1. 07 Aug, 2014 40 commits
    • George Spelvin's avatar
      lib/glob.c: add CONFIG_GLOB_SELFTEST · 5f9be824
      George Spelvin authored
      This was useful during development, and is retained for future
      regression testing.
      
      GCC appears to have no way to place string literals in a particular
      section; adding __initconst to a char pointer leaves the string itself
      in the default string section, where it will not be thrown away after
      module load.
      
      Thus all string constants are kept in explicitly declared and named
      arrays.  Sorry this makes printk a bit harder to read.  At least the
      tests are more compact.
      Signed-off-by: default avatarGeorge Spelvin <linux@horizon.com>
      Cc: Randy Dunlap <rdunlap@infradead.org>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ingo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5f9be824
    • George Spelvin's avatar
      lib: add lib/glob.c · b0125085
      George Spelvin authored
      This is a helper function from drivers/ata/libata_core.c, where it is
      used to blacklist particular device models.  It's being moved to lib/ so
      other drivers may use it for the same purpose.
      
      This implementation in non-recursive, so is safe for the kernel stack.
      
      [akpm@linux-foundation.org: fix sparse warning]
      Signed-off-by: default avatarGeorge Spelvin <linux@horizon.com>
      Cc: Randy Dunlap <rdunlap@infradead.org>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ingo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b0125085
    • Sergey Senozhatsky's avatar
      zlib: clean up some dead code · 62e7ca52
      Sergey Senozhatsky authored
      Cleanup unused `if 0'-ed functions, which have been dead since 2006
      (commits 87c2ce3b ("lib/zlib*: cleanups") by Adrian Bunk and
      4f3865fb ("zlib_inflate: Upgrade library code to a recent version")
      by Richard Purdie):
      
       - zlib_deflateSetDictionary
       - zlib_deflateParams
       - zlib_deflateCopy
       - zlib_inflateSync
       - zlib_syncsearch
       - zlib_inflateSetDictionary
       - zlib_inflatePrime
      Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      62e7ca52
    • Ken Helias's avatar
      klist: use same naming scheme as hlist for klist_add_after() · 0f9859ca
      Ken Helias authored
      The name was modified from hlist_add_after() to hlist_add_behind() when
      adjusting the order of arguments to match the one with
      klist_add_after().  This is necessary to break old code when it would
      use it the wrong way.
      
      Make klist follow this naming scheme for consistency.
      Signed-off-by: default avatarKen Helias <kenhelias@firemail.de>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0f9859ca
    • Ken Helias's avatar
      list: fix order of arguments for hlist_add_after(_rcu) · 1d023284
      Ken Helias authored
      All other add functions for lists have the new item as first argument
      and the position where it is added as second argument.  This was changed
      for no good reason in this function and makes using it unnecessary
      confusing.
      
      The name was changed to hlist_add_behind() to cause unconverted code to
      generate a compile error instead of using the wrong parameter order.
      
      [akpm@linux-foundation.org: coding-style fixes]
      Signed-off-by: default avatarKen Helias <kenhelias@firemail.de>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>	[intel driver bits]
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1d023284
    • Ken Helias's avatar
      list: make hlist_add_after() argument names match hlist_add_after_rcu() · bc18dd33
      Ken Helias authored
      The argument names for hlist_add_after() are poorly chosen because they
      look the same as the ones for hlist_add_before() but have to be used
      differently.
      
      hlist_add_after_rcu() has made a better choice.
      Signed-off-by: default avatarKen Helias <kenhelias@firemail.de>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bc18dd33
    • Neil Zhang's avatar
      kernel/printk/printk.c: fix bool assignements · d25d9fec
      Neil Zhang authored
      Fix coccinelle warnings.
      Signed-off-by: default avatarNeil Zhang <zhangwm@marvell.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d25d9fec
    • Jan Kara's avatar
      printk: enable interrupts before calling console_trylock_for_printk() · 5874af20
      Jan Kara authored
      We need interrupts disabled when calling console_trylock_for_printk()
      only so that cpu id we pass to can_use_console() remains valid (for
      other things console_sem provides all the exclusion we need and
      deadlocks on console_sem due to interrupts are impossible because we use
      down_trylock()).  However if we are rescheduled, we are guaranteed to
      run on an online cpu so we can easily just get the cpu id in
      can_use_console().
      
      We can lose a bit of performance when we enable interrupts in
      vprintk_emit() and then disable them again in console_unlock() but OTOH
      it can somewhat reduce interrupt latency caused by console_unlock().
      
      We differ from (reverted) commit 939f04be in that we avoid calling
      console_unlock() from vprintk_emit() with lockdep enabled as that has
      unveiled quite some bugs leading to system freezes during boot (e.g.
        https://lkml.org/lkml/2014/5/30/242,
        https://lkml.org/lkml/2014/6/28/521).
      Signed-off-by: default avatarJan Kara <jack@suse.cz>
      Tested-by: default avatarAndreas Bombe <aeb@debian.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5874af20
    • Alex Elder's avatar
      printk: miscellaneous cleanups · 249771b8
      Alex Elder authored
      Some small cleanups to kernel/printk/printk.c.  None of them should
      cause any change in behavior.
      
