1. 06 Dec, 2018 1 commit
    • Matthew Wilcox's avatar
      radix tree: Don't return retry entries from lookup · eff3860b
      Matthew Wilcox authored
      Commit 66ee620f ("idr: Permit any valid kernel pointer to be stored")
      changed the radix tree lookup so that it stops when reaching the bottom
      of the tree.  However, the condition was added in the wrong place,
      making it possible to return retry entries to the caller.  Reorder the
      tests to check for the retry entry before checking whether we're at the
      bottom of the tree.  The retry entry should never be found in the tree
      root, so it's safe to defer the check until the end of the loop.
      Add a regression test to the test-suite to be sure this doesn't come
      Fixes: 66ee620f ("idr: Permit any valid kernel pointer to be stored")
      Reported-by: default avatarGreg Kurz <groug@kaod.org>
      Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
  2. 21 Oct, 2018 3 commits
    • Matthew Wilcox's avatar
      radix tree test suite: Convert tag_tagged_items to XArray · 372266ba
      Matthew Wilcox authored
      The tag_tagged_items() function is supposed to test the page-writeback
      tagging code.  Since that has been converted to the XArray, there's
      not much point in testing the radix tree's tagging code.  This requires
      using the pthread mutex embedded in the xarray instead of an external
      lock, so remove the pthread mutexes which protect xarrays/radix trees.
      Also remove radix_tree_iter_tag_set() as this was the last user.
      Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
    • Matthew Wilcox's avatar
      shmem: Convert find_swap_entry to XArray · e21a2955
      Matthew Wilcox authored
      This is a 1:1 conversion.  The major part of this patch is converting
      the test framework from userspace to kernel space and mirroring the
      algorithm now used in find_swap_entry().
      Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
    • Matthew Wilcox's avatar
      xarray: Add XArray load operation · ad3d6c72
      Matthew Wilcox authored
      The xa_load function brings with it a lot of infrastructure; xa_empty(),
      xa_is_err(), and large chunks of the XArray advanced API that are used
      to implement xa_load.
      As the test-suite demonstrates, it is possible to use the XArray functions
      on a radix tree.  The radix tree functions depend on the GFP flags being
      stored in the root of the tree, so it's not possible to use the radix
      tree functions on an XArray.
      Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
  3. 22 Aug, 2018 2 commits
  4. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      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 <5
      All documentation files were explicitly excluded.
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
         For non */uapi/* files that summary was:
         SPDX license identifier                            # files
         GPL-2.0                                              11139
         and resulted in the first patch in this series.
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
         SPDX license identifier                            # files
         GPL-2.0 WITH Linux-syscall-note                        930
         and resulted in the second patch in this series.
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
         SPDX license identifier                            # files
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
         and that resulted in the third patch in this series.
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: default avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: default avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
  5. 07 Mar, 2017 1 commit
    • Matthew Wilcox's avatar
      ida: Free correct IDA bitmap · 4ecd9542
      Matthew Wilcox authored
      There's a relatively rare race where we look at the per-cpu preallocated
      IDA bitmap, see it's NULL, allocate a new one, and atomically update it.
      If the kmalloc() happened to sleep and we were rescheduled to a different
      CPU, or an interrupt came in at the exact right time, another task
      might have successfully allocated a bitmap and already deposited it.
      I forgot what the semantics of cmpxchg() were and ended up freeing the
      wrong bitmap leading to KASAN reporting a use-after-free.
      Dmitry found the bug with syzkaller & wrote the patch.  I wrote the test
      case that will reproduce the bug without his patch being applied.
      Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
  6. 14 Feb, 2017 3 commits
  7. 15 Dec, 2016 8 commits
  8. 11 Oct, 2016 1 commit
    • Ross Zwisler's avatar
      radix-tree tests: add iteration test · eec48525
      Ross Zwisler authored
      There are four cases I can see where we could end up with a NULL 'slot' in
      radix_tree_next_slot().  This unit test exercises all four of them, making
      sure that if in the future we have an unsafe path through
      radix_tree_next_slot(), we'll catch it.
      Here are details on the four cases:
      1) radix_tree_iter_retry() via a non-tagged iteration like
      radix_tree_for_each_slot().  In this case we currently aren't seeing a bug
      because radix_tree_iter_retry() sets
          iter->next_index = iter->index;
      which means that in in the else case in radix_tree_next_slot(), 'count' is
      zero, so we skip over the while() loop and effectively just return NULL
      without ever dereferencing 'slot'.
      2) radix_tree_iter_retry() via tagged iteration like
      radix_tree_for_each_tagged().  This case was giving us NULL pointer
      dereferences in testing, and was fixed with this commit:
      commit 3cb9185c ("radix-tree: fix radix_tree_iter_retry() for tagged
      This fix doesn't explicitly check for 'slot' being NULL, though, it works
      around the NULL pointer dereference by instead zeroing iter->tags in
      radix_tree_iter_retry(), which makes us bail out of the if() case in
      radix_tree_next_slot() before we dereference 'slot'.
      3) radix_tree_iter_next() via via a non-tagged iteration like
      radix_tree_for_each_slot().  This currently happens in shmem_tag_pins()
      and shmem_partial_swap_usage().
      As with non-tagged iteration, 'count' in the else case of
      radix_tree_next_slot() is zero, so we skip over the while() loop and
      effectively just return NULL without ever dereferencing 'slot'.
      4) radix_tree_iter_next() via tagged iteration like
      radix_tree_for_each_tagged().  This happens in shmem_wait_for_pins().
      radix_tree_iter_next() zeros out iter->tags, so we end up exiting
      radix_tree_next_slot() here:
          if (flags & RADIX_TREE_ITER_TAGGED) {
      	    void *canon = slot;
      	    iter->tags >>= 1;
      	    if (unlikely(!iter->tags))
      		    return NULL;
      Link: http://lkml.kernel.org/r/20160815194237.25967-3-ross.zwisler@linux.intel.comSigned-off-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
      Cc: Konstantin Khlebnikov <koct9i@gmail.com>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Shuah Khan <shuahkh@osg.samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
  9. 21 May, 2016 5 commits
  10. 17 Mar, 2016 2 commits