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[119.244.79.106]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3110b9a447bsm1520492a91.3.2025.05.24.06.15.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 24 May 2025 06:15:48 -0700 (PDT) Message-ID: <95b1875c-fe87-4941-9242-551fb9546ccc@gmail.com> Date: Sat, 24 May 2025 22:15:43 +0900 Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH for-next v1] RDMA/core: Avoid hmm_dma_map_alloc() for virtual DMA devices To: Zhu Yanjun , linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, leon@kernel.org, jgg@ziepe.ca, zyjzyj2000@gmail.com Cc: hch@infradead.org References: <20250523184701.11004-1-dskmtsd@gmail.com> Content-Language: en-US From: Daisuke Matsuda In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2025/05/24 16:52, Zhu Yanjun wrote: > 在 2025/5/24 9:31, Zhu Yanjun 写道: >> 在 2025/5/23 20:47, Daisuke Matsuda 写道: >>> 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 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: >>>    >>>    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 >>>    >>> >>> 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 >>> --- >>>   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; >>> + >>> +    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); >>>       if (ret) >>>           return ret; >>> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h >>> index b06a0ed81bdd..10813f348b99 100644 >>> --- a/include/rdma/ib_verbs.h >>> +++ b/include/rdma/ib_verbs.h >>> @@ -36,6 +36,7 @@ >>>   #include >>>   #include >>>   #include >>> +#include >>>   #include >>>   #include >>>   #include >>> @@ -4221,6 +4222,17 @@ static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev, >>>                      dma_attrs); >>>   } >>> +int ib_dma_virt_map_alloc(struct device *dev, struct hmm_dma_map *map, >>> +              size_t nr_entries, size_t dma_entry_size); >>> +static inline int ib_dma_map_alloc(struct ib_device *dev, struct hmm_dma_map *map, >>> +                   size_t nr_entries, size_t dma_entry_size) >>> +{ >>> +    if (ib_uses_virt_dma(dev)) >>> +        return ib_dma_virt_map_alloc(dev->dma_device, map, nr_entries, >>> +                         dma_entry_size); >> >> Other emulated RDMA devices driver also call ib_dma_virt_map_alloc? >> Only rxe will call ib_dma_virt_map_alloc? Only rxe will call ib_dma_virt_map_alloc() because currently only mlx5 and rxe will use ib_dma_map_alloc(). > > As I know, other emulated RDMA driver also implemented ODP, and with the current hmm_dma_map_alloc, it can work well. > So in the above "if (ib_uses_virt_dma(dev))", changed to if (rxe_dev), then go to call ib_dma_virt_map_alloc. Only mlx5 and rxe support ODP. While hmm_dma_map_alloc() works fine for mlx5, it cannot be used for any drivers under drivers/infiniband/sw/ because they all set dma_device to NULL in ib_register_device(). So changing the condition to if (rxe_dev) makes the code too specific. To my understanding, it's generally discouraged to add code in the RDMA core that targets a specific implementation. I have just realized that we can remove an argument "struct device" from ib_dma_virt_map_alloc(). I will post the v2 to fix this. Thanks, Daisuke > > Yanjun.Zhu > >> >> Zhu Yanjun >> >>> +    return hmm_dma_map_alloc(dev->dma_device, map, nr_entries, dma_entry_size); >>> +} >>> + >>>   /** >>>    * ib_dma_map_sgtable_attrs - Map a scatter/gather table to DMA addresses >>>    * @dev: The device for which the DMA addresses are to be created >> >