Since the ringbuffer is lockless, there is no need for it to be
protected by @logbuf_lock. Remove @logbuf_lock writer-protection of
the ringbuffer. The reader-protection is not removed because some
variables, used by readers, are using @logbuf_lock for synchronization:
@syslog_seq, @syslog_time, @syslog_partial, @console_seq,
struct kmsg_dumper.

For PRINTK_NMI_DIRECT_CONTEXT_MASK, @logbuf_lock usage is not removed
because it may be used for dumper synchronization.

Without @logbuf_lock synchronization of vprintk_store() it is no
longer possible to use the single static buffer for temporarily
sprint'ing the message. Instead, use vsnprintf() to determine the
length and perform the real vscnprintf() using the area reserved from
the ringbuffer. This leads to suboptimal packing of the message data,
but will result in less wasted storage than multiple per-cpu buffers
to support lockless temporary sprint'ing.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20201209004453.17720-3-john.ogness@linutronix.de

In preparation for removing logbuf_lock, inline log_output()
and log_store() into vprintk_store(). This will simplify dealing
with the various code branches and fallbacks that are possible.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20201209004453.17720-2-john.ogness@linutronix.de

Commit 849f3127 ("switch /dev/kmsg to ->write_iter()") refactored
devkmsg_write() and left over a dead assignment on the variable 'len'.

Hence, make clang-analyzer warns:

  kernel/printk/printk.c:744:4: warning: Value stored to 'len' is never read
    [clang-analyzer-deadcode.DeadStores]
                          len -= endp - line;
                          ^

Simply remove this obsolete dead assignment here.

Link: https://lore.kernel.org/r/20201130124915.7573-1-lukas.bulwahn@gmail.comSigned-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

Pull printk fixes from Petr Mladek:

 - do not lose trailing newline in pr_cont() calls

 - two trivial fixes for a dead store and a config description

* tag 'printk-for-5.10-rc6-fixup' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk: finalize records with trailing newlines
  printk: remove unneeded dead-store assignment
  init/Kconfig: Fix CPU number in LOG_CPU_MAX_BUF_SHIFT description

Pull writeback fix from Jan Kara:
 "A fix of possible missing string termination in writeback tracepoints"

* tag 'writeback_for_v5.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  trace: fix potenial dangerous pointer

Any record with a trailing newline (LOG_NEWLINE flag) cannot
be continued because the newline has been stripped and will
not be visible if the message is appended. This was already
handled correctly when committing in log_output() but was
not handled correctly when committing in log_store().

Fixes: f5f022e5 ("printk: reimplement log_cont using record extension")
Link: https://lore.kernel.org/r/20201126114836.14750-1-john.ogness@linutronix.deReported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

Pull power management fix from Rafael Wysocki:
 "Fix a recently introduced build issue in the cpufreq SCMI driver
  (Sudeep Holla)"

* tag 'pm-5.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: scmi: Fix build for !CONFIG_COMMON_CLK

0day reported one -22.7% regression for will-it-scale page_fault2
case [1] on a 4 sockets 144 CPU platform, and bisected to it to be
caused by Waiman's optimization (commit bd0b230f) of saving one
'struct page_counter' space for 'struct mem_cgroup'.

Initially we thought it was due to the cache alignment change introduced
by the patch, but further debug shows that it is due to some hot data
members ('vmstats_local', 'vmstats_percpu', 'vmstats') sit in 2 adjacent
cacheline (2N and 2N+1 cacheline), and when adjacent cache line prefetch
is enabled, it triggers an "extended level" of cache false sharing for
2 adjacent cache lines.

