Merge misc fixes from Andrew Morton:
"8 fixes"
* emailed patches from Andrew Morton <[email protected]>:
mm/slub.c: run free_partial() outside of the kmem_cache_node->list_lock
rmap: fix compound check logic in page_remove_file_rmap
mm, rmap: fix false positive VM_BUG() in page_add_file_rmap()
mm/page_alloc.c: recalculate some of node threshold when on/offline memory
mm/page_alloc.c: fix wrong initialization when sysctl_min_unmapped_ratio changes
thp: move shmem_huge_enabled() outside of SYSFS ifdef
revert "ARM: keystone: dts: add psci command definition"
rapidio: dereferencing an error pointer
With debugobjects enabled and using SLAB_DESTROY_BY_RCU, when a
kmem_cache_node is destroyed the call_rcu() may trigger a slab
allocation to fill the debug object pool (__debug_object_init:fill_pool).
Everywhere but during kmem_cache_destroy(), discard_slab() is performed
outside of the kmem_cache_node->list_lock and avoids a lockdep warning
about potential recursion:
=============================================
[ INFO: possible recursive locking detected ]
4.8.0-rc1-gfxbench+ #1 Tainted: G U
---------------------------------------------
rmmod/8895 is trying to acquire lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811c80d7>] get_partial_node.isra.63+0x47/0x430
but task is already holding lock:
(&(&n->list_lock)->rlock){-.-...}, at: [<ffffffff811cbda4>] __kmem_cache_shutdown+0x54/0x320
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(&n->list_lock)->rlock);
lock(&(&n->list_lock)->rlock);
*** DEADLOCK ***
May be due to missing lock nesting notation
5 locks held by rmmod/8895:
#0: (&dev->mutex){......}, at: driver_detach+0x42/0xc0
#1: (&dev->mutex){......}, at: driver_detach+0x50/0xc0
#2: (cpu_hotplug.dep_map){++++++}, at: get_online_cpus+0x2d/0x80
#3: (slab_mutex){+.+.+.}, at: kmem_cache_destroy+0x3c/0x220
#4: (&(&n->list_lock)->rlock){-.-...}, at: __kmem_cache_shutdown+0x54/0x320
stack backtrace:
CPU: 6 PID: 8895 Comm: rmmod Tainted: G U 4.8.0-rc1-gfxbench+ #1
Hardware name: Gigabyte Technology Co., Ltd. H87M-D3H/H87M-D3H, BIOS F11 08/18/2015
Call Trace:
__lock_acquire+0x1646/0x1ad0
lock_acquire+0xb2/0x200
_raw_spin_lock+0x36/0x50
get_partial_node.isra.63+0x47/0x430
___slab_alloc.constprop.67+0x1a7/0x3b0
__slab_alloc.isra.64.constprop.66+0x43/0x80
kmem_cache_alloc+0x236/0x2d0
__debug_object_init+0x2de/0x400
debug_object_activate+0x109/0x1e0
__call_rcu.constprop.63+0x32/0x2f0
call_rcu+0x12/0x20
discard_slab+0x3d/0x40
__kmem_cache_shutdown+0xdb/0x320
shutdown_cache+0x19/0x60
kmem_cache_destroy+0x1ae/0x220
i915_gem_load_cleanup+0x14/0x40 [i915]
i915_driver_unload+0x151/0x180 [i915]
i915_pci_remove+0x14/0x20 [i915]
pci_device_remove+0x34/0xb0
__device_release_driver+0x95/0x140
driver_detach+0xb6/0xc0
bus_remove_driver+0x53/0xd0
driver_unregister+0x27/0x50
pci_unregister_driver+0x25/0x70
i915_exit+0x1a/0x1e2 [i915]
SyS_delete_module+0x193/0x1f0
entry_SYSCALL_64_fastpath+0x1c/0xac
Fixes: 52b4b950b5 ("mm: slab: free kmem_cache_node after destroy sysfs file")
Link: http://lkml.kernel.org/r/[email protected]
Reported-by: Dave Gordon <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
Reviewed-by: Vladimir Davydov <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Dmitry Safonov <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Dave Gordon <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
In page_remove_file_rmap(.) we have the following check:
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
This is meant to check for either HugeTLB pages or THP when a compound
page is passed in.
Unfortunately, if one disables CONFIG_TRANSPARENT_HUGEPAGE, then
PageTransHuge(.) will always return false, provoking BUGs when one runs
the libhugetlbfs test suite.
This patch replaces PageTransHuge(), with PageHead() which will work for
both HugeTLB and THP.
Fixes: dd78fedde4 ("rmap: support file thp")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Steve Capper <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: Huang Shijie <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
PageTransCompound() doesn't distinguish THP from from any other type of
compound pages. This can lead to false-positive VM_BUG_ON() in
page_add_file_rmap() if called on compound page from a driver[1].
