| Commit message (Collapse) | Author | Age | Files | Lines |
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change 'infite' to 'infinite'
change 'concurent' to 'concurrent'
change 'memvers' to 'members'
change 'decendants' to 'descendants'
change 'argumets' to 'arguments'
Link: https://lkml.kernel.org/r/20210316112904.10661-1-cxfcosmos@gmail.com
Signed-off-by: Xiaofeng Cao <caoxiaofeng@yulong.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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s/condtions/conditions/
Link: https://lkml.kernel.org/r/20210317032732.3260835-1-unixbhaskar@gmail.com
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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change 'verifing' to 'verifying'
change 'certaint' to 'certain'
change 'approprpiate' to 'appropriate'
Link: https://lkml.kernel.org/r/20210317100129.12440-1-caoxiaofeng@yulong.com
Signed-off-by: Xiaofeng Cao <caoxiaofeng@yulong.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix some spelling mistakes, and modify the order of the parameter comments
to be consistent with the order of the parameters passed to the function.
Link: https://lkml.kernel.org/r/1615636139-4076-1-git-send-email-zhouchuangao@vivo.com
Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "drivers/char: remove /dev/kmem for good".
Exploring /dev/kmem and /dev/mem in the context of memory hot(un)plug and
memory ballooning, I started questioning the existence of /dev/kmem.
Comparing it with the /proc/kcore implementation, it does not seem to be
able to deal with things like
a) Pages unmapped from the direct mapping (e.g., to be used by secretmem)
-> kern_addr_valid(). virt_addr_valid() is not sufficient.
b) Special cases like gart aperture memory that is not to be touched
-> mem_pfn_is_ram()
Unless I am missing something, it's at least broken in some cases and might
fault/crash the machine.
Looks like its existence has been questioned before in 2005 and 2010 [1],
after ~11 additional years, it might make sense to revive the discussion.
CONFIG_DEVKMEM is only enabled in a single defconfig (on purpose or by
mistake?). All distributions disable it: in Ubuntu it has been disabled
for more than 10 years, in Debian since 2.6.31, in Fedora at least
starting with FC3, in RHEL starting with RHEL4, in SUSE starting from
15sp2, and OpenSUSE has it disabled as well.
1) /dev/kmem was popular for rootkits [2] before it got disabled
basically everywhere. Ubuntu documents [3] "There is no modern user of
/dev/kmem any more beyond attackers using it to load kernel rootkits.".
RHEL documents in a BZ [5] "it served no practical purpose other than to
serve as a potential security problem or to enable binary module drivers
to access structures/functions they shouldn't be touching"
2) /proc/kcore is a decent interface to have a controlled way to read
kernel memory for debugging puposes. (will need some extensions to
deal with memory offlining/unplug, memory ballooning, and poisoned
pages, though)
3) It might be useful for corner case debugging [1]. KDB/KGDB might be a
better fit, especially, to write random memory; harder to shoot
yourself into the foot.
4) "Kernel Memory Editor" [4] hasn't seen any updates since 2000 and seems
to be incompatible with 64bit [1]. For educational purposes,
/proc/kcore might be used to monitor value updates -- or older
kernels can be used.
5) It's broken on arm64, and therefore, completely disabled there.
Looks like it's essentially unused and has been replaced by better
suited interfaces for individual tasks (/proc/kcore, KDB/KGDB). Let's
just remove it.
[1] https://lwn.net/Articles/147901/
[2] https://www.linuxjournal.com/article/10505
[3] https://wiki.ubuntu.com/Security/Features#A.2Fdev.2Fkmem_disabled
[4] https://sourceforge.net/projects/kme/
[5] https://bugzilla.redhat.com/show_bug.cgi?id=154796
Link: https://lkml.kernel.org/r/20210324102351.6932-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210324102351.6932-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Alexander A. Klimov" <grandmaster@al2klimov.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Corentin Labbe <clabbe@baylibre.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Gregory Clement <gregory.clement@bootlin.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hillf Danton <hdanton@sina.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: James Troup <james.troup@canonical.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kairui Song <kasong@redhat.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: openrisc@lists.librecores.org
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Pavel Machek (CIP)" <pavel@denx.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Pierre Morel <pmorel@linux.ibm.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Rich Felker <dalias@libc.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: sparclinux@vger.kernel.org
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Theodore Dubois <tblodt@icloud.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: William Cohen <wcohen@redhat.com>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Allow the developer to specifiy the initial value of the modprobe_path[]
string. This can be used to set it to the empty string initially, thus
effectively disabling request_module() during early boot until userspace
writes a new value via the /proc/sys/kernel/modprobe interface. [1]
When building a custom kernel (often for an embedded target), it's normal
to build everything into the kernel that is needed for booting, and indeed
the initramfs often contains no modules at all, so every such
request_module() done before userspace init has mounted the real rootfs is
a waste of time.
This is particularly useful when combined with the previous patch, which
made the initramfs unpacking asynchronous - for that to work, it had to
make any usermodehelper call wait for the unpacking to finish before
attempting to invoke the userspace helper. By eliminating all such
(known-to-be-futile) calls of usermodehelper, the initramfs unpacking and
the {device,late}_initcalls can proceed in parallel for much longer.
For a relatively slow ppc board I'm working on, the two patches combined
lead to 0.2s faster boot - but more importantly, the fact that the
initramfs unpacking proceeds completely in the background while devices
get probed means I get to handle the gpio watchdog in time without getting
reset.
[1] __request_module() already has an early -ENOENT return when
modprobe_path is the empty string.
Link: https://lkml.kernel.org/r/20210313212528.2956377-3-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "background initramfs unpacking, and CONFIG_MODPROBE_PATH", v3.
These two patches are independent, but better-together.
The second is a rather trivial patch that simply allows the developer to
change "/sbin/modprobe" to something else - e.g. the empty string, so
that all request_module() during early boot return -ENOENT early, without
even spawning a usermode helper, needlessly synchronizing with the
initramfs unpacking.
The first patch delegates decompressing the initramfs to a worker thread,
allowing do_initcalls() in main.c to proceed to the device_ and late_
initcalls without waiting for that decompression (and populating of
rootfs) to finish. Obviously, some of those later calls may rely on the
initramfs being available, so I've added synchronization points in the
firmware loader and usermodehelper paths - there might be other places
that would need this, but so far no one has been able to think of any
places I have missed.
There's not much to win if most of the functionality needed during boot is
only available as modules. But systems with a custom-made .config and
initramfs can boot faster, partly due to utilizing more than one cpu
earlier, partly by avoiding known-futile modprobe calls (which would still
trigger synchronization with the initramfs unpacking, thus eliminating
most of the first benefit).
