1. 16 5月, 2016 1 次提交
  2. 15 5月, 2016 6 次提交
    • L
      Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 5f95063c
      Linus Torvalds 提交于
      Pull x86 fix from Thomas Gleixner:
       "Just the missing compat entry for the new pread/writev2"
      
      * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86: Use compat version for preadv2 and pwritev2
      5f95063c
    • L
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net · 272911b8
      Linus Torvalds 提交于
      Pull networking fixes from David Miller:
      
       1) Fix mvneta/bm dependencies, from Arnd Bergmann.
      
       2) RX completion hw bug workaround in bnxt_en, from Michael Chan.
      
       3) Kernel pointer leak in nf_conntrack, from Linus.
      
       4) Hoplimit route attribute limits not enforced properly, from Paolo
          Abeni.
      
       5) qlcnic driver NULL deref fix from Dan Carpenter.
      
      * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
        arm64: bpf: jit JMP_JSET_{X,K}
        net/route: enforce hoplimit max value
        nf_conntrack: avoid kernel pointer value leak in slab name
        drivers: net: xgene: fix register offset
        drivers: net: xgene: fix statistics counters race condition
        drivers: net: xgene: fix ununiform latency across queues
        drivers: net: xgene: fix sharing of irqs
        drivers: net: xgene: fix IPv4 forward crash
        xen-netback: fix extra_info handling in xenvif_tx_err()
        net: mvneta: bm: fix dependencies again
        bnxt_en: Add workaround to detect bad opaque in rx completion (part 2)
        bnxt_en: Add workaround to detect bad opaque in rx completion (part 1)
        qlcnic: potential NULL dereference in qlcnic_83xx_get_minidump_template()
      272911b8
    • Z
      arm64: bpf: jit JMP_JSET_{X,K} · 98397fc5
      Zi Shen Lim 提交于
      Original implementation commit e54bcde3 ("arm64: eBPF JIT compiler")
      had the relevant code paths, but due to an oversight always fail jiting.
      
      As a result, we had been falling back to BPF interpreter whenever a BPF
      program has JMP_JSET_{X,K} instructions.
      
      With this fix, we confirm that the corresponding tests in lib/test_bpf
      continue to pass, and also jited.
      
      ...
      [    2.784553] test_bpf: #30 JSET jited:1 188 192 197 PASS
      [    2.791373] test_bpf: #31 tcpdump port 22 jited:1 325 677 625 PASS
      [    2.808800] test_bpf: #32 tcpdump complex jited:1 323 731 991 PASS
      ...
      [    3.190759] test_bpf: #237 JMP_JSET_K: if (0x3 & 0x2) return 1 jited:1 110 PASS
      [    3.192524] test_bpf: #238 JMP_JSET_K: if (0x3 & 0xffffffff) return 1 jited:1 98 PASS
      [    3.211014] test_bpf: #249 JMP_JSET_X: if (0x3 & 0x2) return 1 jited:1 120 PASS
      [    3.212973] test_bpf: #250 JMP_JSET_X: if (0x3 & 0xffffffff) return 1 jited:1 89 PASS
      ...
      
      Fixes: e54bcde3 ("arm64: eBPF JIT compiler")
      Signed-off-by: NZi Shen Lim <zlim.lnx@gmail.com>
      Acked-by: NWill Deacon <will.deacon@arm.com>
      Acked-by: NYang Shi <yang.shi@linaro.org>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      98397fc5
    • P
      net/route: enforce hoplimit max value · 626abd59
      Paolo Abeni 提交于
      Currently, when creating or updating a route, no check is performed
      in both ipv4 and ipv6 code to the hoplimit value.
      
      The caller can i.e. set hoplimit to 256, and when such route will
       be used, packets will be sent with hoplimit/ttl equal to 0.
      
      This commit adds checks for the RTAX_HOPLIMIT value, in both ipv4
      ipv6 route code, substituting any value greater than 255 with 255.
      
