1. 15 Nov, 2010 1 commit
    • Greg Thelen's avatar
      ioprio: grab rcu_read_lock in sys_ioprio_{set,get}() · d69b78ba
      Greg Thelen authored
      Using:
      - CONFIG_LOCKUP_DETECTOR=y
      - CONFIG_PREEMPT=y
      - CONFIG_LOCKDEP=y
      - CONFIG_PROVE_LOCKING=y
      - CONFIG_PROVE_RCU=y
      found a missing rcu lock during boot on a 512 MiB x86_64 ubuntu vm:
        ===================================================
        [ INFO: suspicious rcu_dereference_check() usage. ]
        ---------------------------------------------------
        kernel/pid.c:419 invoked rcu_dereference_check() without protection!
      
        other info that might help us debug this:
      
        rcu_scheduler_active = 1, debug_locks = 0
        1 lock held by ureadahead/1355:
         #0:  (tasklist_lock){.+.+..}, at: [<ffffffff8115bc09>] sys_ioprio_set+0x7f/0x29e
      
        stack backtrace:
        Pid: 1355, comm: ureadahead Not tainted 2.6.37-dbg-DEV #1
        Call Trace:
         [<ffffffff8109c10c>] lockdep_rcu_dereference+0xaa/0xb3
         [<ffffffff81088cbf>] find_task_by_pid_ns+0x44/0x5d
         [<ffffffff81088cfa>] find_task_by_vpid+0x22/0x24
         [<ffffffff8115bc3e>] sys_ioprio_set+0xb4/0x29e
         [<ffffffff8147cf21>] ? trace_hardirqs_off_thunk+0x3a/0x3c
         [<ffffffff8105c409>] sysenter_dispatch+0x7/0x2c
         [<ffffffff8147cee2>] ? trace_hardirqs_on_thunk+0x3a/0x3f
      
      The fix is to:
      a) grab rcu lock in sys_ioprio_{set,get}() and
      b) avoid grabbing tasklist_lock.
      Discussion in: http://marc.info/?l=linux-kernel&m=128951324702889Signed-off-by: default avatarGreg Thelen <gthelen@google.com>
      Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
      
      Modified by Jens to remove the now redundant inner rcu lock and
      unlock since they are now protected by the outer lock.
      Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      d69b78ba
  2. 10 Nov, 2010 2 commits
    • Sergey Senozhatsky's avatar
      ioprio: rcu_read_lock/unlock protect find_task_by_vpid call (V2) · f85acd81
      Sergey Senozhatsky authored
      Commit 4221a991 "Add RCU check for
      find_task_by_vpid()" introduced rcu_lockdep_assert to find_task_by_pid_ns=
      
      Assertion failed in sys_ioprio_get. The patch is fixing assertion
      failure in ioprio_set as well.
      
       kernel/pid.c:419 invoked rcu_dereference_check() without protection!
      
       stack backtrace:
       Pid: 4254, comm: iotop Not tainted
       Call Trace:
       [<ffffffff810656f2>] lockdep_rcu_dereference+0xaa/0xb2
       [<ffffffff81053c67>] find_task_by_pid_ns+0x4f/0x68
       [<ffffffff81053c9d>] find_task_by_vpid+0x1d/0x1f
       [<ffffffff811104e2>] sys_ioprio_get+0x50/0x2da
       [<ffffffff81002182>] system_call_fastpath+0x16/0x1b
      
      V2: rcu critical section expanded according to comment by Paul E. McKenney
      Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      f85acd81
    • Daniel J Blueman's avatar
      ioprio: fix RCU locking around task dereference · 1447399b
      Daniel J Blueman authored
      With 2.6.37-rc1, I observe sys_ioprio_set not taking the RCU lock [1]
      across access to the task credentials.
      
      Inspecting the code in fs/ioprio.c, the tasklist_lock is held for read
      across the __task_cred call, which is presumably sufficient to prevent
      the task credentials becoming stale.
      
      ===================================================
      
      [ INFO: suspicious rcu_dereference_check() usage. ]
      
      ---------------------------------------------------
      
      kernel/pid.c:419 invoked rcu_dereference_check() without protection!
      
      other info that might help us debug this:
      
      rcu_scheduler_active = 1, debug_locks = 1
      
      1 lock held by start-stop-daem/2246:
      
       #0:  (tasklist_lock){.?.?..}, at: [<ffffffff811a2dfa>]
      sys_ioprio_set+0x8a/0x400
      
      stack backtrace:
      
      Pid: 2246, comm: start-stop-daem Not tainted 2.6.37-rc1-330cd+ #2
      
      Call Trace:
      
