| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.17 069/319] um: ubd: Fix for processes stuck in D state forever | Date | Wed, 12 Nov 2014 10:13:27 +0900 |
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3.17-stable review patch. If anyone has any objections, please let me know.
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From: Thorsten Knabe <linux@thorsten-knabe.de>
commit 2a2361228c5e6d8c1733f00653481de918598e50 upstream.
Starting with Linux 3.12 processes get stuck in D state forever in UserModeLinux under sync heavy workloads. This bug was introduced by commit 805f11a0d5 (um: ubd: Add REQ_FLUSH suppport). Fix bug by adding a check if FLUSH request was successfully submitted to the I/O thread and keeping the FLUSH request on the request queue on submission failures.
Fixes: 805f11a0d5 (um: ubd: Add REQ_FLUSH suppport) Signed-off-by: Thorsten Knabe <linux@thorsten-knabe.de> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/um/drivers/ubd_kern.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -1277,7 +1277,7 @@ static void do_ubd_request(struct reques while(1){ struct ubd *dev = q->queuedata; - if(dev->end_sg == 0){ + if(dev->request == NULL){ struct request *req = blk_fetch_request(q); if(req == NULL) return; @@ -1299,7 +1299,8 @@ static void do_ubd_request(struct reques return; } prepare_flush_request(req, io_req); - submit_request(io_req, dev); + if (submit_request(io_req, dev) == false) + return; } while(dev->start_sg < dev->end_sg){
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