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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Trond Myklebust" <trond.myklebust@primarydata.com>,
        "Mike Galbraith" <efault@gmx.de>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
Message-ID: <lsq.1528380321.412472560@decadent.org.uk>
Subject: [PATCH 3.16 127/410] NFS: Add a cond_resched() to nfs_commit_release_pages()
In-Reply-To: <lsq.1528380320.647747352@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <trond.myklebust@primarydata.com>

commit 7f1bda447c9bd48b415acedba6b830f61591601f upstream.

The commit list can get very large, and so we need a cond_resched()
in nfs_commit_release_pages() in order to ensure we don't hog the CPU
for excessive periods of time.

Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/nfs/write.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1661,6 +1661,8 @@ static void nfs_commit_release_pages(str
 		set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
 	next:
 		nfs_unlock_and_release_request(req);
+		/* Latency breaker */
+		cond_resched();
 	}
 	nfs_init_cinfo(&cinfo, data->inode, data->dreq);
 	if (atomic_dec_and_test(&cinfo.mds->rpcs_out))