1. 01 Jun, 2012 40 commits
    • Cyrill Gorcunov's avatar
      c/r: prctl: extend PR_SET_MM to set up more mm_struct entries · fe8c7f5c
      Cyrill Gorcunov authored
      During checkpoint we dump whole process memory to a file and the dump
      includes process stack memory.  But among stack data itself, the stack
      carries additional parameters such as command line arguments, environment
      data and auxiliary vector.
      
      So when we do restore procedure and once we've restored stack data itself
      we need to setup mm_struct::arg_start/end, env_start/end, so restored
      process would be able to find command line arguments and environment data
      it had at checkpoint time.  The same applies to auxiliary vector.
      
      For this reason additional PR_SET_MM_(ARG_START | ARG_END | ENV_START |
      ENV_END | AUXV) codes are introduced.
      Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Andrew Vagin <avagin@openvz.org>
      Cc: Serge Hallyn <serge.hallyn@canonical.com>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Vasiliy Kulikov <segoon@openwall.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Michael Kerrisk <mtk.manpages@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fe8c7f5c
    • Cyrill Gorcunov's avatar
      c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat · 5b172087
      Cyrill Gorcunov authored
      We would like to have an ability to restore command line arguments and
      program environment pointers but first we need to obtain them somehow.
      Thus we put these values into /proc/$pid/stat.  The exit_code is needed to
      restore zombie tasks.
      Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Serge Hallyn <serge.hallyn@canonical.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Andrew Vagin <avagin@openvz.org>
      Cc: Vasiliy Kulikov <segoon@openwall.com>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Cc: "Eric W. Biederman" <ebiederm@xmission.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5b172087
    • Cyrill Gorcunov's avatar
      syscalls, x86: add __NR_kcmp syscall · d97b46a6
      Cyrill Gorcunov authored
      While doing the checkpoint-restore in the user space one need to determine
      whether various kernel objects (like mm_struct-s of file_struct-s) are
      shared between tasks and restore this state.
      
      The 2nd step can be solved by using appropriate CLONE_ flags and the
      unshare syscall, while there's currently no ways for solving the 1st one.
      
      One of the ways for checking whether two tasks share e.g.  mm_struct is to
      provide some mm_struct ID of a task to its proc file, but showing such
      info considered to be not that good for security reasons.
      
      Thus after some debates we end up in conclusion that using that named
      'comparison' syscall might be the best candidate.  So here is it --
      __NR_kcmp.
      
      It takes up to 5 arguments - the pids of the two tasks (which
      characteristics should be compared), the comparison type and (in case of
      comparison of files) two file descriptors.
      
      Lookups for pids are done in the caller's PID namespace only.
      
      At moment only x86 is supported and tested.
      
      [akpm@linux-foundation.org: fix up selftests, warnings]
      [akpm@linux-foundation.org: include errno.h]
      [akpm@linux-foundation.org: tweak comment text]
      Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
      Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Andrey Vagin <avagin@openvz.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Glauber Costa <glommer@parallels.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Matt Helsley <matthltc@us.ibm.com>
      Cc: Pekka Enberg <penberg@kernel.org>
      Cc: Eric Dumazet <eric.dumazet@gmail.com>
      Cc: Vasiliy Kulikov <segoon@openwall.com>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Cc: Valdis.Kletnieks@vt.edu
      Cc: Michal Marek <mmarek@suse.cz>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d97b46a6
    • Cyrill Gorcunov's avatar
      fs, proc: introduce /proc/<pid>/task/<tid>/children entry · 81841161
      Cyrill Gorcunov authored
      When we do checkpoint of a task we need to know the list of children the
      task, has but there is no easy and fast way to generate reverse
      parent->children chain from arbitrary <pid> (while a parent pid is
      provided in "PPid" field of /proc/<pid>/status).
      
      So instead of walking over all pids in the system (creating one big
      process tree in memory, just to figure out which children a task has) --
      we add explicit /proc/<pid>/task/<tid>/children entry, because the kernel
      already has this kind of information but it is not yet exported.
      
      This is a first level children, not the whole process tree.
      Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
      Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
      Reviewed-by: default avatarKees Cook <keescook@chromium.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Serge Hallyn <serge.hallyn@canonical.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      81841161
    • Cyrill Gorcunov's avatar
      sysctl: make kernel.ns_last_pid control dependent on CHECKPOINT_RESTORE · 98ed57ee
      Cyrill Gorcunov authored
      For those who doesn't need C/R functionality there is no need to control
      last pid, ie the pid for the next fork() call.
      Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Tejun Heo <tj@kernel.org>
      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>
      98ed57ee
    • Christopher Yeoh's avatar
      aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() · ac34ebb3
      Christopher Yeoh authored
      A cleanup of rw_copy_check_uvector and compat_rw_copy_check_uvector after
      changes made to support CMA in an earlier patch.
      
