f968dc119a
Chen Yu reported a divide-by-zero error when accessing the 'size' resctrl file when a MBA resource is enabled. divide error: 0000 [#1] SMP PTI CPU: 93 PID: 1929 Comm: cat Not tainted 4.19.0-rc2-debug-rdt+ #25 RIP: 0010:rdtgroup_cbm_to_size+0x7e/0xa0 Call Trace: rdtgroup_size_show+0x11a/0x1d0 seq_read+0xd8/0x3b0 Quoting Chen Yu's report: This is because for MB resource, the r->cache.cbm_len is zero, thus calculating size in rdtgroup_cbm_to_size() will trigger the exception. Fix this issue in the 'size' file by getting correct memory bandwidth value which is in MBps when MBA software controller is enabled or in percentage when MBA software controller is disabled. Fixes: d9b48c86eb38 ("x86/intel_rdt: Display resource groups' allocations in bytes") Reported-by: Chen Yu <yu.c.chen@intel.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Chen Yu <yu.c.chen@intel.com> Cc: "H Peter Anvin" <hpa@zytor.com> Cc: "Tony Luck" <tony.luck@intel.com> Cc: "Xiaochen Shen" <xiaochen.shen@intel.com> Link: https://lkml.kernel.org/r/20180904174614.26682-1-yu.c.chen@intel.com Link: https://lkml.kernel.org/r/1537048707-76280-3-git-send-email-fenghua.yu@intel.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.