1. 02 Jun, 2015 9 commits
    • Tejun Heo's avatar
      blkcg: implement task_get_blkcg_css() · fd383c2d
      Tejun Heo authored
      
      
      Implement a wrapper around task_get_css() to acquire the blkcg css for
      a given task.  The wrapper is necessary for cgroup writeback support
      as there will be places outside blkcg proper trying to acquire
      blkcg_css and blkio_cgrp_id will be undefined when !CONFIG_BLK_CGROUP.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      fd383c2d
    • Tejun Heo's avatar
      cgroup, block: implement task_get_css() and use it in bio_associate_current() · ec438699
      Tejun Heo authored
      
      
      bio_associate_current() currently open codes task_css() and
      css_tryget_online() to find and pin $current's blkcg css.  Abstract it
      into task_get_css() which is implemented from cgroup side.  As a task
      is always associated with an online css for every subsystem except
      while the css_set update is propagating, task_get_css() retries till
      css_tryget_online() succeeds.
      
      This is a cleanup and shouldn't lead to noticeable behavior changes.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      ec438699
    • Tejun Heo's avatar
      blkcg: add blkcg_root_css · 496d5e75
      Tejun Heo authored
      
      
      Add global constant blkcg_root_css which points to &blkcg_root.css.
      This will be used by cgroup writeback support.  If blkcg is disabled,
      it's defined as ERR_PTR(-EINVAL).
      
      v2: The declarations moved to include/linux/blk-cgroup.h as suggested
          by Vivek.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      496d5e75
    • Tejun Heo's avatar
      memcg: add mem_cgroup_root_css · 56161634
      Tejun Heo authored
      
      
      Add global mem_cgroup_root_css which points to the root memcg css.
      This will be used by cgroup writeback support.  If memcg is disabled,
      it's defined as ERR_PTR(-EINVAL).
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      aCc: Michal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      56161634
    • Tejun Heo's avatar
      blkcg: always create the blkcg_gq for the root blkcg · ec13b1d6
      Tejun Heo authored
      
      
      Currently, blkcg does a minor optimization where the root blkcg is
      created when the first blkcg policy is activated on a queue and
      destroyed on the deactivation of the last.  On systems where blkcg is
      configured but not used, this saves one blkcg_gq struct per queue.  On
      systems where blkcg is actually used, there's no difference.  The only
      case where this can lead to any meaninful, albeit still minute, save
      in memory consumption is when all blkcg policies are deactivated after
      being widely used in the system, which is a hihgly unlikely scenario.
      
      The conditional existence of root blkcg_gq has already created several
      bugs in blkcg and became an issue once again for the new per-cgroup
      wb_congested mechanism for cgroup writeback support leading to a NULL
      dereference when no blkcg policy is active.  This is really not worth
      bothering with.  This patch makes blkcg always allocate and link the
      root blkcg_gq and release it only on queue destruction.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      ec13b1d6
    • Tejun Heo's avatar
      update !CONFIG_BLK_CGROUP dummies in include/linux/blk-cgroup.h · efa7d1c7
      Tejun Heo authored
      
      
      The header file will be used more widely with the pending cgroup
      writeback support and the current set of dummy declarations aren't
      enough to handle different config combinations.  Update as follows.
      
      * Drop the struct cgroup declaration.  None of the dummy defs need it.
      
      * Define blkcg as an empty struct instead of just declaring it.
      
      * Wrap dummy function defs in CONFIG_BLOCK.  Some functions use block
        data types and none of them are to be used w/o block enabled.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      efa7d1c7
    • Tejun Heo's avatar
      blkcg: move block/blk-cgroup.h to include/linux/blk-cgroup.h · eea8f41c
      Tejun Heo authored
      
      
      cgroup aware writeback support will require exposing some of blkcg
      details.  In preprataion, move block/blk-cgroup.h to
      include/linux/blk-cgroup.h.  This patch is pure file move.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      eea8f41c
    • Greg Thelen's avatar
      memcg: add per cgroup dirty page accounting · c4843a75
      Greg Thelen authored
      When modifying PG_Dirty on cached file pages, update the new
      MEM_CGROUP_STAT_DIRTY counter.  This is done in the same places where
      global NR_FILE_DIRTY is managed.  The new memcg stat is visible in the
      per memcg memory.stat cgroupfs file.  The most recent past attempt at
      this was http://thread.gmane.org/gmane.linux.kernel.cgroups/8632
      
      The new accounting supports future efforts to add per cgroup dirty
      page throttling and writeback.  It also helps an administrator break
      down a container's memory usage and provides evidence to understand
      memcg oom kills (the new dirty count is included in memcg oom kill
      messages).
      