This patch (of 2):
Most of the boot process doesn't actually need anything from the
initramfs, until of course PID1 is to be executed. So instead of doing
the decompressing and populating of the initramfs synchronously in
populate_rootfs() itself, push that off to a worker thread.
This is primarily motivated by an embedded ppc target, where unpacking
even the rather modest sized initramfs takes 0.6 seconds, which is long
enough that the external watchdog becomes unhappy that it doesn't get
attention soon enough. By doing the initramfs decompression in a worker
thread, we get to do the device_initcalls and hence start petting the
watchdog much sooner.
Normal desktops might benefit as well. On my mostly stock Ubuntu kernel,
my initramfs is a 26M xz-compressed blob, decompressing to around 126M.
That takes almost two seconds:
[ 0.201454] Trying to unpack rootfs image as initramfs...
[ 1.976633] Freeing initrd memory: 29416K
Before this patch, these lines occur consecutively in dmesg. With this
patch, the timestamps on these two lines is roughly the same as above, but
with 172 lines inbetween - so more than one cpu has been kept busy doing
work that would otherwise only happen after the populate_rootfs()
finished.
Should one of the initcalls done after rootfs_initcall time (i.e., device_
and late_ initcalls) need something from the initramfs (say, a kernel
module or a firmware blob), it will simply wait for the initramfs
unpacking to be done before proceeding, which should in theory make this
completely safe.
But if some driver pokes around in the filesystem directly and not via one
of the official kernel interfaces (i.e. request_firmware*(),
call_usermodehelper*) that theory may not hold - also, I certainly might
have missed a spot when sprinkling wait_for_initramfs(). So there is an
escape hatch in the form of an initramfs_async= command line parameter.
Link: https://lkml.kernel.org/r/20210313212528.2956377-1-linux@rasmusvillemoes.dk
Link: https://lkml.kernel.org/r/20210313212528.2956377-2-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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No callers in the tree.
Link: https://lkml.kernel.org/r/20210309151723.1907838-2-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It's currently nigh impossible to get these pr_debug()s to print
something. Being guarded by initcall_debug means one has to enable tons
of other debug output during boot, and the system_state condition further
means it's impossible to get them when loading modules later.
Also, the compiler can't know that these global conditions do not change,
so there are W=2 warnings
kernel/async.c:125:9: warning: `calltime' may be used uninitialized in this function [-Wmaybe-uninitialized]
kernel/async.c:300:9: warning: `starttime' may be used uninitialized in this function [-Wmaybe-uninitialized]
Make it possible, for a DYNAMIC_DEBUG kernel, to get these to print their
messages by booting with appropriate 'dyndbg="file async.c +p"' command
line argument. For a non-DYNAMIC_DEBUG kernel, pr_debug() compiles to
nothing.
This does cost doing an unconditional ktime_get() for the starttime value,
but the corresponding ktime_get for the end time can be elided by
factoring it into a function which only gets called if the printk()
arguments end up being evaluated.
Link: https://lkml.kernel.org/r/20210309151723.1907838-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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request_free_mem_region() is used to find an empty range of physical
addresses for hotplugging ZONE_DEVICE memory. It does this by iterating
over the range of possible addresses using region_intersects() to see if
the range is free before calling request_mem_region() to allocate the
region.
However the resource_lock is dropped between these two calls meaning by
the time request_mem_region() is called in request_free_mem_region()
another thread may have already reserved the requested region. This
results in unexpected failures and a message in the kernel log from
hitting this condition:
/*
* mm/hmm.c reserves physical addresses which then
* become unavailable to other users. Conflicts are
* not expected. Warn to aid debugging if encountered.
*/
if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) {
pr_warn("Unaddressable device %s %pR conflicts with %pR",
conflict->name, conflict, res);
These unexpected failures can be corrected by holding resource_lock across
the two calls. This also requires memory allocation to be performed prior
to taking the lock.
Link: https://lkml.kernel.org/r/20210419070109.4780-3-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Muchun Song <smuchun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Refactor the portion of __request_region() done whilst holding the
resource_lock into a separate function to allow callers to hold the lock.
Link: https://lkml.kernel.org/r/20210419070109.4780-2-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Muchun Song <smuchun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Introduce a version of region_intersects() that can be called with the
resource_lock already held.
This will be used in a future fix to __request_free_mem_region().
[akpm@linux-foundation.org: make __region_intersects static]
Link: https://lkml.kernel.org/r/20210419070109.4780-1-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Muchun Song <smuchun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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All functions that search for IORESOURCE_SYSTEM_RAM or IORESOURCE_MEM
resources now properly consider the whole resource tree, not just the
first level. Let's drop the unused first_lvl / siblings_only logic.
Remove documentation that indicates that some functions behave differently,
all consider the full resource tree now.
Link: https://lkml.kernel.org/r/20210325115326.7826-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It used to be true that we can have system RAM (IORESOURCE_SYSTEM_RAM |
IORESOURCE_BUSY) only on the first level in the resource tree. However,
this is no longer holds for driver-managed system RAM (i.e., added via
dax/kmem and virtio-mem), which gets added on lower levels, for example,
inside device containers.
IORESOURCE_SYSTEM_RAM is defined as IORESOURCE_MEM | IORESOURCE_SYSRAM and
just a special type of IORESOURCE_MEM.
The function walk_mem_res() only considers the first level and is used in
arch/x86/mm/ioremap.c:__ioremap_check_mem() only. We currently fail to
identify System RAM added by dax/kmem and virtio-mem as
"IORES_MAP_SYSTEM_RAM", for example, allowing for remapping of such
"normal RAM" in __ioremap_caller().
Let's find all IORESOURCE_MEM | IORESOURCE_BUSY resources, making the
function behave similar to walk_system_ram_res().
Link: https://lkml.kernel.org/r/20210325115326.7826-3-david@redhat.com
Fixes: ebf71552bb0e ("virtio-mem: Add parent resource for all added "System RAM"")
Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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IORESOURCE_SYSTEM_RAM resources
Patch series "kernel/resource: make walk_system_ram_res() and walk_mem_res() search the whole tree", v2.
Playing with kdump+virtio-mem I noticed that kexec_file_load() does not
consider System RAM added via dax/kmem and virtio-mem when preparing the
elf header for kdump. Looking into the details, the logic used in
walk_system_ram_res() and walk_mem_res() seems to be outdated.
walk_system_ram_range() already does the right thing, let's change
walk_system_ram_res() and walk_mem_res(), and clean up.
Loading a kdump kernel via "kexec -p -s" ... will result in the kdump
kernel to also dump dax/kmem and virtio-mem added System RAM now.
