From: Michal Hocko <mhocko@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>, Tejun Heo <tj@kernel.org>,
Jens Axboe <axboe@kernel.dk>, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Marc MERLIN <marc@merlins.org>
Subject: Re: [PATCH] block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcg
Date: Tue, 29 Nov 2016 18:28:54 +0100 [thread overview]
Message-ID: <20161129172854.GF9796@dhcp22.suse.cz> (raw)
In-Reply-To: <CA+55aFw4R7B8pAJ4TNVefdtCVAnZKY28i6_+5jQhoop60-NuQQ@mail.gmail.com>
On Tue 29-11-16 09:17:37, Linus Torvalds wrote:
> On Tue, Nov 29, 2016 at 9:13 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > How does this look like?
>
> No.
>
> I *really* want people to write out that "I am ok with the allocation failing".
>
> It's not an "inconvenience". It's a sign that you are competent and
> that you know it will fail, and that you can handle it.
>
> If you don't show that you know that, we warn about it.
How does this warning help those who are watching the logs? What are
they supposed to do about it? Unlike GFP_ATOMIC there is no tuning you
can possibly do.
>From my experience people tend to report those and worry about them
(quite often confusing them with the real OOM) and we usually only can
explain that this is nothing to worry about... And so then we sprinkle
GFP_NOWARN all over the place as we hit those. Is this really what we
want?
> And no, "GFP_NOWAIT" does *not* mean "I have a good fallback".
I am confused, how can anybody _rely_ on GFP_NOWAIT to succeed?
--
Michal Hocko
SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>, Tejun Heo <tj@kernel.org>,
Jens Axboe <axboe@kernel.dk>, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Marc MERLIN <marc@merlins.org>
Subject: Re: [PATCH] block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcg
Date: Tue, 29 Nov 2016 18:28:54 +0100 [thread overview]
Message-ID: <20161129172854.GF9796@dhcp22.suse.cz> (raw)
In-Reply-To: <CA+55aFw4R7B8pAJ4TNVefdtCVAnZKY28i6_+5jQhoop60-NuQQ@mail.gmail.com>
On Tue 29-11-16 09:17:37, Linus Torvalds wrote:
> On Tue, Nov 29, 2016 at 9:13 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > How does this look like?
>
> No.
>
> I *really* want people to write out that "I am ok with the allocation failing".
>
> It's not an "inconvenience". It's a sign that you are competent and
> that you know it will fail, and that you can handle it.
>
> If you don't show that you know that, we warn about it.
How does this warning help those who are watching the logs? What are
they supposed to do about it? Unlike GFP_ATOMIC there is no tuning you
can possibly do.
>From my experience people tend to report those and worry about them
(quite often confusing them with the real OOM) and we usually only can
explain that this is nothing to worry about... And so then we sprinkle
GFP_NOWARN all over the place as we hit those. Is this really what we
want?
> And no, "GFP_NOWAIT" does *not* mean "I have a good fallback".
I am confused, how can anybody _rely_ on GFP_NOWAIT to succeed?
--
Michal Hocko
SUSE Labs
--
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next prev parent reply other threads:[~2016-11-29 17:29 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-21 15:43 4.8.8 kernel trigger OOM killer repeatedly when I have lots of RAM that should be free Marc MERLIN
2016-11-21 16:30 ` Marc MERLIN
2016-11-21 21:50 ` Vlastimil Babka
2016-11-21 21:50 ` Vlastimil Babka
2016-11-21 21:56 ` Marc MERLIN
2016-11-21 21:56 ` Marc MERLIN
2016-11-21 23:03 ` [PATCH] block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcg Tejun Heo
2016-11-21 23:03 ` Tejun Heo
2016-11-22 15:47 ` Vlastimil Babka
2016-11-22 15:47 ` Vlastimil Babka
