From: Andrew Morton <akpm@linux-foundation.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: linux-mm@kvack.org, Dave Chinner <david@fromorbit.com>,
Neil Brown <neilb@suse.de>, Johannes Weiner <hannes@cmpxchg.org>,
Al Viro <viro@zeniv.linux.org.uk>, Mel Gorman <mgorman@suse.de>,
Rik van Riel <riel@redhat.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [RFC 0/2] mapping_gfp_mask from the page fault path
Date: Tue, 2 Jun 2015 13:22:41 -0700 [thread overview]
Message-ID: <20150602132241.26fbbc98be71920da8485b73@linux-foundation.org> (raw)
In-Reply-To: <1433163603-13229-1-git-send-email-mhocko@suse.cz>
On Mon, 1 Jun 2015 15:00:01 +0200 Michal Hocko <mhocko@suse.cz> wrote:
> I somehow forgot about these patches. The previous version was
> posted here: http://marc.info/?l=linux-mm&m=142668784122763&w=2. The
> first attempt was broken but even when fixed it seems like ignoring
> mapping_gfp_mask in page_cache_read is too fragile because
> filesystems might use locks in their filemap_fault handlers
> which could trigger recursion problems as pointed out by Dave
> http://marc.info/?l=linux-mm&m=142682332032293&w=2.
>
> The first patch should be straightforward fix to obey mapping_gfp_mask
> when allocating for mapping. It can be applied even without the second
> one.
I'm not so sure about that. If only [1/2] is applied then those
filesystems which are setting mapping_gfp_mask to GFP_NOFS will now
actually start using GFP_NOFS from within page_cache_read() etc. The
weaker allocation mode might cause problems.
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next prev parent reply other threads:[~2015-06-02 20:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-01 13:00 Michal Hocko
2015-06-01 13:00 ` [RFC 1/2] mm: do not ignore mapping_gfp_mask in page cache allocation paths Michal Hocko
2015-06-01 13:00 ` [RFC 2/2] mm: Allow GFP_IOFS for page_cache_read page cache allocation Michal Hocko
2015-07-08 11:58 ` Michal Hocko
2015-06-02 20:22 ` Andrew Morton [this message]
2015-06-03 13:04 ` [RFC 0/2] mapping_gfp_mask from the page fault path Tetsuo Handa
2015-06-03 13:42 ` Michal Hocko
2015-06-03 13:28 ` Michal Hocko
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