So exchange the 2 member blocks, while keeping mostly the original
cache alignment, which can restore and even enhance the performance,
and save 64 bytes of space for 'struct mem_cgroup' (from 2880 to 2816,
with 0day's default RHEL-8.3 kernel config)

[1]. https://lore.kernel.org/lkml/20201102091543.GM31092@shao2-debian/

Fixes: bd0b230f ("mm/memcg: unify swap and memsw page counters")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull media fixes from Mauro Carvalho Chehab:

 - a rand Kconfig fixup for mtk-vcodec

 - a fix at h264 handling at cedrus codec driver

 - some warning fixes when config PM is not enabled at marvell-ccic

 - two fixes at venus codec driver: one related to codec profile and the
   other one related to a bad error path which causes an OOPS on module
   re-bind

* tag 'media/v5.10-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  media: venus: pm_helpers: Fix kernel module reload
  media: venus: venc: Fix setting of profile and level
  media: cedrus: h264: Fix check for presence of scaling matrix
  media: media/platform/marvell-ccic: fix warnings when CONFIG_PM is not enabled
  media: mtk-vcodec: fix build breakage when one of VPU or SCP is enabled
  media: mtk-vcodec: move firmware implementations into their own files

The bdi_dev_name() returns a char [64], and
the __entry->name is a char [32].

It maybe dangerous to TP_printk("%s", __entry->name)
after the strncpy().

CC: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201124165205.GA23937@rlkAcked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hui Su <sh_def@163.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Pull cifs fixes from Steve French:
 "Four smb3 fixes for stable: one fixes a memleak, the other three
  address a problem found with decryption offload that can cause a use
  after free"

* tag '5.10-rc5-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb3: Handle error case during offload read path
  smb3: Avoid Mid pending list corruption
  smb3: Call cifs reconnect from demultiplex thread
  cifs: fix a memleak with modefromsid

Twice now, when exercising ext4 looped on shmem huge pages, I have crashed
on the PF_ONLY_HEAD check inside PageWaiters(): ext4_finish_bio() calling
end_page_writeback() calling wake_up_page() on tail of a shmem huge page,
no longer an ext4 page at all.

The problem is that PageWriteback is not accompanied by a page reference
(as the NOTE at the end of test_clear_page_writeback() acknowledges): as
soon as TestClearPageWriteback has been done, that page could be removed
from page cache, freed, and reused for something else by the time that
wake_up_page() is reached.

https://lore.kernel.org/linux-mm/20200827122019.GC14765@casper.infradead.org/
Matthew Wilcox suggested avoiding or weakening the PageWaiters() tail
check; but I'm paranoid about even looking at an unreferenced struct page,
lest its memory might itself have already been reused or hotremoved (and
wake_up_page_bit() may modify that memory with its ClearPageWaiters()).

Then on crashing a second time, realized there's a stronger reason against
that approach.  If my testing just occasionally crashes on that check,
when the page is reused for part of a compound page, wouldn't it be much
more common for the page to get reused as an order-0 page before reaching
wake_up_page()?  And on rare occasions, might that reused page already be
marked PageWriteback by its new user, and already be waited upon?  What
would that look like?

It would look like BUG_ON(PageWriteback) after wait_on_page_writeback()
in write_cache_pages() (though I have never seen that crash myself).

Matthew Wilcox explaining this to himself:
 "page is allocated, added to page cache, dirtied, writeback starts,

  --- thread A ---
  filesystem calls end_page_writeback()
        test_clear_page_writeback()
  --- context switch to thread B ---
  truncate_inode_pages_range() finds the page, it doesn't have writeback set,
  we delete it from the page cache.  Page gets reallocated, dirtied, writeback
  starts again.  Then we call write_cache_pages(), see
  PageWriteback() set, call wait_on_page_writeback()
  --- context switch back to thread A ---
  wake_up_page(page, PG_writeback);
  ... thread B is woken, but because the wakeup was for the old use of
  the page, PageWriteback is still set.

  Devious"

And prior to 2a9127fc ("mm: rewrite wait_on_page_bit_common() logic")
this would have been much less likely: before that, wake_page_function()'s
non-exclusive case would stop walking and not wake if it found Writeback
already set again; whereas now the non-exclusive case proceeds to wake.

I have not thought of a fix that does not add a little overhead: the
simplest fix is for end_page_writeback() to get_page() before calling
test_clear_page_writeback(), then put_page() after wake_up_page().

Was there a chance of missed wakeups before, since a page freed before
reaching wake_up_page() would have PageWaiters cleared?  I think not,
because each waiter does hold a reference on the page.  This bug comes
when the old use of the page, the one we do TestClearPageWriteback on,
had *no* waiters, so no additional page reference beyond the page cache
(and whoever racily freed it).  The reuse of the page has a waiter
holding a reference, and its own PageWriteback set; but the belated
wake_up_page() has woken the reuse to hit that BUG_ON(PageWriteback).

