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commit528871b456upstream. The following commit:9dff0aa95a("perf/core: Don't WARN() for impossible ring-buffer sizes") results in perf recording failures with larger mmap areas: root@skl:/tmp# perf record -g -a failed to mmap with 12 (Cannot allocate memory) The root cause is that the following condition is buggy: if (order_base_2(size) >= MAX_ORDER) goto fail; The problem is that @size is in bytes and MAX_ORDER is in pages, so the right test is: if (order_base_2(size) >= PAGE_SHIFT+MAX_ORDER) goto fail; Fix it. Reported-by: "Jin, Yao" <yao.jin@linux.intel.com> Bisected-by: Borislav Petkov <bp@alien8.de> Analyzed-by: Peter Zijlstra <peterz@infradead.org> Cc: Julien Thierry <julien.thierry@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: <stable@vger.kernel.org> Fixes:9dff0aa95a("perf/core: Don't WARN() for impossible ring-buffer sizes") Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.