        - When CONFIG_PRINTK is defined, parenthesize the value of LOG_LINE_MAX.
        - When CONFIG_PRINTK is *not* defined, there is an extra LOG_LINE_MAX
          definition; delete it.
        - Pull an assignment out of a conditional expression in console_setup().
        - Use isdigit() in console_setup() rather than open coding it.
        - In update_console_cmdline(), drop a NUL-termination assignment;
          the strlcpy() call that precedes it guarantees it's not needed.
        - Simplify some logic in printk_timed_ratelimit().
      Signed-off-by: default avatarAlex Elder <elder@linaro.org>
      Reviewed-by: default avatarPetr Mladek <pmladek@suse.cz>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Jan Kara <jack@suse.cz>
      Cc: John Stultz <john.stultz@linaro.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      249771b8
    • Alex Elder's avatar
      printk: use a clever macro · e99aa461
      Alex Elder authored
      Use the IS_ENABLED() macro rather than #ifdef blocks to set certain
      global values.
      Signed-off-by: default avatarAlex Elder <elder@linaro.org>
      Acked-by: default avatarBorislav Petkov <bp@suse.de>
      Reviewed-by: default avatarPetr Mladek <pmladek@suse.cz>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: John Stultz <john.stultz@linaro.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e99aa461
    • Alex Elder's avatar
      printk: fix some comments · 0b90fec3
      Alex Elder authored
      Fix a few comments that don't accurately describe their corresponding
      code.  It also fixes some minor typographical errors.
      Signed-off-by: default avatarAlex Elder <elder@linaro.org>
      Reviewed-by: default avatarPetr Mladek <pmladek@suse.cz>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Jan Kara <jack@suse.cz>
      Cc: John Stultz <john.stultz@linaro.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0b90fec3
    • Alex Elder's avatar
      printk: rename DEFAULT_MESSAGE_LOGLEVEL · 42a9dc0b
      Alex Elder authored
      Commit a8fe19eb ("kernel/printk: use symbolic defines for console
      loglevels") makes consistent use of symbolic values for printk() log
      levels.
      
      The naming scheme used is different from the one used for
      DEFAULT_MESSAGE_LOGLEVEL though.  Change that symbol name to be
      MESSAGE_LOGLEVEL_DEFAULT for consistency.  And because the value of that
      symbol comes from a similarly-named config option, rename
      CONFIG_DEFAULT_MESSAGE_LOGLEVEL as well.
      Signed-off-by: default avatarAlex Elder <elder@linaro.org>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Jan Kara <jack@suse.cz>
      Cc: John Stultz <john.stultz@linaro.org>
      Cc: Petr Mladek <pmladek@suse.cz>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      42a9dc0b
    • Alex Elder's avatar
      printk: tweak do_syslog() to match comments · e97e1267
      Alex Elder authored
      In do_syslog() there's a path used by kmsg_poll() and kmsg_read() that
      only needs to know whether there's any data available to read (and not
      its size).  These callers only check for non-zero return.  As a
      shortcut, do_syslog() returns the difference between what has been
      logged and what has been "seen."
      
      The comments say that the "count of records" should be returned but it's
      not.  Instead it returns (log_next_idx - syslog_idx), which is a
      difference between buffer offsets--and the result could be negative.
      
      The behavior is the same (it'll be zero or not in the same cases), but
      the count of records is more meaningful and it matches what the comments
      say.  So change the code to return that.
      Signed-off-by: default avatarAlex Elder <elder@linaro.org>
      Cc: Petr Mladek <pmladek@suse.cz>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Joe Perches <joe@perches.com>
      Cc: John Stultz <john.stultz@linaro.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e97e1267
    • Luis R. Rodriguez's avatar
      printk: allow increasing the ring buffer depending on the number of CPUs · 23b2899f
      Luis R. Rodriguez authored
      The default size of the ring buffer is too small for machines with a
      large amount of CPUs under heavy load.  What ends up happening when
      debugging is the ring buffer overlaps and chews up old messages making
      debugging impossible unless the size is passed as a kernel parameter.
      An idle system upon boot up will on average spew out only about one or
      two extra lines but where this really matters is on heavy load and that
      will vary widely depending on the system and environment.
      
      There are mechanisms to help increase the kernel ring buffer for tracing
      through debugfs, and those interfaces even allow growing the kernel ring
      buffer per CPU.  We also have a static value which can be passed upon
      boot.  Relying on debugfs however is not ideal for production, and
      relying on the value passed upon bootup is can only used *after* an
      issue has creeped up.  Instead of being reactive this adds a proactive
      measure which lets you scale the amount of contributions you'd expect to
      the kernel ring buffer under load by each CPU in the worst case
      scenario.
      
