Message-ID: <1438259357.2677.23.camel@perches.com>
Subject: Re: [PATCH] improve lmk to avoid deadlock issue
From: Joe Perches <joe@perches.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Wang, Biao" <biao.wang@intel.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "arve@android.com" <arve@android.com>,
        "riandrews@android.com" <riandrews@android.com>,
        "devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>,
        "Zhang, Di" <di.zhang@intel.com>, "Li, Fei" <fei.li@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Date: Thu, 30 Jul 2015 05:29:17 -0700
In-Reply-To: <20150730100937.GM5180@mwanda>
References: <09CB0B4607EB8F4DB7E0BE3B06BFBD051DA2DCAB@SHSMSX101.ccr.corp.intel.com>
	 <20150730100937.GM5180@mwanda>
Content-Type: text/plain; charset="ISO-8859-1"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1454
Lines: 44

On Thu, 2015-07-30 at 13:09 +0300, Dan Carpenter wrote:
> > diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
[]
> > @@ -127,11 +127,15 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
> >  		if (!p)
> >  			continue;
> >  
> > -		if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
> > -		    time_before_eq(jiffies, lowmem_deathpending_timeout)) {
> > -			task_unlock(p);
> > -			rcu_read_unlock();
> > -			return 0;
> > +		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
> > +			if (time_before_eq(jiffies, lowmem_deathpending_timeout)) {
> 
> 5) This goes over the 80 character limit.  Could you break it up like
> this:
> 
> 		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
> 			if (time_before_eq(jiffies,
> 					   lowmem_deathpending_timeout)) {
> 				task_unlock(p);
> 
> Anyway, thank for this patch.  Please fix these small process issues
> and resend.

Can the task_unlock in each branch be hoisted?

Another way to write this might be to use time_after:

		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
			task_unlock(p);
			if (time_after(jiffies, lowmem_deathpending_timeout))
				continue;
			rcu_read_unlock();
			return 0;
		}


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/