I think we can exclude such cases by checking if the page belong to a
mapping.
The VM_BUG_ON_PAGE() is downgraded to VM_WARN_ON_ONCE(). This path
should not cause any harm to non-THP page, but good to know if we step
on anything else.
[1] http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kirill A. Shutemov <[email protected]>
Reported-by: Laura Abbott <[email protected]>
Tested-by: Laura Abbott <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
The newly introduced shmem_huge_enabled() function has two definitions,
but neither of them is visible if CONFIG_SYSFS is disabled, leading to a
build error:
mm/khugepaged.o: In function `khugepaged':
khugepaged.c:(.text.khugepaged+0x3ca): undefined reference to `shmem_huge_enabled'
This changes the #ifdef guards around the definition to match those that
are used in the header file.
Fixes: e496cf3d78 ("thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Original patch: https://lkml.org/lkml/2016/8/4/32
If riocm_ch_alloc() fails then we end up dereferencing the error
pointer.
The problem is that we're not unwinding in the reverse order from how we
allocate things so it gets confusing. I've changed this around so now
"ch" is NULL when we are done with it after we call riocm_put_channel().
That way we can check if it's NULL and avoid calling riocm_put_channel()
on it twice.
I renamed err_nodev to err_put_new_ch so that it better reflects what
the goto does.
Then because we had flipping things around, it means we don't neeed to
initialize the pointers to NULL and we can remove an if statement and
pull things in an indent level.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: Alexandre Bounine <[email protected]>
Cc: Matt Porter <[email protected]>
Cc: Andre van Herk <[email protected]>
Cc: Barry Wood <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
The unit tests crash when hotplug races the previous probe. This race
requires that the loading of the nfit_test module be terminated with
SIGTERM, and the module to be unloaded while the ars scan is still
running.
In contrast to the normal nfit driver, the unit test calls
acpi_nfit_init() twice to simulate hotplug, whereas the nominal case
goes through the acpi_nfit_notify() event handler. The
acpi_nfit_notify() path is careful to flush the previous region
registration before servicing the hotplug event. The unit test was
missing this guarantee.
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff810cdce7>] pwq_activate_delayed_work+0x47/0x170
[..]
Call Trace:
[<ffffffff810ce186>] pwq_dec_nr_in_flight+0x66/0xa0
[<ffffffff810ce490>] process_one_work+0x2d0/0x680
[<ffffffff810ce331>] ? process_one_work+0x171/0x680
[<ffffffff810ce88e>] worker_thread+0x4e/0x480
[<ffffffff810ce840>] ? process_one_work+0x680/0x680
[<ffffffff810ce840>] ? process_one_work+0x680/0x680
[<ffffffff810d5343>] kthread+0xf3/0x110
[<ffffffff8199846f>] ret_from_fork+0x1f/0x40
[<ffffffff810d5250>] ? kthread_create_on_node+0x230/0x230
Cc: <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Even when PCI is disabled, ARCH_HISI selects HISILICON_IRQ_MBIGEN
triggerring the following config warning:
warning: (ARM64 && HISILICON_IRQ_MBIGEN) selects ARM_GIC_V3_ITS which
has unmet direct dependencies (PCI && PCI_MSI)
This patch makes selection of HISILICON_IRQ_MBIGEN conditional on PCI.
Cc: Ma Jun <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Even when PCI is disabled, ARCH_ALPINE selects ALPINE_MSI triggerring
the following config warning:
warning: (ARCH_ALPINE) selects ALPINE_MSI which has unmet direct
dependencies (PCI)
This patch makes selection of ALPINE_MSI conditional on PCI.
Cc: Arnd Bergmann <[email protected]>
Acked-by: Antoine Tenart <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Clearly QEMU is very permissive in how its PL310 model may be set up,
but the real hardware turns out to be far more particular about things
actually being correct. Fix up the DT description so that the real
thing actually boots:
- The arm,data-latency and arm,tag-latency properties need 3 cells to
be valid, otherwise we end up retaining the default 8-cycle latencies
which leads pretty quickly to lockup.
- The arm,dirty-latency property is only relevant to L210/L220, so get
rid of it.
- The cache geometry override also leads to lockup and/or general
misbehaviour. Irritatingly, the manual doesn't state the actual PL310
configuration, but based on the boardfile code and poking registers
from the Boot Monitor, it would seem to be 8 sets of 16KB ways.
With that, we can successfully boot to enjoy the fun of mismatched FPUs...
Cc: [email protected]
Signed-off-by: Robin Murphy <[email protected]>
Tested-by: Mark Rutland <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
c90bb7b enabled the high speed UARTs of the Jetson TK1. Due to a merge
quirk, wrong addresses were introduced. Fix it and use the correct
addresses.