      The ability to move page accounting between memcg
      (memory.move_charge_at_immigrate) makes this accounting more
      complicated than the global counter.  The existing
      mem_cgroup_{begin,end}_page_stat() lock is used to serialize move
      accounting with stat updates.
      Typical update operation:
      	memcg = mem_cgroup_begin_page_stat(page)
      	if (TestSetPageDirty()) {
      		[...]
      		mem_cgroup_update_page_stat(memcg)
      	}
      	mem_cgroup_end_page_stat(memcg)
      
      Summary of mem_cgroup_end_page_stat() overhead:
      - Without CONFIG_MEMCG it's a no-op
      - With CONFIG_MEMCG and no inter memcg task movement, it's just
        rcu_read_lock()
      - With CONFIG_MEMCG and inter memcg  task movement, it's
        rcu_read_lock() + spin_lock_irqsave()
      
      A memcg parameter is added to several routines because their callers
      now grab mem_cgroup_begin_page_stat() which returns the memcg later
      needed by for mem_cgroup_update_page_stat().
      
      Because mem_cgroup_begin_page_stat() may disable interrupts, some
      adjustments are needed:
      - move __mark_inode_dirty() from __set_page_dirty() to its caller.
        __mark_inode_dirty() locking does not want interrupts disabled.
      - use spin_lock_irqsave(tree_lock) rather than spin_lock_irq() in
        __delete_from_page_cache(), replace_page_cache_page(),
        invalidate_complete_page2(), and __remove_mapping().
      
         text    data     bss      dec    hex filename
      8925147 1774832 1785856 12485835 be84cb vmlinux-!CONFIG_MEMCG-before
      8925339 1774832 1785856 12486027 be858b vmlinux-!CONFIG_MEMCG-after
                                  +192 text bytes
      8965977 1784992 1785856 12536825 bf4bf9 vmlinux-CONFIG_MEMCG-before
      8966750 1784992 1785856 12537598 bf4efe vmlinux-CONFIG_MEMCG-after
                                  +773 text bytes
      
      Performance tests run on v4.0-rc1-36-g4f671fe2
      
      .  Lower is better for
      all metrics, they're all wall clock or cycle counts.  The read and write
      fault benchmarks just measure fault time, they do not include I/O time.
      
      * CONFIG_MEMCG not set:
                                  baseline                              patched
        kbuild                 1m25.030000(+-0.088% 3 samples)       1m25.426667(+-0.120% 3 samples)
        dd write 100 MiB          0.859211561 +-15.10%                  0.874162885 +-15.03%
        dd write 200 MiB          1.670653105 +-17.87%                  1.669384764 +-11.99%
        dd write 1000 MiB         8.434691190 +-14.15%                  8.474733215 +-14.77%
        read fault cycles       254.0(+-0.000% 10 samples)            253.0(+-0.000% 10 samples)
        write fault cycles     2021.2(+-3.070% 10 samples)           1984.5(+-1.036% 10 samples)
      
      * CONFIG_MEMCG=y root_memcg:
                                  baseline                              patched
        kbuild                 1m25.716667(+-0.105% 3 samples)       1m25.686667(+-0.153% 3 samples)
        dd write 100 MiB          0.855650830 +-14.90%                  0.887557919 +-14.90%
        dd write 200 MiB          1.688322953 +-12.72%                  1.667682724 +-13.33%
        dd write 1000 MiB         8.418601605 +-14.30%                  8.673532299 +-15.00%
        read fault cycles       266.0(+-0.000% 10 samples)            266.0(+-0.000% 10 samples)
        write fault cycles     2051.7(+-1.349% 10 samples)           2049.6(+-1.686% 10 samples)
      
