linux-kernel - Re: [PATCH 1/2] mm: add PF_MEMALLOC

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Message-ID: <20160427111555.GJ2179@dhcp22.suse.cz>
Date:	Wed, 27 Apr 2016 13:15:56 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	Dave Chinner <david@...morbit.com>,
	Theodore Ts'o <tytso@....edu>, Chris Mason <clm@...com>,
	Jan Kara <jack@...e.cz>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mm: add PF_MEMALLOC_NOFS

On Wed 27-04-16 19:53:21, Tetsuo Handa wrote:
[...]
> > Let's hope that filesystems will drop direct GFP_NOFS (resp. ~__GFP_FS)
> > usage as much and possible and only use a properly documented
> > memalloc_nofs_{save,restore} checkpoints where they are appropriate.
> 
> Is the story simple enough to monotonically replace GFP_NOFS/GFP_NOIO
> with GFP_KERNEL after memalloc_no{fs,io}_{save,restore} are inserted?
> We sometimes delegate some operations to somebody else. Don't we need to
> convey PF_MEMALLOC_NOFS/PF_MEMALLOC_NOIO flags to APIs which interact with
> other threads?

We can add an api to do that if that is really needed.

-- 
Michal Hocko
SUSE Labs