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Message-ID: <20250524131955.GU7435@unreal>
Date: Sat, 24 May 2025 16:19:55 +0300
From: Leon Romanovsky <leon@...nel.org>
To: Daisuke Matsuda <dskmtsd@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org, jgg@...pe.ca,
zyjzyj2000@...il.com, hch@...radead.org
Subject: Re: [PATCH for-next v1] RDMA/core: Avoid hmm_dma_map_alloc() for
virtual DMA devices
On Fri, May 23, 2025 at 06:47:01PM +0000, Daisuke Matsuda wrote:
> Drivers such as rxe, which use virtual DMA, must not call into the DMA
> mapping core since they lack physical DMA capabilities. Otherwise, a NULL
> pointer dereference is observed as shown below. This patch ensures the RDMA
> core handles virtual and physical DMA paths appropriately.
>
> This fixes the following kernel oops:
>
> BUG: kernel NULL pointer dereference, address: 00000000000002fc
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 1028eb067 P4D 1028eb067 PUD 105da0067 PMD 0
> Oops: Oops: 0000 [#1] SMP NOPTI
> CPU: 3 UID: 1000 PID: 1854 Comm: python3 Tainted: G W 6.15.0-rc1+ #11 PREEMPT(voluntary)
> Tainted: [W]=WARN
> Hardware name: Trigkey Key N/Key N, BIOS KEYN101 09/02/2024
> RIP: 0010:hmm_dma_map_alloc+0x25/0x100
> Code: 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 49 89 d6 49 c1 e6 0c 41 55 41 54 53 49 39 ce 0f 82 c6 00 00 00 49 89 fc <f6> 87 fc 02 00 00 20 0f 84 af 00 00 00 49 89 f5 48 89 d3 49 89 cf
> RSP: 0018:ffffd3d3420eb830 EFLAGS: 00010246
> RAX: 0000000000001000 RBX: ffff8b727c7f7400 RCX: 0000000000001000
> RDX: 0000000000000001 RSI: ffff8b727c7f74b0 RDI: 0000000000000000
> RBP: ffffd3d3420eb858 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 00007262a622a000 R14: 0000000000001000 R15: ffff8b727c7f74b0
> FS: 00007262a62a1080(0000) GS:ffff8b762ac3e000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000000002fc CR3: 000000010a1f0004 CR4: 0000000000f72ef0
> PKRU: 55555554
> Call Trace:
> <TASK>
> ib_init_umem_odp+0xb6/0x110 [ib_uverbs]
> ib_umem_odp_get+0xf0/0x150 [ib_uverbs]
> rxe_odp_mr_init_user+0x71/0x170 [rdma_rxe]
> rxe_reg_user_mr+0x217/0x2e0 [rdma_rxe]
> ib_uverbs_reg_mr+0x19e/0x2e0 [ib_uverbs]
> ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0xd9/0x150 [ib_uverbs]
> ib_uverbs_cmd_verbs+0xd19/0xee0 [ib_uverbs]
> ? mmap_region+0x63/0xd0
> ? __pfx_ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0x10/0x10 [ib_uverbs]
> ib_uverbs_ioctl+0xba/0x130 [ib_uverbs]
> __x64_sys_ioctl+0xa4/0xe0
> x64_sys_call+0x1178/0x2660
> do_syscall_64+0x7e/0x170
> ? syscall_exit_to_user_mode+0x4e/0x250
> ? do_syscall_64+0x8a/0x170
> ? do_syscall_64+0x8a/0x170
> ? syscall_exit_to_user_mode+0x4e/0x250
> ? do_syscall_64+0x8a/0x170
> ? syscall_exit_to_user_mode+0x4e/0x250
> ? do_syscall_64+0x8a/0x170
> ? do_user_addr_fault+0x1d2/0x8d0
> ? irqentry_exit_to_user_mode+0x43/0x250
> ? irqentry_exit+0x43/0x50
> ? exc_page_fault+0x93/0x1d0
> entry_SYSCALL_64_after_hwframe+0x76/0x7e
> RIP: 0033:0x7262a6124ded