      Rather than having an additional check_access parameter to these
      functions, the first paramater type is overloaded to allow the caller to
      specify CHECK_IOVEC_ONLY which means check that the contents of the iovec
      are valid, but do not check the memory that they point to.  This is used
      by process_vm_readv/writev where we need to validate that a iovec passed
      to the syscall is valid but do not want to check the memory that it points
      to at this point because it refers to an address space in another process.
      Signed-off-by: default avatarChris Yeoh <yeohc@au1.ibm.com>
      Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ac34ebb3
    • Sha Zhengju's avatar
      eventfd: change int to __u64 in eventfd_signal() · ee62c6b2
      Sha Zhengju authored
      eventfd_ctx->count is an __u64 counter which is allowed to reach
      ULLONG_MAX.  eventfd_write() adds a __u64 value to "count", but the kernel
      side eventfd_signal() only adds an int value to it.  Make them consistent.
      
      [akpm@linux-foundation.org: update interface documentation]
      Signed-off-by: default avatarSha Zhengju <handai.szj@taobao.com>
      Cc: Davide Libenzi <davidel@xmailserver.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ee62c6b2
    • Vladimir Serbinenko's avatar
      fs/nls: add Apple NLS · 71ca97da
      Vladimir Serbinenko authored
      HFS has support for NLS.  However the relevant NLS tables are missing.
      Here they are automatically transformed from the tables at unicode.org.
      Codepages requiring special handling like CJK, RTL or Brahmic ones are not
      included in this patch.
      
      [akpm@linux-foundation.org: add unicode.org copyright and permission notices]
      Signed-off-by: default avatarVladimir Serbinenko <phcoder@gmail.com>
      Cc: Alan Stern <stern@rowland.harvard.edu>
      Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
      Cc: Clemens Ladisch <clemens@ladisch.de>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      71ca97da
    • Eric W. Biederman's avatar
      pidns: make killed children autoreap · 00c10bc1
      Eric W. Biederman authored
      Force SIGCHLD handling to SIG_IGN so that signals are not generated and so
      that the children autoreap.  This increases the parallelize and in general
      the speed of network namespace shutdown.
      
      Note self reaping childrean can exist past zap_pid_ns_processess but they
      will all be reaped before we allow the pid namespace init task with pid ==
      1 to be reaped.
      
      [akpm@linux-foundation.org: checkpatch fixes]
      Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Cyrill Gorcunov <gorcunov@openvz.org>
      Cc: Louis Rilling <louis.rilling@kerlabs.com>
      Cc: Mike Galbraith <efault@gmx.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      00c10bc1
    • Eric W. Biederman's avatar
      pidns: use task_active_pid_ns in do_notify_parent · 32084504
      Eric W. Biederman authored
      Using task_active_pid_ns is more robust because it works even after we
      have called exit_namespaces.  This change allows us to have parent
      processes that are zombies.  Normally a zombie parent processes is crazy
      and the last thing you would want to have but in the case of not letting
      the init process of a pid namespace be reaped until all of it's children
      are dead and reaped a zombie parent process is exactly what we want.
      Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Cyrill Gorcunov <gorcunov@openvz.org>
      Cc: Louis Rilling <louis.rilling@kerlabs.com>
      Cc: Mike Galbraith <efault@gmx.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      32084504
    • Alexandre Bounine's avatar
      rapidio/tsi721: add DMA engine support · 9eaa3d9b
      Alexandre Bounine authored
      Adds support for DMA Engine API into Tsi721 mport driver.
      
      Includes following changes for Tsi721 driver:
      - Modifies BDMA register offset definitions to support per-channel handling
      - Separates BDMA channel reserved for RIO Maintenance requests
      - Adds DMA Engine callback routines
      Signed-off-by: default avatarAlexandre Bounine <alexandre.bounine@idt.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Vinod Koul <vinod.koul@intel.com>
      Cc: Li Yang <leoli@freescale.com>
      Cc: Matt Porter <mporter@kernel.crashing.org>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9eaa3d9b
    • Alexandre Bounine's avatar
      rapidio: add DMA engine support for RIO data transfers · e42d98eb
      Alexandre Bounine authored
      Adds DMA Engine framework support into RapidIO subsystem.
      
      Uses DMA Engine DMA_SLAVE interface to generate data transfers to/from
      remote RapidIO target devices.
      
      Introduces RapidIO-specific wrapper for prep_slave_sg() interface with an
      extra parameter to pass target specific information.
      