Note: kexec-tools on x86-64 also have to be updated to consider this
memory in the kexec_load() case when processing /proc/iomem.
This patch (of 3):
It used to be true that we can have system RAM (IORESOURCE_SYSTEM_RAM |
IORESOURCE_BUSY) only on the first level in the resource tree. However,
this is no longer holds for driver-managed system RAM (i.e., added via
dax/kmem and virtio-mem), which gets added on lower levels, for example,
inside device containers.
We have two users of walk_system_ram_res(), which currently only
consideres the first level:
a) kernel/kexec_file.c:kexec_walk_resources() -- We properly skip
IORESOURCE_SYSRAM_DRIVER_MANAGED resources via
locate_mem_hole_callback(), so even after this change, we won't be
placing kexec images onto dax/kmem and virtio-mem added memory. No
change.
b) arch/x86/kernel/crash.c:fill_up_crash_elf_data() -- we're currently
not adding relevant ranges to the crash elf header, resulting in them
not getting dumped via kdump.
This change fixes loading a crashkernel via kexec_file_load() and
including dax/kmem and virtio-mem added System RAM in the crashdump on
x86-64. Note that e.g,, arm64 relies on memblock data and, therefore,
always considers all added System RAM already.
Let's find all IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY resources, making
the function behave like walk_system_ram_range().
Link: https://lkml.kernel.org/r/20210325115326.7826-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210325115326.7826-2-david@redhat.com
Fixes: ebf71552bb0e ("virtio-mem: Add parent resource for all added "System RAM"")
Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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LLVM changed the expected function signatures for llvm_gcda_start_file()
and llvm_gcda_emit_function() in the clang-11 release. Drop the older
implementations and require folks to upgrade their compiler if they're
interested in GCOV support.
Link: https://reviews.llvm.org/rGcdd683b516d147925212724b09ec6fb792a40041
Link: https://reviews.llvm.org/rG13a633b438b6500ecad9e4f936ebadf3411d0f44
Link: https://lkml.kernel.org/r/20210312224132.3413602-3-ndesaulniers@google.com
Link: https://lkml.kernel.org/r/20210413183113.2977432-1-ndesaulniers@google.com
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>
Cc: Prasad Sodagudi <psodagud@quicinc.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Using vmalloc() in gcov is really quite wasteful, many of the objects
allocated are really small (e.g. I've seen 24 bytes.) Use kvmalloc() to
automatically pick the better of kmalloc() or vmalloc() depending on the
size.
[johannes.berg@intel.com: fix clang-11+ build]
Link: https://lkml.kernel.org/r/20210412214210.6e1ecca9cdc5.I24459763acf0591d5e6b31c7e3a59890d802f79c@changeid
Link: https://lkml.kernel.org/r/20210315235453.799e7a9d627d.I741d0db096c6f312910f7f1bcdfde0fda20801a4@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Use just a single vmalloc() with struct_size() instead of a separate
kmalloc() for the iter struct.
Link: https://lkml.kernel.org/r/20210315235453.b6de4a92096e.Iac40a5166589cefbff8449e466bd1b38ea7a17af@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There's a lot of duplicated code between gcc and clang implementations,
move it over to fs.c to simplify the code, there's no reason to believe
that for small data like this one would not just implement the simple
convert_to_gcda() function.
Link: https://lkml.kernel.org/r/20210315235453.e3fbb86e99a0.I08a3ee6dbe47ea3e8024956083f162884a958e40@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before machine_restart(),
machine_halt(), and machine_power_off(). The only one that is missing
is machine_kexec().
The dmesg output that it contains can be used to study the shutdown
performance of both kernel and systemd during kexec reboot.
Here is example of dmesg data collected after kexec:
root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail
...
[ 70.914592] psci: CPU3 killed (polled 0 ms)
[ 70.915705] CPU4: shutdown
[ 70.916643] psci: CPU4 killed (polled 4 ms)
[ 70.917715] CPU5: shutdown
[ 70.918725] psci: CPU5 killed (polled 0 ms)
[ 70.919704] CPU6: shutdown
[ 70.920726] psci: CPU6 killed (polled 4 ms)
[ 70.921642] CPU7: shutdown
[ 70.922650] psci: CPU7 killed (polled 0 ms)
Link: https://lkml.kernel.org/r/20210319192326.146000-2-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: James Morris <jmorris@namei.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When vzalloc() returns NULL to sha_regions, no error return code of
kexec_calculate_store_digests() is assigned. To fix this bug, ret is
assigned with -ENOMEM in this case.
Link: https://lkml.kernel.org/r/20210309083904.24321-1-baijiaju1990@gmail.com
Fixes: a43cac0d9dc2 ("kexec: split kexec_file syscall code to kexec_file.c")
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The purpose is to notify the kernel module for fast reboot.
Upstream a patch from the SONiC network operating system [1].
[1]: https://github.com/Azure/sonic-linux-kernel/pull/46
Link: https://lkml.kernel.org/r/20210304124626.13927-1-pmenzel@molgen.mpg.de
Signed-off-by: Joe LeVeque <jolevequ@microsoft.com>
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Guohan Lu <lguohan@gmail.com>
Cc: Joe LeVeque <jolevequ@microsoft.com>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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change 'ancestoral' to 'ancestral'
change 'reuseable' to 'reusable'
delete 'do' grammatically
Link: https://lkml.kernel.org/r/20210317082031.11692-1-caoxiaofeng@yulong.com
Signed-off-by: Xiaofeng Cao <caoxiaofeng@yulong.com>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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All this can happen without a single goto.
Link: https://lkml.kernel.org/r/2072685.XptgVkyDqn@devpool47
Signed-off-by: Rolf Eike Beer <eb@emlix.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a special-case when waiting on a pid (via waitpid, waitid, wait4, etc)
to avoid doing an O(n) scan of children and tracees, and instead do an
O(1) lookup. This improves performance when waiting on a pid from a
thread group with many children and/or tracees.
Time to fork and then call waitpid on the child, from a task that already
has N children [1]:
N | Before | After
-----|---------|------
1 | 74 us | 74 us
20 | 72 us | 75 us
100 | 83 us | 77 us
500 | 99 us | 74 us
1000 | 179 us | 75 us
5000 | 804 us | 79 us
8000 | 1268 us | 78 us
[1]: https://lkml.org/lkml/2021/3/12/1567
This can make a substantial performance improvement for applications with
a thread that has many children or tracees and frequently needs to wait on
them. Tools that use ptrace to intercept syscalls for a large number of
processes are likely to fall into this category. In particular this patch
was developed while building a ptrace-based second generation of the
Shadow emulator [2], for which it allows us to avoid quadratic scaling
(without having to use a workaround that introduces a ~40% performance
penalty) [3]. Other examples of tools that fall into this category which
this patch may help include User Mode Linux [4] and DetTrace [5].