      This is consistent with what is currently done for ADVMSS and MTU
      in the ipv4 code.
      Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      626abd59
    • L
      nf_conntrack: avoid kernel pointer value leak in slab name · 31b0b385
      Linus Torvalds 提交于
      The slab name ends up being visible in the directory structure under
      /sys, and even if you don't have access rights to the file you can see
      the filenames.
      
      Just use a 64-bit counter instead of the pointer to the 'net' structure
      to generate a unique name.
      
      This code will go away in 4.7 when the conntrack code moves to a single
      kmemcache, but this is the backportable simple solution to avoiding
      leaking kernel pointers to user space.
      
      Fixes: 5b3501fa ("netfilter: nf_conntrack: per netns nf_conntrack_cachep")
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      31b0b385
    • L
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · 6ba5b85f
      Linus Torvalds 提交于
      Pull vfs fixes from Al Viro:
       "Overlayfs fixes from Miklos, assorted fixes from me.
      
        Stable fodder of varying severity, all sat in -next for a while"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
        ovl: ignore permissions on underlying lookup
        vfs: add lookup_hash() helper
        vfs: rename: check backing inode being equal
        vfs: add vfs_select_inode() helper
        get_rock_ridge_filename(): handle malformed NM entries
        ecryptfs: fix handling of directory opening
        atomic_open(): fix the handling of create_error
        fix the copy vs. map logics in blk_rq_map_user_iov()
        do_splice_to(): cap the size before passing to ->splice_read()
      6ba5b85f
  3. 14 5月, 2016 16 次提交
  4. 13 5月, 2016 17 次提交
    • M
      Merge remote-tracking branches 'regulator/fix/axp20x', 'regulator/fix/da9063',... · 9689dab3
      Mark Brown 提交于
      Merge remote-tracking branches 'regulator/fix/axp20x', 'regulator/fix/da9063', 'regulator/fix/gpio' and 'regulator/fix/s2mps11' into regulator-linus
      9689dab3
    • M
      Merge remote-tracking branches 'regmap/fix/be', 'regmap/fix/doc' and... · 2a2cd521
      Mark Brown 提交于
      Merge remote-tracking branches 'regmap/fix/be', 'regmap/fix/doc' and 'regmap/fix/spmi' into regmap-linus
      2a2cd521
    • M
      066a0e0b
    • D
      Merge branch 'drm-fixes-4.6' of git://people.freedesktop.org/~agd5f/linux into drm-fixes · e02aacb6
      Dave Airlie 提交于
      DP mode validation regression fix.
      * 'drm-fixes-4.6' of git://people.freedesktop.org/~agd5f/linux:
        drm/amdgpu: fix DP mode validation
        drm/radeon: fix DP mode validation
      e02aacb6
    • P
      xen-netback: fix extra_info handling in xenvif_tx_err() · 72eec92a
      Paul Durrant 提交于
      Patch 562abd39 "xen-netback: support multiple extra info fragments
      passed from frontend" contained a mistake which can result in an in-
      correct number of responses being generated when handling errors
      encountered when processing packets containing extra info fragments.
      This patch fixes the problem.
      Signed-off-by: NPaul Durrant <paul.durrant@citrix.com>
      Reported-by: NJan Beulich <JBeulich@suse.com>
      Cc: Wei Liu <wei.liu2@citrix.com>
      Acked-by: NWei Liu <wei.liu2@citrix.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      72eec92a
    • I
      Merge tag 'perf-urgent-for-mingo-20160512' of... · 636fa4a7
      Ingo Molnar 提交于
      Merge tag 'perf-urgent-for-mingo-20160512' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent
      
      Pull perf/urgent fixes from Arnaldo Carvalho de Melo:
      
      - Fallback to usermode-only counters when perf_event_paranoid > 1, which
        is the case now (Arnaldo Carvalho de Melo)
      