      Uses scatterlist to describe local data buffer.  Address flat data buffer
      on a remote side.
      Signed-off-by: default avatarAlexandre Bounine <alexandre.bounine@idt.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Acked-by: default avatarVinod Koul <vinod.koul@linux.intel.com>
      Cc: Li Yang <leoli@freescale.com>
      Cc: Matt Porter <mporter@kernel.crashing.org>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e42d98eb
    • Doug Ledford's avatar
      ipc/mqueue: add rbtree node caching support · ce2d52cc
      Doug Ledford authored
      When I wrote the first patch that added the rbtree support for message
      queue insertion, it sped up the case where the queue was very full
      drastically from the original code.  It, however, slowed down the case
      where the queue was empty (not drastically though).
      
      This patch caches the last freed rbtree node struct so we can quickly
      reuse it when we get a new message.  This is the common path for any queue
      that very frequently goes from 0 to 1 then back to 0 messages in queue.
      
      Andrew Morton didn't like that we were doing a GFP_ATOMIC allocation in
      msg_insert, so this patch attempts to speculatively allocate a new node
      struct outside of the spin lock when we know we need it, but will still
      fall back to a GFP_ATOMIC allocation if it has to.
      
      Once I added the caching, the necessary various ret = ; spin_unlock
      gyrations in mq_timedsend were getting pretty ugly, so this also slightly
      refactors that function to streamline the flow of the code and the
      function exit.
      
      Finally, while working on getting performance back I made sure that all of
      the node structs were always fully initialized when they were first used,
      rendering the use of kzalloc unnecessary and a waste of CPU cycles.
      
      The net result of all of this is:
      
      1) We will avoid a GFP_ATOMIC allocation when possible, but fall back
         on it when necessary.
      
      2) We will speculatively allocate a node struct using GFP_KERNEL if our
         cache is empty (and save the struct to our cache if it's still empty
         after we have obtained the spin lock).
      
      3) The performance of the common queue empty case has significantly
         improved and is now much more in line with the older performance for
         this case.
      
      The performance changes are:
      
                  Old mqueue      new mqueue      new mqueue + caching
      queue empty
      send/recv   305/288ns       349/318ns       310/322ns
      
      I don't think we'll ever be able to get the recv performance back, but
      that's because the old recv performance was a direct result and
      consequence of the old methods abysmal send performance.  The recv path
      simply must do more so that the send path does not incur such a penalty
      under higher queue depths.
      
      As it turns out, the new caching code also sped up the various queue full
      cases relative to my last patch.  That could be because of the difference
      between the syscall path in 3.3.4-rc5 and 3.3.4-rc6, or because of the
      change in code flow in the mq_timedsend routine.  Regardless, I'll take
      it.  It wasn't huge, and I *would* say it was within the margin for error,
      but after many repeated runs what I'm seeing is that the old numbers trend
      slightly higher (about 10 to 20ns depending on which test is the one
      running).
      
      [akpm@linux-foundation.org: checkpatch fixes]
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ce2d52cc
    • Doug Ledford's avatar
      tools/selftests: add mq_perf_tests · 7820b071
      Doug Ledford authored
      Add the mq_perf_tests tool I used when creating my mq performance patch.
      Also add a local .gitignore to keep the binaries from showing up in git
      status output.
      
      [akpm@linux-foundation.org: checkpatch fixes]
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7820b071
    • Doug Ledford's avatar
      ipc/mqueue: strengthen checks on mqueue creation · 113289cc
      Doug Ledford authored
      We already check the mq attr struct if it's passed in, but now that the
      admin can set system wide defaults separate from maximums, it's actually
      possible to set the defaults to something that would overflow.  So, if
      there is no attr struct passed in to the open call, check the default
      values.
      
      While we are at it, simplify mq_attr_ok() by making it return 0 or an
      error condition, so that way if we add more tests to it later, we have the
      option of what error should be returned instead of the calling location
      having to pick a possibly inaccurate error code.
      
      [akpm@linux-foundation.org: s/ENOMEM/EOVERFLOW/]
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      113289cc
    • Doug Ledford's avatar
      ipc/mqueue: correct mq_attr_ok test · 2c12ea49
      Doug Ledford authored
      While working on the other parts of the mqueue stuff, I noticed that the
      calculation for overflow in mq_attr_ok didn't actually match reality (this
      is especially true since my last patch which changed how we account memory
      slightly).
      
      In particular, we used to test for overflow using:
        msgs * msgsize + msgs * sizeof(struct msg_msg *)
      
      That was never really correct because each message we allocate via
      load_msg() is actually a struct msg_msg followed by the data for the
      message (and if struct msg_msg + data exceeds PAGE_SIZE we end up
      allocating struct msg_msgseg structs too, but accounting for them would
      get really tedious, so let's ignore those...they're only a pointer in size
      anyway).  This patch updates the calculation to be more accurate in
      regards to maximum possible memory consumption by the mqueue.
      