[2]: https://shadow.github.io/
[3]: https://github.com/shadow/shadow/issues/1134#issuecomment-798992292
[4]: https://en.wikipedia.org/wiki/User-mode_Linux
[5]: https://github.com/dettrace/dettrace
Link: https://lkml.kernel.org/r/20210314231544.9379-1-jnewsome@torproject.org
Signed-off-by: James Newsome <jnewsome@torproject.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Christian Brauner <christian@brauner.io>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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init_groups is declared in both cred.h and init_task.h, but it is not
actually referenced anywhere outside of cred.c where it is defined. So
make it static and remove the declarations.
Link: https://lkml.kernel.org/r/20210310220102.2484201-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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An async_func_t returns void - any errors encountered it has to stash
somewhere for consumers to discover later.
Link: https://lkml.kernel.org/r/20210226124355.2503524-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The sysctl_compact_memory is mostly unused in mm/compaction.c It just
acts as a place holder for sysctl to store .data.
But the .data itself is not needed here.
So we can get ride of this variable completely and make .data as NULL.
This will also eliminate the extern declaration from header file. No
functionality is broken or changed this way.
Link: https://lkml.kernel.org/r/1614852224-14671-1-git-send-email-pintu@codeaurora.org
Signed-off-by: Pintu Kumar <pintu@codeaurora.org>
Signed-off-by: Pintu Agarwal <pintu.ping@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add the irq_work_queue() call stack into the KASAN auxiliary stack in
order to improve KASAN reports. this will let us know where the irq work
be queued.
Link: https://lkml.kernel.org/r/20210331063202.28770-1-qiang.zhang@windriver.com
Signed-off-by: Zqiang <qiang.zhang@windriver.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Walter Wu <walter-zh.wu@mediatek.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Why record task_work_add() call stack? Syzbot reports many use-after-free
issues for task_work, see [1]. After seeing the free stack and the
current auxiliary stack, we think they are useless, we don't know where
the work was registered. This work may be the free call stack, so we miss
the root cause and don't solve the use-after-free.
Add the task_work_add() call stack into the KASAN auxiliary stack in order
to improve KASAN reports. It helps programmers solve use-after-free
issues.
[1]: https://groups.google.com/g/syzkaller-bugs/search?q=kasan%20use-after-free%20task_work_run
Link: https://lkml.kernel.org/r/20210316024410.19967-1-walter-zh.wu@mediatek.com
Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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vunmap will remove ptes.
Link: https://lkml.kernel.org/r/20210322021806.892164-3-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Cédric Le Goater <clg@kaod.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Current users of the rstat code can source root-level statistics from
the native counters of their respective subsystem, allowing them to
forego aggregation at the root level. This optimization is currently
implemented inside the generic rstat code, which doesn't track the root
cgroup and doesn't invoke the subsystem flush callbacks on it.
However, the memory controller cannot do this optimization, because
cgroup1 breaks out memory specifically for the local level, including at
the root level. In preparation for the memory controller switching to
rstat, move the optimization from rstat core to the controllers.
Afterwards, rstat will always track the root cgroup for changes and
invoke the subsystem callbacks on it; and it's up to the subsystem to
special-case and skip aggregation of the root cgroup if it can source
this information through other, cheaper means.
This is the case for the io controller and the cgroup base stats. In
their respective flush callbacks, check whether the parent is the root
cgroup, and if so, skip the unnecessary upward propagation.
The extra cost of tracking the root cgroup is negligible: on stat
changes, we actually remove a branch that checks for the root. The
queueing for a flush touches only per-cpu data, and only the first stat
change since a flush requires a (per-cpu) lock.
Link: https://lkml.kernel.org/r/20210209163304.77088-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Rstat currently only supports the default hierarchy in cgroup2. In
order to replace memcg's private stats infrastructure - used in both
cgroup1 and cgroup2 - with rstat, the latter needs to support cgroup1.
The initialization and destruction callbacks for regular cgroups are
already in place. Remove the cgroup_on_dfl() guards to handle cgroup1.
The initialization of the root cgroup is currently hardcoded to only
handle cgrp_dfl_root.cgrp. Move those callbacks to cgroup_setup_root()
and cgroup_destroy_root() to handle the default root as well as the
various cgroup1 roots we may set up during mounting.
The linking of css to cgroups happens in code shared between cgroup1 and
cgroup2 as well. Simply remove the cgroup_on_dfl() guard.
Linkage of the root css to the root cgroup is a bit trickier: per
default, the root css of a subsystem controller belongs to the default
hierarchy (i.e. the cgroup2 root). When a controller is mounted in its
cgroup1 version, the root css is stolen and moved to the cgroup1 root;
on unmount, the css moves back to the default hierarchy. Annotate
rebind_subsystems() to move the root css linkage along between roots.
Link: https://lkml.kernel.org/r/20210209163304.77088-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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For simplification commit 991e7673859e ("mm: memcontrol: account kernel
stack per node") changed the per zone vmalloc backed stack pages
accounting to per node.
By doing that we have lost a certain precision because those pages might
live in different NUMA nodes. In the end NR_KERNEL_STACK_KB exported to
the userspace might be over estimated on some nodes while underestimated
on others. But this is not a real world problem, just a problem found
by reading the code. So there is no actual data to showing how much
impact it has on users.
This doesn't impose any real problem to correctnes of the kernel
behavior as the counter is not used for any internal processing but it
can cause some confusion to the userspace.
Address the problem by accounting each vmalloc backing page to its own
node.
Link: https://lkml.kernel.org/r/20210303151843.81156-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit d6ad3e286d2c ("softlockup: Add sched_clock_tick() to avoid kernel
warning on kgdb resume") introduced touch_softlockup_watchdog_sync().
It solved a problem when the watchdog was touched in an atomic context,
the timer callback was proceed right after releasing interrupts, and the
local clock has not been updated yet. In this case, sched_clock_tick()
was called in watchdog_timer_fn() before updating the timer.
So far so good.
Later commit 5d1c0f4a80a6 ("watchdog: add check for suspended vm in
softlockup detector") added two kvm_check_and_clear_guest_paused()
calls. They touch the watchdog when the guest has been sleeping.
The code makes my head spin around.