      We use num_possible_cpus() to avoid complexities which could be
      introduced by dynamically changing the ring buffer size at run time,
      num_possible_cpus() lets us use the upper limit on possible number of
      CPUs therefore avoiding having to deal with hotplugging CPUs on and off.
      This introduces the kernel configuration option LOG_CPU_MAX_BUF_SHIFT
      which is used to specify the maximum amount of contributions to the
      kernel ring buffer in the worst case before the kernel ring buffer flips
      over, the size is specified as a power of 2.  The total amount of
      contributions made by each CPU must be greater than half of the default
      kernel ring buffer size (1 << LOG_BUF_SHIFT bytes) in order to trigger
      an increase upon bootup.  The kernel ring buffer is increased to the
      next power of two that would fit the required minimum kernel ring buffer
      size plus the additional CPU contribution.  For example if LOG_BUF_SHIFT
      is 18 (256 KB) you'd require at least 128 KB contributions by other CPUs
      in order to trigger an increase of the kernel ring buffer.  With a
      LOG_CPU_BUF_SHIFT of 12 (4 KB) you'd require at least anything over > 64
      possible CPUs to trigger an increase.  If you had 128 possible CPUs the
      amount of minimum required kernel ring buffer bumps to:
      
         ((1 << 18) + ((128 - 1) * (1 << 12))) / 1024 = 764 KB
      
      Since we require the ring buffer to be a power of two the new required
      size would be 1024 KB.
      
      This CPU contributions are ignored when the "log_buf_len" kernel
      parameter is used as it forces the exact size of the ring buffer to an
      expected power of two value.
      
      [pmladek@suse.cz: fix build]
      Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@suse.com>
      Signed-off-by: default avatarPetr Mladek <pmladek@suse.cz>
      Tested-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
      Tested-by: default avatarPetr Mladek <pmladek@suse.cz>
      Reviewed-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
      Cc: Andrew Lunn <andrew@lunn.ch>
      Cc: Stephen Warren <swarren@wwwdotorg.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Petr Mladek <pmladek@suse.cz>
      Cc: Joe Perches <joe@perches.com>
      Cc: Arun KS <arunks.linux@gmail.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Davidlohr Bueso <davidlohr@hp.com>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Jan Kara <jack@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      23b2899f
    • Luis R. Rodriguez's avatar
      printk: make dynamic units clear for the kernel ring buffer · f5405172
      Luis R. Rodriguez authored
      Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@suse.com>
      Suggested-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
      Cc: Andrew Lunn <andrew@lunn.ch>
      Cc: Stephen Warren <swarren@wwwdotorg.org>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Petr Mladek <pmladek@suse.cz>
      Cc: Joe Perches <joe@perches.com>
      Cc: Arun KS <arunks.linux@gmail.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Davidlohr Bueso <davidlohr@hp.com>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Jan Kara <jack@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f5405172
    • Luis R. Rodriguez's avatar
      printk: move power of 2 practice of ring buffer size to a helper · c0a318a3
      Luis R. Rodriguez authored
      In practice the power of 2 practice of the size of the kernel ring
      buffer remains purely historical but not a requirement, specially now
      that we have LOG_ALIGN and use it for both static and dynamic
      allocations.  It could have helped with implicit alignment back in the
      days given the even the dynamically sized ring buffer was guaranteed to
      be aligned so long as CONFIG_LOG_BUF_SHIFT was set to produce a
      __LOG_BUF_LEN which is architecture aligned, since log_buf_len=n would
      be allowed only if it was > __LOG_BUF_LEN and we always ended up
      rounding the log_buf_len=n to the next power of 2 with
      roundup_pow_of_two(), any multiple of 2 then should be also architecture
      aligned.  These assumptions of course relied heavily on
      CONFIG_LOG_BUF_SHIFT producing an aligned value but users can always
      change this.
      
      We now have precise alignment requirements set for the log buffer size
      for both static and dynamic allocations, but lets upkeep the old
      practice of using powers of 2 for its size to help with easy expected
      scalable values and the allocators for dynamic allocations.  We'll reuse
      this later so move this into a helper.
      Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@suse.com>
      Cc: Andrew Lunn <andrew@lunn.ch>
      Cc: Stephen Warren <swarren@wwwdotorg.org>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Petr Mladek <pmladek@suse.cz>
      Cc: Joe Perches <joe@perches.com>
      Cc: Arun KS <arunks.linux@gmail.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Davidlohr Bueso <davidlohr@hp.com>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Jan Kara <jack@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c0a318a3
    • Luis R. Rodriguez's avatar
      printk: make dynamic kernel ring buffer alignment explicit · 70300177
      Luis R. Rodriguez authored
      We have to consider alignment for the ring buffer both for the default
      static size, and then also for when an dynamic allocation is made when
      the log_buf_len=n kernel parameter is passed to set the size
      specifically to a size larger than the default size set by the
      architecture through CONFIG_LOG_BUF_SHIFT.
      
      The default static kernel ring buffer can be aligned properly if
      architectures set CONFIG_LOG_BUF_SHIFT properly, we provide ranges for
      the size though so even if CONFIG_LOG_BUF_SHIFT has a sensible aligned
      value it can be reduced to a non aligned value.  Commit 6ebb017d
      ("printk: Fix alignment of buf causing crash on ARM EABI") by Andrew
      Lunn ensures the static buffer is always aligned and the decision of
      alignment is done by the compiler by using __alignof__(struct log).
      
