From: Gerd Rausch <gerd.rausch@oracle.com>
To: Pavel Machek <pavel@denx.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Santosh Shilimkar <santosh.shilimkar@oracle.com>,
Jakub Kicinski <kuba@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.9 12/16] net/rds: dma_map_sg is entitled to merge entries
Date: Fri, 3 Sep 2021 09:02:41 -0700 [thread overview]
Message-ID: <a5edcbfd-7492-964d-688f-4f2a3f45e4ca@oracle.com> (raw)
In-Reply-To: <20210903065035.GA11871@amd>
Hi Pavel,
On 02/09/2021 23.50, Pavel Machek wrote:
>> [ Upstream commit fb4b1373dcab086d0619c29310f0466a0b2ceb8a ]
>>
>> Function "dma_map_sg" is entitled to merge adjacent entries
>> and return a value smaller than what was passed as "nents".
>>
>> Subsequently "ib_map_mr_sg" needs to work with this value ("sg_dma_len")
>> rather than the original "nents" parameter ("sg_len").
>>
>> This old RDS bug was exposed and reliably causes kernel panics
>> (using RDMA operations "rds-stress -D") on x86_64 starting with:
>> commit c588072bba6b ("iommu/vt-d: Convert intel iommu driver to the iommu ops")
>>
>> Simply put: Linux 5.11 and later.
>
> I see this queued for 4.19 and 5.10 where "iommu/vt-d: Convert intel
> iommu driver to the iommu ops" is not present. It may be okay for
> older kernels, too, but I wanted to double-check.
>
It should be okay for older kernels as well.
The bug has always been there, but only started to cause panics
in cases where "dma_map_sg" actually did merge adjacent entries.
We bisected the crash down to the commit mentioned above (c588072bba6b),
on platforms that use the intel iommu.
That intel-iommu commit wasn't there on Linux-5.10 and older.
But the RDS bug was.
Hope this helps,
Gerd
next prev parent reply other threads:[~2021-09-03 16:02 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 12:26 [PATCH 4.9 00/16] 4.9.282-rc1 review Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 01/16] ARC: Fix CONFIG_STACKDEPOT Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 02/16] can: usb: esd_usb2: esd_usb2_rx_event(): fix the interchange of the CAN RX and TX error counters Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 03/16] Revert "USB: serial: ch341: fix character loss at high transfer rates" Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 04/16] USB: serial: option: add new VID/PID to support Fibocom FG150 Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 05/16] usb: dwc3: gadget: Fix dwc3_calc_trbs_left() Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 06/16] IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs() Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 07/16] e1000e: Fix the max snoop/no-snoop latency for 10M Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 08/16] ip_gre: add validation for csum_start Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 09/16] net: marvell: fix MVNETA_TX_IN_PRGRS bit number Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 10/16] virtio: Improve vq->broken access to avoid any compiler optimization Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 11/16] vringh: Use wiov->used to check for read/write desc order Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 12/16] net/rds: dma_map_sg is entitled to merge entries Greg Kroah-Hartman
2021-09-03 6:50 ` Pavel Machek
2021-09-03 16:02 ` Gerd Rausch [this message]
2021-09-01 12:26 ` [PATCH 4.9 13/16] vt_kdsetmode: extend console locking Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 14/16] fbmem: add margin check to fb_check_caps() Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 15/16] KVM: x86/mmu: Treat NX as used (not reserved) for all !TDP shadow MMUs Greg Kroah-Hartman
2021-09-01 12:26 ` [PATCH 4.9 16/16] Revert "floppy: reintroduce O_NDELAY fix" Greg Kroah-Hartman
2021-09-01 15:45 ` [PATCH 4.9 00/16] 4.9.282-rc1 review Florian Fainelli
2021-09-01 21:24 ` Shuah Khan
2021-09-02 16:10 ` Naresh Kamboju
2021-09-02 21:49 ` Guenter Roeck
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