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  1. 23 Sep, 2021 1 commit
    • Shakeel Butt's avatar
      memcg: flush lruvec stats in the refault · 1f828223
      Shakeel Butt authored 
      Prior to the commit 7e1c0d6f ("memcg: switch lruvec stats to rstat")
and the commit aa48e47e ("memcg: infrastructure to flush memcg
stats"), each lruvec memcg stats can be off by (nr_cgroups * nr_cpus *
32) at worst and for unbounded amount of time.  The commit aa48e47e
moved the lruvec stats to rstat infrastructure and the commit
7e1c0d6f bounded the error for all the lruvec stats to (nr_cpus *
32) at worst for at most 2 seconds.  More specifically it decoupled the
number of stats and the number of cgroups from the error rate.

However this reduction in error comes with the cost of triggering the
slowpath of stats update more frequently.  Previously in the slowpath
the kernel adds the stats up the memcg tree.  After aa48e47e, the
kernel triggers the asyn lruvec stats flush through queue_work().  This
causes regression reports from 0day kernel bot [1] as well as from
phoronix test suite [2].

We tried two options to fix the regression:

 1) Increase the threshold to trigger the slowpath in lruvec stats
    update codepath from 32 to 512.

 2) Remove the slowpath from lruvec stats update codepath and instead
    flush the stats in the page refault codepath. The assumption is that
    the kernel timely flush the stats, so, the update tree would be
    small in the refault codepath to not cause the preformance impact.

Following are the results of will-it-scale/page_fault[1|2|3] benchmark
on four settings i.e.  (1) 5.15-rc1 as baseline (2) 5.15-rc1 with
aa48e47e and 7e1c0d6f reverted (3) 5.15-rc1 with option-1
(4) 5.15-rc1 with option-2.

  test       (1)      (2)               (3)               (4)
  pg_f1   368563   406277 (10.23%)   399693  (8.44%)   416398 (12.97%)
  pg_f2   338399   372133  (9.96%)   369180  (9.09%)   381024 (12.59%)
  pg_f3   500853   575399 (14.88%)   570388 (13.88%)   576083 (15.02%)

From the above result, it seems like the option-2 not only solves the
regression but also improves the performance for at least these
benchmarks.

Feng Tang (intel) ran the aim7 benchmark with these two options and
confirms that option-1 reduces the regression but option-2 removes the
regression.

Michael Larabel (phoronix) ran multiple benchmarks with these options
and reported the results at [3] and it shows for most benchmarks
option-2 removes the regression introduced by the commit aa48e47e
("memcg: infrastructure to flush memcg stats").

Based on the experiment results, this patch proposed the option-2 as the
solution to resolve the regression.

Link: https://lore.kernel.org/all/20210726022421.GB21872@xsang-OptiPlex-9020 [1]
Link: https://www.phoronix.com/scan.php?page=article&item=linux515-compile-regress [2]
Link: https://openbenchmarking.org/result/2109226-DEBU-LINUX5104 [3]
Fixes: aa48e47e ("memcg: infrastructure to flush memcg stats")
Signed-off-by: default avatarShakeel Butt <shakeelb@google.com>
Tested-by: default avatarMichael Larabel <Michael@phoronix.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hillf Danton <hdanton@sina.com>,
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1f828223
  3. 22 Sep, 2021 8 commits
  5. 21 Sep, 2021 6 commits
  7. 20 Sep, 2021 9 commits
    • Linus Torvalds's avatar
      Merge tag 'afs-fixes-20210913' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs · d9fb6784
      Linus Torvalds authored 
      Pull AFS fixes from David Howells:
 "Fixes for AFS problems that can cause data corruption due to
  interaction with another client modifying data cached locally:

   - When d_revalidating a dentry, don't look at the inode to which it
     points. Only check the directory to which the dentry belongs. This
     was confusing things and causing the silly-rename cleanup code to
     remove the file now at the dentry of a file that got deleted.

   - Fix mmap data coherency. When a callback break is received that
     relates to a file that we have cached, the data content may have
     been changed (there are other reasons, such as the user's rights
     having been changed). However, we're checking it lazily, only on
     entry to the kernel, which doesn't happen if we have a writeable
     shared mapped page on that file.

     We make the kernel keep track of mmapped files and clear all PTEs
     mapping to that file as soon as the callback comes in by calling
     unmap_mapping_pages() (we don't necessarily want to zap the
     pagecache). This causes the kernel to be reentered when userspace
     tries to access the mmapped address range again - and at that point
     we can query the server and, if we need to, zap the page cache.