> Code: 04 25 28 00 00 00 48 89 45 c8 31 c0 48 8d 45 10 c7 45 b0 10 00 00 00 48 89 45 b8 48 8d 45 d0 48 89 45 c0 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1a 48 8b 45 c8 64 48 2b 04 25 28 00 00 00
> RSP: 002b:00007fffd08c3960 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007fffd08c39f0 RCX: 00007262a6124ded
> RDX: 00007fffd08c3a10 RSI: 00000000c0181b01 RDI: 0000000000000007
> RBP: 00007fffd08c39b0 R08: 0000000014107820 R09: 00007fffd08c3b44
> R10: 000000000000000c R11: 0000000000000246 R12: 00007fffd08c3b44
> R13: 000000000000000c R14: 00007fffd08c3b58 R15: 0000000014107960
> </TASK>
>
> Fixes: 1efe8c0670d6 ("RDMA/core: Convert UMEM ODP DMA mapping to caching IOVA and page linkage")
> Closes: https://lore.kernel.org/all/3e8f343f-7d66-4f7a-9f08-3910623e322f@gmail.com/
> Signed-off-by: Daisuke Matsuda <dskmtsd@...il.com>
> ---
> drivers/infiniband/core/device.c | 24 ++++++++++++++++++++++++
> drivers/infiniband/core/umem_odp.c | 6 +++---
> include/rdma/ib_verbs.h | 12 ++++++++++++
> 3 files changed, 39 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> index b4e3e4beb7f4..8be4797c66ec 100644
> --- a/drivers/infiniband/core/device.c
> +++ b/drivers/infiniband/core/device.c
> @@ -2864,6 +2864,30 @@ int ib_dma_virt_map_sg(struct ib_device *dev, struct scatterlist *sg, int nents)
> return nents;
> }
> EXPORT_SYMBOL(ib_dma_virt_map_sg);
> +int ib_dma_virt_map_alloc(struct device *dev, struct hmm_dma_map *map,
> + size_t nr_entries, size_t dma_entry_size)
> +{
> + if (!(nr_entries * PAGE_SIZE / dma_entry_size))
> + return -EINVAL;
> +
> + map->dma_entry_size = dma_entry_size;
> + map->pfn_list = kvcalloc(nr_entries, sizeof(*map->pfn_list),
> + GFP_KERNEL | __GFP_NOWARN);
> + if (!map->pfn_list)
> + return -ENOMEM;
pfn_list is enough, virtual devices doesn't go through path which needs
dma_list. They use simple CPU address to DMA address translation.
> +
> + map->dma_list = kvcalloc(nr_entries, sizeof(*map->dma_list),
> + GFP_KERNEL | __GFP_NOWARN);
> + if (!map->dma_list)
> + goto err_dma;
> +
> + return 0;
> +
> +err_dma:
> + kvfree(map->pfn_list);
> + return -ENOMEM;
> +}
> +EXPORT_SYMBOL(ib_dma_virt_map_alloc);
> #endif /* CONFIG_INFINIBAND_VIRT_DMA */
>
> static const struct rdma_nl_cbs ibnl_ls_cb_table[RDMA_NL_LS_NUM_OPS] = {
> diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
> index 51d518989914..aa03f3fc84d0 100644
> --- a/drivers/infiniband/core/umem_odp.c
> +++ b/drivers/infiniband/core/umem_odp.c
> @@ -75,9 +75,9 @@ static int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
> if (unlikely(end < page_size))
> return -EOVERFLOW;
>
> - ret = hmm_dma_map_alloc(dev->dma_device, &umem_odp->map,
> - (end - start) >> PAGE_SHIFT,
> - 1 << umem_odp->page_shift);
> + ret = ib_dma_map_alloc(dev, &umem_odp->map,
> + (end - start) >> PAGE_SHIFT,
> + 1 << umem_odp->page_shift);
There is no need in extra function, implement if(ib_uses_virt_dma...) here.
Thanks
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