Re: [PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
Thomas Huth writes: > On Wed, 25 Feb 2015 16:11:27 +0100 > Cornelia Huck wrote: > >> On Wed, 25 Feb 2015 15:36:02 +0100 >> "Michael S. Tsirkin" wrote: >> >> > virtio balloon has this code: >> > wait_event_interruptible(vb->config_change, >> > (diff = towards_target(vb)) != 0 >> > || vb->need_stats_update >> > || kthread_should_stop() >> > || freezing(current)); >> > >> > Which is a problem because towards_target() call might block after >> > wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing >> > the task_struct::state collision typical of nesting of sleeping >> > primitives >> > >> > See also http://lwn.net/Articles/628628/ or Thomas's >> > bug report >> > http://article.gmane.org/gmane.linux.kernel.virtualization/24846 >> > for a fuller explanation. >> > >> > To fix, rewrite using wait_woken. >> > >> > Cc: sta...@vger.kernel.org >> > Reported-by: Thomas Huth >> > Signed-off-by: Michael S. Tsirkin >> > --- >> > >> > changes from v1: >> >remove wait_event_interruptible >> >noticed by Cornelia Huck >> > >> > drivers/virtio/virtio_balloon.c | 19 ++- >> > 1 file changed, 14 insertions(+), 5 deletions(-) >> > >> >> I was able to reproduce Thomas' original problem and can confirm that >> it is gone with this patch. >> >> Reviewed-by: Cornelia Huck > > Right, I just applied the patch on my system, too, and the problem is > indeed gone! Thanks for the quick fix! > > Tested-by: Thomas Huth Applied. Thanks, Rusty. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
Thomas Huth th...@linux.vnet.ibm.com writes: On Wed, 25 Feb 2015 16:11:27 +0100 Cornelia Huck cornelia.h...@de.ibm.com wrote: On Wed, 25 Feb 2015 15:36:02 +0100 Michael S. Tsirkin m...@redhat.com wrote: virtio balloon has this code: wait_event_interruptible(vb-config_change, (diff = towards_target(vb)) != 0 || vb-need_stats_update || kthread_should_stop() || freezing(current)); Which is a problem because towards_target() call might block after wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing the task_struct::state collision typical of nesting of sleeping primitives See also http://lwn.net/Articles/628628/ or Thomas's bug report http://article.gmane.org/gmane.linux.kernel.virtualization/24846 for a fuller explanation. To fix, rewrite using wait_woken. Cc: sta...@vger.kernel.org Reported-by: Thomas Huth th...@linux.vnet.ibm.com Signed-off-by: Michael S. Tsirkin m...@redhat.com --- changes from v1: remove wait_event_interruptible noticed by Cornelia Huck cornelia.h...@de.ibm.com drivers/virtio/virtio_balloon.c | 19 ++- 1 file changed, 14 insertions(+), 5 deletions(-) I was able to reproduce Thomas' original problem and can confirm that it is gone with this patch. Reviewed-by: Cornelia Huck cornelia.h...@de.ibm.com Right, I just applied the patch on my system, too, and the problem is indeed gone! Thanks for the quick fix! Tested-by: Thomas Huth th...@linux.vnet.ibm.com Applied. Thanks, Rusty. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
On Wed, 25 Feb 2015 16:11:27 +0100 Cornelia Huck wrote: > On Wed, 25 Feb 2015 15:36:02 +0100 > "Michael S. Tsirkin" wrote: > > > virtio balloon has this code: > > wait_event_interruptible(vb->config_change, > > (diff = towards_target(vb)) != 0 > > || vb->need_stats_update > > || kthread_should_stop() > > || freezing(current)); > > > > Which is a problem because towards_target() call might block after > > wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing > > the task_struct::state collision typical of nesting of sleeping > > primitives > > > > See also http://lwn.net/Articles/628628/ or Thomas's > > bug report > > http://article.gmane.org/gmane.linux.kernel.virtualization/24846 > > for a fuller explanation. > > > > To fix, rewrite using wait_woken. > > > > Cc: sta...@vger.kernel.org > > Reported-by: Thomas Huth > > Signed-off-by: Michael S. Tsirkin > > --- > > > > changes from v1: > > remove wait_event_interruptible > > noticed by Cornelia Huck > > > > drivers/virtio/virtio_balloon.c | 19 ++- > > 1 file changed, 14 insertions(+), 5 deletions(-) > > > > I was able to reproduce Thomas' original problem and can confirm that > it is gone with this patch. > > Reviewed-by: Cornelia Huck Right, I just applied the patch on my system, too, and the problem is indeed gone! Thanks for the quick fix! Tested-by: Thomas Huth -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