Scenario 1:
+ guest did sleep:
+ PVCLOCK_GUEST_STOPPED is set
+ 1st watchdog_timer_fn() invocation:
+ the watchdog is not touched yet
+ is_softlockup() returns too big delay
+ kvm_check_and_clear_guest_paused():
+ clear PVCLOCK_GUEST_STOPPED
+ call touch_softlockup_watchdog_sync()
+ set SOFTLOCKUP_DELAY_REPORT
+ set softlockup_touch_sync
+ return from the timer callback
+ 2nd watchdog_timer_fn() invocation:
+ call sched_clock_tick() even though it is not needed.
The timer callback was invoked again only because the clock
has already been updated in the meantime.
+ call kvm_check_and_clear_guest_paused() that does nothing
because PVCLOCK_GUEST_STOPPED has been cleared already.
+ call update_report_ts() and return. This is fine. Except
that sched_clock_tick() might allow to set it already
during the 1st invocation.
Scenario 2:
+ guest did sleep
+ 1st watchdog_timer_fn() invocation
+ same as in 1st scenario
+ guest did sleep again:
+ set PVCLOCK_GUEST_STOPPED again
+ 2nd watchdog_timer_fn() invocation
+ SOFTLOCKUP_DELAY_REPORT is set from 1st invocation
+ call sched_clock_tick()
+ call kvm_check_and_clear_guest_paused()
+ clear PVCLOCK_GUEST_STOPPED
+ call touch_softlockup_watchdog_sync()
+ set SOFTLOCKUP_DELAY_REPORT
+ set softlockup_touch_sync
+ call update_report_ts() (set real timestamp immediately)
+ return from the timer callback
+ 3rd watchdog_timer_fn() invocation
+ timestamp is set from 2nd invocation
+ softlockup_touch_sync is set but not checked because
the real timestamp is already set
Make the code more straightforward:
1. Always call kvm_check_and_clear_guest_paused() at the very
beginning to handle PVCLOCK_GUEST_STOPPED. It touches the watchdog
when the quest did sleep.
2. Handle the situation when the watchdog has been touched
(SOFTLOCKUP_DELAY_REPORT is set).
Call sched_clock_tick() when touch_*sync() variant was used. It makes
sure that the timestamp will be up to date even when it has been
touched in atomic context or quest did sleep.
As a result, kvm_check_and_clear_guest_paused() is called on a single
location. And the right timestamp is always set when returning from the
timer callback.
Link: https://lkml.kernel.org/r/20210311122130.6788-7-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Any parallel softlockup reports are skipped when one CPU is already
printing backtraces from all CPUs.
The exclusive rights are synchronized using one bit in
soft_lockup_nmi_warn. There is also one memory barrier that does not make
much sense.
Use two barriers on the right location to prevent mixing two reports.
[pmladek@suse.com: use bit lock operations to prevent multiple soft-lockup reports]
Link: https://lkml.kernel.org/r/YFSVsLGVWMXTvlbk@alley
Link: https://lkml.kernel.org/r/20210311122130.6788-6-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The softlockup detector does some gymnastic with the variable
soft_watchdog_warn. It was added by the commit 58687acba59266735ad
("lockup_detector: Combine nmi_watchdog and softlockup detector").
The purpose is not completely clear. There are the following clues. They
describe the situation how it looked after the above mentioned commit:
1. The variable was checked with a comment "only warn once".
2. The variable was set when softlockup was reported. It was cleared
only when the CPU was not longer in the softlockup state.
3. watchdog_touch_ts was not explicitly updated when the softlockup
was reported. Without this variable, the report would normally
be printed again during every following watchdog_timer_fn()
invocation.
The logic has got even more tangled up by the commit ed235875e2ca98
("kernel/watchdog.c: print traces for all cpus on lockup detection").
After this commit, soft_watchdog_warn is set only when
softlockup_all_cpu_backtrace is enabled. But multiple reports from all
CPUs are prevented by a new variable soft_lockup_nmi_warn.
Conclusion:
The variable probably never worked as intended. In each case, it has not
worked last many years because the softlockup was reported repeatedly
after the full period defined by watchdog_thresh.
The reason is that watchdog gets touched in many known slow paths, for
example, in printk_stack_address(). This code is called also when
printing the softlockup report. It means that the watchdog timestamp gets
updated after each report.
Solution:
Simply remove the logic. People want the periodic report anyway.
Link: https://lkml.kernel.org/r/20210311122130.6788-5-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The softlockup detector currently shows the time spent since the last
report. As a result it is not clear whether a CPU is infinitely hogged by
a single task or if it is a repeated event.
The situation can be simulated with a simply busy loop:
while (true)
cpu_relax();
The softlockup detector produces:
[ 168.277520] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865]
[ 196.277604] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865]
[ 236.277522] watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [cat:4865]
But it should be, something like:
[ 480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943]
[ 508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943]
[ 548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943]
[ 576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943]
For the better output, add an additional timestamp of the last report.
Only this timestamp is reset when the watchdog is intentionally touched
from slow code paths or when printing the report.
Link: https://lkml.kernel.org/r/20210311122130.6788-4-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The softlockup situation might stay for a long time or even forever. When
it happens, the softlockup debug messages are printed in regular intervals
defined by get_softlockup_thresh().
There is a mystery. The repeated message is printed after the full
interval that is defined by get_softlockup_thresh(). But the timer
callback is called more often as defined by sample_period. The code looks
like the soflockup should get reported in every sample_period when it was
once behind the thresh.
It works only by chance. The watchdog is touched when printing the stall
report, for example, in printk_stack_address().
Make the behavior clear and predictable by explicitly updating the
timestamp in watchdog_timer_fn() when the report gets printed.
Link: https://lkml.kernel.org/r/20210311122130.6788-3-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "watchdog/softlockup: Report overall time and some cleanup", v2.
I dug deep into the softlockup watchdog history when time permitted this
year. And reworked the patchset that fixed timestamps and cleaned up the
code[2].
I split it into very small steps and did even more code clean up. The
result looks quite strightforward and I am pretty confident with the
changes.
[1] v2: https://lore.kernel.org/r/20201210160038.31441-1-pmladek@suse.com
[2] v1: https://lore.kernel.org/r/20191024114928.15377-1-pmladek@suse.com
This patch (of 6):
There are many touch_*watchdog() functions. They are called in situations
where the watchdog could report false positives or create unnecessary
noise. For example, when CPU is entering idle mode, a virtual machine is
stopped, or a lot of messages are printed in the atomic context.
These functions set SOFTLOCKUP_RESET instead of a real timestamp. It
allows to call them even in a context where jiffies might be outdated.
For example, in an atomic context.
The real timestamp is set by __touch_watchdog() that is called from the
watchdog timer callback.
Rename this callback to update_touch_ts(). It better describes the effect
and clearly distinguish is from the other touch_*watchdog() functions.
