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If something calls ioremap() with an address not aligned to PAGE_SIZE, the returned address might be not aligned as well. This led to a probe registered on exactly the returned address, but the entire page was armed for mmiotracing. On calling iounmap() the address passed to unregister_kmmio_probe() was PAGE_SIZE aligned by the caller leading to a complete freeze of the machine. We should always page align addresses while (un)registerung mappings, because the mmiotracer works on top of pages, not mappings. We still keep track of the probes based on their real addresses and lengths though, because the mmiotrace still needs to know what are mapped memory regions. Also move the call to mmiotrace_iounmap() prior page aligning the address, so that all probes are unregistered properly, otherwise the kernel ends up failing memory allocations randomly after disabling the mmiotracer. Tested-by: Lyude <lyude@redhat.com> Signed-off-by: Karol Herbst <kherbst@redhat.com> Acked-by: Pekka Paalanen <ppaalanen@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: nouveau@lists.freedesktop.org Link: http://lkml.kernel.org/r/20171127075139.4928-1-kherbst@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.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.