Thierry let me know, that there is another patch (b5896f67ab in
linux-next) in preparation which removes all the '0,' prefixes of unit
addresses on Tegra124 and is planned to go upstream in 4.8, so
this patch will get reverted then.
But for the moment, this patch is necessary to fix current misbehaviour.
Fixes: c90bb7b9b9 ("ARM: tegra: Add high speed UARTs to Jetson TK1 device tree")
Signed-off-by: Ralf Ramsauer <[email protected]>
Acked-by: Thierry Reding <[email protected]>
Cc: [email protected] # v4.7
Cc: [email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
This syscon needs to be looked up by clocks, flash protection
and other consumers.
Signed-off-by: Linus Walleij <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
This syscon needs to be looked up by flash protection, CLCD
display output settings and other consumers.
Signed-off-by: Linus Walleij <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
For unknown reasons, we have to enable three symbols for a platform
to use a reset controller driver, otherwise we get a Kconfig
warning:
warning: (MACH_OX810SE) selects RESET_OXNAS which has unmet direct dependencies (RESET_CONTROLLER)
This selects the other two symbols for oxnas.
Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Neil Armstrong <[email protected]>
The machine specific header files are exported for traditional
platforms, but not for the ones that use ARCH_MULTIPLATFORM, as
they could conflict with one another.
In case of ARM_SINGLE_ARMV7M, we end up also exporting them,
but that appears to be a mistake, and we should treat it the
same way as ARCH_MULTIPLATFORM here.
'make W=1' warns about this because it passes -Wmissing-includes
to gcc and the directories are not actually present.
Signed-off-by: Arnd Bergmann <[email protected]>
Three platforms used to have header files in include/mach that
are now all gone, but the removed directories are still being
included, which leads to -Wmissing-include-dirs warnings.
This removes the extra -I flags.
Signed-off-by: Arnd Bergmann <[email protected]>
Pull btrfs fixes from Chris Mason:
"Some fixes for btrfs send/recv and fsync from Filipe and Robbie Ko.
Bonus points to Filipe for already having xfstests in place for many
of these"
* 'for-linus-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: remove unused function btrfs_add_delayed_qgroup_reserve()
Btrfs: improve performance on fsync against new inode after rename/unlink
Btrfs: be more precise on errors when getting an inode from disk
Btrfs: send, don't bug on inconsistent snapshots
Btrfs: send, avoid incorrect leaf accesses when sending utimes operations
Btrfs: send, fix invalid leaf accesses due to incorrect utimes operations
Btrfs: send, fix warning due to late freeing of orphan_dir_info structures
Btrfs: incremental send, fix premature rmdir operations
Btrfs: incremental send, fix invalid paths for rename operations
Btrfs: send, add missing error check for calls to path_loop()
Btrfs: send, fix failure to move directories with the same name around
Btrfs: add missing check for writeback errors on fsync
A single fix for a boot crash since a commit in the merge window. Metag
was unusual in calling show_mem() early, before setup_per_cpu_pageset(),
which is no longer safe. It doesn't add much value to the log, so the
fix just drops the call.
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Merge tag 'metag-for-v4.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag
Pull metag architecture fix from James Hogan:
"A single fix for a boot crash since a commit in the merge window.
Metag was unusual in calling show_mem() early, before setup_per_cpu_pageset(),
which is no longer safe. It doesn't add much value to the log, so the
fix just drops the call"
* tag 'metag-for-v4.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag:
metag: Drop show_mem() from mem_init()
If get_maintainer is not given any filename arguments on the command line,
the standard input is read for a patch.
But checking if a VCS has a file named &STDIN is not a good idea and fails.
Verify the nominal input file is not &STDIN before checking the VCS.
Fixes: 4cad35a7ca ("get_maintainer.pl: reduce need for command-line option -f")
Reported-by: Christopher Covington <[email protected]>
Signed-off-by: Joe Perches <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
The Memory Protection Keys "rights register" (PKRU) is
XSAVE-managed, and is saved/restored along with the FPU state.
When kernel code accesses FPU regsisters, it does a delicate
dance with preempt. Otherwise, the context switching code can
get confused as to whether the most up-to-date state is in the
registers themselves or in the XSAVE buffer.
But, PKRU is not a normal FPU register. Using it does not
generate the normal device-not-available (#NM) exceptions which
means we can not manage it lazily, and the kernel completley
disallows using lazy mode when it is enabled.
The dance with preempt *only* occurs when managing the FPU
lazily. Since we never manage PKRU lazily, we do not have to do
the dance with preempt; we can access it directly. Doing it
this way saves a ton of complicated code (and is faster too).
Further, the XSAVES reenabling failed to patch a bit of code
in fpu__xfeature_set_state() the checked for compacted buffers.