Another motivation is that two timestamps are going to be used. One will
be used for the total softlockup time. The other will be used to measure
time since the last report. The new function name will help to
distinguish which timestamp is being updated.
Link: https://lkml.kernel.org/r/20210311122130.6788-1-pmladek@suse.com
Link: https://lkml.kernel.org/r/20210311122130.6788-2-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kconfig updates from Masahiro Yamada:
- Change 'option defconfig' to the environment variable
KCONFIG_DEFCONFIG_LIST
- Refactor tinyconfig without using allnoconfig_y
- Remove 'option allnoconfig_y' syntax
- Change 'option modules' to 'modules'
- Do not use /boot/config-* etc. as base config for cross-compilation
- Fix a search bug in nconf
- Various code cleanups
* tag 'kconfig-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
kconfig: refactor .gitignore
kconfig: highlight xconfig 'comment' lines with '***'
kconfig: highlight gconfig 'comment' lines with '***'
kconfig: gconf: remove unused code
kconfig: remove unused PACKAGE definition
kconfig: nconf: stop endless search loops
kconfig: split menu.c out of parser.y
kconfig: nconf: refactor in print_in_middle()
kconfig: nconf: remove meaningless wattrset() call from show_menu()
kconfig: nconf: change set_config_filename() to void function
kconfig: nconf: refactor attributes setup code
kconfig: nconf: remove unneeded default for menu prompt
kconfig: nconf: get rid of (void) casts from wattrset() calls
kconfig: nconf: fix NORMAL attributes
kconfig: mconf,nconf: remove unneeded '\0' termination after snprintf()
kconfig: use /boot/config-* etc. as DEFCONFIG_LIST only for native build
kconfig: change sym_change_count to a boolean flag
kconfig: nconf: fix core dump when searching in empty menu
kconfig: lxdialog: A spello fix and a punctuation added
kconfig: streamline_config.pl: Couple of typo fixes
...
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allnoconfig_y is an ugly hack that sets a symbol to 'y' by allnoconfig.
allnoconfig does not mean a minimal set of CONFIG options because a
bunch of prompts are hidden by 'if EMBEDDED' or 'if EXPERT', but I do
not like to hack Kconfig this way.
Use the pre-existing feature, KCONFIG_ALLCONFIG, to provide a one
liner config fragment. CONFIG_EMBEDDED=y is still forced when
allnoconfig is invoked as a part of tinyconfig.
No change in the .config file produced by 'make tinyconfig'.
The output of 'make allnoconfig' will be changed; we will get
CONFIG_EMBEDDED=n because allnoconfig literally sets all symbols to n.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Evaluate $(call cc-option,...) etc. only for build targets
- Add CONFIG_VMLINUX_MAP to generate .map file when linking vmlinux
- Remove unnecessary --gcc-toolchains Clang flag because the --prefix
flag finds the toolchains
- Do not pass Clang's --prefix flag when using the integrated as
- Check the assembler version in Kconfig time
- Add new CONFIG options, AS_VERSION, AS_IS_GNU, AS_IS_LLVM to clean up
some dependencies in Kconfig
- Fix invalid Module.symvers creation when building only modules
without vmlinux
- Fix false-positive modpost warnings when CONFIG_TRIM_UNUSED_KSYMS is
set, but there is no module to build
- Refactor module installation Makefile
- Support zstd for module compression
- Convert alpha and ia64 to use generic shell scripts to generate the
syscall headers
- Add a new elfnote to indicate if the kernel was built with LTO, which
will be used by pahole
- Flatten the directory structure under include/config/ so CONFIG
options and filenames match
- Change the deb source package name from linux-$(KERNELRELEASE) to
linux-upstream
* tag 'kbuild-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (42 commits)
kbuild: Add $(KBUILD_HOSTLDFLAGS) to 'has_libelf' test
kbuild: deb-pkg: change the source package name to linux-upstream
tools: do not include scripts/Kbuild.include
kbuild: redo fake deps at include/config/*.h
kbuild: remove TMPO from try-run
MAINTAINERS: add pattern for dummy-tools
kbuild: add an elfnote for whether vmlinux is built with lto
ia64: syscalls: switch to generic syscallhdr.sh
ia64: syscalls: switch to generic syscalltbl.sh
alpha: syscalls: switch to generic syscallhdr.sh
alpha: syscalls: switch to generic syscalltbl.sh
sysctl: use min() helper for namecmp()
kbuild: add support for zstd compressed modules
kbuild: remove CONFIG_MODULE_COMPRESS
kbuild: merge scripts/Makefile.modsign to scripts/Makefile.modinst
kbuild: move module strip/compression code into scripts/Makefile.modinst
kbuild: refactor scripts/Makefile.modinst
kbuild: rename extmod-prefix to extmod_prefix
kbuild: check module name conflict for external modules as well
kbuild: show the target directory for depmod log
...
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Make include/config/foo/bar.h fake deps files generation simpler.
* delete .h suffix
those aren't header files, shorten filenames,
* delete tolower()
Linux filesystems can deal with both upper and lowercase
filenames very well,
* put everything in 1 directory
Presumably 'mkdir -p' split is from dark times when filesystems
handled huge directories badly, disks were round adding to
seek times.
x86_64 allmodconfig lists 12364 files in include/config.
../obj/include/config/
├── 104_QUAD_8
├── 60XX_WDT
├── 64BIT
...
