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commit957ac8c421upstream. PMD faults on a zero length file on a file system mounted with -o dax will not generate SIGBUS as expected. fd = open(...O_TRUNC); addr = mmap(NULL, 2*1024*1024, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); *addr = 'a'; <expect SIGBUS> The problem is this code in dax_iomap_pmd_fault: max_pgoff = (i_size_read(inode) - 1) >> PAGE_SHIFT; If the inode size is zero, we end up with a max_pgoff that is way larger than 0. :) Fix it by using DIV_ROUND_UP, as is done elsewhere in the kernel. I tested this with some simple test code that ensured that SIGBUS was received where expected. Fixes:642261ac99("dax: add struct iomap based DAX PMD support") Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.