That check caused fpu__xfeature_set_state() to silently refuse to
work when the kernel is using compacted XSAVE buffers. This
broke execute-only and future pkey_mprotect() support when using
compact XSAVE buffers.
But, removing fpu__xfeature_set_state() gets rid of this issue,
in addition to the nice cleanup and speedup.
This fixes the same thing as a fix that Sai posted:
https://lkml.org/lkml/2016/7/25/637
The fix that he posted is a much more obviously correct, but I
think we should just do this instead.
Reported-by: Sai Praneeth Prakhya <[email protected]>
Signed-off-by: Dave Hansen <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Quentin Casasnovas <[email protected]>
Cc: Ravi Shankar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Yu-Cheng Yu <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Building an X86_64 kernel with W=1 throws a total of 9,948 lines of warnings of
this form for both 32-bit and 64-bit syscall tables. Given that the entire rest
of the build for my config only generates 8,375 lines of output, this is a big
reduction in the warnings generated.
The warnings follow this pattern:
./arch/x86/include/generated/asm/syscalls_32.h:885:21: warning: initialized field overwritten [-Woverride-init]
__SYSCALL_I386(379, compat_sys_pwritev2, )
^
arch/x86/entry/syscall_32.c:13:46: note: in definition of macro '__SYSCALL_I386'
#define __SYSCALL_I386(nr, sym, qual) [nr] = sym,
^~~
./arch/x86/include/generated/asm/syscalls_32.h:885:21: note: (near initialization for 'ia32_sys_call_table[379]')
__SYSCALL_I386(379, compat_sys_pwritev2, )
^
arch/x86/entry/syscall_32.c:13:46: note: in definition of macro '__SYSCALL_I386'
#define __SYSCALL_I386(nr, sym, qual) [nr] = sym,
Since we intentionally build the syscall tables this way, ignore that one
warning in the two files.
Signed-off-by: Valdis Kletnieks <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
There's a subtle preemption race on UP kernels:
Usually current->mm (and therefore mm->pgd) stays the same during the
lifetime of a task so it does not matter if a task gets preempted during
the read and write of the CR3.
But then, there is this scenario on x86-UP:
TaskA is in do_exit() and exit_mm() sets current->mm = NULL followed by:
-> mmput()
-> exit_mmap()
-> tlb_finish_mmu()
-> tlb_flush_mmu()
-> tlb_flush_mmu_tlbonly()
-> tlb_flush()
-> flush_tlb_mm_range()
-> __flush_tlb_up()
-> __flush_tlb()
-> __native_flush_tlb()
At this point current->mm is NULL but current->active_mm still points to
the "old" mm.
Let's preempt taskA _after_ native_read_cr3() by taskB. TaskB has its
own mm so CR3 has changed.
Now preempt back to taskA. TaskA has no ->mm set so it borrows taskB's
mm and so CR3 remains unchanged. Once taskA gets active it continues
where it was interrupted and that means it writes its old CR3 value
back. Everything is fine because userland won't need its memory
anymore.
Now the fun part:
Let's preempt taskA one more time and get back to taskB. This
time switch_mm() won't do a thing because oldmm (->active_mm)
is the same as mm (as per context_switch()). So we remain
with a bad CR3 / PGD and return to userland.
The next thing that happens is handle_mm_fault() with an address for
the execution of its code in userland. handle_mm_fault() realizes that
it has a PTE with proper rights so it returns doing nothing. But the
CPU looks at the wrong PGD and insists that something is wrong and
faults again. And again. And one more time…
This pagefault circle continues until the scheduler gets tired of it and
puts another task on the CPU. It gets little difficult if the task is a
RT task with a high priority. The system will either freeze or it gets
fixed by the software watchdog thread which usually runs at RT-max prio.
But waiting for the watchdog will increase the latency of the RT task
which is no good.
Fix this by disabling preemption across the critical code section.
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Acked-by: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
[ Prettified the changelog. ]
Signed-off-by: Ingo Molnar <[email protected]>
We have some tests that assume we're using std=gnu99, which is fine on
most compilers, but some old compilers use a different default.
So make it explicit that we want to use std=gnu99.
Signed-off-by: Michael Ellerman <[email protected]>
For SKL and later Intel chips, we control the power well per codec
basis via link_power callback since the commit [03b135cebc: ALSA:
hda - remove dependency on i915 power well for SKL].
However, there are a few exceptional cases where the gfx registers are
accessed from the audio driver: namely the wakeup override bit
toggling at (both system and runtime) resume. This seems causing a
kernel warning when accessed during the power well down (and likely
resulting in the bogus register accesses).
This patch puts the proper power up / down sequence around the resume
code so that the wakeup bit is fiddled properly while the power is
up. (The other callback, sync_audio_rate, is used only in the PCM
callback, so it's guaranteed in the power-on.)