2016-11-22 16:48 ` Tejun Heo
2016-11-22 16:48 ` Tejun Heo
2016-11-22 22:13 ` Linus Torvalds
2016-11-22 22:13 ` Linus Torvalds
2016-11-23 8:50 ` Vlastimil Babka
2016-11-23 8:50 ` Vlastimil Babka
2016-11-28 17:19 ` Tejun Heo
2016-11-28 17:19 ` Tejun Heo
2016-11-29 7:25 ` Michal Hocko
2016-11-29 7:25 ` Michal Hocko
2016-11-29 16:38 ` Tejun Heo
2016-11-29 16:38 ` Tejun Heo
2016-11-29 16:57 ` Vlastimil Babka
2016-11-29 16:57 ` Vlastimil Babka
2016-11-29 17:13 ` Michal Hocko
2016-11-29 17:13 ` Michal Hocko
2016-11-29 17:17 ` Linus Torvalds
2016-11-29 17:17 ` Linus Torvalds
2016-11-29 17:28 ` Michal Hocko [this message]
2016-11-29 17:28 ` Michal Hocko
2016-11-29 17:48 ` Linus Torvalds
2016-11-29 17:48 ` Linus Torvalds
2016-11-22 16:00 ` Jens Axboe
2016-11-22 16:00 ` Jens Axboe
2016-11-22 16:06 ` 4.8.8 kernel trigger OOM killer repeatedly when I have lots of RAM that should be free Marc MERLIN
2016-11-22 16:06 ` Marc MERLIN
2016-11-22 16:14 ` Vlastimil Babka
2016-11-22 16:14 ` Vlastimil Babka
2016-11-22 16:25 ` Michal Hocko
2016-11-22 16:25 ` Michal Hocko
2016-11-22 16:47 ` Marc MERLIN
2016-11-22 16:47 ` Marc MERLIN
2016-11-22 16:38 ` Greg Kroah-Hartman
2016-11-22 16:38 ` Greg Kroah-Hartman
2016-11-29 16:25 ` Michal Hocko
2016-11-29 16:25 ` Michal Hocko
2016-11-29 16:25 ` Michal Hocko
2016-11-29 16:43 ` Patch "mm, oom: stop pre-mature high-order OOM killer invocations" has been added to the 4.8-stable tree gregkh
2016-11-29 16:43 ` 4.8.8 kernel trigger OOM killer repeatedly when I have lots of RAM that should be free Greg Kroah-Hartman
2016-11-29 16:43 ` Greg Kroah-Hartman
2016-11-22 19:38 ` Linus Torvalds
2016-11-22 19:38 ` Linus Torvalds
2016-11-23 6:34 ` Michal Hocko
2016-11-23 6:34 ` Michal Hocko
2016-11-23 6:53 ` Hillf Danton
2016-11-23 6:53 ` Hillf Danton
2016-11-23 7:00 ` Michal Hocko
2016-11-23 7:00 ` Michal Hocko
2016-11-23 9:18 ` Vlastimil Babka
2016-11-23 9:18 ` Vlastimil Babka
2016-11-28 7:23 ` Michal Hocko
2016-11-28 7:23 ` Michal Hocko
2016-11-28 20:55 ` Marc MERLIN
2016-11-29 15:55 ` Marc MERLIN
2016-11-29 15:55 ` Marc MERLIN
2016-11-29 16:07 ` Michal Hocko
2016-11-29 16:07 ` Michal Hocko
2016-11-29 16:34 ` Marc MERLIN
2016-11-29 16:34 ` Marc MERLIN
2016-11-29 17:07 ` Linus Torvalds
2016-11-29 17:07 ` Linus Torvalds
2016-11-29 17:40 ` Marc MERLIN
2016-11-29 17:40 ` Marc MERLIN
2016-11-29 18:01 ` Linus Torvalds
2016-11-29 18:01 ` Linus Torvalds
2016-11-30 17:47 ` Marc MERLIN
2016-11-30 17:47 ` Marc MERLIN
2016-11-30 18:14 ` Linus Torvalds
2016-11-30 18:21 ` Marc MERLIN
2016-11-30 18:21 ` Marc MERLIN
2016-11-30 18:27 ` Jens Axboe
2016-11-30 18:27 ` Jens Axboe
2016-11-30 20:30 ` Tejun Heo
2016-11-30 20:30 ` Tejun Heo
2016-12-01 13:50 ` Kent Overstreet
2016-12-01 13:50 ` Kent Overstreet
2016-12-01 18:16 ` Linus Torvalds
2016-12-01 18:16 ` Linus Torvalds
2016-12-01 18:30 ` Jens Axboe
2016-12-01 18:30 ` Jens Axboe
2016-12-01 18:37 ` Linus Torvalds
2016-12-01 18:37 ` Linus Torvalds
2016-12-01 18:46 ` Jens Axboe
2016-12-01 18:46 ` Jens Axboe
2016-11-29 20:11 ` Holger Hoffstätte
2016-11-29 23:01 ` Marc MERLIN
2016-11-29 23:01 ` Marc MERLIN
2016-11-30 13:58 ` Tetsuo Handa
2016-11-30 13:58 ` Tetsuo Handa
2017-05-02 4:12 ` Marc MERLIN
2017-05-02 4:12 ` Marc MERLIN
2017-05-02 7:44 ` Michal Hocko
2017-05-02 7:44 ` Michal Hocko
2017-05-02 14:15 ` Marc MERLIN
2017-05-02 14:15 ` Marc MERLIN
2017-05-02 10:44 ` Tetsuo Handa
2017-05-02 10:44 ` Tetsuo Handa
2016-11-29 16:15 ` Marc MERLIN
2016-11-29 16:15 ` Marc MERLIN
2016-11-22 21:46 ` Simon Kirby
2016-11-22 21:46 ` Simon Kirby
2016-11-28 8:06 ` Vlastimil Babka
2016-11-28 8:06 ` Vlastimil Babka
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