       [<ffffffff8109f5f4>] lockdep_rcu_dereference+0xa4/0xc0
      
       [<ffffffff81085651>] find_task_by_pid_ns+0x81/0x90
      
       [<ffffffff8108567d>] find_task_by_vpid+0x1d/0x20
      
       [<ffffffff811a3160>] sys_ioprio_set+0x3f0/0x400
      
       [<ffffffff816efa79>] ? trace_hardirqs_on_thunk+0x3a/0x3f
      
       [<ffffffff81003482>] system_call_fastpath+0x16/0x1b
      
      Take the RCU lock for read across acquiring the pointer to the task
      credentials and dereferencing it.
      Signed-off-by: default avatarDaniel J Blueman <daniel.blueman@gmail.com>
      
      Fixed up by Jens to fix missing rcu_read_unlock() on mismatches.
      Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
      1447399b
  3. 30 Mar, 2010 1 commit
    • Tejun Heo's avatar
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      Tejun Heo authored
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
      
      percpu.h is included by sched.h and module.h and thus ends up being
      included when building most .c files.  percpu.h includes slab.h which
      in turn includes gfp.h making everything defined by the two files
      universally available and complicating inclusion dependencies.
      
      percpu.h -> slab.h dependency is about to be removed.  Prepare for
      this change by updating users of gfp and slab facilities include those
      headers directly instead of assuming availability.  As this conversion
      needs to touch large number of source files, the following script is
      used as the basis of conversion.
      
        http://userweb.kernel.org/~tj/misc/slabh-sweep.py
      
      The script does the followings.
      
      * Scan files for gfp and slab usages and update includes such that
        only the necessary includes are there.  ie. if only gfp is used,
        gfp.h, if slab is used, slab.h.
      
      * When the script inserts a new include, it looks at the include
        blocks and try to put the new include such that its order conforms
        to its surrounding.  It's put in the include block which contains
        core kernel includes, in the same order that the rest are ordered -
        alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
        doesn't seem to be any matching order.
      
      * If the script can't find a place to put a new include (mostly
        because the file doesn't have fitting include block), it prints out
        an error message indicating which .h file needs to be added to the
        file.
      
      The conversion was done in the following steps.
      
      1. The initial automatic conversion of all .c files updated slightly
         over 4000 files, deleting around 700 includes and adding ~480 gfp.h
         and ~3000 slab.h inclusions.  The script emitted errors for ~400
         files.
      
      2. Each error was manually checked.  Some didn't need the inclusion,
         some needed manual addition while adding it to implementation .h or
         embedding .c file was more appropriate for others.  This step added
         inclusions to around 150 files.
      
      3. The script was run again and the output was compared to the edits
         from #2 to make sure no file was left behind.
      
      4. Several build tests were done and a couple of problems were fixed.
         e.g. lib/decompress_*.c used malloc/free() wrappers around slab
         APIs requiring slab.h to be added manually.
      
      5. The script was run on all .h files but without automatically
         editing them as sprinkling gfp.h and slab.h inclusions around .h
         files could easily lead to inclusion dependency hell.  Most gfp.h
         inclusion directives were ignored as stuff from gfp.h was usually
         wildly available and often used in preprocessor macros.  Each
         slab.h inclusion directive was examined and added manually as
         necessary.
      
      6. percpu.h was updated not to include slab.h.
      
      7. Build test were done on the following configurations and failures
         were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
         distributed build env didn't work with gcov compiles) and a few
         more options had to be turned off depending on archs to make things
         build (like ipr on powerpc/64 which failed due to missing writeq).
      
         * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
         * powerpc and powerpc64 SMP allmodconfig
         * sparc and sparc64 SMP allmodconfig
         * ia64 SMP allmodconfig
         * s390 SMP allmodconfig
         * alpha SMP allmodconfig
         * um on x86_64 SMP allmodconfig
      
      8. percpu.h modifications were reverted so that it could be applied as
         a separate patch and serve as bisection point.
      
      Given the fact that I had only a couple of failures from tests on step
      6, I'm fairly confident about the coverage of this conversion patch.
      If there is a breakage, it's likely to be something in one of the arch
      headers which should be easily discoverable easily on most builds of
      the specific arch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Guess-its-ok-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  4. 14 Jan, 2009 1 commit
  5. 05 Jan, 2009 1 commit
  6. 13 Nov, 2008 4 commits
  7. 20 Aug, 2008 1 commit
    • Ken Chen's avatar
      fix setpriority(PRIO_PGRP) thread iterator breakage · 2d70b68d
      Ken Chen authored
      When user calls sys_setpriority(PRIO_PGRP ...) on a NPTL style multi-LWP
      process, only the task leader of the process is affected, all other
      sibling LWP threads didn't receive the setting.  The problem was that the
      iterator used in sys_setpriority() only iteartes over one task for each
      process, ignoring all other sibling thread.
      