Also, by this proper power up/down, the instantaneous flip of wakeup
bit in the resume callback that was introduced by the commit
[033ea349a7: ALSA: hda - Fix Skylake codec timeout] becomes
superfluous, as snd_hdac_display_power() already does it. So we can
clean it up together.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96214
Fixes: 03b135cebc ('ALSA: hda - remove dependency on i915 power well for SKL')
Cc: <[email protected]> # v4.2+
Tested-by: Hans de Goede <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>
When using if_changed, we need to add FORCE as a dependency (see
Documentation/kbuild/makefiles.txt) otherwise we don't get command line
change checking amongst other things. This has resulted in vdsos not
being rebuilt when switching between big and little endian.
The vdso64/32ld commands have to be changed around to avoid pulling
FORCE into the linker command line (code copied from x86).
Signed-off-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
When we introduced the little endian support, we added the endian flags
to CC directly using override. I don't know the history of why we did
that, I suspect no one does.
Although this mostly works, it has one bug, which is that CROSS32CC
doesn't get -mbig-endian. That means when the compiler is little endian
by default and the user is building big endian, vdso32 is incorrectly
compiled as little endian and the kernel fails to build.
Instead we can add the endian flags to cflags-y/aflags-y, and then
append those to KBUILD_CFLAGS/KBUILD_AFLAGS.
This has the advantage of being 1) less ugly, 2) the documented way of
adding flags in the arch Makefile and 3) it fixes building vdso32 with a
LE toolchain.
Signed-off-by: Michael Ellerman <[email protected]>
Ville Syrjälä reports "The first time I run hwclock after rebooting
I get this:
open("/dev/rtc", O_RDONLY) = 3
ioctl(3, PHN_SET_REGS or RTC_UIE_ON, 0) = 0
select(4, [3], NULL, NULL, {10, 0}) = 0 (Timeout)
ioctl(3, PHN_NOT_OH or RTC_UIE_OFF, 0) = 0
close(3) = 0
On all subsequent runs I get this:
open("/dev/rtc", O_RDONLY) = 3
ioctl(3, PHN_SET_REGS or RTC_UIE_ON, 0) = -1 EINVAL (Invalid argument)
ioctl(3, RTC_RD_TIME, 0x7ffd76b3ae70) = -1 EINVAL (Invalid argument)
close(3) = 0"
This was caused by a stupid typo in a patch that should have been
a simple rename to move around contents of a header file, but
accidentally wrote zeroes into the rtc rather than reading from
it:
463a86304c ("char/genrtc: x86: remove remnants of asm/rtc.h")
Reported-by: Ville Syrjälä <[email protected]>
Tested-by: Jarkko Nikula <[email protected]>
Tested-by: Ville Syrjälä <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Cc: Alessandro Zummo <[email protected]>
Cc: Alexandre Belloni <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Fixes: 463a86304c ("char/genrtc: x86: remove remnants of asm/rtc.h")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
When the lock holder vCPU is racing with the queue head:
CPU 0 (lock holder) CPU1 (queue head)
=================== =================
spin_lock(); spin_lock();
pv_kick_node(): pv_wait_head_or_lock():
if (!lp) {
lp = pv_hash(lock, pn);
xchg(&l->locked, _Q_SLOW_VAL);
}
WRITE_ONCE(pn->state, vcpu_halted);
cmpxchg(&pn->state,
vcpu_halted, vcpu_hashed);
WRITE_ONCE(l->locked, _Q_SLOW_VAL);
(void)pv_hash(lock, pn);
In this case, lock holder inserts the pv_node of queue head into the
hash table and set _Q_SLOW_VAL unnecessary. This patch avoids it by
restoring/setting vcpu_hashed state after failing adaptive locking
spinning.
Signed-off-by: Wanpeng Li <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Pan Xinhui <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Waiman Long <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
The following warning can be triggered by hot-unplugging the CPU
on which an active SCHED_DEADLINE task is running on:
WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3531 lock_release+0x690/0x6a0
releasing a pinned lock
Call Trace:
dump_stack+0x99/0xd0
__warn+0xd1/0xf0
? dl_task_timer+0x1a1/0x2b0
warn_slowpath_fmt+0x4f/0x60
? sched_clock+0x13/0x20
lock_release+0x690/0x6a0
? enqueue_pushable_dl_task+0x9b/0xa0
? enqueue_task_dl+0x1ca/0x480
_raw_spin_unlock+0x1f/0x40
dl_task_timer+0x1a1/0x2b0
? push_dl_task.part.31+0x190/0x190
WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3649 lock_unpin_lock+0x181/0x1a0
unpinning an unpinned lock
Call Trace:
dump_stack+0x99/0xd0
__warn+0xd1/0xf0
warn_slowpath_fmt+0x4f/0x60
lock_unpin_lock+0x181/0x1a0
dl_task_timer+0x127/0x2b0
? push_dl_task.part.31+0x190/0x190
As per the comment before this code, its safe to drop the RQ lock
here, and since we (potentially) change rq, unpin and repin to avoid
the splat.
