linux.git/mm/percpu.c, branch v4.19

percpu: stop leaking bitmap metadata blocks

2018-10-07T21:50:12+00:00

The commit ca460b3c9627 ("percpu: introduce bitmap metadata blocks")
introduced bitmap metadata blocks. These metadata blocks are allocated
whenever a new chunk is created, but they are never freed. Fix it.

Fixes: ca460b3c9627 ("percpu: introduce bitmap metadata blocks")
Signed-off-by: Mike Rapoport 
Cc: stable@vger.kernel.org
Signed-off-by: Dennis Zhou

/proc/meminfo: add percpu populated pages count

2018-08-22T17:52:45+00:00

Currently, percpu memory only exposes allocation and utilization
information via debugfs.  This more or less is only really useful for
understanding the fragmentation and allocation information at a per-chunk
level with a few global counters.  This is also gated behind a config.
BPF and cgroup, for example, have seen an increase in use causing
increased use of percpu memory.  Let's make it easier for someone to
identify how much memory is being used.

This patch adds the "Percpu" stat to meminfo to more easily look up how
much percpu memory is in use.  This number includes the cost for all
allocated backing pages and not just insight at the per a unit, per chunk
level.  Metadata is excluded.  I think excluding metadata is fair because
the backing memory scales with the numbere of cpus and can quickly
outweigh the metadata.  It also makes this calculation light.

Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com
Signed-off-by: Dennis Zhou 
Acked-by: Tejun Heo 
Acked-by: Roman Gushchin 
Reviewed-by: Andrew Morton 
Acked-by: David Rientjes 
Acked-by: Vlastimil Babka 
Cc: Johannes Weiner 
Cc: Christoph Lameter 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2018-04-03T03:20:12+00:00

Pul removal of obsolete architecture ports from Arnd Bergmann:
 "This removes the entire architecture code for blackfin, cris, frv,
  m32r, metag, mn10300, score, and tile, including the associated device
  drivers.

  I have been working with the (former) maintainers for each one to
  ensure that my interpretation was right and the code is definitely
  unused in mainline kernels. Many had fond memories of working on the
  respective ports to start with and getting them included in upstream,
  but also saw no point in keeping the port alive without any users.

  In the end, it seems that while the eight architectures are extremely
  different, they all suffered the same fate: There was one company in
  charge of an SoC line, a CPU microarchitecture and a software
  ecosystem, which was more costly than licensing newer off-the-shelf
  CPU cores from a third party (typically ARM, MIPS, or RISC-V). It
  seems that all the SoC product lines are still around, but have not
  used the custom CPU architectures for several years at this point. In
  contrast, CPU instruction sets that remain popular and have actively
  maintained kernel ports tend to all be used across multiple licensees.

  [ See the new nds32 port merged in the previous commit for the next
    generation of "one company in charge of an SoC line, a CPU
    microarchitecture and a software ecosystem"   - Linus ]

  The removal came out of a discussion that is now documented at
  https://lwn.net/Articles/748074/. Unlike the original plans, I'm not
  marking any ports as deprecated but remove them all at once after I
  made sure that they are all unused. Some architectures (notably tile,
  mn10300, and blackfin) are still being shipped in products with old
  kernels, but those products will never be updated to newer kernel
  releases.

  After this series, we still have a few architectures without mainline
  gcc support:

   - unicore32 and hexagon both have very outdated gcc releases, but the
     maintainers promised to work on providing something newer. At least
     in case of hexagon, this will only be llvm, not gcc.

   - openrisc, risc-v and nds32 are still in the process of finishing
     their support or getting it added to mainline gcc in the first
     place. They all have patched gcc-7.3 ports that work to some
     degree, but complete upstream support won't happen before gcc-8.1.
     Csky posted their first kernel patch set last week, their situation
     will be similar

  [ Palmer Dabbelt points out that RISC-V support is in mainline gcc
    since gcc-7, although gcc-7.3.0 is the recommended minimum  - Linus ]"

This really says it all:

 2498 files changed, 95 insertions(+), 467668 deletions(-)

* tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: (74 commits)
  MAINTAINERS: UNICORE32: Change email account
  staging: iio: remove iio-trig-bfin-timer driver
  tty: hvc: remove tile driver
  tty: remove bfin_jtag_comm and hvc_bfin_jtag drivers
  serial: remove tile uart driver
  serial: remove m32r_sio driver
  serial: remove blackfin drivers
  serial: remove cris/etrax uart drivers
  usb: Remove Blackfin references in USB support
  usb: isp1362: remove blackfin arch glue
  usb: musb: remove blackfin port
  usb: host: remove tilegx platform glue
  pwm: remove pwm-bfin driver
  i2c: remove bfin-twi driver
  spi: remove blackfin related host drivers
  watchdog: remove bfin_wdt driver
  can: remove bfin_can driver
  mmc: remove bfin_sdh driver
  input: misc: remove blackfin rotary driver
  input: keyboard: remove bf54x driver
  ...

treewide: simplify Kconfig dependencies for removed archs

2018-03-26T13:55:57+00:00

A lot of Kconfig symbols have architecture specific dependencies.
In those cases that depend on architectures we have already removed,
they can be omitted.

