Re: [PATCH v2 1/1] fix a dead loop when in heavy low memory

Re: [PATCH v2 1/1] fix a dead loop when in heavy low memory

[Greg KH]

On Sun, Dec 27, 2015 at 03:39:42AM +0800, Figo wrote:
> Android System UI hang when run heavy monkey stress test.

What changed from v1 of this patch?  Please describe that below the ---
line.

> 
> Signed-off-by: Figo <tianfei.zhang@intel.com>

I need a "full" name here, not a "short" name, sorry, before I can do
anything with this patch.

thanks,

greg k-h

[PATCH v2 1/1] fix a dead loop when in heavy low memory

[Figo]

Android System UI hang when run heavy monkey stress test.

Run this monkey stress test script with more than 100
apps/games installed:

adb shell "monkey --ignore-crashes --ignore-timeouts
--kill-process-after-error --ignore-security-exceptions
 --throttle 200 -v 20000000"

kernel log:
[ 1526.272125] lowmem_scan start: 128, 213da, ofree -9849 34419, ma 529
[ 1526.272260] lowmemorykiller: select 'dTi-lm' (27289), adj 647, size 10630, to kill
[ 1526.272299] lowmem_d_timeout=4296194081
[ 1526.272303] Killing 'dTi-lm' (27289), adj 647,
[ 1526.272303]    to free 42520kB on behalf of 'servicemanager' (2365) because
[ 1526.272303]    cache 137676kB is below limit 221184kB for oom_score_adj 529
[ 1526.272303]    Free memory is -39396kB above reserved
[ 1526.272304] lowmem_scan end: 128, 213da, return 10630
[ 1526.272710] lowmem_scan start: 128, 213da, ofree -9849 34373, ma 529
[ 1526.272832] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296193081, 4296194081
[ 1526.274450] lowmem_scan start: 128, 280da, ofree -9601 34327, ma 529
[ 1526.274695] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296193083, 4296194081
[ 1526.282292] lowmem_scan start: 128, 213da, ofree -9703 34327, ma 529
[ 1526.282727] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296193090, 4296194081
[ 1526.316888] lowmem_scan start: 128, 213da, ofree -9766 34465, ma 529
[ 1526.317019] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296193125, 4296194081
[ 1526.319311] lowmem_scan start: 128, 213da, ofree -9856 34419, ma 529
[ 1526.319442] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296193125, 4296194081
[ 1526.322026] lowmem_scan start: 128, 280da, ofree -9841 34327, ma 529
[ 1526.360831] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296193166, 4296194081
[ 1526.532233] lowmem_scan start: 128, 213da, ofree -9846 34511, ma 529
[ 1526.644046] lowmem_scan start: 128, 213da, ofree -9785 34235, ma 529
[ 1527.437578] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296194246, 4296195109
[ 1527.442559] lowmem_scan start: 128, 213da, ofree -9850 41884, ma 529
[ 1527.459540] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296194268, 4296195109
[ 1527.500352] lowmem: TIF_MEMDIE, adj=647, dTi-lm, jiffies=4296194309, 4296195109

when this happened, the android system UI will hang, no process can be
select to kill.

i found the the value of "lowmem_deathpending_timeout" will be modified
strangely, like in last killing, the value is 4296194081, but why not it
had changed to 4296195109? so it will cause the deadloop in low memory
state which will cause the android system UI hang, because no process will
 be kill.

commit e5d7965f88a3 ("staging: android: lowmemorykiller: Don't wait more
than one second for a process to die") said wait 1 seconds, i think it no
need to wait 1 second, because we don't select the process with
"TIF_MEMDIE" to kill.