Signed-off-by: Wanpeng Li <[email protected]>
[ Rewrote changelog. ]
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Luca Abeni <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Commit:
6e998916df ("sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistency")
fixed a problem whereby clock_nanosleep() followed by clock_gettime() could
allow a task to wake early. It addressed the problem by calling the scheduling
classes update_curr() when the cputimer starts.
Said change induced a considerable performance regression on the syscalls
times() and clock_gettimes(CLOCK_PROCESS_CPUTIME_ID). There are some
debuggers and applications that monitor their own performance that
accidentally depend on the performance of these specific calls.
This patch mitigates the performace loss by prefetching data in the CPU
cache, as stalls due to cache misses appear to be where most time is spent
in our benchmarks.
Here are the performance gain of this patch over v4.7-rc7 on a Sandy Bridge
box with 32 logical cores and 2 NUMA nodes. The test is repeated with a
variable number of threads, from 2 to 4*num_cpus; the results are in
seconds and correspond to the average of 10 runs; the percentage gain is
computed with (before-after)/before so a positive value is an improvement
(it's faster). The improvement varies between a few percents for 5-20
threads and more than 10% for 2 or >20 threads.
pound_clock_gettime:
threads 4.7-rc7 patched 4.7-rc7
[num] [secs] [secs (percent)]
2 3.48 3.06 ( 11.83%)
5 3.33 3.25 ( 2.40%)
8 3.37 3.26 ( 3.30%)
12 3.32 3.37 ( -1.60%)
21 4.01 3.90 ( 2.74%)
30 3.63 3.36 ( 7.41%)
48 3.71 3.11 ( 16.27%)
79 3.75 3.16 ( 15.74%)
110 3.81 3.25 ( 14.80%)
128 3.88 3.31 ( 14.76%)
pound_times:
threads 4.7-rc7 patched 4.7-rc7
[num] [secs] [secs (percent)]
2 3.65 3.25 ( 11.03%)
5 3.45 3.17 ( 7.92%)
8 3.52 3.22 ( 8.69%)
12 3.29 3.36 ( -2.04%)
21 4.07 3.92 ( 3.78%)
30 3.87 3.40 ( 12.17%)
48 3.79 3.16 ( 16.61%)
79 3.88 3.28 ( 15.42%)
110 3.90 3.38 ( 13.35%)
128 4.00 3.38 ( 15.45%)
pound_clock_gettime and pound_clock_gettime are two benchmarks included in
the MMTests framework. They launch a given number of threads which
repeatedly call times() or clock_gettimes(). The results above can be
reproduced with cloning MMTests from github.com and running the "poundtime"
workload:
$ git clone https://github.com/gormanm/mmtests.git
$ cd mmtests
$ cp configs/config-global-dhp__workload_poundtime config
$ ./run-mmtests.sh --run-monitor $(uname -r)
The above will run "poundtime" measuring the kernel currently running on
the machine; Once a new kernel is installed and the machine rebooted,
running again
$ cd mmtests
$ ./run-mmtests.sh --run-monitor $(uname -r)
will produce results to compare with. A comparison table will be output
with:
$ cd mmtests/work/log
$ ../../compare-kernels.sh
the table will contain a lot of entries; grepping for "Amean" (as in
"arithmetic mean") will give the tables presented above. The source code
for the two benchmarks is reported at the end of this changelog for
clairity.
The cache misses addressed by this patch were found using a combination of
`perf top`, `perf record` and `perf annotate`. The incriminated lines were
found to be
struct sched_entity *curr = cfs_rq->curr;
and
delta_exec = now - curr->exec_start;
in the function update_curr() from kernel/sched/fair.c. This patch
prefetches the data from memory just before update_curr is called in the
interested execution path.