Reported-by: syzbot+3622cea378100f45d59f@syzkaller.appspotmail.com
Reported-by: Qian Cai <cai@lca.pw>
Fixes: 2a9127fc ("mm: rewrite wait_on_page_bit_common() logic")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull s390 fix from Heiko Carstens:
 "Disable interrupts when restoring fpu and vector registers, otherwise
  KVM guests might see corrupted register contents"

* tag 's390-5.10-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: fix fpu restore in entry.S

Pull ARC fixes from Vineet Gupta:
 "A couple more stack unwinder related fixes:

   - More stack unwinding updates

   - Misc minor fixes"

* tag 'arc-5.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: stack unwinding: reorganize how initial register state setup
  ARC: stack unwinding: don't assume non-current task is sleeping
  ARC: mm: fix spelling mistakes
  ARC: bitops: Remove unecessary operation and value

Pull Hyper-V fix from Wei Liu:
 "One patch from Dexuan to fix VRAM cache type in Hyper-V framebuffer
  driver"

* tag 'hyperv-fixes-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  video: hyperv_fb: Fix the cache type when mapping the VRAM

Pull SCMI cpufreq driver fix for 5.10-rc6 from Viresh Kumar:

"This fixes a build issues with SCMI cpufreq driver in the
 !CONFIG_COMMON_CLK case."

* 'cpufreq/arm/fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm:
  cpufreq: scmi: Fix build for !CONFIG_COMMON_CLK

We need to disable interrupts in load_fpu_regs(). Otherwise an
interrupt might come in after the registers are loaded, but before
CIF_FPU is cleared in load_fpu_regs(). When the interrupt returns,
CIF_FPU will be cleared and the registers will never be restored.

The entry.S code usually saves the interrupt state in __SF_EMPTY on the
stack when disabling/restoring interrupts. sie64a however saves the pointer
to the sie control block in __SF_SIE_CONTROL, which references the same
location.  This is non-obvious to the reader. To avoid thrashing the sie
control block pointer in load_fpu_regs(), move the __SIE_* offsets eight
bytes after __SF_EMPTY on the stack.

Cc: <stable@vger.kernel.org> # 5.8
Fixes: 0b0ed657 ("s390: remove critical section cleanup from entry.S")
Reported-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Commit 8410e7f3 ("cpufreq: scmi: Fix OPP addition failure with a
dummy clock provider") registers a dummy clock provider using
devm_of_clk_add_hw_provider. These *_hw_provider functions are defined
only when CONFIG_COMMON_CLK=y. One possible fix is to add the Kconfig
dependency, but since we plan to move away from the clock dependency
for scmi cpufreq, it is preferrable to avoid that.

Let us just conditionally compile out the offending call to
devm_of_clk_add_hw_provider. It also uses the variable 'dev' outside
of the #ifdef block to avoid build warning.

Fixes: 8410e7f3 ("cpufreq: scmi: Fix OPP addition failure with a dummy clock provider")
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Pull HID fixes from Jiri Kosina:

 - Various functionality / regression fixes for Logitech devices from
   Hans de Goede

 - Fix for (recently added) GPIO support in mcp2221 driver from Lars
   Povlsen

 - Power management handling fix/quirk in i2c-hid driver for certain
   BIOSes that have strange aproach to power-cycle from Hans de Goede

 - a few device ID additions and device-specific quirks

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid:
  HID: logitech-dj: Fix Dinovo Mini when paired with a MX5x00 receiver
  HID: logitech-dj: Fix an error in mse_bluetooth_descriptor
  HID: Add Logitech Dinovo Edge battery quirk
  HID: logitech-hidpp: Add HIDPP_CONSUMER_VENDOR_KEYS quirk for the Dinovo Edge
  HID: logitech-dj: Handle quad/bluetooth keyboards with a builtin trackpad
  HID: add HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE for Gamevice devices
  HID: mcp2221: Fix GPIO output handling
  HID: hid-sensor-hub: Fix issue with devices with no report ID
  HID: i2c-hid: Put ACPI enumerated devices in D3 on shutdown
  HID: add support for Sega Saturn
  HID: cypress: Support Varmilo Keyboards' media hotkeys
  HID: ite: Replace ABS_MISC 120/121 events with touchpad on/off keypresses
  HID: logitech-hidpp: Add PID for MX Anywhere 2
  HID: uclogic: Add ID for Trust Flex Design Tablet

Pull scheduler fixes from Thomas Gleixner:
 "A couple of scheduler fixes:

   - Make the conditional update of the overutilized state work
     correctly by caching the relevant flags state before overwriting
     them and checking them afterwards.

