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  1. 15 Jul, 2020 3 commits
    • Amir Goldstein's avatar
      fsnotify: fold fsnotify() call into fsnotify_parent() · c738fbab
      Amir Goldstein authored 
      All (two) callers of fsnotify_parent() also call fsnotify() to notify
the child inode. Move the second fsnotify() call into fsnotify_parent().

This will allow more flexibility in making decisions about which of the
two event falvors should be sent.

Using 'goto notify_child' in the inline helper seems a bit strange, but
it mimics the code in __fsnotify_parent() for clarity and the goto
pattern will become less strage after following patches are applied.

Link: https://lore.kernel.org/r/20200708111156.24659-2-amir73il@gmail.comSigned-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
      c738fbab
    • Mel Gorman's avatar
      fsnotify: Rearrange fast path to minimise overhead when there is no watcher · 71d73410
      Mel Gorman authored 
      The fsnotify paths are trivial to hit even when there are no watchers and
they are surprisingly expensive. For example, every successful vfs_write()
hits fsnotify_modify which calls both fsnotify_parent and fsnotify unless
FMODE_NONOTIFY is set which is an internal flag invisible to userspace.
As it stands, fsnotify_parent is a guaranteed functional call even if there
are no watchers and fsnotify() does a substantial amount of unnecessary
work before it checks if there are any watchers. A perf profile showed
that applying mnt->mnt_fsnotify_mask in fnotify() was almost half of the
total samples taken in that function during a test. This patch rearranges
the fast paths to reduce the amount of work done when there are no
watchers.

The test motivating this was "perf bench sched messaging --pipe". Despite
the fact the pipes are anonymous, fsnotify is still called a lot and
the overhead is noticeable even though it's completely pointless. It's
likely the overhead is negligible for real IO so this is an extreme
example. This is a comparison of hackbench using processes and pipes on
a 1-socket machine with 8 CPU threads without fanotify watchers.

                              5.7.0                  5.7.0
                            vanilla      fastfsnotify-v1r1
Amean     1       0.4837 (   0.00%)      0.4630 *   4.27%*
Amean     3       1.5447 (   0.00%)      1.4557 (   5.76%)
Amean     5       2.6037 (   0.00%)      2.4363 (   6.43%)
Amean     7       3.5987 (   0.00%)      3.4757 (   3.42%)
Amean     12      5.8267 (   0.00%)      5.6983 (   2.20%)
Amean     18      8.4400 (   0.00%)      8.1327 (   3.64%)
Amean     24     11.0187 (   0.00%)     10.0290 *   8.98%*
Amean     30     13.1013 (   0.00%)     12.8510 (   1.91%)
Amean     32     13.9190 (   0.00%)     13.2410 (   4.87%)

                       5.7.0       5.7.0
                     vanilla fastfsnotify-v1r1
Duration User         157.05      152.79
Duration System      1279.98     1219.32
Duration Elapsed      182.81      174.52

This is showing that the latencies are improved by roughly 2-9%. The
variability is not shown but some of these results are within the noise
as this workload heavily overloads the machine. That said, the system CPU
usage is reduced by quite a bit so it makes sense to avoid the overhead
even if it is a bit tricky to detect at times. A perf profile of just 1
group of tasks showed that 5.14% of samples taken were in either fsnotify()
or fsnotify_parent(). With the patch, 2.8% of samples were in fsnotify,
mostly function entry and the initial check for watchers.  The check for
watchers is complicated enough that inlining it may be controversial.

[Amir] Slightly simplify with mnt_or_sb_mask => marks_mask

Link: https://lore.kernel.org/r/20200708111156.24659-1-amir73il@gmail.comSigned-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
      71d73410
    • Jan Kara's avatar
      fanotify: Avoid softlockups when reading many events · 47aaabde
      Jan Kara authored 
      When user provides large buffer for events and there are lots of events
available, we can try to copy them all to userspace without scheduling
which can softlockup the kernel (furthermore exacerbated by the
contention on notification_lock). Add a scheduling point after copying
each event.

Note that usually the real underlying problem is the cost of fanotify
event merging and the resulting contention on notification_lock but this
is a cheap way to somewhat reduce the problem until we can properly
address that.
Reported-by: default avatarFrancesco Ruggeri <fruggeri@arista.com>
Link: https://lore.kernel.org/lkml/20200714025417.A25EB95C0339@us180.sjc.aristanetworks.comReviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
      47aaabde
  3. 08 Jul, 2020 3 commits
    • Randy Dunlap's avatar
      Documentation: update for gcc 4.9 requirement · 0bddd227
      Randy Dunlap authored 
      Update Documentation for the gcc v4.9 upgrade requirement.

