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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: commitd10bcf947a("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:d10bcf947a("RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs") Fixes:0425e3e6e0("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.