Acked-by: Kalle Valo 
Acked-by: Alexandre Belloni 
Signed-off-by: Arnd Bergmann

mm: Allow to kill tasks doing pcpu_alloc() and waiting for pcpu_balance_workfn()

2018-03-19T16:38:50+00:00

In case of memory deficit and low percpu memory pages,
pcpu_balance_workfn() takes pcpu_alloc_mutex for a long
time (as it makes memory allocations itself and waits
for memory reclaim). If tasks doing pcpu_alloc() are
choosen by OOM killer, they can't exit, because they
are waiting for the mutex.

The patch makes pcpu_alloc() to care about killing signal
and use mutex_lock_killable(), when it's allowed by GFP
flags. This guarantees, a task does not miss SIGKILL
from OOM killer.

Signed-off-by: Kirill Tkhai 
Signed-off-by: Tejun Heo

percpu: include linux/sched.h for cond_resched()

2018-03-19T16:38:18+00:00

microblaze build broke due to missing declaration of the
cond_resched() invocation added recently.  Let's include linux/sched.h
explicitly.

Signed-off-by: Tejun Heo 
Reported-by: kbuild test robot

percpu: add a schedule point in pcpu_balance_workfn()

2018-02-23T16:52:34+00:00

When a large BPF percpu map is destroyed, I have seen
pcpu_balance_workfn() holding cpu for hundreds of milliseconds.

On KASAN config and 112 hyperthreads, average time to destroy a chunk
is ~4 ms.

[ 2489.841376] destroy chunk 1 in 4148689 ns
...
[ 2490.093428] destroy chunk 32 in 4072718 ns

Signed-off-by: Eric Dumazet 
Signed-off-by: Tejun Heo

percpu: allow select gfp to be passed to underlying allocators

2018-02-18T13:33:01+00:00

The prior patch added support for passing gfp flags through to the
underlying allocators. This patch allows users to pass along gfp flags
(currently only __GFP_NORETRY and __GFP_NOWARN) to the underlying
allocators. This should allow users to decide if they are ok with
failing allocations recovering in a more graceful way.

Additionally, gfp passing was done as additional flags in the previous
patch. Instead, change this to caller passed semantics. GFP_KERNEL is
also removed as the default flag. It continues to be used for internally
caused underlying percpu allocations.

V2:
Removed gfp_percpu_mask in favor of doing it inline.
Removed GFP_KERNEL as a default flag for __alloc_percpu_gfp.

Signed-off-by: Dennis Zhou 
Suggested-by: Daniel Borkmann 
Acked-by: Christoph Lameter 
Signed-off-by: Tejun Heo

percpu: add __GFP_NORETRY semantics to the percpu balancing path

2018-02-18T13:33:00+00:00

Percpu memory using the vmalloc area based chunk allocator lazily
populates chunks by first requesting the full virtual address space
required for the chunk and subsequently adding pages as allocations come
through. To ensure atomic allocations can succeed, a workqueue item is
used to maintain a minimum number of empty pages. In certain scenarios,
such as reported in [1], it is possible that physical memory becomes
quite scarce which can result in either a rather long time spent trying
to find free pages or worse, a kernel panic.

This patch adds support for __GFP_NORETRY and __GFP_NOWARN passing them
through to the underlying allocators. This should prevent any
unnecessary panics potentially caused by the workqueue item. The passing
of gfp around is as additional flags rather than a full set of flags.
The next patch will change these to caller passed semantics.

V2:
Added const modifier to gfp flags in the balance path.
Removed an extra whitespace.

[1] https://lkml.org/lkml/2018/2/12/551

Signed-off-by: Dennis Zhou 
Suggested-by: Daniel Borkmann 
Reported-by: syzbot+adb03f3f0bb57ce3acda@syzkaller.appspotmail.com
Acked-by: Christoph Lameter 
Signed-off-by: Tejun Heo

percpu: match chunk allocator declarations with definitions

2018-02-18T13:33:00+00:00

At some point the function declaration parameters got out of sync with
the function definitions in percpu-vm.c and percpu-km.c. This patch
makes them match again.

Signed-off-by: Dennis Zhou 
Acked-by: Christoph Lameter 
Signed-off-by: Tejun Heo