Fixes: 5429ef62 ("compiler/gcc: Raise minimum GCC version for kernel builds to 4.8")
Fixes: 6ec4476a ("Raise gcc version requirement to 4.9")
Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Acked-by: default avatarJonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0bddd227
    • Linus Torvalds's avatar
      Merge tag 'sound-5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound · 63e1968a
      Linus Torvalds authored 
      Pull sound fixes from Takashi Iwai:
 "A collection of small, mostly device-specific fixes.

  The significant one is the regression fix for USB-audio implicit
  feedback devices due to the incorrect frame size calculation, which
  landed in 5.8 and stable trees.

  In addition, a few usual HD-audio and USB-audio quirks, Intel HDMI
  fixes, ASoC fsl and rt5682 fixes, as well as the fix in
  compress-offload partial drain operation"

* tag 'sound-5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: compress: fix partial_drain completion state
  ALSA: usb-audio: Add implicit feedback quirk for RTX6001
  ALSA: usb-audio: add quirk for MacroSilicon MS2109
  ALSA: hda/realtek: Enable headset mic of Acer Veriton N4660G with ALC269VC
  ALSA: hda/realtek: Enable headset mic of Acer C20-820 with ALC269VC
  ALSA: hda/realtek - Enable audio jacks of Acer vCopperbox with ALC269VC
  ALSA: hda/realtek - Fix Lenovo Thinkpad X1 Carbon 7th quirk subdevice id
  ALSA: hda/hdmi: improve debug traces for stream lookups
  ALSA: hda/hdmi: fix failures at PCM open on Intel ICL and later
  ALSA: opl3: fix infoleak in opl3
  ALSA: usb-audio: Replace s/frame/packet/ where appropriate
  ALSA: usb-audio: Fix packet size calculation
  AsoC: amd: add missing snd- module prefix to the acp3x-rn driver kernel module
  ALSA: hda - let hs_mic be picked ahead of hp_mic
  ASoC: rt5682: fix the pop noise while OMTP type headset plugin
  ASoC: fsl_mqs: Fix unchecked return value for clk_prepare_enable
  ASoC: fsl_mqs: Don't check clock is NULL before calling clk API
      63e1968a
    • Linus Torvalds's avatar
      Raise gcc version requirement to 4.9 · 6ec4476a
      Linus Torvalds authored 
      I realize that we fairly recently raised it to 4.8, but the fact is, 4.9
is a much better minimum version to target.

We have a number of workarounds for actual bugs in pre-4.9 gcc versions
(including things like internal compiler errors on ARM), but we also
have some syntactic workarounds for lacking features.

In particular, raising the minimum to 4.9 means that we can now just
assume _Generic() exists, which is likely the much better replacement
for a lot of very convoluted built-time magic with conditionals on
sizeof and/or __builtin_choose_expr() with same_type() etc.

Using _Generic also means that you will need to have a very recent
version of 'sparse', but thats easy to build yourself, and much less of
a hassle than some old gcc version can be.

The latest (in a long string) of reasons for minimum compiler version
upgrades was commit 5435f73d ("efi/x86: Fix build with gcc 4").

Ard points out that RHEL 7 uses gcc-4.8, but the people who stay back on
old RHEL versions persumably also don't build their own kernels anyway.
And maybe they should cross-built or just have a little side affair with
a newer compiler?
Acked-by: default avatarArd Biesheuvel <ardb@kernel.org>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6ec4476a
  5. 07 Jul, 2020 17 commits
  7. 06 Jul, 2020 10 commits
  9. 05 Jul, 2020 7 commits
    • Linus Torvalds's avatar
      Linux 5.8-rc4 · dcb7fd82
      Linus Torvalds authored
      dcb7fd82
    • Linus Torvalds's avatar
      x86/ldt: use "pr_info_once()" instead of open-coding it badly · bb5a93aa
      Linus Torvalds authored 
      Using a mutex for "print this warning only once" is so overdesigned as
to be actively offensive to my sensitive stomach.

Just use "pr_info_once()" that already does this, although in a
(harmlessly) racy manner that can in theory cause the message to be
printed twice if more than one CPU races on that "is this the first
time" test.

[ If somebody really cares about that harmless data race (which sounds
  very unlikely indeed), that person can trivially fix printk_once() by
  using a simple atomic access, preferably with an optimistic non-atomic
  test first before even bothering to treat the pointless "make sure it
  is _really_ just once" case.

  A mutex is most definitely never the right primitive to use for
  something like this. ]

Yes, this is a small and meaningless detail in a code path that hardly
matters.  But let's keep some code quality standards here, and not
accept outrageously bad code.

