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Date:   Sun, 23 Jan 2022 23:31:13 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     NeilBrown <neilb@suse.de>
Cc:     Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Chuck Lever <chuck.lever@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>,
        Christoph Hellwig <hch@infradead.org>,
        David Howells <dhowells@redhat.com>, linux-nfs@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 05/23] MM: reclaim mustn't enter FS for SWP_FS_OPS
 swap-space
Message-ID: <Ye5VwTxLAYOprjyy@infradead.org>
References: <164299573337.26253.7538614611220034049.stgit@noble.brown>
 <164299611276.26253.11555458501911153645.stgit@noble.brown>
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On Mon, Jan 24, 2022 at 02:48:32PM +1100, NeilBrown wrote:
> If swap-out is using filesystem operations (SWP_FS_OPS), then it is not
> safe to enter the FS for reclaim.
> So only down-grade the requirement for swap pages to __GFP_IO after
> checking that SWP_FS_OPS are not being used.
> 
> This makes the calculation of "may_enter_fs" slightly more complex, so
> move it into a separate function.  with that done, there is little value
> in maintaining the bool variable any more.  So replace the
> may_enter_fs variable with a may_enter_fs() function.  This removes any
> risk for the variable becoming out-of-date.

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>