      Introduce a new macro do_each_pid_thread / while_each_pid_thread to walk
      each thread of a process.  Convert 4 call sites in {set/get}priority and
      ioprio_{set/get}.
      Signed-off-by: default avatarKen Chen <kenchen@google.com>
      Cc: Oleg Nesterov <oleg@tv-sign.ru>
      Cc: Roland McGrath <roland@redhat.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jens Axboe <jens.axboe@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2d70b68d
  8. 28 Jan, 2008 3 commits
  9. 07 Nov, 2007 1 commit
  10. 19 Oct, 2007 2 commits
    • Pavel Emelyanov's avatar
      Uninline find_task_by_xxx set of functions · 228ebcbe
      Pavel Emelyanov authored
      The find_task_by_something is a set of macros are used to find task by pid
      depending on what kind of pid is proposed - global or virtual one.  All of
      them are wrappers above the most generic one - find_task_by_pid_type_ns() -
      and just substitute some args for it.
      
      It turned out, that dereferencing the current->nsproxy->pid_ns construction
      and pushing one more argument on the stack inline cause kernel text size to
      grow.
      
      This patch moves all this stuff out-of-line into kernel/pid.c.  Together
      with the next patch it saves a bit less than 400 bytes from the .text
      section.
      Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
      Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
      Cc: Oleg Nesterov <oleg@tv-sign.ru>
      Cc: Paul Menage <menage@google.com>
      Cc: "Eric W. Biederman" <ebiederm@xmission.com>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      228ebcbe
    • Pavel Emelyanov's avatar
      pid namespaces: changes to show virtual ids to user · b488893a
      Pavel Emelyanov authored
      This is the largest patch in the set. Make all (I hope) the places where
      the pid is shown to or get from user operate on the virtual pids.
      
      The idea is:
       - all in-kernel data structures must store either struct pid itself
         or the pid's global nr, obtained with pid_nr() call;
       - when seeking the task from kernel code with the stored id one
         should use find_task_by_pid() call that works with global pids;
       - when showing pid's numerical value to the user the virtual one
         should be used, but however when one shows task's pid outside this
         task's namespace the global one is to be used;
       - when getting the pid from userspace one need to consider this as
         the virtual one and use appropriate task/pid-searching functions.
      
      [akpm@linux-foundation.org: build fix]
      [akpm@linux-foundation.org: nuther build fix]
      [akpm@linux-foundation.org: yet nuther build fix]
      [akpm@linux-foundation.org: remove unneeded casts]
      Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
      Signed-off-by: default avatarAlexey Dobriyan <adobriyan@openvz.org>
      Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
      Cc: Oleg Nesterov <oleg@tv-sign.ru>
      Cc: Paul Menage <menage@google.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>
      b488893a
  11. 12 Feb, 2007 1 commit
  12. 12 Oct, 2006 1 commit
    • Vasily Tarasov's avatar
      [PATCH] block layer: ioprio_best function fix · d58cdfb8
      Vasily Tarasov authored
      Currently ioprio_best function first checks wethere aioprio or bioprio equals
      IOPRIO_CLASS_NONE (ioprio_valid() macros does that) and if it is so it returns
      bioprio/aioprio appropriately. Thus the next four lines, that set aclass/bclass
      to IOPRIO_CLASS_BE, if aclass/bclass == IOPRIO_CLASS_NONE, are never executed.
      
      The second problem: if aioprio from class IOPRIO_CLASS_NONE and bioprio from
      class IOPRIO_CLASS_IDLE are passed to ioprio_best function, it will return
      IOPRIO_CLASS_IDLE. It means that during __make_request we can merge two
      requests and set the priority of merged request to IDLE, while one of
      the initial requests originates from a process with NONE (default) priority.
      So we can get a situation when a process with default ioprio will experience
      IO starvation, while there is no process from real-time class in the system.
      
      Just removing ioprio_valid check should correct situation.
      Signed-off-by: default avatarVasily Tarasov <vtaras@openvz.org>
      Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
      d58cdfb8
  13. 30 Sep, 2006 3 commits
  14. 21 Aug, 2006 3 commits
  15. 30 Jun, 2006 1 commit
  16. 23 Jun, 2006 1 commit
  17. 11 Jan, 2006 1 commit
  18. 08 Nov, 2005 1 commit
  19. 20 Aug, 2005 1 commit
  20. 07 Jul, 2005 1 commit
  21. 27 Jun, 2005 1 commit
    • Jens Axboe's avatar
      [PATCH] Update cfq io scheduler to time sliced design · 22e2c507
      Jens Axboe authored
      This updates the CFQ io scheduler to the new time sliced design (cfq
      v3).  It provides full process fairness, while giving excellent
      aggregate system throughput even for many competing processes.  It
      supports io priorities, either inherited from the cpu nice value or set
      directly with the ioprio_get/set syscalls.  The latter closely mimic
      set/getpriority.
      
      This import is based on my latest from -mm.
      Signed-off-by: default avatarJens Axboe <axboe@suse.de>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      22e2c507