     Ideally, I would check each file at the point of notification, but
     that involves poking the server[*] - which is holding an exclusive
     lock on the vnode it is changing, waiting for all the clients it
     notified to reply. This could then deadlock against the server.
     Further, invalidating the pagecache might call ->launder_page(),
     which would try to write to the file, which would definitely
     deadlock. (AFS doesn't lease file access).

     [*] Checking to see if the file content has changed is a matter of
         comparing the current data version number, but we have to ask
         the server for that. We also need to get a new callback promise
         and we need to poke the server for that too.

   - Add some more points at which the inode is validated, since we're
     doing it lazily, notably in ->read_iter() and ->page_mkwrite(), but
     also when performing some directory operations.

     Ideally, checking in ->read_iter() would be done in some derivation
     of filemap_read(). If we're going to call the server to read the
     file, then we get the file status fetch as part of that.

   - The above is now causing us to make a lot more calls to
     afs_validate() to check the inode - and afs_validate() takes the
     RCU read lock each time to make a quick check (ie.
     afs_check_validity()). This is entirely for the purpose of checking
     cb_s_break to see if the server we're using reinitialised its list
     of callbacks - however this isn't a very common event, so most of
     the time we're taking this needlessly.

     Add a new cell-wide counter to count the number of
     reinitialisations done by any server and check that - and only if
     that changes, take the RCU read lock and check the server list (the
     server list may change, but the cell a file is part of won't).

   - Don't update vnode->cb_s_break and ->cb_v_break inside the validity
     checking loop. The cb_lock is done with read_seqretry, so we might
     go round the loop a second time after resetting those values - and
     that could cause someone else checking validity to miss something
     (I think).

  Also included are patches for fixes for some bugs encountered whilst
  debugging this:

   - Fix a leak of afs_read objects and fix a leak of keys hidden by
     that.

   - Fix a leak of pages that couldn't be added to extend a writeback.

   - Fix the maintenance of i_blocks when i_size is changed by a local
     write or a local dir edit"

Link: https://bugzilla.kernel.org/show_bug.cgi?id=214217 [1]
Link: https://lore.kernel.org/r/163111665183.283156.17200205573146438918.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163113612442.352844.11162345591911691150.stgit@warthog.procyon.org.uk/ # i_blocks patch

* tag 'afs-fixes-20210913' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  afs: Fix updating of i_blocks on file/dir extension
  afs: Fix corruption in reads at fpos 2G-4G from an OpenAFS server
  afs: Try to avoid taking RCU read lock when checking vnode validity
  afs: Fix mmap coherency vs 3rd-party changes
  afs: Fix incorrect triggering of sillyrename on 3rd-party invalidation
  afs: Add missing vnode validation checks
  afs: Fix page leak
  afs: Fix missing put on afs_read objects and missing get on the key therein
      d9fb6784
    • Linus Torvalds's avatar
      Merge tag '5.15-rc1-ksmbd' of git://git.samba.org/ksmbd · 707a63e9
      Linus Torvalds authored 
      Pull ksmbd server fixes from Steve French:
 "Three ksmbd fixes, including an important security fix for path
  processing, and a buffer overflow check, and a trivial fix for
  incorrect header inclusion"

* tag '5.15-rc1-ksmbd' of git://git.samba.org/ksmbd:
  ksmbd: add validation for FILE_FULL_EA_INFORMATION of smb2_get_info
  ksmbd: prevent out of share access
  ksmbd: transport_rdma: Don't include rwlock.h directly
      707a63e9
    • Linus Torvalds's avatar
      Merge tag '5.15-rc1-smb3' of git://git.samba.org/sfrench/cifs-2.6 · fdf50784
      Linus Torvalds authored 
      Pull cifs client fixes from Steve French:

 - two deferred close fixes (for bugs found with xfstests 478 and 461)

 - a deferred close improvement in rename

 - two trivial fixes for incorrect Linux comment formatting of multiple
   cifs files (pointed out by automated kernel test robot and
   checkpatch)

