| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.18 083/144] nfs: fix high load average due to callback thread sleeping | Date | Thu, 8 Nov 2018 13:50:54 -0800 |
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3.18-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 5d05e54af3cdbb13cf19c557ff2184781b91a22c ]
Chuck pointed out a problem that crept in with commit 6ffa30d3f734 (nfs: don't call blocking operations while !TASK_RUNNING). Linux counts tasks in uninterruptible sleep against the load average, so this caused the system's load average to be pinned at at least 1 when there was a NFSv4.1+ mount active.
Not a huge problem, but it's probably worth fixing before we get too many complaints about it. This patch converts the code back to use TASK_INTERRUPTIBLE sleep, simply has it flush any signals on each loop iteration. In practice no one should really be signalling this thread at all, so I think this is reasonably safe.
With this change, there's also no need to game the hung task watchdog so we can also convert the schedule_timeout call back to a normal schedule.
Cc: <stable@vger.kernel.org> Reported-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> Tested-by: Chuck Lever <chuck.lever@oracle.com> Fixes: commit 6ffa30d3f734 (“nfs: don't call blocking . . .”) Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/nfs/callback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index 3b8cdb8298c4..a78558a25035 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -128,7 +128,7 @@ nfs41_callback_svc(void *vrqstp) if (try_to_freeze()) continue; - prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_UNINTERRUPTIBLE); + prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE); spin_lock_bh(&serv->sv_cb_lock); if (!list_empty(&serv->sv_cb_list)) { req = list_first_entry(&serv->sv_cb_list, @@ -142,10 +142,10 @@ nfs41_callback_svc(void *vrqstp) error); } else { spin_unlock_bh(&serv->sv_cb_lock); - /* schedule_timeout to game the hung task watchdog */ - schedule_timeout(60 * HZ); + schedule(); finish_wait(&serv->sv_cb_waitq, &wq); } + flush_signals(current); } return 0; } -- 2.17.1
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