├── ZSWAP_DEFAULT_ON
├── ZSWAP_ZPOOL_DEFAULT
└── ZSWAP_ZPOOL_DEFAULT_ZBUD
0 directories, 12364 files
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core:
- bpf:
- allow bpf programs calling kernel functions (initially to
reuse TCP congestion control implementations)
- enable task local storage for tracing programs - remove the
need to store per-task state in hash maps, and allow tracing
programs access to task local storage previously added for
BPF_LSM
- add bpf_for_each_map_elem() helper, allowing programs to walk
all map elements in a more robust and easier to verify fashion
- sockmap: support UDP and cross-protocol BPF_SK_SKB_VERDICT
redirection
- lpm: add support for batched ops in LPM trie
- add BTF_KIND_FLOAT support - mostly to allow use of BTF on
s390 which has floats in its headers files
- improve BPF syscall documentation and extend the use of kdoc
parsing scripts we already employ for bpf-helpers
- libbpf, bpftool: support static linking of BPF ELF files
- improve support for encapsulation of L2 packets
- xdp: restructure redirect actions to avoid a runtime lookup,
improving performance by 4-8% in microbenchmarks
- xsk: build skb by page (aka generic zerocopy xmit) - improve
performance of software AF_XDP path by 33% for devices which don't
need headers in the linear skb part (e.g. virtio)
- nexthop: resilient next-hop groups - improve path stability on
next-hops group changes (incl. offload for mlxsw)
- ipv6: segment routing: add support for IPv4 decapsulation
- icmp: add support for RFC 8335 extended PROBE messages
- inet: use bigger hash table for IP ID generation
- tcp: deal better with delayed TX completions - make sure we don't
give up on fast TCP retransmissions only because driver is slow in
reporting that it completed transmitting the original
- tcp: reorder tcp_congestion_ops for better cache locality
- mptcp:
- add sockopt support for common TCP options
- add support for common TCP msg flags
- include multiple address ids in RM_ADDR
- add reset option support for resetting one subflow
- udp: GRO L4 improvements - improve 'forward' / 'frag_list'
co-existence with UDP tunnel GRO, allowing the first to take place
correctly even for encapsulated UDP traffic
- micro-optimize dev_gro_receive() and flow dissection, avoid
retpoline overhead on VLAN and TEB GRO
- use less memory for sysctls, add a new sysctl type, to allow using
u8 instead of "int" and "long" and shrink networking sysctls
- veth: allow GRO without XDP - this allows aggregating UDP packets
before handing them off to routing, bridge, OvS, etc.
- allow specifing ifindex when device is moved to another namespace
- netfilter:
- nft_socket: add support for cgroupsv2
- nftables: add catch-all set element - special element used to
define a default action in case normal lookup missed
- use net_generic infra in many modules to avoid allocating
per-ns memory unnecessarily
- xps: improve the xps handling to avoid potential out-of-bound
accesses and use-after-free when XPS change race with other
re-configuration under traffic
- add a config knob to turn off per-cpu netdev refcnt to catch
underflows in testing
Device APIs:
- add WWAN subsystem to organize the WWAN interfaces better and
hopefully start driving towards more unified and vendor-
independent APIs
- ethtool:
- add interface for reading IEEE MIB stats (incl. mlx5 and bnxt
support)
- allow network drivers to dump arbitrary SFP EEPROM data,
current offset+length API was a poor fit for modern SFP which
define EEPROM in terms of pages (incl. mlx5 support)
- act_police, flow_offload: add support for packet-per-second
policing (incl. offload for nfp)
- psample: add additional metadata attributes like transit delay for
packets sampled from switch HW (and corresponding egress and
policy-based sampling in the mlxsw driver)
- dsa: improve support for sandwiched LAGs with bridge and DSA
- netfilter:
- flowtable: use direct xmit in topologies with IP forwarding,
bridging, vlans etc.
- nftables: counter hardware offload support
- Bluetooth:
- improvements for firmware download w/ Intel devices
- add support for reading AOSP vendor capabilities
- add support for virtio transport driver
- mac80211:
- allow concurrent monitor iface and ethernet rx decap
- set priority and queue mapping for injected frames
- phy: add support for Clause-45 PHY Loopback
- pci/iov: add sysfs MSI-X vector assignment interface to distribute
MSI-X resources to VFs (incl. mlx5 support)
New hardware/drivers:
- dsa: mv88e6xxx: add support for Marvell mv88e6393x - 11-port
Ethernet switch with 8x 1-Gigabit Ethernet and 3x 10-Gigabit
interfaces.
- dsa: support for legacy Broadcom tags used on BCM5325, BCM5365 and
BCM63xx switches
- Microchip KSZ8863 and KSZ8873; 3x 10/100Mbps Ethernet switches
- ath11k: support for QCN9074 a 802.11ax device
- Bluetooth: Broadcom BCM4330 and BMC4334
- phy: Marvell 88X2222 transceiver support
- mdio: add BCM6368 MDIO mux bus controller
- r8152: support RTL8153 and RTL8156 (USB Ethernet) chips
- mana: driver for Microsoft Azure Network Adapter (MANA)
- Actions Semi Owl Ethernet MAC
- can: driver for ETAS ES58X CAN/USB interfaces
Pure driver changes:
- add XDP support to: enetc, igc, stmmac
- add AF_XDP support to: stmmac
- virtio:
- page_to_skb() use build_skb when there's sufficient tailroom
(21% improvement for 1000B UDP frames)
- support XDP even without dedicated Tx queues - share the Tx
queues with the stack when necessary
- mlx5:
- flow rules: add support for mirroring with conntrack, matching
on ICMP, GTP, flex filters and more
- support packet sampling with flow offloads
- persist uplink representor netdev across eswitch mode changes
- allow coexistence of CQE compression and HW time-stamping
- add ethtool extended link error state reporting
- ice, iavf: support flow filters, UDP Segmentation Offload
- dpaa2-switch:
- move the driver out of staging
- add spanning tree (STP) support
- add rx copybreak support
- add tc flower hardware offload on ingress traffic
- ionic:
- implement Rx page reuse
- support HW PTP time-stamping
- octeon: support TC hardware offloads - flower matching on ingress
and egress ratelimitting.
- stmmac:
- add RX frame steering based on VLAN priority in tc flower
- support frame preemption (FPE)
- intel: add cross time-stamping freq difference adjustment
- ocelot:
- support forwarding of MRP frames in HW
- support multiple bridges
- support PTP Sync one-step timestamping
- dsa: mv88e6xxx, dpaa2-switch: offload bridge port flags like
learning, flooding etc.
- ipa: add IPA v4.5, v4.9 and v4.11 support (Qualcomm SDX55, SM8350,
SC7280 SoCs)
- mt7601u: enable TDLS support
- mt76:
- add support for 802.3 rx frames (mt7915/mt7615)
- mt7915 flash pre-calibration support
- mt7921/mt7663 runtime power management fixes"
* tag 'net-next-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2451 commits)
net: selftest: fix build issue if INET is disabled
net: netrom: nr_in: Remove redundant assignment to ns
net: tun: Remove redundant assignment to ret
net: phy: marvell: add downshift support for M88E1240
net: dsa: ksz: Make reg_mib_cnt a u8 as it never exceeds 255
net/sched: act_ct: Remove redundant ct get and check
icmp: standardize naming of RFC 8335 PROBE constants
bpf, selftests: Update array map tests for per-cpu batched ops
bpf: Add batched ops support for percpu array
bpf: Implement formatted output helpers with bstr_printf
seq_file: Add a seq_bprintf function
sfc: adjust efx->xdp_tx_queue_count with the real number of initialized queues
net:nfc:digital: Fix a double free in digital_tg_recv_dep_req
net: fix a concurrency bug in l2tp_tunnel_register()
net/smc: Remove redundant assignment to rc
mpls: Remove redundant assignment to err
llc2: Remove redundant assignment to rc
net/tls: Remove redundant initialization of record
rds: Remove redundant assignment to nr_sig
dt-bindings: net: mdio-gpio: add compatible for microchip,mdio-smi0
...