A comparison of the total number of cycles before and after the patch
follows; the data is obtained using `perf stat -r 10 -ddd <program>`
running over the same sequence of number of threads used above (a positive
gain is an improvement):
threads cycles before cycles after gain
2 19,699,563,964 +-1.19% 17,358,917,517 +-1.85% 11.88%
5 47,401,089,566 +-2.96% 45,103,730,829 +-0.97% 4.85%
8 80,923,501,004 +-3.01% 71,419,385,977 +-0.77% 11.74%
12 112,326,485,473 +-0.47% 110,371,524,403 +-0.47% 1.74%
21 193,455,574,299 +-0.72% 180,120,667,904 +-0.36% 6.89%
30 315,073,519,013 +-1.64% 271,222,225,950 +-1.29% 13.92%
48 321,969,515,332 +-1.48% 273,353,977,321 +-1.16% 15.10%
79 337,866,003,422 +-0.97% 289,462,481,538 +-1.05% 14.33%
110 338,712,691,920 +-0.78% 290,574,233,170 +-0.77% 14.21%
128 348,384,794,006 +-0.50% 292,691,648,206 +-0.66% 15.99%
A comparison of cache miss vs total cache loads ratios, before and after
the patch (again from the `perf stat -r 10 -ddd <program>` tables):
threads L1 misses/total*100 L1 misses/total*100 gain
before after
2 7.43 +-4.90% 7.36 +-4.70% 0.94%
5 13.09 +-4.74% 13.52 +-3.73% -3.28%
8 13.79 +-5.61% 12.90 +-3.27% 6.45%
12 11.57 +-2.44% 8.71 +-1.40% 24.72%
21 12.39 +-3.92% 9.97 +-1.84% 19.53%
30 13.91 +-2.53% 11.73 +-2.28% 15.67%
48 13.71 +-1.59% 12.32 +-1.97% 10.14%
79 14.44 +-0.66% 13.40 +-1.06% 7.20%
110 15.86 +-0.50% 14.46 +-0.59% 8.83%
128 16.51 +-0.32% 15.06 +-0.78% 8.78%
As a final note, the following shows the evolution of performance figures
in the "poundtime" benchmark and pinpoints commit 6e998916df
("sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistency") as a
major source of degradation, mostly unaddressed to this day (figures
expressed in seconds).
pound_clock_gettime:
threads parent of 6e998916df 4.7-rc7
6e998916df itself
2 2.23 3.68 ( -64.56%) 3.48 (-55.48%)
5 2.83 3.78 ( -33.42%) 3.33 (-17.43%)
8 2.84 4.31 ( -52.12%) 3.37 (-18.76%)
12 3.09 3.61 ( -16.74%) 3.32 ( -7.17%)
21 3.14 4.63 ( -47.36%) 4.01 (-27.71%)
30 3.28 5.75 ( -75.37%) 3.63 (-10.80%)
48 3.02 6.05 (-100.56%) 3.71 (-22.99%)
79 2.88 6.30 (-118.90%) 3.75 (-30.26%)
110 2.95 6.46 (-119.00%) 3.81 (-29.24%)
128 3.05 6.42 (-110.08%) 3.88 (-27.04%)
pound_times:
threads parent of 6e998916df 4.7-rc7
6e998916df itself
2 2.27 3.73 ( -64.71%) 3.65 (-61.14%)
5 2.78 3.77 ( -35.56%) 3.45 (-23.98%)
8 2.79 4.41 ( -57.71%) 3.52 (-26.05%)
12 3.02 3.56 ( -17.94%) 3.29 ( -9.08%)
21 3.10 4.61 ( -48.74%) 4.07 (-31.34%)
30 3.33 5.75 ( -72.53%) 3.87 (-16.01%)
48 2.96 6.06 (-105.04%) 3.79 (-28.10%)
79 2.88 6.24 (-116.83%) 3.88 (-34.81%)
110 2.98 6.37 (-114.08%) 3.90 (-31.12%)
128 3.10 6.35 (-104.61%) 4.00 (-28.87%)
The source code of the two benchmarks follows. To compile the two:
NR_THREADS=42
for FILE in pound_times pound_clock_gettime; do
gcc -lrt -O2 -lpthread -DNUM_THREADS=$NR_THREADS $FILE.c -o $FILE
done
==== BEGIN pound_times.c ====
struct tms start;
void *pound (void *threadid)
{
struct tms end;
int oldutime = 0;
int utime;
int i;
for (i = 0; i < 5000000 / NUM_THREADS; i++) {
times(&end);
utime = ((int)end.tms_utime - (int)start.tms_utime);
if (oldutime > utime) {
printf("utime decreased, was %d, now %d!\n", oldutime, utime);
}
oldutime = utime;
}
pthread_exit(NULL);
}
int main()
{
pthread_t th[NUM_THREADS];
long i;
times(&start);
for (i = 0; i < NUM_THREADS; i++) {
pthread_create (&th[i], NULL, pound, (void *)i);
}
pthread_exit(NULL);
return 0;
}
==== END pound_times.c ====
==== BEGIN pound_clock_gettime.c ====
void *pound (void *threadid)
{
struct timespec ts;
int rc, i;
unsigned long prev = 0, this = 0;
for (i = 0; i < 5000000 / NUM_THREADS; i++) {
rc = clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts);
if (rc < 0)
perror("clock_gettime");
this = (ts.tv_sec * 1000000000) + ts.tv_nsec;
if (0 && this < prev)
printf("%lu ns timewarp at iteration %d\n", prev - this, i);
prev = this;
}
pthread_exit(NULL);
}
int main()
{
pthread_t th[NUM_THREADS];
long rc, i;
pid_t pgid;
for (i = 0; i < NUM_THREADS; i++) {
rc = pthread_create(&th[i], NULL, pound, (void *)i);
if (rc < 0)
perror("pthread_create");
}
pthread_exit(NULL);
return 0;
}
==== END pound_clock_gettime.c ====
Suggested-by: Mike Galbraith <[email protected]>
Signed-off-by: Giovanni Gherdovich <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stanislaw Gruszka <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Current code in cpudeadline.c has a bug in re-heapifying when adding a
new element at the end of the heap, because a deadline value of 0 is
temporarily set in the new elem, then cpudl_change_key() is called
with the actual elem deadline as param.