      - Do not reassign parg after collapse_tree() in libtraceevent, which
        may cause tool crashes (Steven Rostedt)
      
      - Fix the build on Fedora Rawhide, where readdir_r() is deprecated and
        also wrt -Werror=unused-const-variable= + x86_32_regoffset_table on
        !x86_64 (Arnaldo Carvalho de Melo)
      
      - Fix the build on Ubuntu 12.04.5, where dwarf_getlocations() isn't
        available, i.e. libdw-dev < 0.157 (Arnaldo Carvalho de Melo)
      Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      636fa4a7
    • L
      Merge branch 'akpm' (patches from Andrew) · a2ccb68b
      Linus Torvalds 提交于
      Merge fixes from Andrew Morton:
       "4 fixes"
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>:
        mm: thp: calculate the mapcount correctly for THP pages during WP faults
        ksm: fix conflict between mmput and scan_get_next_rmap_item
        ocfs2: fix posix_acl_create deadlock
        ocfs2: revert using ocfs2_acl_chmod to avoid inode cluster lock hang
      a2ccb68b
    • A
      mm: thp: calculate the mapcount correctly for THP pages during WP faults · 6d0a07ed
      Andrea Arcangeli 提交于
      This will provide fully accuracy to the mapcount calculation in the
      write protect faults, so page pinning will not get broken by false
      positive copy-on-writes.
      
      total_mapcount() isn't the right calculation needed in
      reuse_swap_page(), so this introduces a page_trans_huge_mapcount()
      that is effectively the full accurate return value for page_mapcount()
      if dealing with Transparent Hugepages, however we only use the
      page_trans_huge_mapcount() during COW faults where it strictly needed,
      due to its higher runtime cost.
      
      This also provide at practical zero cost the total_mapcount
      information which is needed to know if we can still relocate the page
      anon_vma to the local vma. If page_trans_huge_mapcount() returns 1 we
      can reuse the page no matter if it's a pte or a pmd_trans_huge
      triggering the fault, but we can only relocate the page anon_vma to
      the local vma->anon_vma if we're sure it's only this "vma" mapping the
      whole THP physical range.
      
      Kirill A. Shutemov discovered the problem with moving the page
      anon_vma to the local vma->anon_vma in a previous version of this
      patch and another problem in the way page_move_anon_rmap() was called.
      
      Andrew Morton discovered that CONFIG_SWAP=n wouldn't build in a
      previous version, because reuse_swap_page must be a macro to call
      page_trans_huge_mapcount from swap.h, so this uses a macro again
      instead of an inline function. With this change at least it's a less
      dangerous usage than it was before, because "page" is used only once
      now, while with the previous code reuse_swap_page(page++) would have
      called page_mapcount on page+1 and it would have increased page twice
      instead of just once.
      
      Dean Luick noticed an uninitialized variable that could result in a
      rmap inefficiency for the non-THP case in a previous version.
      
      Mike Marciniszyn said:
      
      : Our RDMA tests are seeing an issue with memory locking that bisects to
      : commit 61f5d698 ("mm: re-enable THP")
      :
      : The test program registers two rather large MRs (512M) and RDMA
      : writes data to a passive peer using the first and RDMA reads it back
      : into the second MR and compares that data.  The sizes are chosen randomly
      : between 0 and 1024 bytes.
      :
      : The test will get through a few (<= 4 iterations) and then gets a
      : compare error.
      :
      : Tracing indicates the kernel logical addresses associated with the individual
      : pages at registration ARE correct , the data in the "RDMA read response only"
      : packets ARE correct.
      :
      : The "corruption" occurs when the packet crosse two pages that are not physically
      : contiguous.   The second page reads back as zero in the program.
      :
      : It looks like the user VA at the point of the compare error no longer points to
      : the same physical address as was registered.
      :
      : This patch totally resolves the issue!
      