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Uses the already in-place infrastructure provided by the
'generic_map_*_batch' functions.
No tweak was needed as it transparently handles the percpu variant.
As arrays don't have delete operations, let it return a error to
user space (default behaviour).
Suggested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210424214510.806627-2-pctammela@mojatatu.com
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BPF has three formatted output helpers: bpf_trace_printk, bpf_seq_printf
and bpf_snprintf. Their signatures specify that all arguments are
provided from the BPF world as u64s (in an array or as registers). All
of these helpers are currently implemented by calling functions such as
snprintf() whose signatures take a variable number of arguments, then
placed in a va_list by the compiler to call vsnprintf().
"d9c9e4db bpf: Factorize bpf_trace_printk and bpf_seq_printf" introduced
a bpf_printf_prepare function that fills an array of u64 sanitized
arguments with an array of "modifiers" which indicate what the "real"
size of each argument should be (given by the format specifier). The
BPF_CAST_FMT_ARG macro consumes these arrays and casts each argument to
its real size. However, the C promotion rules implicitely cast them all
back to u64s. Therefore, the arguments given to snprintf are u64s and
the va_list constructed by the compiler will use 64 bits for each
argument. On 64 bit machines, this happens to work well because 32 bit
arguments in va_lists need to occupy 64 bits anyway, but on 32 bit
architectures this breaks the layout of the va_list expected by the
called function and mangles values.
In "88a5c690b6 bpf: fix bpf_trace_printk on 32 bit archs", this problem
had been solved for bpf_trace_printk only with a "horrid workaround"
that emitted multiple calls to trace_printk where each call had
different argument types and generated different va_list layouts. One of
the call would be dynamically chosen at runtime. This was ok with the 3
arguments that bpf_trace_printk takes but bpf_seq_printf and
bpf_snprintf accept up to 12 arguments. Because this approach scales
code exponentially, it is not a viable option anymore.
Because the promotion rules are part of the language and because the
construction of a va_list is an arch-specific ABI, it's best to just
avoid variadic arguments and va_lists altogether. Thankfully the
kernel's snprintf() has an alternative in the form of bstr_printf() that
accepts arguments in a "binary buffer representation". These binary
buffers are currently created by vbin_printf and used in the tracing
subsystem to split the cost of printing into two parts: a fast one that
only dereferences and remembers values, and a slower one, called later,
that does the pretty-printing.
This patch refactors bpf_printf_prepare to construct binary buffers of
arguments consumable by bstr_printf() instead of arrays of arguments and
modifiers. This gets rid of BPF_CAST_FMT_ARG and greatly simplifies the
bpf_printf_prepare usage but there are a few gotchas that change how
bpf_printf_prepare needs to do things.
Currently, bpf_printf_prepare uses a per cpu temporary buffer as a
generic storage for strings and IP addresses. With this refactoring, the
temporary buffers now holds all the arguments in a structured binary
format.
To comply with the format expected by bstr_printf, certain format
specifiers also need to be pre-formatted: %pB and %pi6/%pi4/%pI4/%pI6.
Because vsnprintf subroutines for these specifiers are hard to expose,
we pre-format these arguments with calls to snprintf().
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210427174313.860948-3-revest@chromium.org
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Rely on netif_receive_skb_list routine to send skbs converted from
xdp_frames in cpu_map_kthread_run in order to improve i-cache usage.
The proposed patch has been tested running xdp_redirect_cpu bpf sample
available in the kernel tree that is used to redirect UDP frames from
ixgbe driver to a cpumap entry and then to the networking stack. UDP
frames are generated using pktgen. Packets are discarded by the UDP
layer.
$ xdp_redirect_cpu --cpu <cpu> --progname xdp_cpu_map0 --dev <eth>
bpf-next: ~2.35Mpps
bpf-next + cpumap skb-list: ~2.72Mpps
Rename drops counter in kmem_alloc_drops since now it reports just
kmem_cache_alloc_bulk failures
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/c729f83e5d7482d9329e0f165bdbe5adcefd1510.1619169700.git.lorenzo@kernel.org
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Similarly as b02709587ea3 ("bpf: Fix propagation of 32-bit signed bounds
from 64-bit bounds."), we also need to fix the propagation of 32 bit
unsigned bounds from 64 bit counterparts. That is, really only set the
u32_{min,max}_value when /both/ {umin,umax}_value safely fit in 32 bit
space. For example, the register with a umin_value == 1 does /not/ imply
that u32_min_value is also equal to 1, since umax_value could be much
larger than 32 bit subregister can hold, and thus u32_min_value is in
the interval [0,1] instead.
Before fix, invalid tracking result of R2_w=inv1:
[...]
5: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0) R10=fp0
5: (35) if r2 >= 0x1 goto pc+1
[...] // goto path
7: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umin_value=1) R10=fp0
7: (b6) if w2 <= 0x1 goto pc+1
[...] // goto path
9: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,smin_value=-9223372036854775807,smax_value=9223372032559808513,umin_value=1,umax_value=18446744069414584321,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_max_value=1) R10=fp0
9: (bc) w2 = w2
10: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv1 R10=fp0
[...]
After fix, correct tracking result of R2_w=inv(id=0,umax_value=1,var_off=(0x0; 0x1)):
[...]
5: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0) R10=fp0
5: (35) if r2 >= 0x1 goto pc+1
[...] // goto path
7: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umin_value=1) R10=fp0
7: (b6) if w2 <= 0x1 goto pc+1
[...] // goto path
9: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,smax_value=9223372032559808513,umax_value=18446744069414584321,var_off=(0x0; 0xffffffff00000001),s32_min_value=0,s32_max_value=1,u32_max_value=1) R10=fp0
9: (bc) w2 = w2
10: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,umax_value=1,var_off=(0x0; 0x1)) R10=fp0
[...]
Thus, same issue as in b02709587ea3 holds for unsigned subregister tracking.
Also, align __reg64_bound_u32() similarly to __reg64_bound_s32() as done in
b02709587ea3 to make them uniform again.
Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Reported-by: Manfred Paul (@_manfp)
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
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bpf_trace_printk uses a shared static buffer to hold strings before they
are printed. A recent refactoring moved the locking of that buffer after
it gets filled by mistake.
Fixes: d9c9e4db186a ("bpf: Factorize bpf_trace_printk and bpf_seq_printf")
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210427112958.773132-1-revest@chromium.org
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