* tag '5.15-rc1-smb3' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: Not to defer close on file when lock is set
  cifs: Fix soft lockup during fsstress
  cifs: Deferred close performance improvements
  cifs: fix incorrect kernel doc comments
  cifs: remove pathname for file from SPDX header
      fdf50784
    • Linus Torvalds's avatar
      Merge tag 'spi-fix-v5.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi · 4c17ca27
      Linus Torvalds authored 
      Pull spi fixes from Mark BrownL
 "This contains a couple of fixes, one fix for handling of zero length
  transfers on Rockchip devices and a warning fix which will conflict
  with a version you did but cleans up some extra unneeded forward
  declarations as well which seems a bit neater"

* tag 'spi-fix-v5.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: tegra20-slink: Declare runtime suspend and resume functions conditionally
  spi: rockchip: handle zero length transfers without timing out
      4c17ca27
    • Linus Torvalds's avatar
      Merge tag 'regulator-fix-v5.15-rc2' of... · 2ff59bad
      Linus Torvalds authored 
      Merge tag 'regulator-fix-v5.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator

Pull regulator fixes from Mark Brown:
 "A couple of small device specific fixes that have been sent since the
  merge window, neither of which stands out particularly"

* tag 'regulator-fix-v5.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: max14577: Revert "regulator: max14577: Add proper module aliases strings"
  regulator: qcom-rpmh-regulator: fix pm8009-1 ldo7 resource name
      2ff59bad
    • Guenter Roeck's avatar
      drm/nouveau/nvkm: Replace -ENOSYS with -ENODEV · e8f71f89
      Guenter Roeck authored 
      nvkm test builds fail with the following error.

  drivers/gpu/drm/nouveau/nvkm/engine/device/ctrl.c: In function 'nvkm_control_mthd_pstate_info':
  drivers/gpu/drm/nouveau/nvkm/engine/device/ctrl.c:60:35: error: overflow in conversion from 'int' to '__s8' {aka 'signed char'} changes value from '-251' to '5'

The code builds on most architectures, but fails on parisc where ENOSYS
is defined as 251.

Replace the error code with -ENODEV (-19).  The actual error code does
not really matter and is not passed to userspace - it just has to be
negative.

Fixes: 7238eca4 ("drm/nouveau: expose pstate selection per-power source in sysfs")
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e8f71f89
    • Linus Torvalds's avatar
      sparc64: fix pci_iounmap() when CONFIG_PCI is not set · d8b1e10a
      Linus Torvalds authored 
      Guenter reported [1] that the pci_iounmap() changes remain problematic,
with sparc64 allnoconfig and tinyconfig still not building due to the
header file changes and confusion with the arch-specific pci_iounmap()
implementation.

I'm pretty convinced that sparc should just use GENERIC_IOMAP instead of
doing its own thing, since it turns out that the sparc64 version of
pci_iounmap() is somewhat buggy (see [2]).  But in the meantime, this
just fixes the build by avoiding the trivial re-definition of the empty
case.

Link: https://lore.kernel.org/lkml/20210920134424.GA346531@roeck-us.net/ [1]
Link: https://lore.kernel.org/lkml/CAHk-=wgheheFx9myQyy5osh79BAazvmvYURAtub2gQtMvLrhqQ@mail.gmail.com/ [2]
Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d8b1e10a
    • Linus Torvalds's avatar
      Linux 5.15-rc2 · e4e737bb
      Linus Torvalds authored
      e4e737bb
    • Linus Torvalds's avatar
      pci_iounmap'2: Electric Boogaloo: try to make sense of it all · 316e8d79
      Linus Torvalds authored 
      Nathan Chancellor reports that the recent change to pci_iounmap in
commit 9caea000 ("parisc: Declare pci_iounmap() parisc version only
when CONFIG_PCI enabled") causes build errors on arm64.

It took me about two hours to convince myself that I think I know what
the logic of that mess of #ifdef's in the <asm-generic/io.h> header file
really aim to do, and rewrite it to be easier to follow.

Famous last words.

Anyway, the code has now been lifted from that grotty header file into
lib/pci_iomap.c, and has fairly extensive comments about what the logic
is.  It also avoids indirecting through another confusing (and badly
named) helper function that has other preprocessor config conditionals.

Let's see what odd architecture did something else strange in this area
to break things.  But my arm64 cross build is clean.

Fixes: 9caea000 ("parisc: Declare pci_iounmap() parisc version only when CONFIG_PCI enabled")
Reported-by: default avatarNathan Chancellor <nathan@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Ulrich Teichert <krypton@ulrich-teichert.org>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      316e8d79
  9. 19 Sep, 2021 16 commits
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