      [akpm@linux-foundation.org: add a local to simplify overflow-checking expression]
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2c12ea49
    • Doug Ledford's avatar
      ipc/mqueue: improve performance of send/recv · d6629859
      Doug Ledford authored
      The existing implementation of the POSIX message queue send and recv
      functions is, well, abysmal.  Even worse than abysmal.  I submitted a
      patch to increase the maximum POSIX message queue limit to 65536 due to
      customer needs, however, upon looking over the send/recv implementation, I
      realized that my customer needs help with that too even if they don't know
      it.  The basic problem is that, given the fairly typical use case scenario
      for a large queue of queueing lots of messages all at the same priority (I
      verified with my customer that this is indeed what their app does), the
      msg_insert routine is basically a frikkin' bubble sort.  I mean, whoa,
      that's *so* middle school.
      
      OK, OK, to not slam the original author too much, I'm sure they didn't
      envision a queue depth of 50,000+ messages.  No one would think that
      moving elements in an array, one at a time, and dereferencing each pointer
      in that array to check priority of the message being pointed too, again
      one at a time, for 50,000+ times would be good.  So let's assume that, as
      is typical, the users have found a way to break our code simply by using
      it in a way we didn't envision.  Fair enough.
      
      "So, just how broken is it?", you ask.  I wondered the same thing, so I
      wrote an app to let me know.  It's my next patch.  It gave me some
      interesting results.  Here's what it tested:
      
      Interference with other apps - In continuous mode, the app just sits there
      and hits a message queue forever, while you go do something productive on
      another terminal using other CPUs.  You then measure how long it takes you
      to do that something productive.  Then you restart the app in fake
      continuous mode, and it sits in a tight loop on a CPU while you repeat
      your tests.  The whole point of this is to keep one CPU tied up (so it
      can't be used in your other work) but in one case tied up hitting the
      mqueue code so we can see the effect of walking that 65,528 element array
      one pointer at a time on the global CPU cache.  If it's bad, then it will
      slow down your app on the other CPUs just by polluting cache mercilessly.
      In the fake case, it will be in a tight loop, but not polluting cache.
      Testing the mqueue subsystem directly - Here we just run a number of tests
      to see how the mqueue subsystem performs under different conditions.  A
      couple conditions are known to be worst case for the old system, and some
      routines, so this tests all of them.
      
      So, on to the results already:
      
      Subsystem/Test                  Old                         New
      
      Time to compile linux
      kernel (make -j12 on a
      6 core CPU)
        Running mqueue test     user 49m10.744s             user 45m26.294s
      			   sys  5m51.924s              sys  4m59.894s
      			 total 55m02.668s            total 50m26.188s
      
        Running fake test       user 45m32.686s             user 45m18.552s
                                 sys  5m12.465s              sys  4m56.468s
                               total 50m45.151s            total 50m15.020s
      
        % slowdown from mqueue
          cache thrashing            ~8%                         ~.5%
      
      Avg time to send/recv (in nanoseconds per message)
        when queue empty            305/288                    349/318
        when queue full (65528 messages)
          constant priority      526589/823                    362/314
          increasing priority    403105/916                    495/445
          decreasing priority     73420/594                    482/409
          random priority        280147/920                    546/436
      
      Time to fill/drain queue (65528 messages, in seconds)
        constant priority         17.37/.12                    .13/.12
        increasing priority        4.14/.14                    .21/.18
        decreasing priority       12.93/.13                    .21/.18
        random priority            8.88/.16                    .22/.17
      
      So, I think the results speak for themselves.  It's possible this
      implementation could be improved by cacheing at least one priority level
      in the node tree (that would bring the queue empty performance more in
      line with the old implementation), but this works and is *so* much better
      than what we had, especially for the common case of a single priority in
      use, that further refinements can be in follow on patches.
      
      [akpm@linux-foundation.org: fix typo in comment, remove stray semicolon]
      [levinsasha928@gmail.com: use correct gfp flags in msg_insert]
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarSasha Levin <levinsasha928@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d6629859
    • Doug Ledford's avatar
      selftests: add mq_open_tests · 50069a58
      Doug Ledford authored
      Add a directory to house POSIX message queue subsystem specific tests.
      Add first test which checks the operation of mq_open() under various
      corner conditions.
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Doug Ledford <dledford@redhat.com>
      Cc: Joe Korty <joe.korty@ccur.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Cc: Serge E. Hallyn <serue@us.ibm.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      50069a58
    • KOSAKI Motohiro's avatar
      mqueue: separate mqueue default value from maximum value · cef0184c
      KOSAKI Motohiro authored
      Commit b231cca4 ("message queues: increase range limits") changed
      mqueue default value when attr parameter is specified NULL from hard
      coded value to fs.mqueue.{msg,msgsize}_max sysctl value.
      
      This made large side effect.  When user need to use two mqueue
      applications 1) using !NULL attr parameter and it require big message
      size and 2) using NULL attr parameter and only need small size message,
      app (1) require to raise fs.mqueue.msgsize_max and app (2) consume large
      memory size even though it doesn't need.
      
