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[PATCH 3.14 24/29] rds: rds_ib_device.refcount overflow

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 3.14 24/29] rds: rds_ib_device.refcount overflow
Date 2015-08-09 00:50 +0200
Message-ID <pVl6b-45c-29@gated-at.bofh.it> (permalink)
References <pVktr-3jX-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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3.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Wengang Wang <wen.gang.wang@oracle.com>

commit 4fabb59449aa44a585b3603ffdadd4c5f4d0c033 upstream.

Fixes: 3e0249f9c05c ("RDS/IB: add refcount tracking to struct rds_ib_device")

There lacks a dropping on rds_ib_device.refcount in case rds_ib_alloc_fmr
failed(mr pool running out). this lead to the refcount overflow.

A complain in line 117(see following) is seen. From vmcore:
s_ib_rdma_mr_pool_depleted is 2147485544 and rds_ibdev->refcount is -2147475448.
That is the evidence the mr pool is used up. so rds_ib_alloc_fmr is very likely
to return ERR_PTR(-EAGAIN).

115 void rds_ib_dev_put(struct rds_ib_device *rds_ibdev)
116 {
117         BUG_ON(atomic_read(&rds_ibdev->refcount) <= 0);
118         if (atomic_dec_and_test(&rds_ibdev->refcount))
119                 queue_work(rds_wq, &rds_ibdev->free_work);
120 }

fix is to drop refcount when rds_ib_alloc_fmr failed.

Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Reviewed-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/rds/ib_rdma.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -759,8 +759,10 @@ void *rds_ib_get_mr(struct scatterlist *
 	}
 
 	ibmr = rds_ib_alloc_fmr(rds_ibdev);
-	if (IS_ERR(ibmr))
+	if (IS_ERR(ibmr)) {
+		rds_ib_dev_put(rds_ibdev);
 		return ibmr;
+	}
 
 	ret = rds_ib_map_fmr(rds_ibdev, ibmr, sg, nents);
 	if (ret == 0)


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Thread

[PATCH 3.14 00/29] 3.14.50-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 11/29] mmc: sdhci-esdhc: Make 8BIT bus work Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 04/29] ARC: make sure instruction_pointer() returns unsigned value Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 26/29] avr32: handle NULL as a valid clock object Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 07/29] ALSA: usb-audio: add dB range mapping for some devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 15/29] Input: usbtouchscreen - avoid unresponsive TSC-30 touch screen Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 16/29] blkcg: fix gendisk reference leak in blkg_conf_prep() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 17/29] ata: pmp: add quirk for Marvell 4140 SATA PMP Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 24/29] rds: rds_ib_device.refcount overflow Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 23/29] x86/efi: Use all 64 bit of efi_memmap in setup_e820() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 20/29] xhci: report U3 when link is in resume state Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 10/29] mac80211: clear subdir_stations when removing debugfs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 19/29] xhci: Calculate old endpoints correctly on device reset Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 03/29] s390/sclp: clear upper register halves in _sclp_print_early Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 27/29] iscsi-target: Fix use-after-free during TPG session shutdown Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 02/29] freeing unlinked file indefinitely delayed Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  [PATCH 3.14 01/29] mm: avoid setting up anonymous pages into file mapping Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-09 00:50 +0200
  Re: [PATCH 3.14 00/29] 3.14.50-stable review Guenter Roeck <linux@roeck-us.net> - 2015-08-09 05:20 +0200
    Re: [PATCH 3.14 00/29] 3.14.50-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-08-10 21:20 +0200
  Re: [PATCH 3.14 00/29] 3.14.50-stable review Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2015-08-10 07:10 +0200

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