      When log_buf_len=n is used we allocate the ring buffer dynamically.
      Dynamic allocation varies, for the early allocation called before
      setup_arch() memblock_virt_alloc() requests a page aligment and for the
      default kernel allocation memblock_virt_alloc_nopanic() requests no
      special alignment, which in turn ends up aligning the allocation to
      SMP_CACHE_BYTES, which is L1 cache aligned.
      
      Since we already have the required alignment for the kernel ring buffer
      though we can do better and request explicit alignment for LOG_ALIGN.
      This does that to be safe and make dynamic allocation alignment
      explicit.
      Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@suse.com>
      Tested-by: default avatarPetr Mladek <pmladek@suse.cz>
      Acked-by: default avatarPetr Mladek <pmladek@suse.cz>
      Cc: Andrew Lunn <andrew@lunn.ch>
      Cc: Stephen Warren <swarren@wwwdotorg.org>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Petr Mladek <pmladek@suse.cz>
      Cc: Joe Perches <joe@perches.com>
      Cc: Arun KS <arunks.linux@gmail.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Davidlohr Bueso <davidlohr@hp.com>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Jan Kara <jack@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      70300177
    • Geoff Levand's avatar
    • Joe Perches's avatar
      fs.h, drivers/hwmon/asus_atk0110.c: fix DEFINE_SIMPLE_ATTRIBUTE semicolon definition and use · 68be3029
      Joe Perches authored
      The DEFINE_SIMPLE_ATTRIBUTE macro should not end in a ; Fix the one use
      in the kernel tree that did not have a semicolon.
      Signed-off-by: default avatarJoe Perches <joe@perches.com>
      Acked-by: default avatarGuenter Roeck <linux@roeck-us.net>
      Acked-by: default avatarLuca Tettamanti <kronos.it@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      68be3029
    • Jiri Kosina's avatar
      ./Makefile: tell gcc optimizer to never introduce new data races · 69102311
      Jiri Kosina authored
      We have been chasing a memory corruption bug, which turned out to be
      caused by very old gcc (4.3.4), which happily turned conditional load
      into a non-conditional one, and that broke correctness (the condition
      was met only if lock was held) and corrupted memory.
      
      This particular problem with that particular code did not happen when
      never gccs were used.  I've brought this up with our gcc folks, as I
      wanted to make sure that this can't really happen again, and it turns
      out it actually can.
      
      Quoting Martin Jambor <mjambor@suse.cz>:
       "More current GCCs are more careful when it comes to replacing a
        conditional load with a non-conditional one, most notably they check
        that a store happens in each iteration of _a_ loop but they assume
        loops are executed.  They also perform a simple check whether the
        store cannot trap which currently passes only for non-const
        variables.  A simple testcase demonstrating it on an x86_64 is for
        example the following:
      
        $ cat cond_store.c
      
        int g_1 = 1;
      
        int g_2[1024] __attribute__((section ("safe_section"), aligned (4096)));
      
        int c = 4;
      
        int __attribute__ ((noinline))
        foo (void)
        {
          int l;
          for (l = 0; (l != 4); l++) {
            if (g_1)
              return l;
            for (g_2[0] = 0; (g_2[0] >= 26); ++g_2[0])
              ;
          }
          return 2;
        }
      
        int main (int argc, char* argv[])
        {
          if (mprotect (g_2, sizeof(g_2), PROT_READ) == -1)
            {
              int e = errno;
              error (e, e, "mprotect error %i", e);
            }
          foo ();
          __builtin_printf("OK\n");
          return 0;
        }
        /* EOF */
        $ ~/gcc/trunk/inst/bin/gcc cond_store.c -O2 --param allow-store-data-races=0
        $ ./a.out
        OK
        $ ~/gcc/trunk/inst/bin/gcc cond_store.c -O2 --param allow-store-data-races=1
        $ ./a.out
        Segmentation fault
      
        The testcase fails the same at least with 4.9, 4.8 and 4.7.  Therefore
        I would suggest building kernels with this parameter set to zero. I
        also agree with Jikos that the default should be changed for -O2.  I
        have run most of the SPEC 2k6 CPU benchmarks (gamess and dealII
        failed, at -O2, not sure why) compiled with and without this option
        and did not see any real difference between respective run-times"
      
      Hopefully the default will be changed in newer gccs, but let's force it
      for kernel builds so that we are on a safe side even when older gcc are
      used.
      
      The code in question was out-of-tree printk-in-NMI (yeah, surprise
      suprise, once again) patch written by Petr Mladek, let me quote his
      comment from our internal bugzilla:
      
       "I have spent few days investigating inconsistent state of kernel ring buffer.
        It went out that it was caused by speculative store generated by
        gcc-4.3.4.
      
