATCH v3] " Anton Vorontsov
2012-02-03 16:36 ` Oleg Nesterov [this message]
2012-02-03 16:30 ` [PATCH] " Oleg Nesterov
2012-02-06 16:29 ` [PATCH 1/6] oom: Make find_lock_task_mm() sparse-aware Anton Vorontsov
2012-02-06 16:35 ` Greg KH
2012-02-06 18:59 ` Anton Vorontsov
2012-02-06 19:18 ` Greg KH
2012-02-06 21:27 ` KOSAKI Motohiro
2012-02-07 4:48 ` [PATCH v2 " Anton Vorontsov
2012-02-07 5:17 ` KOSAKI Motohiro
2012-02-08 15:27 ` Oleg Nesterov
2012-02-09 16:45 ` [PATCH] sched: Turn lock_task_sighand() into a static inline Anton Vorontsov
2012-02-11 23:10 ` [tip:sched/core] " tip-bot for Anton Vorontsov
2012-02-15 13:52 ` Peter Zijlstra
2012-02-06 16:29 ` [PATCH 2/6] oom: Get rid of sparse warnings Anton Vorontsov
2012-02-06 21:33 ` KOSAKI Motohiro
2012-02-07 4:20 ` [PATCH v2 " Anton Vorontsov
2012-02-07 5:38 ` KOSAKI Motohiro
2012-02-07 6:23 ` Anton Vorontsov
2012-02-08 18:13 ` KOSAKI Motohiro
2012-02-06 16:29 ` [PATCH 3/6] staging: android/lowmemorykiller: Don't grab tasklist_lock Anton Vorontsov
2012-02-06 16:36 ` Greg KH
2012-02-06 16:42 ` Anton Vorontsov
2012-02-09 0:56 ` Greg KH
2012-02-08 15:32 ` Oleg Nesterov
2012-02-06 16:29 ` [PATCH 4/6] staging: android/lowmemorykiller: Better mm handling Anton Vorontsov
2012-02-06 21:36 ` KOSAKI Motohiro
2012-02-08 15:34 ` Oleg Nesterov
2012-02-06 16:29 ` [PATCH 5/6] staging: android/lowmemorykiller: No need for task->signal check Anton Vorontsov
2012-02-06 21:38 ` KOSAKI Motohiro
2012-02-08 15:35 ` Oleg Nesterov
2012-02-06 16:30 ` [PATCH 6/6] staging: android/lowmemorykiller: Do not kill kernel threads Anton Vorontsov
2012-02-06 21:38 ` KOSAKI Motohiro
2012-02-08 15:36 ` Oleg Nesterov
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