RDMA/hns: Fix sg offset non-zero issue

When run perftest in many times, the system will report a BUG as follows:

   BUG: Bad rss-counter state mm:(____ptrval____) idx:0 val:-1
   BUG: Bad rss-counter state mm:(____ptrval____) idx:1 val:1

We tested with different kernel version and found it started from the the
following commit:

commit d10bcf947a3e ("RDMA/umem: Combine contiguous PAGE_SIZE regions in
SGEs")

In this commit, the sg->offset is always 0 when sg_set_page() is called in
ib_umem_get() and the drivers are not allowed to change the sgl, otherwise
it will get bad page descriptor when unfolding SGEs in __ib_umem_release()
as sg_page_count() will get wrong result while sgl->offset is not 0.

However, there is a weird sgl usage in the current hns driver, the driver
modified sg->offset after calling ib_umem_get(), which caused we iterate
past the wrong number of pages in for_each_sg_page iterator.

This patch fixes it by correcting the non-standard sgl usage found in the
hns_roce_db_map_user() function.

Fixes: d10bcf947a3e ("RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs")
Fixes: 0425e3e6e0c7 ("RDMA/hns: Support flush cqe for hip08 in kernel space")
Link: https://lore.kernel.org/r/1562808737-45723-1-git-send-email-oulijun@huawei.com
Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/infiniband/hw/hns/hns_roce_db.c b/drivers/infiniband/hw/hns/hns_roce_db.c
index 627aa46ef683b8ec4467acc1404033f21822f627..c00714c2f16a60ca4c9a92c8148f73add6dddc56 100644 (file)
--- a/drivers/infiniband/hw/hns/hns_roce_db.c
+++ b/drivers/infiniband/hw/hns/hns_roce_db.c
@@ -12,13 +12,15 @@ int hns_roce_db_map_user(struct hns_roce_ucontext *context,
                         struct ib_udata *udata, unsigned long virt,
                         struct hns_roce_db *db)
 {
+       unsigned long page_addr = virt & PAGE_MASK;
        struct hns_roce_user_db_page *page;
+       unsigned int offset;
        int ret = 0;
 
        mutex_lock(&context->page_mutex);
 
        list_for_each_entry(page, &context->page_list, list)
-               if (page->user_virt == (virt & PAGE_MASK))
+               if (page->user_virt == page_addr)
                        goto found;
 
        page = kmalloc(sizeof(*page), GFP_KERNEL);
@@ -28,8 +30,8 @@ int hns_roce_db_map_user(struct hns_roce_ucontext *context,
        }
 
        refcount_set(&page->refcount, 1);
-       page->user_virt = (virt & PAGE_MASK);
-       page->umem = ib_umem_get(udata, virt & PAGE_MASK, PAGE_SIZE, 0, 0);
+       page->user_virt = page_addr;
+       page->umem = ib_umem_get(udata, page_addr, PAGE_SIZE, 0, 0);
        if (IS_ERR(page->umem)) {
                ret = PTR_ERR(page->umem);
                kfree(page);
@@ -39,10 +41,9 @@ int hns_roce_db_map_user(struct hns_roce_ucontext *context,
        list_add(&page->list, &context->page_list);
 
 found:
-       db->dma = sg_dma_address(page->umem->sg_head.sgl) +
-                 (virt & ~PAGE_MASK);
-       page->umem->sg_head.sgl->offset = virt & ~PAGE_MASK;
-       db->virt_addr = sg_virt(page->umem->sg_head.sgl);
+       offset = virt - page_addr;
+       db->dma = sg_dma_address(page->umem->sg_head.sgl) + offset;
+       db->virt_addr = sg_virt(page->umem->sg_head.sgl) + offset;
        db->u.user_page = page;
        refcount_inc(&page->refcount);