        The problem is in assembly generated for make_free_space(). The functions is
        called the following way:
      
        + vprintk_emit();
            + log = MAIN_LOG; // with logbuf_lock
               or
               log = NMI_LOG; // with nmi_logbuf_lock
               cont_add(log, ...);
                + cont_flush(log, ...);
                    + log_store(log, ...);
                          + log_make_free_space(log, ...);
      
        If called with log = NMI_LOG then only nmi_log_* global variables are safe to
        modify but the generated code does store also into (main_)log_* global
        variables:
      
        <log_make_free_space>:
               55                      push   %rbp
               89 f6                   mov    %esi,%esi
      
               48 8b 05 03 99 51 01    mov    0x1519903(%rip),%rax       # ffffffff82620868 <nmi_log_next_id>
               44 8b 1d ec 98 51 01    mov    0x15198ec(%rip),%r11d      # ffffffff82620858 <log_next_idx>
               8b 35 36 60 14 01       mov    0x1146036(%rip),%esi       # ffffffff8224cfa8 <log_buf_len>
               44 8b 35 33 60 14 01    mov    0x1146033(%rip),%r14d      # ffffffff8224cfac <nmi_log_buf_len>
               4c 8b 2d d0 98 51 01    mov    0x15198d0(%rip),%r13       # ffffffff82620850 <log_next_seq>
               4c 8b 25 11 61 14 01    mov    0x1146111(%rip),%r12       # ffffffff8224d098 <log_buf>
               49 89 c2                mov    %rax,%r10
               48 21 c2                and    %rax,%rdx
               48 8b 1d 0c 99 55 01    mov    0x155990c(%rip),%rbx       # ffffffff826608a0 <nmi_log_buf>
               49 c1 ea 20             shr    $0x20,%r10
               48 89 55 d0             mov    %rdx,-0x30(%rbp)
               44 29 de                sub    %r11d,%esi
               45 29 d6                sub    %r10d,%r14d
               4c 8b 0d 97 98 51 01    mov    0x1519897(%rip),%r9	# ffffffff82620840 <log_first_seq>
               eb 7e                   jmp    ffffffff81107029	<log_make_free_space+0xe9>
        [...]
               85 ff                   test   %edi,%edi                  # edi = 1 for NMI_LOG
               4c 89 e8                mov    %r13,%rax
               4c 89 ca                mov    %r9,%rdx
               74 0a                   je     ffffffff8110703d	<log_make_free_space+0xfd>
               8b 15 27 98 51 01       mov    0x1519827(%rip),%edx       # ffffffff82620860 <nmi_log_first_id>
               48 8b 45 d0             mov    -0x30(%rbp),%rax
               48 39 c2                cmp    %rax,%rdx                  # end of loop
               0f 84 da 00 00 00       je     ffffffff81107120 <log_make_free_space+0x1e0>
        [...]
               85 ff                   test   %edi,%edi                  # edi = 1 for NMI_LOG
               4c 89 0d 17 97 51 01    mov    %r9,0x1519717(%rip)        # ffffffff82620840 <log_first_seq>
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^
                                       KABOOOM
               74 35                   je     ffffffff81107160		 <log_make_free_space+0x220>
      
        It stores log_first_seq when edi == NMI_LOG. This instructions are used also
        when edi == MAIN_LOG but the store is done speculatively before the condition
        is decided.  It is unsafe because we do not have "logbuf_lock" in NMI context
        and some other process migh modify "log_first_seq" in parallel"
      
      I believe that the best course of action is both
      
       - building kernel (and anything multi-threaded, I guess) with that
         optimization turned off
       - persuade gcc folks to change the default for future releases
      Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
      Cc: Martin Jambor <mjambor@suse.cz>
      Cc: Petr Mladek <pmladek@suse.cz>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Marek Polacek <polacek@redhat.com>
      Cc: Jakub Jelinek <jakub@redhat.com>
      Cc: Steven Noonan <steven@uplinklabs.net>
      Cc: Richard Biener <richard.guenther@gmail.com>
      Cc: Dan Carpenter <dan.carpenter@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      69102311
    • Dan Streetman's avatar
      mm/zpool: update zswap to use zpool · 12d79d64
      Dan Streetman authored
      Change zswap to use the zpool api instead of directly using zbud.  Add a
      boot-time param to allow selecting which zpool implementation to use,
      with zbud as the default.
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Tested-by: default avatarSeth Jennings <sjennings@variantweb.net>
      Cc: Weijie Yang <weijie.yang@samsung.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      12d79d64
    • Dan Streetman's avatar
      mm/zpool: zbud/zsmalloc implement zpool · c795779d
      Dan Streetman authored
      Update zbud and zsmalloc to implement the zpool api.
      
      [fengguang.wu@intel.com: make functions static]
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Tested-by: default avatarSeth Jennings <sjennings@variantweb.net>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Cc: Weijie Yang <weijie.yang@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c795779d
    • Dan Streetman's avatar
      mm/zpool: implement common zpool api to zbud/zsmalloc · af8d417a
      Dan Streetman authored
      Add zpool api.
      
      zpool provides an interface for memory storage, typically of compressed
      memory.  Users can select what backend to use; currently the only
      implementations are zbud, a low density implementation with up to two
      compressed pages per storage page, and zsmalloc, a higher density
      implementation with multiple compressed pages per storage page.
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Tested-by: default avatarSeth Jennings <sjennings@variantweb.net>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Cc: Weijie Yang <weijie.yang@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      af8d417a
    • Dan Streetman's avatar
      mm/zbud: change zbud_alloc size type to size_t · 99eef8e9
      Dan Streetman authored
      Change the type of the zbud_alloc() size param from unsigned int to
      size_t.
      