   - Fix a data race in the wakeup path which caused loadavg on ARM64
     platforms to become a random number generator.

   - Fix the ordering of the iowaiter accounting operations so it can't
     be decremented before it is incremented.

   - Fix a bug in the deadline scheduler vs. priority inheritance when a
     non-deadline task A has inherited the parameters of a deadline task
     B and then blocks on a non-deadline task C.

     The second inheritance step used the static deadline parameters of
     task A, which are usually 0, instead of further propagating task
     B's parameters. The zero initialized parameters trigger a bug in
     the deadline scheduler"

* tag 'sched-urgent-2020-11-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Fix priority inheritance with multiple scheduling classes
  sched: Fix rq->nr_iowait ordering
  sched: Fix data-race in wakeup
  sched/fair: Fix overutilized update in enqueue_task_fair()

Pull perf fix from Thomas Gleixner:
 "A single fix for the x86 perf sysfs interfaces which used kobject
  attributes instead of device attributes and therefore making clang's
  control flow integrity checker upset"

* tag 'perf-urgent-2020-11-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86: fix sysfs type mismatches

Pull locking fix from Thomas Gleixner:
 "A single fix for lockdep which makes the recursion protection cover
  graph lock/unlock"

* tag 'locking-urgent-2020-11-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Put graph lock/unlock under lock_recursion protection

Pull EFI fixes from Borislav Petkov:
 "Forwarded EFI fixes from Ard Biesheuvel:

   - fix memory leak in efivarfs driver

   - fix HYP mode issue in 32-bit ARM version of the EFI stub when built
     in Thumb2 mode

   - avoid leaking EFI pgd pages on allocation failure"

* tag 'efi-urgent-for-v5.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/x86: Free efi_pgd with free_pages()
  efivarfs: fix memory leak in efivarfs_create()
  efi/arm: set HSCTLR Thumb2 bit correctly for HVC calls from HYP

Pull x86 fixes from Borislav Petkov:

 - An IOMMU VT-d build fix when CONFIG_PCI_ATS=n along with a revert of
   same because the proper one is going through the IOMMU tree (Thomas
   Gleixner)

 - An Intel microcode loader fix to save the correct microcode patch to
   apply during resume (Chen Yu)

 - A fix to not access user memory of other processes when dumping
   opcode bytes (Thomas Gleixner)

* tag 'x86_urgent_for_v5.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert "iommu/vt-d: Take CONFIG_PCI_ATS into account"
  x86/dumpstack: Do not try to access user space code of other tasks
  x86/microcode/intel: Check patch signature before saving microcode for early loading
  iommu/vt-d: Take CONFIG_PCI_ATS into account

Merge misc fixes from Andrew Morton:
 "8 patches.

  Subsystems affected by this patch series: mm (madvise, pagemap,
  readahead, memcg, userfaultfd), kbuild, and vfs"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm: fix madvise WILLNEED performance problem
  libfs: fix error cast of negative value in simple_attr_write()
  mm/userfaultfd: do not access vma->vm_mm after calling handle_userfault()
  mm: memcg/slab: fix root memcg vmstats
  mm: fix readahead_page_batch for retry entries
  mm: fix phys_to_target_node() and memory_add_physaddr_to_nid() exports
  compiler-clang: remove version check for BPF Tracing
  mm/madvise: fix memory leak from process_madvise

Pull staging and IIO fixes from Greg KH:
 "Here are some small Staging and IIO driver fixes for 5.10-rc5. They
  include:

   - IIO fixes for reported regressions and problems

   - new device ids for IIO drivers

   - new device id for rtl8723bs driver

   - staging ralink driver Kconfig dependency fix

   - staging mt7621-pci bus resource fix

  All of these have been in linux-next all week with no reported issues"

* tag 'staging-5.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  iio: accel: kxcjk1013: Add support for KIOX010A ACPI DSM for setting tablet-mode
  iio: accel: kxcjk1013: Replace is_smo8500_device with an acpi_type enum
  docs: ABI: testing: iio: stm32: remove re-introduced unsupported ABI
  iio: light: fix kconfig dependency bug for VCNL4035
  iio/adc: ingenic: Fix AUX/VBAT readings when touchscreen is used
  iio/adc: ingenic: Fix battery VREF for JZ4770 SoC
  staging: rtl8723bs: Add 024c:0627 to the list of SDIO device-ids
  staging: ralink-gdma: fix kconfig dependency bug for DMA_RALINK
  staging: mt7621-pci: avoid to request pci bus resources
  iio: imu: st_lsm6dsx: set 10ms as min shub slave timeout
  counter/ti-eqep: Fix regmap max_register
  iio: adc: stm32-adc: fix a regression when using dma and irq
  iio: adc: mediatek: fix unset field
  iio: cros_ec: Use default frequencies when EC returns invalid information

Pull tty fixes from Greg KH:
 "Here are some small tty/serial fixes for 5.10-rc5 that resolve some
  reported issues:

   - speakup crash when telling the kernel to use a device that isn't
     really there

   - imx serial driver fixes for reported problems

   - ar933x_uart driver fix for probe error handling path

  All have been in linux-next for a while with no reported issues"

* tag 'tty-5.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: ar933x_uart: disable clk on error handling path in probe
  tty: serial: imx: keep console clocks always on
  speakup: Do not let the line discipline be used several times
  tty: serial: imx: fix potential deadlock

Pull ext4 fixes from Ted Ts'o:
 "A final set of miscellaneous bug fixes for ext4"

* tag 'ext4_for_linus_fixes2' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix bogus warning in ext4_update_dx_flag()
  jbd2: fix kernel-doc markups
  ext4: drop fast_commit from /proc/mounts

When doing a lookup in a directory, the afs filesystem uses a bulk
status fetch to speculatively retrieve the statuses of up to 48 other
vnodes found in the same directory and it will then either update extant
inodes or create new ones - effectively doing 'lookup ahead'.

To avoid the possibility of deadlocking itself, however, the filesystem
doesn't lock all of those inodes; rather just the directory inode is
locked (by the VFS).

When the operation completes, afs_inode_init_from_status() or
afs_apply_status() is called, depending on whether the inode already
exists, to commit the new status.

A case exists, however, where the speculative status fetch operation may
straddle a modification operation on one of those vnodes.  What can then
happen is that the speculative bulk status RPC retrieves the old status,
and whilst that is happening, the modification happens - which returns
an updated status, then the modification status is committed, then we
attempt to commit the speculative status.

This results in something like the following being seen in dmesg:

	kAFS: vnode modified {100058:861} 8->9 YFS.InlineBulkStatus

showing that for vnode 861 on volume 100058, we saw YFS.InlineBulkStatus
say that the vnode had data version 8 when we'd already recorded version
9 due to a local modification.  This was causing the cache to be
invalidated for that vnode when it shouldn't have been.  If it happens
on a data file, this might lead to local changes being lost.

Fix this by ignoring speculative status updates if the data version
doesn't match the expected value.

Note that it is possible to get a DV regression if a volume gets
restored from a backup - but we should get a callback break in such a
case that should trigger a recheck anyway.  It might be worth checking
the volume creation time in the volsync info and, if a change is
observed in that (as would happen on a restore), invalidate all caches
associated with the volume.

Fixes: 5cf9dd55 ("afs: Prospectively look up extra files when doing a single lookup")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The calculation of the end page index was incorrect, leading to a
regression of 70% when running stress-ng.

With this fix, we instead see a performance improvement of 3%.

Fixes: e6e88712 ("mm: optimise madvise WILLNEED")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Link: https://lkml.kernel.org/r/20201109134851.29692-1-willy@infradead.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The attr->set() receive a value of u64, but simple_strtoll() is used for
doing the conversion.  It will lead to the error cast if user inputs a
negative value.