      Link: http://lkml.kernel.org/r/1462547040-1737-2-git-send-email-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
      Reviewed-by: N"Kirill A. Shutemov" <kirill@shutemov.name>
      Reviewed-by: NDean Luick <dean.luick@intel.com>
      Tested-by: NAlex Williamson <alex.williamson@redhat.com>
      Tested-by: NMike Marciniszyn <mike.marciniszyn@intel.com>
      Tested-by: NJosh Collier <josh.d.collier@intel.com>
      Cc: Marc Haber <mh+linux-kernel@zugschlus.de>
      Cc: <stable@vger.kernel.org>	[4.5]
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6d0a07ed
    • Z
      ksm: fix conflict between mmput and scan_get_next_rmap_item · 7496fea9
      Zhou Chengming 提交于
      A concurrency issue about KSM in the function scan_get_next_rmap_item.
      
      task A (ksmd):				|task B (the mm's task):
      					|
      mm = slot->mm;				|
      down_read(&mm->mmap_sem);		|
      					|
      ...					|
      					|
      spin_lock(&ksm_mmlist_lock);		|
      					|
      ksm_scan.mm_slot go to the next slot;	|
      					|
      spin_unlock(&ksm_mmlist_lock);		|
      					|mmput() ->
      					|	ksm_exit():
      					|
      					|spin_lock(&ksm_mmlist_lock);
      					|if (mm_slot && ksm_scan.mm_slot != mm_slot) {
      					|	if (!mm_slot->rmap_list) {
      					|		easy_to_free = 1;
      					|		...
      					|
      					|if (easy_to_free) {
      					|	mmdrop(mm);
      					|	...
      					|
      					|So this mm_struct may be freed in the mmput().
      					|
      up_read(&mm->mmap_sem);			|
      
      As we can see above, the ksmd thread may access a mm_struct that already
      been freed to the kmem_cache.  Suppose a fork will get this mm_struct from
      the kmem_cache, the ksmd thread then call up_read(&mm->mmap_sem), will
      cause mmap_sem.count to become -1.
      
      As suggested by Andrea Arcangeli, unmerge_and_remove_all_rmap_items has
      the same SMP race condition, so fix it too.  My prev fix in function
      scan_get_next_rmap_item will introduce a different SMP race condition, so
      just invert the up_read/spin_unlock order as Andrea Arcangeli said.
      
      Link: http://lkml.kernel.org/r/1462708815-31301-1-git-send-email-zhouchengming1@huawei.comSigned-off-by: NZhou Chengming <zhouchengming1@huawei.com>
      Suggested-by: NAndrea Arcangeli <aarcange@redhat.com>
      Reviewed-by: NAndrea Arcangeli <aarcange@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Geliang Tang <geliangtang@163.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Hanjun Guo <guohanjun@huawei.com>
      Cc: Ding Tianhong <dingtianhong@huawei.com>
      Cc: Li Bin <huawei.libin@huawei.com>
      Cc: Zhen Lei <thunder.leizhen@huawei.com>
      Cc: Xishi Qiu <qiuxishi@huawei.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7496fea9
    • J
      ocfs2: fix posix_acl_create deadlock · c25a1e06
      Junxiao Bi 提交于
      Commit 702e5bc6 ("ocfs2: use generic posix ACL infrastructure")
      refactored code to use posix_acl_create.  The problem with this function
      is that it is not mindful of the cluster wide inode lock making it
      unsuitable for use with ocfs2 inode creation with ACLs.  For example,
      when used in ocfs2_mknod, this function can cause deadlock as follows.
      The parent dir inode lock is taken when calling posix_acl_create ->
      get_acl -> ocfs2_iop_get_acl which takes the inode lock again.  This can
      cause deadlock if there is a blocked remote lock request waiting for the
      lock to be downconverted.  And same deadlock happened in ocfs2_reflink.
      This fix is to revert back using ocfs2_init_acl.
      