      Technically, this should not make any difference, as the zbud
      implementation already restricts the size to well within either type's
      limits; but as zsmalloc (and kmalloc) use size_t, and zpool will use
      size_t, this brings the size parameter type in line with zsmalloc/zpool.
      Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
      Acked-by: default avatarSeth Jennings <sjennings@variantweb.net>
      Tested-by: default avatarSeth Jennings <sjennings@variantweb.net>
      Cc: Weijie Yang <weijie.yang@samsung.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      99eef8e9
    • Weijie Yang's avatar
      zram: replace global tb_lock with fine grain lock · d2d5e762
      Weijie Yang authored
      Currently, we use a rwlock tb_lock to protect concurrent access to the
      whole zram meta table.  However, according to the actual access model,
      there is only a small chance for upper user to access the same
      table[index], so the current lock granularity is too big.
      
      The idea of optimization is to change the lock granularity from whole
      meta table to per table entry (table -> table[index]), so that we can
      protect concurrent access to the same table[index], meanwhile allow the
      maximum concurrency.
      
      With this in mind, several kinds of locks which could be used as a
      per-entry lock were tested and compared:
      
      Test environment:
      x86-64 Intel Core2 Q8400, system memory 4GB, Ubuntu 12.04,
      kernel v3.15.0-rc3 as base, zram with 4 max_comp_streams LZO.
      
      iozone test:
      iozone -t 4 -R -r 16K -s 200M -I +Z
      (1GB zram with ext4 filesystem, take the average of 10 tests, KB/s)
      
            Test       base      CAS    spinlock    rwlock   bit_spinlock
      -------------------------------------------------------------------
       Initial write  1381094   1425435   1422860   1423075   1421521
             Rewrite  1529479   1641199   1668762   1672855   1654910
                Read  8468009  11324979  11305569  11117273  10997202
             Re-read  8467476  11260914  11248059  11145336  10906486
        Reverse Read  6821393   8106334   8282174   8279195   8109186
         Stride read  7191093   8994306   9153982   8961224   9004434
         Random read  7156353   8957932   9167098   8980465   8940476
      Mixed workload  4172747   5680814   5927825   5489578   5972253
        Random write  1483044   1605588   1594329   1600453   1596010
              Pwrite  1276644   1303108   1311612   1314228   1300960
               Pread  4324337   4632869   4618386   4457870   4500166
      
      To enhance the possibility of access the same table[index] concurrently,
      set zram a small disksize(10MB) and let threads run with large loop
      count.
      
      fio test:
      fio --bs=32k --randrepeat=1 --randseed=100 --refill_buffers
      --scramble_buffers=1 --direct=1 --loops=3000 --numjobs=4
      --filename=/dev/zram0 --name=seq-write --rw=write --stonewall
      --name=seq-read --rw=read --stonewall --name=seq-readwrite
      --rw=rw --stonewall --name=rand-readwrite --rw=randrw --stonewall
      (10MB zram raw block device, take the average of 10 tests, KB/s)
      
          Test     base     CAS    spinlock    rwlock  bit_spinlock
      -------------------------------------------------------------
      seq-write   933789   999357   1003298    995961   1001958
       seq-read  5634130  6577930   6380861   6243912   6230006
         seq-rw  1405687  1638117   1640256   1633903   1634459
        rand-rw  1386119  1614664   1617211   1609267   1612471
      
      All the optimization methods show a higher performance than the base,
      however, it is hard to say which method is the most appropriate.
      
      On the other hand, zram is mostly used on small embedded system, so we
      don't want to increase any memory footprint.
      
      This patch pick the bit_spinlock method, pack object size and page_flag
      into an unsigned long table.value, so as to not increase any memory
      overhead on both 32-bit and 64-bit system.
      
      On the third hand, even though different kinds of locks have different
      performances, we can ignore this difference, because: if zram is used as
      zram swapfile, the swap subsystem can prevent concurrent access to the
      same swapslot; if zram is used as zram-blk for set up filesystem on it,
      the upper filesystem and the page cache also prevent concurrent access
      of the same block mostly.  So we can ignore the different performances
      among locks.
      Acked-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Reviewed-by: default avatarDavidlohr Bueso <davidlohr@hp.com>
      Signed-off-by: default avatarWeijie Yang <weijie.yang@samsung.com>
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Cc: Jerome Marchand <jmarchan@redhat.com>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d2d5e762
    • Minchan Kim's avatar
      zram: use size_t instead of u16 · 023b409f
      Minchan Kim authored
      Some architectures (eg, hexagon and PowerPC) could use PAGE_SHIFT of 16
      or more.  In these cases u16 is not sufficiently large to represent a
      compressed page's size so use size_t.
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Reported-by: default avatarWeijie Yang <weijie.yang@samsung.com>
      Acked-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Cc: Jerome Marchand <jmarchan@redhat.com>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      023b409f
    • Sergey Senozhatsky's avatar
      zram: remove unused SECTOR_SIZE define · a830eff7
      Sergey Senozhatsky authored
      Drop SECTOR_SIZE define, because it's not used.
      Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Cc: Weijie Yang <weijie.yang@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a830eff7
    • Sergey Senozhatsky's avatar
      zram: rename struct `table' to `zram_table_entry' · cb8f2eec
      Sergey Senozhatsky authored
      Andrew Morton has recently noted that `struct table' actually represents
      table entry and, thus, should be renamed.  Rename to `zram_table_entry'.
      Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Cc: Weijie Yang <weijie.yang@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      cb8f2eec
    • Max Filippov's avatar
      mm/highmem: make kmap cache coloring aware · 15de36a4
      Max Filippov authored
      User-visible effect:
       Architectures that choose this method of maintaining cache coherency
      (MIPS and xtensa currently) are able to use high memory on cores with
      aliasing data cache.  Without this fix such architectures can not use
      high memory (in case of xtensa it means that at most 128 MBytes of
      physical memory is available).
      