Link: https://lore.kernel.org/lkml/CAHk-=wgV9toS7GU3KmNpj8hCS9SeF+A0voHS8F275_mgLhL4Lw@mail.gmail.com/
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bb5a93aa
    • Linus Torvalds's avatar
      Merge tag 'x86-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 72674d48
      Linus Torvalds authored 
      Pull x86 fixes from Thomas Gleixner:
 "A series of fixes for x86:

   - Reset MXCSR in kernel_fpu_begin() to prevent using a stale user
     space value.

   - Prevent writing MSR_TEST_CTRL on CPUs which are not explicitly
     whitelisted for split lock detection. Some CPUs which do not
     support it crash even when the MSR is written to 0 which is the
     default value.

   - Fix the XEN PV fallout of the entry code rework

   - Fix the 32bit fallout of the entry code rework

   - Add more selftests to ensure that these entry problems don't come
     back.

   - Disable 16 bit segments on XEN PV. It's not supported because XEN
     PV does not implement ESPFIX64"

* tag 'x86-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ldt: Disable 16-bit segments on Xen PV
  x86/entry/32: Fix #MC and #DB wiring on x86_32
  x86/entry/xen: Route #DB correctly on Xen PV
  x86/entry, selftests: Further improve user entry sanity checks
  x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER
  selftests/x86: Consolidate and fix get/set_eflags() helpers
  selftests/x86/syscall_nt: Clear weird flags after each test
  selftests/x86/syscall_nt: Add more flag combinations
  x86/entry/64/compat: Fix Xen PV SYSENTER frame setup
  x86/entry: Move SYSENTER's regs->sp and regs->flags fixups into C
  x86/entry: Assert that syscalls are on the right stack
  x86/split_lock: Don't write MSR_TEST_CTRL on CPUs that aren't whitelisted
  x86/fpu: Reset MXCSR to default in kernel_fpu_begin()
      72674d48
    • Linus Torvalds's avatar
      Merge tag 'irq-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · f23dbe18
      Linus Torvalds authored 
      Pull irq fixes from Thomas Gleixner:
 "A set of interrupt chip driver fixes:

   - Ensure the atomicity of affinity updates in the GIC driver

   - Don't try to sleep in atomic context when waiting for the GICv4.1
     to respond. Use polling instead.

   - Typo fixes in Kconfig and warnings"

* tag 'irq-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic: Atomically update affinity
  irqchip/riscv-intc: Fix a typo in a pr_warn()
  irqchip/gic-v4.1: Use readx_poll_timeout_atomic() to fix sleep in atomic
  irqchip/loongson-pci-msi: Fix a typo in Kconfig
      f23dbe18
    • Linus Torvalds's avatar
      Merge tag 'core-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 5465a324
      Linus Torvalds authored 
      Pull rcu fixlet from Thomas Gleixner:
 "A single fix for a printk format warning in RCU"

* tag 'core-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcuperf: Fix printk format warning
      5465a324
    • Linus Torvalds's avatar
      Merge tag 'kbuild-fixes-v5.8-2' of... · 4bc92736
      Linus Torvalds authored 
      Merge tag 'kbuild-fixes-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes frin Masahiro Yamada:

 - fix various bugs in xconfig

 - fix some issues in cross-compilation using Clang

 - fix documentation

* tag 'kbuild-fixes-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  .gitignore: Do not track `defconfig` from `make savedefconfig`
  kbuild: make Clang build userprogs for target architecture
  kbuild: fix CONFIG_CC_CAN_LINK(_STATIC) for cross-compilation with Clang
  kconfig: qconf: parse newer types at debug info
  kconfig: qconf: navigate menus on hyperlinks
  kconfig: qconf: don't show goback button on splitMode
  kconfig: qconf: simplify the goBack() logic
  kconfig: qconf: re-implement setSelected()
  kconfig: qconf: make debug links work again
  kconfig: qconf: make search fully work again on split mode
  kconfig: qconf: cleanup includes
  docs: kbuild: fix ReST formatting
  gcc-plugins: fix gcc-plugins directory path in documentation
      4bc92736
    • Linus Torvalds's avatar
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 19a61a75
      Linus Torvalds authored 
      Pull SCSI fixes from James Bottomley:
 "Four small fixes in three drivers.

  The mptfusion one has actually caused user visible issues in certain
  kernel configurations"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: mptfusion: Don't use GFP_ATOMIC for larger DMA allocations
  scsi: libfc: Skip additional kref updating work event
  scsi: libfc: Handling of extra kref
  scsi: qla2xxx: Fix a condition in qla2x00_find_all_fabric_devs()
      19a61a75
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