      Doug Ledford propsed to switch back it to static hard coded value.
      However it also has a compatibility problem.  Some applications might
      started depend on the default value is tunable.
      
      The solution is to separate default value from maximum value.
      Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Acked-by: default avatarDoug Ledford <dledford@redhat.com>
      Acked-by: default avatarJoe Korty <joe.korty@ccur.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Acked-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      cef0184c
    • KOSAKI Motohiro's avatar
      mqueue: don't use kmalloc with KMALLOC_MAX_SIZE · fd1f87d2
      KOSAKI Motohiro authored
      KMALLOC_MAX_SIZE is not a good threshold.  It is extremely high and
      problematic.  Unfortunately, some silly drivers depend on this and we
      can't change it.  But any new code needn't use such extreme ugly high
      order allocations.  It brings us awful fragmentation issues and system
      slowdown.
      Signed-off-by: default avatarKOSAKI Motohiro <mkosaki@jp.fujitsu.com>
      Acked-by: default avatarDoug Ledford <dledford@redhat.com>
      Acked-by: default avatarJoe Korty <joe.korty@ccur.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Cc: Serge E. Hallyn <serue@us.ibm.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Cc: Joe Korty <joe.korty@ccur.com>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fd1f87d2
    • KOSAKI Motohiro's avatar
      mqueue: revert bump up DFLT_*MAX · e6315bb1
      KOSAKI Motohiro authored
      Mqueue limitation is slightly naieve parameter likes other ipcs because
      unprivileged user can consume kernel memory by using ipcs.
      
      Thus, too aggressive raise bring us security issue.  Example, current
      setting allow evil unprivileged user use 256GB (= 256 * 1024 * 1024*1024)
      and it's enough large to system will belome unresponsive.  Don't do that.
      
      Instead, every admin should adjust the knobs for their own systems.
      Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Acked-by: default avatarDoug Ledford <dledford@redhat.com>
      Acked-by: default avatarJoe Korty <joe.korty@ccur.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Acked-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Cc: Dave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e6315bb1
    • Doug Ledford's avatar
      ipc/mqueue: update maximums for the mqueue subsystem · 5b5c4d1a
      Doug Ledford authored
      Commit b231cca4 ("message queues: increase range limits") changed the
      maximum size of a message in a message queue from INT_MAX to 8192*128.
      Unfortunately, we had customers that relied on a size much larger than
      8192*128 on their production systems.  After reviewing POSIX, we found
      that it is silent on the maximum message size.  We did find a couple other
      areas in which it was not silent.  Fix up the mqueue maximums so that the
      customer's system can continue to work, and document both the POSIX and
      real world requirements in ipc_namespace.h so that we don't have this
      issue crop back up.
      
      Also, commit 9cf18e1d ("ipc: HARD_MSGMAX should be higher not lower
      on 64bit") fiddled with HARD_MSGMAX without realizing that the number was
      intentionally in place to limit the msg queue depth to one that was small
      enough to kmalloc an array of pointers (hence why we divided 128k by
      sizeof(long)).  If we wish to meet POSIX requirements, we have no choice
      but to change our allocation to a vmalloc instead (at least for the large
      queue size case).  With that, it's possible to increase our allowed
      maximum to the POSIX requirements (or more if we choose).
      
      [sfr@canb.auug.org.au: using vmalloc requires including vmalloc.h]
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Serge E. Hallyn <serue@us.ibm.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Cc: Joe Korty <joe.korty@ccur.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5b5c4d1a
    • Doug Ledford's avatar
      ipc/mqueue: enforce hard limits · 02967ea0
      Doug Ledford authored
      In two places we don't enforce the hard limits for CAP_SYS_RESOURCE apps.
      In preparation for making more reasonable hard limits, start enforcing
      them even on CAP_SYS_RESOURCE.
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Serge E. Hallyn <serue@us.ibm.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Cc: Joe Korty <joe.korty@ccur.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      02967ea0
    • Doug Ledford's avatar
      ipc/mqueue: switch back to using non-max values on create · 858ee378
      Doug Ledford authored
      Commit b231cca4 ("message queues: increase range limits") changed
      how we create a queue that does not include an attr struct passed to
      open so that it creates the queue with whatever the maximum values are.
      However, if the admin has set the maximums to allow flexibility in
      creating a queue (aka, both a large size and large queue are allowed,
      but combined they create a queue too large for the RLIMIT_MSGQUEUE of
      the user), then attempts to create a queue without an attr struct will
      fail.  Switch back to using acceptable defaults regardless of what the
      maximums are.
      
