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From: David Howells <dhowells@redhat.com>
To: Zhaoyang Huang <huangzhaoyang@gmail.com>
Cc: dhowells@redhat.com, Marc Dionne <marc.dionne@auristor.com>,
	Zhaoyang Huang <zhaoyang.huang@unisoc.com>,
	linux-cachefs@redhat.com, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] fs: judging context via current_is_kswapd instead of gfp_flag
Date: Tue, 21 Dec 2021 15:00:20 +0000	[thread overview]
Message-ID: <73896.1640098820@warthog.procyon.org.uk> (raw)
In-Reply-To: <CAGWkznHcuiwPPMZE95nYG=EFkM8NmLUQZooS5+a+GigP50qksg@mail.gmail.com>

Zhaoyang Huang <huangzhaoyang@gmail.com> wrote:

> > > -             if (!(gfp_flags & __GFP_DIRECT_RECLAIM) || !(gfp_flags & __GFP_FS))
> > > +             if (current_is_kswapd() || !(gfp_flags & __GFP_FS))
> > >                       return false;
> > >               wait_on_page_fscache(page);
> ...
> If the gfp flag here is used for judging kswapd context, I think the
> answer is yes as kswapd applied __GFP_DIRECT_RECLAIM.

Now I come to look at applying it, I'm not sure whether this change is right.

I don't know if kswapd has anything to do with it.  The check is to see if
we're allowed to block at this point - and wait is just for the completion of
a DIO write to disk.

It would seem like gfpflags_allow_blocking() is the right thing to call - and
that should use current_is_kswapd() if appropriate.

David


  parent reply	other threads:[~2021-12-21 15:01 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-08  8:37 Huangzhaoyang
2021-12-08 20:26 ` David Howells
2021-12-10  1:19   ` Zhaoyang Huang
2021-12-21 15:00   ` David Howells [this message]
2021-12-22  8:02     ` Zhaoyang Huang

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