linux-ext4 - Re: [PATCH] ext4: Fix deadlock on page reclaim

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Message-ID: <20190730234716.GY7689@dread.disaster.area>
Date:   Wed, 31 Jul 2019 09:47:16 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Damien Le Moal <Damien.LeMoal@....com>
Cc:     Andreas Dilger <adilger@...ger.ca>,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Christoph Hellwig <hch@...radead.org>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Naohiro Aota <Naohiro.Aota@....com>,
        Masato Suzuki <masato.suzuki@....com>
Subject: Re: [PATCH] ext4: Fix deadlock on page reclaim

On Tue, Jul 30, 2019 at 02:06:33AM +0000, Damien Le Moal wrote:
> If we had a pread_nofs()/pwrite_nofs(), that would work. Or we could define a
> RWF_NORECLAIM flag for pwritev2()/preadv2(). This last one could actually be the
> cleanest approach.

Clean, yes, but I'm not sure we want to expose kernel memory reclaim
capabilities to userspace... It would be misleading, too, because we
still want to allow reclaim to occur, just not have reclaim recurse
into other filesystems....

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com