Re: [PATCH for-next v1] RDMA/core: Avoid hmm_dma_map_alloc() for virtual DMA devices
From: Daisuke Matsuda
Date: Sat May 24 2025 - 09:16:00 EST
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 <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@xxxxxxxxx/
Signed-off-by: Daisuke Matsuda <dskmtsd@xxxxxxxxx>
---
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?
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