* [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll
@ 2011-02-15 9:35 Michal Hocko
2011-02-15 10:11 ` Rusty Russell
2011-02-15 12:39 ` Michal Hocko
0 siblings, 2 replies; 6+ messages in thread
From: Michal Hocko @ 2011-02-15 9:35 UTC (permalink / raw)
To: Rusty Russell; +Cc: Michael S. Tsirkin, virtualization, netdev, linux-kernel
Hi,
we have started seeing a lot of allocator messages complaining about
failed allocations from virtnet_poll in soft IRQ. Could you consider the
following patch, please?
The patch is based on 2.6.38-rc4.
---
>From aabc19f22915dafeac0f1f6aa7cb7e49a8021ba1 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.cz>
Date: Tue, 15 Feb 2011 10:20:59 +0100
Subject: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll
virtnet_poll is called from soft IRQ and it tries to allocate GFP_ATOMIC
memory (through try_fill_recv). This allocation can fail and we are
falling back to schedule_delayed_work in that case.
Let's add __GFP_NOWARN to the allocation flags to get rid of the
allocator complains for failed allocations:
[22798.508903] The following is only an harmless informational message.
[22798.508909] Unless you get a _continuous_flood_ of these messages it means
[22798.508911] everything is working fine. Allocations from irqs cannot be
[22798.508913] perfectly reliable and the kernel is designed to handle that.
[22798.508917] loop3: page allocation failure. order:0, mode:0x20, alloc_flags:0x30 pflags:0x80208040
Signed-off-by: Michal Hocko <mhocko@suse.cz>
---
drivers/net/virtio_net.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 90a23e4..aea1e51 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -477,7 +477,7 @@ again:
}
if (vi->num < vi->max / 2) {
- if (!try_fill_recv(vi, GFP_ATOMIC))
+ if (!try_fill_recv(vi, GFP_ATOMIC|__GFP_NOWARN))
schedule_delayed_work(&vi->refill, 0);
}
--
1.7.2.3
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll
2011-02-15 9:35 [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll Michal Hocko
@ 2011-02-15 10:11 ` Rusty Russell
2011-02-15 10:25 ` Michal Hocko
2011-02-15 12:39 ` Michal Hocko
1 sibling, 1 reply; 6+ messages in thread
From: Rusty Russell @ 2011-02-15 10:11 UTC (permalink / raw)
To: Michal Hocko; +Cc: Michael S. Tsirkin, virtualization, netdev, linux-kernel
On Tue, 15 Feb 2011 08:05:27 pm Michal Hocko wrote:
> Hi,
> we have started seeing a lot of allocator messages complaining about
> failed allocations from virtnet_poll in soft IRQ. Could you consider the
> following patch, please?
Do we really want to silence this? Isn't warning about it kind of the
point? Your network is probably sucking if this happens...
Cheers,
Rusty.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll
2011-02-15 10:11 ` Rusty Russell
@ 2011-02-15 10:25 ` Michal Hocko
2011-02-15 11:09 ` Rusty Russell
0 siblings, 1 reply; 6+ messages in thread
From: Michal Hocko @ 2011-02-15 10:25 UTC (permalink / raw)
To: Rusty Russell; +Cc: Michael S. Tsirkin, virtualization, netdev, linux-kernel
On Tue 15-02-11 20:41:29, Rusty Russell wrote:
> On Tue, 15 Feb 2011 08:05:27 pm Michal Hocko wrote:
> > Hi,
> > we have started seeing a lot of allocator messages complaining about
> > failed allocations from virtnet_poll in soft IRQ. Could you consider the
> > following patch, please?
>
> Do we really want to silence this? Isn't warning about it kind of the
> point? Your network is probably sucking if this happens...
What can user do about it? Is the low level memory allocator message
very much usefull for him? Maybe we can add a printk_once in the fail
path with some more useful and virtio specific message.