Use kstrtoull() instead of simple_strtoll() to convert a string got from
the user to an unsigned value.  The former will return '-EINVAL' if it
gets a negetive value, but the latter can't handle the situation
correctly.  Make 'val' unsigned long long as what kstrtoull() takes,
this will eliminate the compile warning on no 64-bit architectures.

Fixes: f7b88631 ("fs/libfs.c: fix simple_attr_write() on 32bit machines")
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lkml.kernel.org/r/1605341356-11872-1-git-send-email-yangyicong@hisilicon.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Alexander reported a syzkaller / KASAN finding on s390, see below for
complete output.

In do_huge_pmd_anonymous_page(), the pre-allocated pagetable will be
freed in some cases.  In the case of userfaultfd_missing(), this will
happen after calling handle_userfault(), which might have released the
mmap_lock.  Therefore, the following pte_free(vma->vm_mm, pgtable) will
access an unstable vma->vm_mm, which could have been freed or re-used
already.

For all architectures other than s390 this will go w/o any negative
impact, because pte_free() simply frees the page and ignores the
passed-in mm.  The implementation for SPARC32 would also access
mm->page_table_lock for pte_free(), but there is no THP support in
SPARC32, so the buggy code path will not be used there.

For s390, the mm->context.pgtable_list is being used to maintain the 2K
pagetable fragments, and operating on an already freed or even re-used
mm could result in various more or less subtle bugs due to list /
pagetable corruption.

Fix this by calling pte_free() before handle_userfault(), similar to how
it is already done in __do_huge_pmd_anonymous_page() for the WRITE /
non-huge_zero_page case.

Commit 6b251fc9 ("userfaultfd: call handle_userfault() for
userfaultfd_missing() faults") actually introduced both, the
do_huge_pmd_anonymous_page() and also __do_huge_pmd_anonymous_page()
changes wrt to calling handle_userfault(), but only in the latter case
it put the pte_free() before calling handle_userfault().

  BUG: KASAN: use-after-free in do_huge_pmd_anonymous_page+0xcda/0xd90 mm/huge_memory.c:744
  Read of size 8 at addr 00000000962d6988 by task syz-executor.0/9334

  CPU: 1 PID: 9334 Comm: syz-executor.0 Not tainted 5.10.0-rc1-syzkaller-07083-g4c9720875573 #0
  Hardware name: IBM 3906 M04 701 (KVM/Linux)
  Call Trace:
    do_huge_pmd_anonymous_page+0xcda/0xd90 mm/huge_memory.c:744
    create_huge_pmd mm/memory.c:4256 [inline]
    __handle_mm_fault+0xe6e/0x1068 mm/memory.c:4480
    handle_mm_fault+0x288/0x748 mm/memory.c:4607
    do_exception+0x394/0xae0 arch/s390/mm/fault.c:479
    do_dat_exception+0x34/0x80 arch/s390/mm/fault.c:567
    pgm_check_handler+0x1da/0x22c arch/s390/kernel/entry.S:706
    copy_from_user_mvcos arch/s390/lib/uaccess.c:111 [inline]
    raw_copy_from_user+0x3a/0x88 arch/s390/lib/uaccess.c:174
    _copy_from_user+0x48/0xa8 lib/usercopy.c:16
    copy_from_user include/linux/uaccess.h:192 [inline]
    __do_sys_sigaltstack kernel/signal.c:4064 [inline]
    __s390x_sys_sigaltstack+0xc8/0x240 kernel/signal.c:4060
    system_call+0xe0/0x28c arch/s390/kernel/entry.S:415

  Allocated by task 9334:
    slab_alloc_node mm/slub.c:2891 [inline]
    slab_alloc mm/slub.c:2899 [inline]
    kmem_cache_alloc+0x118/0x348 mm/slub.c:2904
    vm_area_dup+0x9c/0x2b8 kernel/fork.c:356
    __split_vma+0xba/0x560 mm/mmap.c:2742
    split_vma+0xca/0x108 mm/mmap.c:2800
    mlock_fixup+0x4ae/0x600 mm/mlock.c:550
    apply_vma_lock_flags+0x2c6/0x398 mm/mlock.c:619
    do_mlock+0x1aa/0x718 mm/mlock.c:711
    __do_sys_mlock2 mm/mlock.c:738 [inline]
    __s390x_sys_mlock2+0x86/0xa8 mm/mlock.c:728
    system_call+0xe0/0x28c arch/s390/kernel/entry.S:415