On Wed, 25 Feb 2015 15:36:02 +0100 "Michael S. Tsirkin" wrote: > virtio balloon has this code: > wait_event_interruptible(vb->config_change, > (diff = towards_target(vb)) != 0 > || vb->need_stats_update > || kthread_should_stop() > || freezing(current)); > > Which is a problem because towards_target() call might block after > wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing > the task_struct::state collision typical of nesting of sleeping > primitives > > See also http://lwn.net/Articles/628628/ or Thomas's > bug report > http://article.gmane.org/gmane.linux.kernel.virtualization/24846 > for a fuller explanation. > > To fix, rewrite using wait_woken. > > Cc: sta...@vger.kernel.org > Reported-by: Thomas Huth > Signed-off-by: Michael S. Tsirkin > --- > > changes from v1: > remove wait_event_interruptible > noticed by Cornelia Huck > > drivers/virtio/virtio_balloon.c | 19 ++- > 1 file changed, 14 insertions(+), 5 deletions(-) > I was able to reproduce Thomas' original problem and can confirm that it is gone with this patch. Reviewed-by: Cornelia Huck -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
virtio balloon has this code:
wait_event_interruptible(vb->config_change,
(diff = towards_target(vb)) != 0
|| vb->need_stats_update
|| kthread_should_stop()
|| freezing(current));
Which is a problem because towards_target() call might block after
wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing
the task_struct::state collision typical of nesting of sleeping
primitives
See also http://lwn.net/Articles/628628/ or Thomas's
bug report
http://article.gmane.org/gmane.linux.kernel.virtualization/24846
for a fuller explanation.
To fix, rewrite using wait_woken.
Cc: sta...@vger.kernel.org
Reported-by: Thomas Huth
Signed-off-by: Michael S. Tsirkin
---
changes from v1:
remove wait_event_interruptible
noticed by Cornelia Huck
drivers/virtio/virtio_balloon.c | 19 ++-
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 0413157..5a6ad6d 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -29,6 +29,7 @@
#include
#include
#include
+#include
/*
* Balloon device works in 4K page units. So each page is pointed to by
@@ -334,17 +335,25 @@ static int virtballoon_oom_notify(struct notifier_block
*self,
static int balloon(void *_vballoon)
{
struct virtio_balloon *vb = _vballoon;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
set_freezable();
while (!kthread_should_stop()) {
s64 diff;
try_to_freeze();
- wait_event_interruptible(vb->config_change,
-(diff = towards_target(vb)) != 0
-|| vb->need_stats_update
-|| kthread_should_stop()
-|| freezing(current));
+
+ add_wait_queue(>config_change, );
+ for (;;) {
+ if ((diff = towards_target(vb)) != 0 ||
+ vb->need_stats_update ||
+ kthread_should_stop() ||
+ freezing(current))
+ break;
+ wait_woken(, TASK_INTERRUPTIBLE,
MAX_SCHEDULE_TIMEOUT);
+ }
+ remove_wait_queue(>config_change, );
+
if (vb->need_stats_update)
stats_handle_request(vb);
if (diff > 0)
--
MST
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
virtio balloon has this code:
wait_event_interruptible(vb-config_change,
(diff = towards_target(vb)) != 0
|| vb-need_stats_update
|| kthread_should_stop()
|| freezing(current));
Which is a problem because towards_target() call might block after
wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing
the task_struct::state collision typical of nesting of sleeping
primitives
See also http://lwn.net/Articles/628628/ or Thomas's
bug report
http://article.gmane.org/gmane.linux.kernel.virtualization/24846
for a fuller explanation.
To fix, rewrite using wait_woken.