      The problem:
       VIPT cache with way size larger than MMU page size may suffer from
      aliasing problem: a single physical address accessed via different
      virtual addresses may end up in multiple locations in the cache.
      Virtual mappings of a physical address that always get cached in
      different cache locations are said to have different colors.  L1 caching
      hardware usually doesn't handle this situation leaving it up to
      software.  Software must avoid this situation as it leads to data
      corruption.
      
      What can be done:
       One way to handle this is to flush and invalidate data cache every time
      page mapping changes color.  The other way is to always map physical
      page at a virtual address with the same color.  Low memory pages already
      have this property.  Giving architecture a way to control color of high
      memory page mapping allows reusing of existing low memory cache alias
      handling code.
      
      How this is done with this patch:
       Provide hooks that allow architectures with aliasing cache to align
      mapping address of high pages according to their color.  Such
      architectures may enforce similar coloring of low- and high-memory page
      mappings and reuse existing cache management functions to support
      highmem.
      
      This code is based on the implementation of similar feature for MIPS by
      Leonid Yegoshin.
      Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
      Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
      Cc: Chris Zankel <chris@zankel.net>
      Cc: Marc Gauthier <marc@cadence.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Steven Hill <Steven.Hill@imgtec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      15de36a4
    • Peter Zijlstra's avatar
      mmu_notifier: add call_srcu and sync function for listener to delay call and sync · b972216e
      Peter Zijlstra authored
      When kernel device drivers or subsystems want to bind their lifespan to
      t= he lifespan of the mm_struct, they usually use one of the following
      methods:
      
      1. Manually calling a function in the interested kernel module.  The
         funct= ion call needs to be placed in mmput.  This method was rejected
         by several ker= nel maintainers.
      
      2. Registering to the mmu notifier release mechanism.
      
      The problem with the latter approach is that the mmu_notifier_release
      cal= lback is called from__mmu_notifier_release (called from exit_mmap).
      That functi= on iterates over the list of mmu notifiers and don't expect
      the release call= back function to remove itself from the list.
      Therefore, the callback function= in the kernel module can't release the
      mmu_notifier_object, which is actuall= y the kernel module's object
      itself.  As a result, the destruction of the kernel module's object must
      to be done in a delayed fashion.
      
      This patch adds support for this delayed callback, by adding a new
      mmu_notifier_call_srcu function that receives a function ptr and calls
      th= at function with call_srcu.  In that function, the kernel module
      releases its object.  To use mmu_notifier_call_srcu, the calling module
      needs to call b= efore that a new function called
      mmu_notifier_unregister_no_release that as its= name implies,
      unregisters a notifier without calling its notifier release call= back.
      
      This patch also adds a function that will call barrier_srcu so those
      kern= el modules can sync with mmu_notifier.
      Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarJérôme Glisse <jglisse@redhat.com>
      Signed-off-by: default avatarOded Gabbay <oded.gabbay@amd.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b972216e
    • Chintan Pandya's avatar
      mm: BUG when __kmap_atomic_idx equals KM_TYPE_NR · 1d352bfd
      Chintan Pandya authored
      __kmap_atomic_idx is per_cpu variable.  Each CPU can use KM_TYPE_NR
      entries from FIXMAP i.e.  from 0 to KM_TYPE_NR - 1.  Allowing
      __kmap_atomic_idx to over- shoot to KM_TYPE_NR can mess up with next
      CPU's 0th entry which is a bug.  Hence BUG_ON if __kmap_atomic_idx >=
      KM_TYPE_NR.
      
      Fix the off-by-on in this test.
      Signed-off-by: default avatarChintan Pandya <cpandya@codeaurora.org>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1d352bfd
    • Johannes Weiner's avatar
      mm: memcontrol: clean up reclaim size variable use in try_charge() · 61e02c74
      Johannes Weiner authored
      Charge reclaim and OOM currently use the charge batch variable, but
      batching is already disabled at that point.  To simplify the charge
      logic, the batch variable is reset to the original request size when
      reclaim is entered, so it's functionally equal, but it's misleading.
      
      Switch reclaim/OOM to nr_pages, which is the original request size.
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      61e02c74
    • Sasha Levin's avatar
      kernel/smp.c:on_each_cpu_cond(): fix warning in fallback path · 618fde87
      Sasha Levin authored
      The rarely-executed memry-allocation-failed callback path generates a
      WARN_ON_ONCE() when smp_call_function_single() succeeds.  Presumably
      it's supposed to warn on failures.
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Cc: Christoph Lameter <cl@gentwo.org>
      Cc: Gilad Ben-Yossef <gilad@benyossef.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Tejun Heo <htejun@gmail.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      618fde87
    • Rik van Riel's avatar
      mm: change confusing #ifdef use in __access_remote_vm · dbffcd03
      Rik van Riel authored
      This patch changes confusing #ifdef use in __access_remote_vm into
      merely ugly #ifdef use.
      