  Freed by task 9333:
    slab_free mm/slub.c:3142 [inline]
    kmem_cache_free+0x7c/0x4b8 mm/slub.c:3158
    __vma_adjust+0x7b2/0x2508 mm/mmap.c:960
    vma_merge+0x87e/0xce0 mm/mmap.c:1209
    userfaultfd_release+0x412/0x6b8 fs/userfaultfd.c:868
    __fput+0x22c/0x7a8 fs/file_table.c:281
    task_work_run+0x200/0x320 kernel/task_work.c:151
    tracehook_notify_resume include/linux/tracehook.h:188 [inline]
    do_notify_resume+0x100/0x148 arch/s390/kernel/signal.c:538
    system_call+0xe6/0x28c arch/s390/kernel/entry.S:416

  The buggy address belongs to the object at 00000000962d6948 which belongs to the cache vm_area_struct of size 200
  The buggy address is located 64 bytes inside of 200-byte region [00000000962d6948, 00000000962d6a10)
  The buggy address belongs to the page: page:00000000313a09fe refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x962d6 flags: 0x3ffff00000000200(slab)
  raw: 3ffff00000000200 000040000257e080 0000000c0000000c 000000008020ba00
  raw: 0000000000000000 000f001e00000000 ffffffff00000001 0000000096959501
  page dumped because: kasan: bad access detected
  page->mem_cgroup:0000000096959501

  Memory state around the buggy address:
   00000000962d6880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   00000000962d6900: 00 fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb
  >00000000962d6980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                        ^
   00000000962d6a00: fb fb fc fc fc fc fc fc fc fc 00 00 00 00 00 00
   00000000962d6a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ==================================================================

Fixes: 6b251fc9 ("userfaultfd: call handle_userfault() for userfaultfd_missing() faults")
Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: <stable@vger.kernel.org>	[4.3+]
Link: https://lkml.kernel.org/r/20201110190329.11920-1-gerald.schaefer@linux.ibm.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If we reparent the slab objects to the root memcg, when we free the slab
object, we need to update the per-memcg vmstats to keep it correct for
the root memcg.  Now this at least affects the vmstat of
NR_KERNEL_STACK_KB for !CONFIG_VMAP_STACK when the thread stack size is
smaller than the PAGE_SIZE.

David said:
 "I assume that without this fix that the root memcg's vmstat would
  always be inflated if we reparented"

Fixes: ec9f0238 ("mm: workingset: fix vmstat counters for shadow nodes")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: <stable@vger.kernel.org>	[5.3+]
Link: https://lkml.kernel.org/r/20201110031015.15715-1-songmuchun@bytedance.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Both btrfs and fuse have reported faults caused by seeing a retry entry
instead of the page they were looking for.  This was caused by a missing
check in the iterator.

As can be seen in the below panic log, the accessing 0x402 causes a
panic.  In the xarray.h, 0x402 means RETRY_ENTRY.

