* How to avoid or reduce GFP_ATOMIC allocation failed
@ 2019-03-08 5:37 wuzhouhui
2019-03-08 7:21 ` Greg KH
0 siblings, 1 reply; 4+ messages in thread
From: wuzhouhui @ 2019-03-08 5:37 UTC (permalink / raw)
To: kernelnewbies
Hi,
I check kernel code and found that GFP_ATOMIC allocation will
use emergency pool and maybe failed if emergency pool is not
enough. And GFP_ATOMIC doesn't trigger reclaim (because of
ATOMIC) even if there are a lot of page caches. So my question
is how to avoid or reduce GFP_ATOMIC allocation failed if there
are enough reclaimable memory? Is there some kernel parameters
can be configured?
Thanks.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: How to avoid or reduce GFP_ATOMIC allocation failed
2019-03-08 5:37 How to avoid or reduce GFP_ATOMIC allocation failed wuzhouhui
@ 2019-03-08 7:21 ` Greg KH
2019-03-08 7:34 ` wuzhouhui
0 siblings, 1 reply; 4+ messages in thread
From: Greg KH @ 2019-03-08 7:21 UTC (permalink / raw)
To: wuzhouhui; +Cc: kernelnewbies
On Fri, Mar 08, 2019 at 01:37:26PM +0800, wuzhouhui wrote:
> Hi,
>
> I check kernel code and found that GFP_ATOMIC allocation will
> use emergency pool and maybe failed if emergency pool is not
> enough. And GFP_ATOMIC doesn't trigger reclaim (because of
> ATOMIC) even if there are a lot of page caches. So my question
> is how to avoid or reduce GFP_ATOMIC allocation failed if there
> are enough reclaimable memory? Is there some kernel parameters
> can be configured?
Have you seen the ATOMIC pools be used up and not able to be reclaimed
in real-world usages? If so, I'm sure the mm developers would love to
hear from you about this as I really do not think that is a situation
that can happen easily, if at all.
And no, I do not think there are any such parameters, the kernel should
be self-tuning for things like this.
thanks,
greg k-h
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Re: How to avoid or reduce GFP_ATOMIC allocation failed
2019-03-08 7:21 ` Greg KH
@ 2019-03-08 7:34 ` wuzhouhui
2019-03-08 7:40 ` greg kh
0 siblings, 1 reply; 4+ messages in thread
From: wuzhouhui @ 2019-03-08 7:34 UTC (permalink / raw)
To: greg kh; +Cc: kernelnewbies
> -----Original Messages-----
> From: "Greg KH" <greg@kroah.com>
> Sent Time: 2019-03-08 15:21:52 (Friday)
> To: wuzhouhui <wuzhouhui14@mails.ucas.ac.cn>
> Cc: kernelnewbies@kernelnewbies.org
> Subject: Re: How to avoid or reduce GFP_ATOMIC allocation failed
>
> On Fri, Mar 08, 2019 at 01:37:26PM +0800, wuzhouhui wrote:
> > Hi,
> >
> > I check kernel code and found that GFP_ATOMIC allocation will
> > use emergency pool and maybe failed if emergency pool is not
> > enough. And GFP_ATOMIC doesn't trigger reclaim (because of
> > ATOMIC) even if there are a lot of page caches. So my question
> > is how to avoid or reduce GFP_ATOMIC allocation failed if there
> > are enough reclaimable memory? Is there some kernel parameters
> > can be configured?
>
> Have you seen the ATOMIC pools be used up and not able to be reclaimed
> in real-world usages? If so, I'm sure the mm developers would love to
No, I haven't seen this scenario. But I encountered the similar issue
with [1] (order is 5 in my scenario), and this issue is not resolved for
now.
Thanks.
[1] https://stackoverflow.com/questions/53936183/linux-disk-cache-and-kmalloc-with-gfp-atomic#
> hear from you about this as I really do not think that is a situation
> that can happen easily, if at all.
>
> And no, I do not think there are any such parameters, the kernel should
> be self-tuning for things like this.
>
> thanks,
>
> greg k-h
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Re: How to avoid or reduce GFP_ATOMIC allocation failed
2019-03-08 7:34 ` wuzhouhui
@ 2019-03-08 7:40 ` greg kh
0 siblings, 0 replies; 4+ messages in thread
From: greg kh @ 2019-03-08 7:40 UTC (permalink / raw)
To: wuzhouhui; +Cc: kernelnewbies
On Fri, Mar 08, 2019 at 03:34:18PM +0800, wuzhouhui wrote:
> > -----Original Messages-----
> > From: "Greg KH" <greg@kroah.com>
> > Sent Time: 2019-03-08 15:21:52 (Friday)
> > To: wuzhouhui <wuzhouhui14@mails.ucas.ac.cn>
> > Cc: kernelnewbies@kernelnewbies.org
> > Subject: Re: How to avoid or reduce GFP_ATOMIC allocation failed
> >
> > On Fri, Mar 08, 2019 at 01:37:26PM +0800, wuzhouhui wrote:
> > > Hi,
> > >
> > > I check kernel code and found that GFP_ATOMIC allocation will
> > > use emergency pool and maybe failed if emergency pool is not
> > > enough. And GFP_ATOMIC doesn't trigger reclaim (because of
> > > ATOMIC) even if there are a lot of page caches. So my question
> > > is how to avoid or reduce GFP_ATOMIC allocation failed if there
> > > are enough reclaimable memory? Is there some kernel parameters
> > > can be configured?
> >
> > Have you seen the ATOMIC pools be used up and not able to be reclaimed
> > in real-world usages? If so, I'm sure the mm developers would love to
>
> No, I haven't seen this scenario. But I encountered the similar issue
> with [1] (order is 5 in my scenario), and this issue is not resolved for
> now.
Please work with the company that created your out-of-tree kernel
networking code as it sounds like they do not know how to properly
handle this type of problem :)
good luck!
greg k-h
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^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-03-08 7:42 UTC | newest]
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2019-03-08 5:37 How to avoid or reduce GFP_ATOMIC allocation failed wuzhouhui
2019-03-08 7:21 ` Greg KH
2019-03-08 7:34 ` wuzhouhui
2019-03-08 7:40 ` greg kh
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