      Note: so far, we only know of a few applications that rely on this
      behavior (specifically, set the maximums in /proc, then run the
      application which calls mq_open() without passing in an attr struct, and
      the application expects the newly created message queue to have the
      maximum sizes that were set in /proc used on the mq_open() call, and all
      of those applications that we know of are actually part of regression
      test suites that were coded to do something like this:
      
      for size in 4096 65536 $((1024 * 1024)) $((16 * 1024 * 1024)); do
      	echo $size > /proc/sys/fs/mqueue/msgsize_max
      	mq_open || echo "Error opening mq with size $size"
      done
      
      These test suites that depend on any behavior like this are broken.  The
      concept that programs should rely upon the system wide maximum in order
      to get their desired results instead of simply using a attr struct to
      specify what they want is fundamentally unfriendly programming practice
      for any multi-tasking OS.
      
      Fixing this will break those few apps that we know of (and those app
      authors recognize the brokenness of their code and the need to fix it).
      However, the following patch "mqueue: separate mqueue default value"
      allows a workaround in the form of new knobs for the default msg queue
      creation parameters for any software out there that we don't already
      know about that might rely on this behavior at the moment.
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Cc: Serge E. Hallyn <serue@us.ibm.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Cc: Joe Korty <joe.korty@ccur.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      858ee378
    • Doug Ledford's avatar
      ipc/mqueue: cleanup definition names and locations · 93e6f119
      Doug Ledford authored
      Since commit b231cca4 ("message queues: increase range limits") on
      Oct 18, 2008, calls to mq_open() that did not pass in an attribute
      struct and expected to get default values for the size of the queue and
      the max message size now get the system wide maximums instead of
      hardwired defaults like they used to get.
      
      This was uncovered when one of the earlier patches in this patch set
      increased the default system wide maximums at the same time it increased
      the hard ceiling on the system wide maximums (a customer specifically
      needed the hard ceiling brought back up, the new ceiling that commit
      b231cca4 introduced was too low for their production systems).  By
      increasing the default maximums and not realising they were tied to any
      attempt to create a message queue without an attribute struct, I had
      inadvertently made it such that all message queue creation attempts
      without an attribute struct were failing because the new default
      maximums would create a queue that exceeded the default rlimit for
      message queue bytes.
      
      As a result, the system wide defaults were brought back down to their
      previous levels, and the system wide ceilings on the maximums were
      raised to meet the customer's needs.  However, the fact that the no
      attribute struct behavior of mq_open() could be broken by changing the
      system wide maximums for message queues was seen as fundamentally broken
      itself.  So we hardwired the no attribute case back like it used to be.
      But, then we realized that on the very off chance that some piece of
      software in the wild depended on that behavior, we could work around
      that issue by adding two new knobs to /proc that allowed setting the
      defaults for message queues created without an attr struct separately
      from the system wide maximums.
      
      What is not an option IMO is to leave the current behavior in place.  No
      piece of software should ever rely on setting the system wide maximums
      in order to get a desired message queue.  Such a reliance would be so
      fundamentally multitasking OS unfriendly as to not really be tolerable.
      Fortunately, we don't know of any software in the wild that uses this
      except for a regression test program that caught the issue in the first
      place.  If there is though, we have made accommodations with the two new
      /proc knobs (and that's all the accommodations such fundamentally broken
      software can be allowed)..
      
      This patch:
      
      The various defines for minimums and maximums of the sysctl controllable
      mqueue values are scattered amongst different files and named
      inconsistently.  Move them all into ipc_namespace.h and make them have
      consistent names.  Additionally, make the number of queues per namespace
      also have a minimum and maximum and use the same sysctl function as the
      other two settable variables.
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      Acked-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
      Cc: Amerigo Wang <amwang@redhat.com>
      Cc: Joe Korty <joe.korty@ccur.com>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Manfred Spraul <manfred@colorfullife.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      93e6f119
    • maximilian attems's avatar
      kexec: export kexec.h to user space · 29a5c67e
      maximilian attems authored
      Add userspace definitions, guard all relevant kernel structures.  While at
      it document stuff and remove now useless userspace hint.
      
      It is easy to add the relevant system call to respective libc's, but it
      seems pointless to have to duplicate the data structures.
      
      This is based on the kexec-tools headers, with the exception of just using
      int on return (succes or failure) and using size_t instead of 'unsigned
      long int' for the number of segments argument of kexec_load().
      Signed-off-by: default avatarmaximilian attems <max@stro.at>
      Cc: Simon Horman <horms@verge.net.au>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Haren Myneni <hbabu@us.ibm.com>
      Cc: "Eric W. Biederman" <ebiederm@xmission.com>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      29a5c67e
    • Anton Vorontsov's avatar
      kernel/cpu.c: document clear_tasks_mm_cpumask() · e4cc2f87
      Anton Vorontsov authored
      Add more comments on clear_tasks_mm_cpumask, plus adds a runtime check:
      the function is only suitable for offlined CPUs, and if called
      inappropriately, the kernel should scream aloud.
      
