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[68.160.141.91]) by smtp.gmail.com with ESMTPSA id bb29-20020a05622a1b1d00b00418122186ccsm3481815qtb.12.2023.11.06.07.30.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Nov 2023 07:30:46 -0800 (PST) Date: Mon, 6 Nov 2023 10:30:45 -0500 From: Mike Snitzer To: Keith Busch Cc: Mikulas Patocka , Christoph Hellwig , Juergen Gross , Stefano Stabellini , xen-devel@lists.xenproject.org, iommu@lists.linux.dev, Marek Marczykowski-G'orecki , Jens Axboe , Sagi Grimberg , Jan Kara , Vlastimil Babka , Andrew Morton , Matthew Wilcox , Michal Hocko , stable@vger.kernel.org, regressions@lists.linux.dev, Alasdair Kergon , dm-devel@lists.linux.dev, linux-mm@kvack.org Subject: Re: swiotlb-xen: provide the "max_mapping_size" method Message-ID: References: <3cb4133c-b6db-9187-a678-11ed8c9456e@redhat.com> <11a9886d-316c-edcd-d6da-24ad0b9a2b4@redhat.com> <20231106071008.GB17022@lst.de> <928b5df7-fada-cf2f-6f6a-257a84547c3@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 25D7C80010 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: pb3dhxzps7dhwy1jhmwr7xemi1p45s95 X-HE-Tag: 1699284647-32892 X-HE-Meta: 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 jKq0y3Hy 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Nov 06 2023 at 10:16P -0500, Keith Busch wrote: > On Mon, Nov 06, 2023 at 03:59:40PM +0100, Mikulas Patocka wrote: > > There's a bug that when using the XEN hypervisor with dm-crypt 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. > > > > [1] https://lore.kernel.org/stable/ZTNH0qtmint%2FzLJZ@mail-itl/ > > This should be a "Link:" tag. > > > Signed-off-by: Mikulas Patocka > > Reported-by: Marek Marczykowski-G'orecki > > Tested-by: Marek Marczykowski-G'orecki > > Suggested-by: Keith Busch > > I was about to send the same thing. I did a little more than suggest > this: it's is the very patch I wrote for testing, minus the redundant > nvme bits! But since you already have a commit message for it... > > Acked-by: Keith Busch No, this patch should be attributed to you Keith. Mikulas, I like that you ran with getting a fix prepared but please update the patch so Keith is the author and use Link: as suggested for the v2. Note: you'll still use your Signed-off-by since you had a role in getting this patch together (but please move yours to the end of the header). Mike > > > Suggested-by: Christoph Hellwig > > Cc: stable@vger.kernel.org > > > > --- > > drivers/xen/swiotlb-xen.c | 1 + > > 1 file changed, 1 insertion(+) > > > > Index: linux-stable/drivers/xen/swiotlb-xen.c > > =================================================================== > > --- linux-stable.orig/drivers/xen/swiotlb-xen.c 2023-11-03 17:57:18.000000000 +0100 > > +++ linux-stable/drivers/xen/swiotlb-xen.c 2023-11-06 15:30:59.000000000 +0100 > > @@ -405,4 +405,5 @@ 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, > > }; >