From: Michal Hocko <mhocko@kernel.org>
To: David Rientjes <rientjes@google.com>
Cc: Mike Snitzer <snitzer@redhat.com>,
Mikulas Patocka <mpatocka@redhat.com>,
Junaid Shahid <junaids@google.com>,
Alasdair Kergon <agk@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, andreslc@google.com, gthelen@google.com,
vbabka@suse.cz, linux-kernel@vger.kernel.org
Subject: Re: dm ioctl: Restore __GFP_HIGH in copy_params()
Date: Tue, 23 May 2017 08:05:35 +0200 [thread overview]
Message-ID: <20170523060534.GA12813@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.10.1705221325200.30407@chino.kir.corp.google.com>
On Mon 22-05-17 13:35:41, David Rientjes wrote:
> On Mon, 22 May 2017, Mike Snitzer wrote:
[...]
> > While adding the __GFP_NOFAIL flag would serve to document expectations
> > I'm left unconvinced that the memory allocator will _not fail_ for an
> > order-0 page -- as Mikulas said most ioctls don't need more than 4K.
>
> __GFP_NOFAIL would make no sense in kvmalloc() calls, ever, it would never
> fallback to vmalloc :)
Sorry, I could have been more specific. You would have to opencode
kvmalloc obviously. It is documented to not support this flag for the
reasons you have mentioned above.
> I'm hoping this can get merged during the 4.12 window to fix the broken
> commit d224e9381897.
I obviously disagree. Relying on memory reserves for _correctness_ is
clearly broken by design, full stop. But it is dm code and you are going
it is responsibility of the respective maintainers to support this code.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2017-05-23 6:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170518185040.108293-1-junaids@google.com>
[not found] ` <20170518190406.GB2330@dhcp22.suse.cz>
[not found] ` <alpine.DEB.2.10.1705181338090.132717@chino.kir.corp.google.com>
2017-05-19 2:50 ` [PATCH] dm ioctl: Restore __GFP_HIGH in copy_params() Junaid Shahid
2017-05-19 7:46 ` Michal Hocko
2017-05-19 23:43 ` Mikulas Patocka
2017-05-22 9:37 ` Michal Hocko
2017-05-22 12:00 ` Mikulas Patocka
2017-05-22 12:09 ` Michal Hocko
2017-05-22 14:52 ` Mikulas Patocka
2017-05-22 15:03 ` Michal Hocko
2017-05-22 18:04 ` Mike Snitzer
2017-05-22 20:35 ` David Rientjes
2017-05-22 23:35 ` Mike Snitzer
2017-05-23 6:05 ` Michal Hocko [this message]
2017-05-23 16:44 ` Mikulas Patocka
2017-05-25 8:58 ` Michal Hocko
2017-05-23 6:49 ` Michal Hocko
[not found] ` <alpine.LRH.2.02.1705191949340.17646@file01.intranet.prod.int.rdu2.redhat.com>
[not found] ` <20170520083412.GD11925@dhcp22.suse.cz>
2017-05-20 19:00 ` [PATCH] " Mikulas Patocka
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