      * CONFIG_MEMCG=y non-root_memcg:
                                  baseline                              patched
        kbuild                 1m26.120000(+-0.273% 3 samples)       1m25.763333(+-0.127% 3 samples)
        dd write 100 MiB          0.861723964 +-15.25%                  0.818129350 +-14.82%
        dd write 200 MiB          1.669887569 +-13.30%                  1.698645885 +-13.27%
        dd write 1000 MiB         8.383191730 +-14.65%                  8.351742280 +-14.52%
        read fault cycles       265.7(+-0.172% 10 samples)            267.0(+-0.000% 10 samples)
        write fault cycles     2070.6(+-1.512% 10 samples)           2084.4(+-2.148% 10 samples)
      
      As expected anon page faults are not affected by this patch.
      
      tj: Updated to apply on top of the recent cancel_dirty_page() changes.
      Signed-off-by: default avatarSha Zhengju <handai.szj@gmail.com>
      Signed-off-by: default avatarGreg Thelen <gthelen@google.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      c4843a75
    • Tejun Heo's avatar
      page_writeback: revive cancel_dirty_page() in a restricted form · 11f81bec
      Tejun Heo authored
      cancel_dirty_page() had some issues and b9ea2515
      
       ("page_writeback:
      clean up mess around cancel_dirty_page()") replaced it with
      account_page_cleaned() which makes the caller responsible for clearing
      the dirty bit; unfortunately, the planned changes for cgroup writeback
      support requires synchronization between dirty bit manipulation and
      stat updates.  While we can open-code such synchronization in each
      account_page_cleaned() callsite, that's gonna be unnecessarily awkward
      and verbose.
      
      This patch revives cancel_dirty_page() but in a more restricted form.
      All it does is TestClearPageDirty() followed by account_page_cleaned()
      invocation if the page was dirty.  This helper covers all
      account_page_cleaned() usages except for __delete_from_page_cache()
      which is a special case anyway and left alone.  As this leaves no
      module user for account_page_cleaned(), EXPORT_SYMBOL() is dropped
      from it.
      
      This patch just revives cancel_dirty_page() as a trivial wrapper to
      replace equivalent usages and doesn't introduce any functional
      changes.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      11f81bec
  2. 01 Jun, 2015 1 commit
    • Keith Busch's avatar
      blk-mq: Shared tag enhancements · f26cdc85
      Keith Busch authored
      
      
      Storage controllers may expose multiple block devices that share hardware
      resources managed by blk-mq. This patch enhances the shared tags so a
      low-level driver can access the shared resources not tied to the unshared
      h/w contexts. This way the LLD can dynamically add and delete disks and
      request queues without having to track all the request_queue hctx's to
      iterate outstanding tags.
      Signed-off-by: default avatarKeith Busch <keith.busch@intel.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      f26cdc85
  3. 29 May, 2015 2 commits
  4. 26 May, 2015 1 commit
  5. 22 May, 2015 2 commits
    • Christoph Hellwig's avatar
      block, dm: don't copy bios for request clones · 5f1b670d
      Christoph Hellwig authored
      
      
      Currently dm-multipath has to clone the bios for every request sent
      to the lower devices, which wastes cpu cycles and ties down memory.
      
      This patch instead adds a new REQ_CLONE flag that instructs req_bio_endio
      to not complete bios attached to a request, which we set on clone
      requests similar to bios in a flush sequence.  With this change I/O
      errors on a path failure only get propagated to dm-multipath, which
      can then either resubmit the I/O or complete the bios on the original
      request.
      
      I've done some basic testing of this on a Linux target with ALUA support,
      and it survives path failures during I/O nicely.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      5f1b670d
    • Mike Snitzer's avatar
      block: remove management of bi_remaining when restoring original bi_end_io · 326e1dbb
      Mike Snitzer authored
      Commit c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for
      non-chains") regressed all existing callers that followed this pattern:
       1) saving a bio's original bi_end_io
       2) wiring up an intermediate bi_end_io
       3) restoring the original bi_end_io from intermediate bi_end_io
       4) calling bio_endio() to execute the restored original bi_end_io
      
      The regression was due to BIO_CHAIN only ever getting set if
      bio_inc_remaining() is called.  For the above pattern it isn't set until
      step 3 above (step 2 would've needed to establish BIO_CHAIN).  As such
      the first bio_endio(), in step 2 above, never decremented __bi_remaining
      before calling the intermediate bi_end_io -- leaving __bi_remaining with
      the value 1 instead of 0.  When bio_inc_remaining() occurred during step
      3 it brought it to a value of 2.  When the second bio_endio() was
      called, in step 4 above, it should've called the original bi_end_io but
      it didn't because there was an extra reference that wasn't dropped (due
      to atomic operations being optimized away since BIO_CHAIN wasn't set
      upfront).
      