      Addresses bug https://bugzilla.kernel.org/show_bug.cgi?id=81651Signed-off-by: default avatarRik van Riel <riel@redhat.com>
      Reported-by: default avatarDavid Binderman <dcb314@hotmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      dbffcd03
    • Peter Feiner's avatar
      mm: softdirty: respect VM_SOFTDIRTY in PTE holes · 68b5a652
      Peter Feiner authored
      After a VMA is created with the VM_SOFTDIRTY flag set, /proc/pid/pagemap
      should report that the VMA's virtual pages are soft-dirty until
      VM_SOFTDIRTY is cleared (i.e., by the next write of "4" to
      /proc/pid/clear_refs).  However, pagemap ignores the VM_SOFTDIRTY flag
      for virtual addresses that fall in PTE holes (i.e., virtual addresses
      that don't have a PMD, PUD, or PGD allocated yet).
      
      To observe this bug, use mmap to create a VMA large enough such that
      there's a good chance that the VMA will occupy an unused PMD, then test
      the soft-dirty bit on its pages.  In practice, I found that a VMA that
      covered a PMD's worth of address space was big enough.
      
      This patch adds the necessary VMA lookup to the PTE hole callback in
      /proc/pid/pagemap's page walk and sets soft-dirty according to the VMAs'
      VM_SOFTDIRTY flag.
      Signed-off-by: default avatarPeter Feiner <pfeiner@google.com>
      Acked-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Hugh Dickins <hughd@google.com>
      Acked-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      68b5a652
    • Kirill A. Shutemov's avatar
      mm: mark fault_around_bytes __read_mostly · 3a91053a
      Kirill A. Shutemov authored
      fault_around_bytes can only be changed via debugfs.  Let's mark it
      read-mostly.
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Suggested-by: default avatarDavid Rientjes <rientjes@google.com>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3a91053a
    • Kirill A. Shutemov's avatar
      mm: close race between do_fault_around() and fault_around_bytes_set() · aecd6f44
      Kirill A. Shutemov authored
      Things can go wrong if fault_around_bytes will be changed under
      do_fault_around(): between fault_around_mask() and fault_around_pages().
      
      Let's read fault_around_bytes only once during do_fault_around() and
      calculate mask based on the reading.
      
      Note: fault_around_bytes can only be updated via debug interface.  Also
      I've tried but was not able to trigger a bad behaviour without the
      patch.  So I would not consider this patch as urgent.
      Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Cc: David Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      aecd6f44
    • Jerome Marchand's avatar
      memcg, vmscan: Fix forced scan of anonymous pages · 2ab051e1
      Jerome Marchand authored
      When memory cgoups are enabled, the code that decides to force to scan
      anonymous pages in get_scan_count() compares global values (free,
      high_watermark) to a value that is restricted to a memory cgroup (file).
      It make the code over-eager to force anon scan.
      
      For instance, it will force anon scan when scanning a memcg that is
      mainly populated by anonymous page, even when there is plenty of file
      pages to get rid of in others memcgs, even when swappiness == 0.  It
      breaks user's expectation about swappiness and hurts performance.
      
      This patch makes sure that forced anon scan only happens when there not
      enough file pages for the all zone, not just in one random memcg.
      
      [hannes@cmpxchg.org: cleanups]
      Signed-off-by: default avatarJerome Marchand <jmarchan@redhat.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2ab051e1
    • Jerome Marchand's avatar
      mm, vmscan: fix an outdated comment still mentioning get_scan_ratio · 7c0db9e9
      Jerome Marchand authored
      Quite a while ago, get_scan_ratio() has been renamed get_scan_count(),
      however a comment in shrink_active_list() still mention it.  This patch
      fixes the outdated comment.
      Signed-off-by: default avatarJerome Marchand <jmarchan@redhat.com>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7c0db9e9
    • David Rientjes's avatar
      mm, oom: remove unnecessary exit_state check · fb794bcb
      David Rientjes authored
      The oom killer scans each process and determines whether it is eligible
      for oom kill or whether the oom killer should abort because of
      concurrent memory freeing.  It will abort when an eligible process is
      found to have TIF_MEMDIE set, meaning it has already been oom killed and
      we're waiting for it to exit.
      
      Processes with task->mm == NULL should not be considered because they
      are either kthreads or have already detached their memory and killing
      them would not lead to memory freeing.  That memory is only freed after
      exit_mm() has returned, however, and not when task->mm is first set to
      NULL.
      
      Clear TIF_MEMDIE after exit_mm()'s mmput() so that an oom killed process
      is no longer considered for oom kill, but only until exit_mm() has
      returned.  This was fragile in the past because it relied on
      exit_notify() to be reached before no longer considering TIF_MEMDIE
      processes.
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fb794bcb