      Fixes: 702e5bc6 ("ocfs2: use generic posix ACL infrastructure")
      Signed-off-by: NTariq Saeed <tariq.x.saeed@oracle.com>
      Signed-off-by: NJunxiao Bi <junxiao.bi@oracle.com>
      Cc: Mark Fasheh <mfasheh@suse.de>
      Cc: Joel Becker <jlbec@evilplan.org>
      Cc: Joseph Qi <joseph.qi@huawei.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c25a1e06
    • J
      ocfs2: revert using ocfs2_acl_chmod to avoid inode cluster lock hang · 5ee0fbd5
      Junxiao Bi 提交于
      Commit 743b5f14 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()")
      introduced this issue.  ocfs2_setattr called by chmod command holds
      cluster wide inode lock when calling posix_acl_chmod.  This latter
      function in turn calls ocfs2_iop_get_acl and ocfs2_iop_set_acl.  These
      two are also called directly from vfs layer for getfacl/setfacl commands
      and therefore acquire the cluster wide inode lock.  If a remote
      conversion request comes after the first inode lock in ocfs2_setattr,
      OCFS2_LOCK_BLOCKED will be set.  And this will cause the second call to
      inode lock from the ocfs2_iop_get_acl() to block indefinetly.
      
      The deleted version of ocfs2_acl_chmod() calls __posix_acl_chmod() which
      does not call back into the filesystem.  Therefore, we restore
      ocfs2_acl_chmod(), modify it slightly for locking as needed, and use that
      instead.
      
      Fixes: 743b5f14 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()")
      Signed-off-by: NTariq Saeed <tariq.x.saeed@oracle.com>
      Signed-off-by: NJunxiao Bi <junxiao.bi@oracle.com>
      Cc: Mark Fasheh <mfasheh@suse.de>
      Cc: Joel Becker <jlbec@evilplan.org>
      Cc: Joseph Qi <joseph.qi@huawei.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5ee0fbd5
    • A
      net: mvneta: bm: fix dependencies again · 2073dbad
      Arnd Bergmann 提交于
      I tried to fix this before, but my previous fix was incomplete
      and we can still get the same link error in randconfig builds
      because of the way that Kconfig treats the
      
      	default y if MVNETA=y && MVNETA_BM_ENABLE
      
      line that does not actually trigger when MVNETA_BM_ENABLE=m,
      unlike I intended.
      Changing the line to use MVNETA_BM_ENABLE!=n however has
      the desired effect and hopefully makes all configurations
      work as expected.
      Signed-off-by: NArnd Bergmann <arnd@arndb.de>
      Fixes: 019ded3a ("net: mvneta: bm: clarify dependencies")
      Acked-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      2073dbad
    • L
      Merge tag 'keys-fixes-20160512' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs · 02c9c0e9
      Linus Torvalds 提交于
      Pull keyring fix from David Howells:
       "Fix ASN.1 indefinite length object parsing"
      
      * tag 'keys-fixes-20160512' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
        KEYS: Fix ASN.1 indefinite length object parsing
      02c9c0e9
    • L
      Merge tag 'sound-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound · e5ad8b6d
      Linus Torvalds 提交于
      Pull sound fixes from Takashi Iwai:
       "This is a pretty boring pull request as you wish: including a few
        small and trivial HD-audio and USB-audio quirks and a couple of small
        regression fixes in HD-audio"
      
      * tag 'sound-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
        ALSA: usb-audio: Yet another Phoneix Audio device quirk
        ALSA: hda - Fix regression on ATI HDMI audio
        ALSA: hda - Fix subwoofer pin on ASUS N751 and N551
        ALSA: hda - Fix broken reconfig
        ALSA: hda - Fix white noise on Asus UX501VW headset
        ALSA: usb-audio: Quirk for yet another Phoenix Audio devices (v2)
      e5ad8b6d
    • L
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input · ed1e33dd
      Linus Torvalds 提交于
      Pull input subsystem fixes from Dmitry Torokhov.
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
        Input: twl6040-vibra - fix DT node memory management
        Input: max8997-haptic - fix NULL pointer dereference
        Input: byd - update copyright header
      ed1e33dd
    • A
      perf stat: Fallback to user only counters when perf_event_paranoid > 1 · 42ef8a78
      Arnaldo Carvalho de Melo 提交于
      After 0161028b ("perf/core: Change the default paranoia level to 2")
      'perf stat' fails for users without CAP_SYS_ADMIN, so just use
      'perf_evsel__fallback()' to have the same behaviour as 'perf record',
      i.e. set perf_event_attr.exclude_kernel to 1.
      