However, the function compares the new deadline to set with the one
previously in the elem, which is 0. So, if current absolute deadlines
grew so much to have negative values as s64, the comparison in
cpudl_change_key() makes the wrong decision. Instead, as from
dl_time_before(), the kernel should handle correctly abs deadlines
wrap-arounds.
This patch fixes the problem with a minimally invasive change that
forces cpudl_change_key() to heapify up in this case.
Signed-off-by: Tommaso Cucinotta <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Luca Abeni <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
There's a perf stat bug easy to observer on a machine with only one cgroup:
$ perf stat -e cycles -I 1000 -C 0 -G /
# time counts unit events
1.000161699 <not counted> cycles /
2.000355591 <not counted> cycles /
3.000565154 <not counted> cycles /
4.000951350 <not counted> cycles /
We'd expect some output there.
The underlying problem is that there is an optimization in
perf_cgroup_sched_{in,out}() that skips the switch of cgroup events
if the old and new cgroups in a task switch are the same.
This optimization interacts with the current code in two ways
that cause a CPU context's cgroup (cpuctx->cgrp) to be NULL even if a
cgroup event matches the current task. These are:
1. On creation of the first cgroup event in a CPU: In current code,
cpuctx->cpu is only set in perf_cgroup_sched_in, but due to the
aforesaid optimization, perf_cgroup_sched_in will run until the next
cgroup switches in that CPU. This may happen late or never happen,
depending on system's number of cgroups, CPU load, etc.
2. On deletion of the last cgroup event in a cpuctx: In list_del_event,
cpuctx->cgrp is set NULL. Any new cgroup event will not be sched in
because cpuctx->cgrp == NULL until a cgroup switch occurs and
perf_cgroup_sched_in is executed (updating cpuctx->cgrp).
This patch fixes both problems by setting cpuctx->cgrp in list_add_event,
mirroring what list_del_event does when removing a cgroup event from CPU
context, as introduced in:
commit 68cacd2916 ("perf_events: Fix stale ->cgrp pointer in update_cgrp_time_from_cpuctx()")
With this patch, cpuctx->cgrp is always set/clear when installing/removing
the first/last cgroup event in/from the CPU context. With cpuctx->cgrp
correctly set, event_filter_match works as intended when events are
sched in/out.
After the fix, the output is as expected:
$ perf stat -e cycles -I 1000 -a -G /
# time counts unit events
1.004699159 627342882 cycles /
2.007397156 615272690 cycles /
3.010019057 616726074 cycles /
Signed-off-by: David Carrillo-Cisneros <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vegard Nossum <[email protected]>
Cc: Vince Weaver <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Vegard Nossum reported that perf fuzzing generates a NULL
pointer dereference crash:
> Digging a bit deeper into this, it seems the event itself is getting
> created by perf_event_open() and it gets added to the pmu_event_list
> through:
>
> perf_event_open()
> - perf_event_alloc()
> - account_event()
> - account_pmu_sb_event()
> - attach_sb_event()
>
> so at this point the event is being attached but its ->ctx is still
> NULL. It seems like ->ctx is set just a bit later in
> perf_event_open(), though.
>
> But before that, __schedule() comes along and creates a stack trace
> similar to the one above:
>
> __schedule()
> - __perf_event_task_sched_out()
> - perf_iterate_sb()
> - perf_iterate_sb_cpu()
> - event_filter_match()
> - perf_cgroup_match()
> - __get_cpu_context()
> - (dereference ctx which is NULL)
>
> So I guess the question is... should the event be attached (= put on
> the list) before ->ctx gets set? Or should the cgroup code check for a
> NULL ->ctx?
The latter seems like the simplest solution. Moving the list-add later
creates a bit of a mess.
Reported-by: Vegard Nossum <[email protected]>
Tested-by: Vegard Nossum <[email protected]>
Tested-by: Vince Weaver <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: David Carrillo-Cisneros <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: f2fb6bef92 ("perf/core: Optimize side-band event delivery")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
