This is a note to let you know that I've just added the patch titled
swiotlb-xen: provide the "max_mapping_size" method
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
swiotlb-xen-provide-the-max_mapping_size-method.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From bff2a2d453a1b683378b4508b86b84389f551a00 Mon Sep 17 00:00:00 2001
From: Keith Busch <kbusch@xxxxxxxxxx>
Date: Mon, 6 Nov 2023 18:12:30 +0100
Subject: swiotlb-xen: provide the "max_mapping_size" method
MIME-Version: 1.0
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From: Keith Busch <kbusch@xxxxxxxxxx>
commit bff2a2d453a1b683378b4508b86b84389f551a00 upstream.
There's a bug that when using the XEN hypervisor with bios with large
multi-page bio vectors on NVMe, the kernel deadlocks [1].
The deadlocks are caused by inability to map a large bio vector -
dma_map_sgtable always returns an error, this gets propagated to the block
layer as BLK_STS_RESOURCE and the block layer retries the request
indefinitely.
XEN uses the swiotlb framework to map discontiguous pages into contiguous
runs that are submitted to the PCIe device. The swiotlb framework has a
limitation on the length of a mapping - this needs to be announced with
the max_mapping_size method to make sure that the hardware drivers do not
create larger mappings.
Without max_mapping_size, the NVMe block driver would create large
mappings that overrun the maximum mapping size.
Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/stable/ZTNH0qtmint%2FzLJZ@mail-itl/ [1]
Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Suggested-by: Christoph Hellwig <hch@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/151bef41-e817-aea9-675-a35fdac4ed@xxxxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/xen/swiotlb-xen.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -564,4 +564,5 @@ const struct dma_map_ops xen_swiotlb_dma
.get_sgtable = dma_common_get_sgtable,
.alloc_pages = dma_common_alloc_pages,
.free_pages = dma_common_free_pages,
+ .max_mapping_size = swiotlb_max_mapping_size,
};
Patches currently in stable-queue which might be from kbusch@xxxxxxxxxx are
queue-5.15/swiotlb-xen-provide-the-max_mapping_size-method.patch
queue-5.15/nvmet-nul-terminate-the-nqns-passed-in-the-connect-c.patch