      Now:
      
        [acme@jouet linux]$ perf stat usleep 1
      
         Performance counter stats for 'usleep 1':
      
                0.352536      task-clock:u (msec)  #   0.423 CPUs utilized
                       0      context-switches:u   #   0.000 K/sec
                       0      cpu-migrations:u     #   0.000 K/sec
                      49      page-faults:u        #   0.139 M/sec
                 309,407      cycles:u             #   0.878 GHz
                 243,791      instructions:u       #   0.79  insn per cycle
                  49,622      branches:u           # 140.757 M/sec
                   3,884      branch-misses:u      #   7.83% of all branches
      
             0.000834174 seconds time elapsed
      
        [acme@jouet linux]$
      Reported-by: NIngo Molnar <mingo@kernel.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: David Ahern <dsahern@gmail.com>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Masami Hiramatsu <mhiramat@kernel.org>
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Wang Nan <wangnan0@huawei.com>
      Link: http://lkml.kernel.org/n/tip-b20jmx4dxt5hpaa9t2rroi0o@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      42ef8a78
    • A
      perf evsel: Handle EACCESS + perf_event_paranoid=2 in fallback() · 08094828
      Arnaldo Carvalho de Melo 提交于
      Now with the default for the kernel.perf_event_paranoid sysctl being 2 [1]
      we need to fall back to :u, i.e. to set perf_event_attr.exclude_kernel
      to 1.
      
      Before:
      
        [acme@jouet linux]$ perf record usleep 1
        Error:
        You may not have permission to collect stats.
      
        Consider tweaking /proc/sys/kernel/perf_event_paranoid,
        which controls use of the performance events system by
        unprivileged users (without CAP_SYS_ADMIN).
      
        The current value is 2:
      
          -1: Allow use of (almost) all events by all users
        >= 0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
        >= 1: Disallow CPU event access by users without CAP_SYS_ADMIN
        >= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN
        [acme@jouet linux]$
      
      After:
      
        [acme@jouet linux]$ perf record usleep 1
        [ perf record: Woken up 1 times to write data ]
        [ perf record: Captured and wrote 0.016 MB perf.data (7 samples) ]
        [acme@jouet linux]$ perf evlist
        cycles:u
        [acme@jouet linux]$ perf evlist -v
        cycles:u: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, exclude_kernel: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1
        [acme@jouet linux]$
      
      And if the user turns on verbose mode, an explanation will appear:
      
        [acme@jouet linux]$ perf record -v usleep 1
        Warning:
        kernel.perf_event_paranoid=2, trying to fall back to excluding kernel samples
        mmap size 528384B
        [ perf record: Woken up 1 times to write data ]
        Looking at the vmlinux_path (8 entries long)
        Using /lib/modules/4.6.0-rc7+/build/vmlinux for symbols
        [ perf record: Captured and wrote 0.016 MB perf.data (7 samples) ]
        [acme@jouet linux]$
      
      [1] 0161028b ("perf/core: Change the default paranoia level to 2")
      Reported-by: NIngo Molnar <mingo@kernel.org>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: David Ahern <dsahern@gmail.com>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Masami Hiramatsu <mhiramat@kernel.org>
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Wang Nan <wangnan0@huawei.com>
      Link: http://lkml.kernel.org/n/tip-b20jmx4dxt5hpaa9t2rroi0o@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      08094828