  BUG: kernel NULL pointer dereference, address: 0000000000000402
  CPU: 14 PID: 306003 Comm: as Not tainted 5.9.0-1-amd64 #1 Debian 5.9.1-1
  Hardware name: Lenovo ThinkSystem SR665/7D2VCTO1WW, BIOS D8E106Q-1.01 05/30/2020
  RIP: 0010:fuse_readahead+0x152/0x470 [fuse]
  Code: 41 8b 57 18 4c 8d 54 10 ff 4c 89 d6 48 8d 7c 24 10 e8 d2 e3 28 f9 48 85 c0 0f 84 fe 00 00 00 44 89 f2 49 89 04 d4 44 8d 72 01 <48> 8b 10 41 8b 4f 1c 48 c1 ea 10 83 e2 01 80 fa 01 19 d2 81 e2 01
  RSP: 0018:ffffad99ceaebc50 EFLAGS: 00010246
  RAX: 0000000000000402 RBX: 0000000000000001 RCX: 0000000000000002
  RDX: 0000000000000000 RSI: ffff94c5af90bd98 RDI: ffffad99ceaebc60
  RBP: ffff94ddc1749a00 R08: 0000000000000402 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000100 R12: ffff94de6c429ce0
  R13: ffff94de6c4d3700 R14: 0000000000000001 R15: ffffad99ceaebd68
  FS:  00007f228c5c7040(0000) GS:ffff94de8ed80000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000402 CR3: 0000001dbd9b4000 CR4: 0000000000350ee0
  Call Trace:
    read_pages+0x83/0x270
    page_cache_readahead_unbounded+0x197/0x230
    generic_file_buffered_read+0x57a/0xa20
    new_sync_read+0x112/0x1a0
    vfs_read+0xf8/0x180
    ksys_read+0x5f/0xe0
    do_syscall_64+0x33/0x80
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 042124cc ("mm: add new readahead_control API")
Reported-by: David Sterba <dsterba@suse.com>
Reported-by: Wonhyuk Yang <vvghjk1234@gmail.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20201103142852.8543-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20201103124349.16722-1-vvghjk1234@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The core-mm has a default __weak implementation of phys_to_target_node()
to mirror the weak definition of memory_add_physaddr_to_nid().  That
symbol is exported for modules.  However, while the export in
mm/memory_hotplug.c exported the symbol in the configuration cases of:

	CONFIG_NUMA_KEEP_MEMINFO=y
	CONFIG_MEMORY_HOTPLUG=y

...and:

	CONFIG_NUMA_KEEP_MEMINFO=n
	CONFIG_MEMORY_HOTPLUG=y

...it failed to export the symbol in the case of:

	CONFIG_NUMA_KEEP_MEMINFO=y
	CONFIG_MEMORY_HOTPLUG=n

Not only is that broken, but Christoph points out that the kernel should
not be exporting any __weak symbol, which means that
memory_add_physaddr_to_nid() example that phys_to_target_node() copied
is broken too.

Rework the definition of phys_to_target_node() and
memory_add_physaddr_to_nid() to not require weak symbols.  Move to the
common arch override design-pattern of an asm header defining a symbol
to replace the default implementation.

The only common header that all memory_add_physaddr_to_nid() producing
architectures implement is asm/sparsemem.h.  In fact, powerpc already
defines its memory_add_physaddr_to_nid() helper in sparsemem.h.
Double-down on that observation and define phys_to_target_node() where
necessary in asm/sparsemem.h.  An alternate consideration that was
discarded was to put this override in asm/numa.h, but that entangles
with the definition of MAX_NUMNODES relative to the inclusion of
linux/nodemask.h, and requires powerpc to grow a new header.

The dependency on NUMA_KEEP_MEMINFO for DEV_DAX_HMEM_DEVICES is invalid
now that the symbol is properly exported / stubbed in all combinations
of CONFIG_NUMA_KEEP_MEMINFO and CONFIG_MEMORY_HOTPLUG.

[dan.j.williams@intel.com: v4]
  Link: https://lkml.kernel.org/r/160461461867.1505359.5301571728749534585.stgit@dwillia2-desk3.amr.corp.intel.com
[dan.j.williams@intel.com: powerpc: fix create_section_mapping compile warning]
  Link: https://lkml.kernel.org/r/160558386174.2948926.2740149041249041764.stgit@dwillia2-desk3.amr.corp.intel.com

Fixes: a035b6bf ("mm/memory_hotplug: introduce default phys_to_target_node() implementation")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lkml.kernel.org/r/160447639846.1133764.7044090803980177548.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

bpftrace parses the kernel headers and uses Clang under the hood.

Remove the version check when __BPF_TRACING__ is defined (as bpftrace
does) so that this tool can continue to parse kernel headers, even with
older clang sources.

Fixes: commit 1f7a44f6 ("compiler-clang: add build check for clang 10.0.1")
Reported-by: Chen Yu <yu.chen.surf@gmail.com>
Reported-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lkml.kernel.org/r/20201104191052.390657-1-ndesaulniers@google.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>