Cc: sta...@vger.kernel.org
Reported-by: Thomas Huth th...@linux.vnet.ibm.com
Signed-off-by: Michael S. Tsirkin m...@redhat.com
---
changes from v1:
remove wait_event_interruptible
noticed by Cornelia Huck cornelia.h...@de.ibm.com
drivers/virtio/virtio_balloon.c | 19 ++-
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 0413157..5a6ad6d 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -29,6 +29,7 @@
#include linux/module.h
#include linux/balloon_compaction.h
#include linux/oom.h
+#include linux/wait.h
/*
* Balloon device works in 4K page units. So each page is pointed to by
@@ -334,17 +335,25 @@ static int virtballoon_oom_notify(struct notifier_block
*self,
static int balloon(void *_vballoon)
{
struct virtio_balloon *vb = _vballoon;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
set_freezable();
while (!kthread_should_stop()) {
s64 diff;
try_to_freeze();
- wait_event_interruptible(vb-config_change,
-(diff = towards_target(vb)) != 0
-|| vb-need_stats_update
-|| kthread_should_stop()
-|| freezing(current));
+
+ add_wait_queue(vb-config_change, wait);
+ for (;;) {
+ if ((diff = towards_target(vb)) != 0 ||
+ vb-need_stats_update ||
+ kthread_should_stop() ||
+ freezing(current))
+ break;
+ wait_woken(wait, TASK_INTERRUPTIBLE,
MAX_SCHEDULE_TIMEOUT);
+ }
+ remove_wait_queue(vb-config_change, wait);
+
if (vb-need_stats_update)
stats_handle_request(vb);
if (diff 0)
--
MST
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
On Wed, 25 Feb 2015 16:11:27 +0100 Cornelia Huck cornelia.h...@de.ibm.com wrote: On Wed, 25 Feb 2015 15:36:02 +0100 Michael S. Tsirkin m...@redhat.com wrote: virtio balloon has this code: wait_event_interruptible(vb-config_change, (diff = towards_target(vb)) != 0 || vb-need_stats_update || kthread_should_stop() || freezing(current)); Which is a problem because towards_target() call might block after wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing the task_struct::state collision typical of nesting of sleeping primitives See also http://lwn.net/Articles/628628/ or Thomas's bug report http://article.gmane.org/gmane.linux.kernel.virtualization/24846 for a fuller explanation. To fix, rewrite using wait_woken. Cc: sta...@vger.kernel.org Reported-by: Thomas Huth th...@linux.vnet.ibm.com Signed-off-by: Michael S. Tsirkin m...@redhat.com --- changes from v1: remove wait_event_interruptible noticed by Cornelia Huck cornelia.h...@de.ibm.com drivers/virtio/virtio_balloon.c | 19 ++- 1 file changed, 14 insertions(+), 5 deletions(-) I was able to reproduce Thomas' original problem and can confirm that it is gone with this patch. Reviewed-by: Cornelia Huck cornelia.h...@de.ibm.com Right, I just applied the patch on my system, too, and the problem is indeed gone! Thanks for the quick fix! Tested-by: Thomas Huth th...@linux.vnet.ibm.com -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] virtio-balloon: do not call blocking ops when !TASK_RUNNING
On Wed, 25 Feb 2015 15:36:02 +0100 Michael S. Tsirkin m...@redhat.com wrote: virtio balloon has this code: wait_event_interruptible(vb-config_change, (diff = towards_target(vb)) != 0 || vb-need_stats_update || kthread_should_stop() || freezing(current)); Which is a problem because towards_target() call might block after wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing the task_struct::state collision typical of nesting of sleeping primitives See also http://lwn.net/Articles/628628/ or Thomas's bug report http://article.gmane.org/gmane.linux.kernel.virtualization/24846 for a fuller explanation. To fix, rewrite using wait_woken. Cc: sta...@vger.kernel.org Reported-by: Thomas Huth th...@linux.vnet.ibm.com Signed-off-by: Michael S. Tsirkin m...@redhat.com --- changes from v1: remove wait_event_interruptible noticed by Cornelia Huck cornelia.h...@de.ibm.com drivers/virtio/virtio_balloon.c | 19 ++- 1 file changed, 14 insertions(+), 5 deletions(-) I was able to reproduce Thomas' original problem and can confirm that it is gone with this patch. Reviewed-by: Cornelia Huck cornelia.h...@de.ibm.com -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