      [akpm@linux-foundation.org: tweak comment: s/walks up/walks/, use 80 cols]
      Suggested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Suggested-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e4cc2f87
    • Anton Vorontsov's avatar
      um: properly check all process' threads for a live mm · 2c922c51
      Anton Vorontsov authored
      kill_off_processes() might miss a valid process, this is because checking
      for process->mm is not enough.  Process' main thread may exit or detach
      its mm via use_mm(), but other threads may still have a valid mm.
      
      To catch this we use find_lock_task_mm(), which walks up all threads and
      returns an appropriate task (with task lock held).
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Richard Weinberger <richard@nod.at>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2c922c51
    • Anton Vorontsov's avatar
      um: fix possible race on task->mm · 137d1a26
      Anton Vorontsov authored
      Checking for task->mm is dangerous as ->mm might disappear (exit_mm()
      assigns NULL under task_lock(), so tasklist lock is not enough).
      
      We can't use get_task_mm()/mmput() pair as mmput() might sleep, so let's
      take the task lock while we care about its mm.
      
      Note that we should also use find_lock_task_mm() to check all process'
      threads for a valid mm, but for uml we'll do it in a separate patch.
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Richard Weinberger <richard@nod.at>
      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>
      137d1a26
    • Anton Vorontsov's avatar
      um: should hold tasklist_lock while traversing processes · 9bd0a077
      Anton Vorontsov authored
      Traversing the tasks requires holding tasklist_lock, otherwise it is
      unsafe.
      
      p.s.  However, I'm not sure that calling os_kill_ptraced_process() in the
      atomic context is correct.  It seem to work, but please take a closer
      look.
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Richard Weinberger <richard@nod.at>
      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>
      9bd0a077
    • Anton Vorontsov's avatar
      blackfin: fix possible deadlock in decode_address() · af1be5a5
      Anton Vorontsov authored
      Oleg Nesterov found an interesting deadlock possibility:
      
      > sysrq_showregs_othercpus() does smp_call_function(showacpu)
      > and showacpu() show_stack()->decode_address(). Now suppose that IPI
      > interrupts the task holding read_lock(tasklist).
      
      To fix this, blackfin should not grab the write_ variant of the
      tasklist lock, read_ one is enough.
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Mike Frysinger <vapier@gentoo.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      af1be5a5
    • Anton Vorontsov's avatar
      blackfin: a couple of task->mm handling fixes · 2214f707
      Anton Vorontsov authored
      The patch fixes two problems:
      
      1. Working with task->mm w/o getting mm or grabing the task lock is
         dangerous as ->mm might disappear (exit_mm() assigns NULL under
         task_lock(), so tasklist lock is not enough).
      
         We can't use get_task_mm()/mmput() pair as mmput() might sleep,
         so we have to take the task lock while handle its mm.
      
      2. Checking for process->mm is not enough because process' main
         thread may exit or detach its mm via use_mm(), but other threads
         may still have a valid mm.
      
         To catch this we use find_lock_task_mm(), which walks up all
         threads and returns an appropriate task (with task lock held).
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Mike Frysinger <vapier@gentoo.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2214f707
    • Anton Vorontsov's avatar
      sh: use clear_tasks_mm_cpumask() · 1198c8b9
      Anton Vorontsov authored
      Checking for process->mm is not enough because process' main thread may
      exit or detach its mm via use_mm(), but other threads may still have a
      valid mm.
      
      To fix this we would need to use find_lock_task_mm(), which would walk up
      all threads and returns an appropriate task (with task lock held).
      
      clear_tasks_mm_cpumask() has the issue fixed, so let's use it.
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Paul Mundt <lethal@linux-sh.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1198c8b9
    • Anton Vorontsov's avatar
      powerpc: use clear_tasks_mm_cpumask() · 73863ab0
      Anton Vorontsov authored
      Current CPU hotplug code has some task->mm handling issues:
      
      1. Working with task->mm w/o getting mm or grabing the task lock is
         dangerous as ->mm might disappear (exit_mm() assigns NULL under
         task_lock(), so tasklist lock is not enough).
      
         We can't use get_task_mm()/mmput() pair as mmput() might sleep,
         so we must take the task lock while handle its mm.
      
      2. Checking for process->mm is not enough because process' main
         thread may exit or detach its mm via use_mm(), but other threads
         may still have a valid mm.
      
         To fix this we would need to use find_lock_task_mm(), which would
         walk up all threads and returns an appropriate task (with task
         lock held).
      
      clear_tasks_mm_cpumask() has all the issues fixed, so let's use it.
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      73863ab0
    • Anton Vorontsov's avatar
      arm: use clear_tasks_mm_cpumask() · 3eaa73bd
      Anton Vorontsov authored
      Checking for process->mm is not enough because process' main thread may
      exit or detach its mm via use_mm(), but other threads may still have a
      valid mm.
      