Signed-off-by: Figo <tianfei.zhang@intel.com>
---
 drivers/staging/android/lowmemorykiller.c |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index e679d84..13c7182 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -59,8 +59,6 @@ static int lowmem_minfree[6] = {
 };
 static int lowmem_minfree_size = 4;
 
-static unsigned long lowmem_deathpending_timeout;
-
 #define lowmem_print(level, x...)			\
 	do {						\
 		if (lowmem_debug_level >= (level))	\
@@ -128,11 +126,9 @@ 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)) {
+		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
 			task_unlock(p);
-			rcu_read_unlock();
-			return 0;
+			continue;
 		}
 		oom_score_adj = p->signal->oom_score_adj;
 		if (oom_score_adj < min_score_adj) {
@@ -170,7 +166,6 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
 		lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
 			     selected->pid, selected->comm,
 			     selected_oom_score_adj, selected_tasksize);
-		lowmem_deathpending_timeout = jiffies + HZ;
 		rem += selected_tasksize;
 	}
 
-- 
1.7.9.5

RE: [PATCH v2 1/1] fix a dead loop when in heavy low memory

[Zhang, Tianfei]

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> > Android System UI hang when run heavy monkey stress test.
> 
> What changed from v1 of this patch?  Please describe that below the ---
> line.
V2£¬I just modify my comments.

> 
> >
> > Signed-off-by: Figo <tianfei.zhang@intel.com>
> 
> I need a "full" name here, not a "short" name, sorry, before I can do anything
> with this patch.

 my name? my Full name is Figo.zhang

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Re: [PATCH v2 1/1] fix a dead loop when in heavy low memory

[Harald Arnesen]

Greg KH [2015-12-26 19:12]:

> I need a "full" name here, not a "short" name, sorry, before I can do
> anything with this patch.

I don't know if that is the case here, but:

You know, of course, that there are societies in this world  where only
one name is used?
-- 
Hilsen Harald

Re: [PATCH v2 1/1] fix a dead loop when in heavy low memory

[Greg KH]

On Sun, Dec 27, 2015 at 12:42:31AM +0100, Harald Arnesen wrote:
> Greg KH [2015-12-26 19:12]:
> 
> > I need a "full" name here, not a "short" name, sorry, before I can do
> > anything with this patch.
> 
> I don't know if that is the case here, but:
> 
> You know, of course, that there are societies in this world  where only
> one name is used?

Yes, but that obviously is not the case here, please give me more
credit, I've been dealing with this for a _very_ long time...

greg k-h

Re: [PATCH v2 1/1] fix a dead loop when in heavy low memory

[Greg KH]

On Sat, Dec 26, 2015 at 11:24:14PM +0000, Zhang, Tianfei wrote:
> > > Android System UI hang when run heavy monkey stress test.
> > 
> > What changed from v1 of this patch?  Please describe that below the ---
> > line.
> V2，I just modify my comments.

Then say so.  How am I supposed to know?

> > > Signed-off-by: Figo <tianfei.zhang@intel.com>
> > 
> > I need a "full" name here, not a "short" name, sorry, before I can do anything
> > with this patch.
> 
>  my name? my Full name is Figo.zhang

Great, please use that, but why does your email address show a different
name?  Intel has standards that you have to follow when submitting
Linux kernel patches, please consult them before you resend.

thanks,

greg k-h

RE: [PATCH v2 1/1] fix a dead loop when in heavy low memory

[Zhang, Tianfei]

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> Great, please use that, but why does your email address show a different
> name?  Intel has standards that you have to follow when submitting Linux
> kernel patches, please consult them before you resend.
> 

Hi greg, I should resend this patch using [PATCH RESEND v2 1/1]?
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Re: [PATCH v2 1/1] fix a dead loop when in heavy low memory

[Greg KH]

On Sun, Dec 27, 2015 at 12:19:08AM +0000, Zhang, Tianfei wrote:
> > Great, please use that, but why does your email address show a different
> > name?  Intel has standards that you have to follow when submitting Linux
> > kernel patches, please consult them before you resend.
> > 
> 
> Hi greg, I should resend this patch using [PATCH RESEND v2 1/1]?

I can't take it as-is, so of course you should resend it...