Thanks
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll
2011-02-15 10:25 ` Michal Hocko
@ 2011-02-15 11:09 ` Rusty Russell
2011-02-15 12:42 ` Michal Hocko
0 siblings, 1 reply; 6+ messages in thread
From: Rusty Russell @ 2011-02-15 11:09 UTC (permalink / raw)
To: Michal Hocko; +Cc: Michael S. Tsirkin, virtualization, netdev, linux-kernel
On Tue, 15 Feb 2011 08:55:50 pm Michal Hocko wrote:
> On Tue 15-02-11 20:41:29, Rusty Russell wrote:
> > On Tue, 15 Feb 2011 08:05:27 pm Michal Hocko wrote:
> > > Hi,
> > > we have started seeing a lot of allocator messages complaining about
> > > failed allocations from virtnet_poll in soft IRQ. Could you consider the
> > > following patch, please?
> >
> > Do we really want to silence this? Isn't warning about it kind of the
> > point? Your network is probably sucking if this happens...
>
> What can user do about it? Is the low level memory allocator message
> very much usefull for him? Maybe we can add a printk_once in the fail
> path with some more useful and virtio specific message.
That's an argument against ever printing any message.
What we need to know is why does this happen with virtio_net and not other
cards? If it happens to them too, and they silently fall back, all good.
I want to make sure we're not papering over a real problem...
Thanks,
Rusty.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll
2011-02-15 11:09 ` Rusty Russell
@ 2011-02-15 12:42 ` Michal Hocko
0 siblings, 0 replies; 6+ messages in thread
From: Michal Hocko @ 2011-02-15 12:42 UTC (permalink / raw)
To: Rusty Russell; +Cc: Michael S. Tsirkin, virtualization, netdev, linux-kernel
On Tue 15-02-11 21:39:03, Rusty Russell wrote:
> On Tue, 15 Feb 2011 08:55:50 pm Michal Hocko wrote:
> > On Tue 15-02-11 20:41:29, Rusty Russell wrote:
> > > On Tue, 15 Feb 2011 08:05:27 pm Michal Hocko wrote:
> > > > Hi,
> > > > we have started seeing a lot of allocator messages complaining about
> > > > failed allocations from virtnet_poll in soft IRQ. Could you consider the
> > > > following patch, please?
> > >
> > > Do we really want to silence this? Isn't warning about it kind of the
> > > point? Your network is probably sucking if this happens...
> >
> > What can user do about it? Is the low level memory allocator message
> > very much usefull for him? Maybe we can add a printk_once in the fail
> > path with some more useful and virtio specific message.
>
> That's an argument against ever printing any message.
Well, honestly, I do not see much point for this message but it is there
for ages so it maybe it is valueable for somebody...
>
> What we need to know is why does this happen with virtio_net and not other
> cards?
The machine just happened to be short on memory due to a strong memory
pressure.
> If it happens to them too, and they silently fall back, all good.
>
> I want to make sure we're not papering over a real problem...
>
> Thanks,
> Rusty.
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll
2011-02-15 9:35 [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll Michal Hocko
2011-02-15 10:11 ` Rusty Russell
@ 2011-02-15 12:39 ` Michal Hocko
1 sibling, 0 replies; 6+ messages in thread
From: Michal Hocko @ 2011-02-15 12:39 UTC (permalink / raw)
To: Rusty Russell; +Cc: Michael S. Tsirkin, virtualization, netdev, linux-kernel
On Tue 15-02-11 10:35:27, Michal Hocko wrote:
[...]
> [22798.508903] The following is only an harmless informational message.
> [22798.508909] Unless you get a _continuous_flood_ of these messages it means
> [22798.508911] everything is working fine. Allocations from irqs cannot be
> [22798.508913] perfectly reliable and the kernel is designed to handle that.
I have just realized that the above text is SLES specific so only the
line below with stack trace and memory info is printed. Sorry for confusion
> [22798.508917] loop3: page allocation failure. order:0, mode:0x20, alloc_flags:0x30 pflags:0x80208040
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
^ permalink raw reply [flat|nested] 6+ messages in thread
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2011-02-15 9:35 [PATCH] virtio: use __GFP_NOWARN for try_fill_recv in virtnet_poll Michal Hocko
2011-02-15 10:11 ` Rusty Russell
2011-02-15 10:25 ` Michal Hocko
2011-02-15 11:09 ` Rusty Russell
2011-02-15 12:42 ` Michal Hocko
2011-02-15 12:39 ` Michal Hocko
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