      To fix this we would need to use find_lock_task_mm(), which would walk up
      all threads and returns an appropriate task (with task lock held).
      
      clear_tasks_mm_cpumask() has this issue fixed, so let's use it.
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3eaa73bd
    • Anton Vorontsov's avatar
      cpu: introduce clear_tasks_mm_cpumask() helper · cb79295e
      Anton Vorontsov authored
      Many architectures clear tasks' mm_cpumask like this:
      
      	read_lock(&tasklist_lock);
      	for_each_process(p) {
      		if (p->mm)
      			cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
      	}
      	read_unlock(&tasklist_lock);
      
      Depending on the context, the code above may have several problems,
      such as:
      
      1. Working with task->mm w/o getting mm or grabing the task lock is
         dangerous as ->mm might disappear (exit_mm() assigns NULL under
         task_lock(), so tasklist lock is not enough).
      
      2. Checking for process->mm is not enough because process' main
         thread may exit or detach its mm via use_mm(), but other threads
         may still have a valid mm.
      
      This patch implements a small helper function that does things
      correctly, i.e.:
      
      1. We take the task's lock while whe handle its mm (we can't use
         get_task_mm()/mmput() pair as mmput() might sleep);
      
      2. To catch exited main thread case, we use find_lock_task_mm(),
         which walks up all threads and returns an appropriate task
         (with task lock held).
      
      Also, Per Peter Zijlstra's idea, now we don't grab tasklist_lock in
      the new helper, instead we take the rcu read lock. We can do this
      because the function is called after the cpu is taken down and marked
      offline, so no new tasks will get this cpu set in their mm mask.
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Cc: Richard Weinberger <richard@nod.at>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Russell King <rmk@arm.linux.org.uk>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Mike Frysinger <vapier@gentoo.org>
      Cc: Paul Mundt <lethal@linux-sh.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      cb79295e
    • Konstantin Khlebnikov's avatar
      fork: call complete_vfork_done() after clearing child_tid and flushing rss-counters · f7505d64
      Konstantin Khlebnikov authored
      Child should wake up the parent from vfork() only after finishing all
      operations with shared mm.  There is no sense in using
      CLONE_CHILD_CLEARTID together with CLONE_VFORK, but it looks more accurate
      now.
      Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
      Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f7505d64
    • Konstantin Khlebnikov's avatar
      proc/smaps: show amount of nonlinear ptes in vma · bca15543
      Konstantin Khlebnikov authored
      Currently, nonlinear mappings can not be distinguished from ordinary
      mappings.  This patch adds into /proc/pid/smaps line "Nonlinear: <size>
      kB", where size is amount of nonlinear ptes in vma, this line appears only
      if VM_NONLINEAR is set.  This information may be useful not only for
      checkpoint/restore project.
      
      Requested by Pavel Emelyanov.
      Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bca15543
    • Konstantin Khlebnikov's avatar
      proc/smaps: carefully handle migration entries · b1d4d9e0
      Konstantin Khlebnikov authored
      Currently smaps reports migration entries as "swap", as result "swap" can
      appears in shared mapping.
      
      This patch converts migration entries into pages and handles them as usual.
      Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b1d4d9e0
    • Konstantin Khlebnikov's avatar
      proc: report file/anon bit in /proc/pid/pagemap · 052fb0d6
      Konstantin Khlebnikov authored
      This is an implementation of Andrew's proposal to extend the pagemap file
      bits to report what is missing about tasks' working set.
      
      The problem with the working set detection is multilateral.  In the criu
      (checkpoint/restore) project we dump the tasks' memory into image files
      and to do it properly we need to detect which pages inside mappings are
      really in use.  The mincore syscall I though could help with this did not.
       First, it doesn't report swapped pages, thus we cannot find out which
      parts of anonymous mappings to dump.  Next, it does report pages from page
      cache as present even if they are not mapped, and it doesn't make that has
      not been cow-ed.
      
      Note, that issue with swap pages is critical -- we must dump swap pages to
      image file.  But the issues with file pages are optimization -- we can
      take all file pages to image, this would be correct, but if we know that a
      page is not mapped or not cow-ed, we can remove them from dump file.  The
      dump would still be self-consistent, though significantly smaller in size
      (up to 10 times smaller on real apps).
      
      Andrew noticed, that the proc pagemap file solved 2 of 3 above issues --
      it reports whether a page is present or swapped and it doesn't report not
      mapped page cache pages.  But, it doesn't distinguish cow-ed file pages
      from not cow-ed.
      
      I would like to make the last unused bit in this file to report whether the
      page mapped into respective pte is PageAnon or not.
      
      [comment stolen from Pavel Emelyanov's v1 patch]
      Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Matt Mackall <mpm@selenic.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Rik van Riel <riel@redhat.com>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      052fb0d6