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Message-ID: <c71dcd9b-ab75-4f13-8170-71c71d911779@linux.dev>
Date: Sat, 24 May 2025 09:52:48 +0200
From: Zhu Yanjun <yanjun.zhu@...ux.dev>
To: Daisuke Matsuda <dskmtsd@...il.com>, linux-kernel@...r.kernel.org,
linux-rdma@...r.kernel.org, leon@...nel.org, jgg@...pe.ca,
zyjzyj2000@...il.com
Cc: hch@...radead.org
Subject: Re: [PATCH for-next v1] RDMA/core: Avoid hmm_dma_map_alloc() for
virtual DMA devices
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 <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@...il.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;
>> +
>> + 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 <linux/irqflags.h>
>> #include <linux/preempt.h>
>> #include <linux/dim.h>
>> +#include <linux/hmm-dma.h>
>> #include <uapi/rdma/ib_user_verbs.h>
>> #include <rdma/rdma_counter.h>
>> #include <rdma/restrack.h>
>> @@ -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?
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.
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
>
--
Best Regards,
Yanjun.Zhu
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