M. Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his
32bit 3GB mem machine. (https://bugzilla.kernel.org/show_bug.cgi?id=16771)
Also he was bisected first bad commit is below
commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c
Author: KOSAKI Motohiro <[email protected]>
Date: Fri Jun 4 14:15:05 2010 -0700
vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure
At first impression, this seemed very strange because the above commit only
chenged function return value and hibernate_preallocate_memory() ignore
return value of shrink_all_memory(). But it's related.
Now, page allocation from hibernation code may enter infinite loop if
the system has highmem.
The reasons are two. 1) hibernate_preallocate_memory() call
alloc_pages() wrong order 2) vmscan don't care enough OOM case when
oom_killer_disabled.
This patch only fix (2). Why is oom_killer_disabled so special?
because when hibernation case, zone->all_unreclaimable never be turned on.
hibernation freeze all tasks at first, then kswapd can't works in this
case, and zone->all_unreclaimable is only turned from kswapd.
Cc: Johannes Weiner <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: M. Vefa Bicakci <[email protected]>
Cc: [email protected]
Signed-off-by: KOSAKI Motohiro <[email protected]>
---
mm/vmscan.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index c391c32..1919d8a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -40,6 +40,7 @@
#include <linux/memcontrol.h>
#include <linux/delayacct.h>
#include <linux/sysctl.h>
+#include <linux/oom.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -1931,7 +1932,7 @@ out:
return sc->nr_reclaimed;
/* top priority shrink_zones still had more to do? don't OOM, then */
- if (scanning_global_lru(sc) && !all_unreclaimable)
+ if (scanning_global_lru(sc) && !all_unreclaimable && !oom_killer_disabled)
return 1;
return 0;
--
1.6.5.2
Hi KOSAKI,
On Wed, Sep 1, 2010 at 9:31 AM, KOSAKI Motohiro
<[email protected]> wrote:
> M. Vefa Bicakci reported 2.6.35 kernel hang up when hibernation on his
> 32bit 3GB mem machine. (https://bugzilla.kernel.org/show_bug.cgi?id=16771)
> Also he was bisected first bad commit is below
>
> ?commit bb21c7ce18eff8e6e7877ca1d06c6db719376e3c
> ?Author: KOSAKI Motohiro <[email protected]>
> ?Date: ? Fri Jun 4 14:15:05 2010 -0700
>
> ? ? vmscan: fix do_try_to_free_pages() return value when priority==0 reclaim failure
>
> At first impression, this seemed very strange because the above commit only
> chenged function return value and hibernate_preallocate_memory() ignore
> return value of shrink_all_memory(). But it's related.
>
> Now, page allocation from hibernation code may enter infinite loop if
> the system has highmem.
>
> The reasons are two. 1) hibernate_preallocate_memory() call
> alloc_pages() wrong order 2) vmscan don't care enough OOM case when
> oom_killer_disabled.
>
> This patch only fix (2). Why is oom_killer_disabled so special?
> because when hibernation case, zone->all_unreclaimable never be turned on.
> hibernation freeze all tasks at first, then kswapd can't works in this
> case, and zone->all_unreclaimable is only turned from kswapd.
Nice catch!!
There is some comment below.
>
> Cc: Johannes Weiner <[email protected]>
> Cc: Rik van Riel <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: M. Vefa Bicakci <[email protected]>
> Cc: [email protected]
> Signed-off-by: KOSAKI Motohiro <[email protected]>
> ---
> ?mm/vmscan.c | ? ?3 ++-
> ?1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c391c32..1919d8a 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -40,6 +40,7 @@
> ?#include <linux/memcontrol.h>
> ?#include <linux/delayacct.h>
> ?#include <linux/sysctl.h>
> +#include <linux/oom.h>
>
> ?#include <asm/tlbflush.h>
> ?#include <asm/div64.h>
> @@ -1931,7 +1932,7 @@ out:
> ? ? ? ? ? ? ? ?return sc->nr_reclaimed;
>
> ? ? ? ?/* top priority shrink_zones still had more to do? don't OOM, then */
> - ? ? ? if (scanning_global_lru(sc) && !all_unreclaimable)
> + ? ? ? if (scanning_global_lru(sc) && !all_unreclaimable && !oom_killer_disabled)
> ? ? ? ? ? ? ? ?return 1;
>
> ? ? ? ?return 0;
> --
> 1.6.5.2
>
I don't like use oom_killer_disabled directly.
That's because we have wrapper inline functions to handle the
variable(ex, oom_killer_[disable/enable]).
It means we are reluctant to use the global variable directly.
So should we make new function as is_oom_killer_disable?
I think NO.
As I read your description, this problem is related to only hibernation.
Since hibernation freezes all processes(include kswapd), this problem
happens. Of course, now oom_killer_disabled is used by only
hibernation. But it can be used others in future(Off-topic : I don't
want it). Others can use it without freezing processes. Then kswapd
can set zone->all_unreclaimable and the problem can't happen.
So I want to use sc->hibernation_mode which is already used
do_try_to_free_pages instead of oom_killer_disabled.
--
Kind regards,
Minchan Kim
Hi
Thank you for good commenting!
> I don't like use oom_killer_disabled directly.
> That's because we have wrapper inline functions to handle the
> variable(ex, oom_killer_[disable/enable]).
> It means we are reluctant to use the global variable directly.
> So should we make new function as is_oom_killer_disable?
>
> I think NO.
>
> As I read your description, this problem is related to only hibernation.
> Since hibernation freezes all processes(include kswapd), this problem
> happens. Of course, now oom_killer_disabled is used by only
> hibernation. But it can be used others in future(Off-topic : I don't
> want it). Others can use it without freezing processes. Then kswapd
> can set zone->all_unreclaimable and the problem can't happen.
>
> So I want to use sc->hibernation_mode which is already used
> do_try_to_free_pages instead of oom_killer_disabled.
Unfortunatelly, It's impossible. shrink_all_memory() turn on
sc->hibernation_mode. but other hibernation caller merely call
alloc_pages(). so we don't have any hint.
On Wed, Sep 1, 2010 at 10:55 AM, KOSAKI Motohiro
<[email protected]> wrote:
> Hi
>
> Thank you for good commenting!
>
>
>> I don't like use oom_killer_disabled directly.
>> That's because we have wrapper inline functions to handle the
>> variable(ex, oom_killer_[disable/enable]).
>> It means we are reluctant to use the global variable directly.
>> So should we make new function as is_oom_killer_disable?
>>
>> I think NO.
>>
>> As I read your description, this problem is related to only hibernation.
>> Since hibernation freezes all processes(include kswapd), this problem
>> happens. Of course, now oom_killer_disabled is used by only
>> hibernation. But it can be used others in future(Off-topic : I don't
>> want it). Others can use it without freezing processes. Then kswapd
>> can set zone->all_unreclaimable and the problem can't happen.
>>
>> So I want to use sc->hibernation_mode which is already used
>> do_try_to_free_pages instead of oom_killer_disabled.
>
> Unfortunatelly, It's impossible. shrink_all_memory() turn on
> sc->hibernation_mode. but other hibernation caller merely call
> alloc_pages(). so we don't have any hint.
>
Ahh.. True. Sorry for that.
I will think some better method.
if I can't find it, I don't mind this patch. :)
Thanks.
--
Kind regards,
Minchan Kim