From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
JianKang Chen <chenjiankang1@huawei.com>,
Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
xieyisheng1@huawei.com, guohanjun@huawei.com,
wangkefeng.wang@huawei.com
Subject: Re: [PATCH] mm: drop VM_BUG_ON from __get_free_pages
Date: Wed, 27 Jun 2018 09:54:03 +0200 [thread overview]
Message-ID: <20180627075403.GG32348@dhcp22.suse.cz> (raw)
In-Reply-To: <e0f4426d-1b7c-e590-aae0-e8f7ae3bb948@suse.cz>
On Wed 27-06-18 09:50:01, Vlastimil Babka wrote:
> On 06/27/2018 09:34 AM, Michal Hocko wrote:
> > On Tue 26-06-18 10:04:16, Andrew Morton wrote:
> >
> > And as I've argued before the code would be wrong regardless. We would
> > leak the memory or worse touch somebody's else kmap without knowing
> > that. So we have a choice between a mem leak, data corruption k or a
> > silent fixup. I would prefer the last option. And blowing up on a BUG
> > is not much better on something that is easily fixable. I am not really
> > convinced that & ~__GFP_HIGHMEM is something to lose sleep over.
>
> Maybe put the fixup into a "#ifdef CONFIG_HIGHMEM" block and then modern
> systems won't care? In that case it could even be if (WARN_ON_ONCE(...))
> so future cases with wrong expectations would become known.
Yes that could be done as well. Or maybe we can make __GFP_HIGHMEM 0 for
!HIGHMEM systems. Does something really rely on it being non-zero?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-06-27 7:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-22 16:28 Michal Hocko
2018-06-26 13:57 ` Vlastimil Babka
2018-06-26 14:44 ` Michal Hocko
2018-06-26 17:04 ` Andrew Morton
2018-06-27 7:34 ` Michal Hocko
2018-06-27 7:39 ` Michal Hocko
2018-06-27 7:50 ` Vlastimil Babka
2018-06-27 7:54 ` Michal Hocko [this message]
2018-06-27 10:47 ` Vlastimil Babka
2018-06-27 11:05 ` Michal Hocko
2018-06-27 21:14 ` Andrew Morton
2018-06-27 21:24 ` Michal Hocko
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