Eric Lee / smarc-fsl-linux-kernel

02 Nov, 2017

1 commit

  • b24413180   License cleanup: add SPDX GPL-2.0 license identifier to files with no license ... Browse Code »

    Many source files in the tree are missing licensing information, which
    makes it harder for compliance tools to determine the correct license.

    By default all files without license information are under the default
    license of the kernel, which is GPL version 2.

    Update the files which contain no license information with the 'GPL-2.0'
    SPDX license identifier. The SPDX identifier is a legally binding
    shorthand, which can be used instead of the full boiler plate text.

    This patch is based on work done by Thomas Gleixner and Kate Stewart and
    Philippe Ombredanne.

    How this work was done:

    Patches were generated and checked against linux-4.14-rc6 for a subset of
    the use cases:
    - file had no licensing information it it.
    - file was a */uapi/* one with no licensing information in it,
    - file was a */uapi/* one with existing licensing information,

    Further patches will be generated in subsequent months to fix up cases
    where non-standard license headers were used, and references to license
    had to be inferred by heuristics based on keywords.

    The analysis to determine which SPDX License Identifier to be applied to
    a file was done in a spreadsheet of side by side results from of the
    output of two independent scanners (ScanCode & Windriver) producing SPDX
    tag:value files created by Philippe Ombredanne. Philippe prepared the
    base worksheet, and did an initial spot review of a few 1000 files.

    The 4.13 kernel was the starting point of the analysis with 60,537 files
    assessed. Kate Stewart did a file by file comparison of the scanner
    results in the spreadsheet to determine which SPDX license identifier(s)
    to be applied to the file. She confirmed any determination that was not
    immediately clear with lawyers working with the Linux Foundation.

    Criteria used to select files for SPDX license identifier tagging was:
    - Files considered eligible had to be source code files.
    - Make and config files were included as candidates if they contained >5
    lines of source
    - File already had some variant of a license header in it (even if
    Reviewed-by: Philippe Ombredanne
    Reviewed-by: Thomas Gleixner
    Signed-off-by: Greg Kroah-Hartman

    Greg Kroah-Hartman
     

18 Mar, 2016

1 commit

  • 95813b8fa   mm/page_ref: add tracepoint to track down page reference manipulation ... Browse Code »

    CMA allocation should be guaranteed to succeed by definition, but,
    unfortunately, it would be failed sometimes. It is hard to track down
    the problem, because it is related to page reference manipulation and we
    don't have any facility to analyze it.

    This patch adds tracepoints to track down page reference manipulation.
    With it, we can find exact reason of failure and can fix the problem.
    Following is an example of tracepoint output. (note: this example is
    stale version that printing flags as the number. Recent version will
    print it as human readable string.)

    -9018 [004] 92.678375: page_ref_set: pfn=0x17ac9 flags=0x0 count=1 mapcount=0 mapping=(nil) mt=4 val=1
    -9018 [004] 92.678378: kernel_stack:
    => get_page_from_freelist (ffffffff81176659)
    => __alloc_pages_nodemask (ffffffff81176d22)
    => alloc_pages_vma (ffffffff811bf675)
    => handle_mm_fault (ffffffff8119e693)
    => __do_page_fault (ffffffff810631ea)
    => trace_do_page_fault (ffffffff81063543)
    => do_async_page_fault (ffffffff8105c40a)
    => async_page_fault (ffffffff817581d8)
    [snip]
    -9018 [004] 92.678379: page_ref_mod: pfn=0x17ac9 flags=0x40048 count=2 mapcount=1 mapping=0xffff880015a78dc1 mt=4 val=1
    [snip]
    ...
    ...
    -9131 [001] 93.174468: test_pages_isolated: start_pfn=0x17800 end_pfn=0x17c00 fin_pfn=0x17ac9 ret=fail
    [snip]
    -9018 [004] 93.174843: page_ref_mod_and_test: pfn=0x17ac9 flags=0x40068 count=0 mapcount=0 mapping=0xffff880015a78dc1 mt=4 val=-1 ret=1
    => release_pages (ffffffff8117c9e4)
    => free_pages_and_swap_cache (ffffffff811b0697)
    => tlb_flush_mmu_free (ffffffff81199616)
    => tlb_finish_mmu (ffffffff8119a62c)
    => exit_mmap (ffffffff811a53f7)
    => mmput (ffffffff81073f47)
    => do_exit (ffffffff810794e9)
    => do_group_exit (ffffffff81079def)
    => SyS_exit_group (ffffffff81079e74)
    => entry_SYSCALL_64_fastpath (ffffffff817560b6)

    This output shows that problem comes from exit path. In exit path, to
    improve performance, pages are not freed immediately. They are gathered
    and processed by batch. During this process, migration cannot be
    possible and CMA allocation is failed. This problem is hard to find
    without this page reference tracepoint facility.

    Enabling this feature bloat kernel text 30 KB in my configuration.

    text data bss dec hex filename
    12127327 2243616 1507328 15878271 f2487f vmlinux_disabled
    12157208 2258880 1507328 15923416 f2f8d8 vmlinux_enabled

    Note that, due to header file dependency problem between mm.h and
    tracepoint.h, this feature has to open code the static key functions for
    tracepoints. Proposed by Steven Rostedt in following link.

    https://lkml.org/lkml/2015/12/9/699

    [arnd@arndb.de: crypto/async_pq: use __free_page() instead of put_page()]
    [iamjoonsoo.kim@lge.com: fix build failure for xtensa]
    [akpm@linux-foundation.org: tweak Kconfig text, per Vlastimil]
    Signed-off-by: Joonsoo Kim
    Acked-by: Michal Nazarewicz
    Acked-by: Vlastimil Babka
    Cc: Minchan Kim
    Cc: Mel Gorman
    Cc: "Kirill A. Shutemov"
    Cc: Sergey Senozhatsky
    Acked-by: Steven Rostedt
    Signed-off-by: Arnd Bergmann
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Joonsoo Kim