linux-kernel - [PATCH] fix mm leakage of block request in SCSI FiberChannel transport

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Date:	Thu, 25 Nov 2010 21:53:05 +0800
From:	Hillf Danton <dhillf@...il.com>
To:	linux-scsi@...r.kernel.org
Cc:	Joe Eykholt <jeykholt@...co.com>,
	Robert Love <robert.w.love@...el.com>,
	Mike Christie <michaelc@...wisc.edu>,
	"James E.J. Bottomley" <James.Bottomley@...e.de>,
	devel@...n-fcoe.org, linux-kernel@...r.kernel.org
Subject: [PATCH] fix mm leakage of block request in SCSI FiberChannel transport

When blk_rq_timed_out_timer run, only requests that are not completed
are selected for processing with LLD callback function.

In the case of fc_bsg_job_timeout, if BLK_EH_NOT_HANDLED returned, the
block layer will be signaled to do nothing for the request, but the
request still remains uncompleted since it is already marked with
REQ_ATOM_COMPLETE by the timer function and blk_complete_request()
will check it. Thus mm leakage is triggered.

It is fixed by returning BLK_EH_HANDLED, instead of
BLK_EH_NOT_HANDLED, with warning also recorded.

Thanks all for comments when preparing this work.

Signed-off-by: Hillf Danton <dhillf@...il.com>
---

--- a/drivers/scsi/scsi_transport_fc.c	2010-11-01 19:54:12.000000000 +0800
+++ b/drivers/scsi/scsi_transport_fc.c	2010-11-24 20:55:12.000000000 +0800
@@ -3626,9 +3626,9 @@ fc_bsg_job_timeout(struct request *req)

 	/* the blk_end_sync_io() doesn't check the error */
 	if (done)
-		return BLK_EH_NOT_HANDLED;
-	else
-		return BLK_EH_HANDLED;
+		printk(KERN_WARNING "%s: fixing mm leak...done\n", __func__);
+
+	return BLK_EH_HANDLED;
 }

 static int
--
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