      Fix this issue by removing the __bi_remaining management complexity for
      all callers that use the above pattern -- bio_chain() is the only
      interface that _needs_ to be concerned with __bi_remaining.  For the
      above pattern callers just expect the bi_end_io they set to get called!
      Remove bio_endio_nodec() and also remove all bio_inc_remaining() calls
      that aren't associated with the bio_chain() interface.
      
      Also, the bio_inc_remaining() interface has been moved local to bio.c.
      
      Fixes: c4cf5261
      
       ("bio: skip atomic inc/dec of ->bi_remaining for non-chains")
      Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      326e1dbb
  6. 20 May, 2015 2 commits
    • Ming Lei's avatar
      block: replace trylock with mutex_lock in blkdev_reread_part() · b04a5636
      Ming Lei authored
      
      
      The only possible problem of using mutex_lock() instead of trylock
      is about deadlock.
      
      If there aren't any locks held before calling blkdev_reread_part(),
      deadlock can't be caused by this conversion.
      
      If there are locks held before calling blkdev_reread_part(),
      and if these locks arn't required in open, close handler and I/O
      path, deadlock shouldn't be caused too.
      
      Both user space's ioctl(BLKRRPART) and md_setup_drive() from
      init/do_mounts_md.c belongs to the 1st case, so the conversion is safe
      for the two cases.
      
      For loop, the previous patches in this pathset has fixed the ABBA lock
      dependency, so the conversion is OK.
      
      For nbd, tx_lock is held when calling the function:
      
      	- both open and release won't hold the lock
      	- when blkdev_reread_part() is run, I/O thread has been stopped
      	already, so tx_lock won't be acquired in I/O path at that time.
      	- so the conversion won't cause deadlock for nbd
      
      For dasd, both dasd_open(), dasd_release() and request function don't
      acquire any mutex/semphone, so the conversion should be safe.
      Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
      Tested-by: default avatarJarod Wilson <jarod@redhat.com>
      Acked-by: default avatarJarod Wilson <jarod@redhat.com>
      Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      b04a5636
    • Jarod Wilson's avatar
      block: export blkdev_reread_part() and __blkdev_reread_part() · be324177
      Jarod Wilson authored
      
      
      This patch exports blkdev_reread_part() for block drivers, also
      introduce __blkdev_reread_part().
      
      For some drivers, such as loop, reread of partitions can be run
      from the release path, and bd_mutex may already be held prior to
      calling ioctl_by_bdev(bdev, BLKRRPART, 0), so introduce
      __blkdev_reread_part for use in such cases.
      
      CC: Christoph Hellwig <hch@lst.de>
      CC: Jens Axboe <axboe@kernel.dk>
      CC: Tejun Heo <tj@kernel.org>
      CC: Alexander Viro <viro@zeniv.linux.org.uk>
      CC: Markus Pargmann <mpa@pengutronix.de>
      CC: Stefan Weinhuber <wein@de.ibm.com>
      CC: Stefan Haberland <stefan.haberland@de.ibm.com>
      CC: Sebastian Ott <sebott@linux.vnet.ibm.com>
      CC: Fabian Frederick <fabf@skynet.be>
      CC: Ming Lei <ming.lei@canonical.com>
      CC: David Herrmann <dh.herrmann@gmail.com>
      CC: Andrew Morton <akpm@linux-foundation.org>
      CC: Peter Zijlstra <peterz@infradead.org>
      CC: nbd-general@lists.sourceforge.net
      CC: linux-s390@vger.kernel.org
      Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarJarod Wilson <jarod@redhat.com>
      Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      be324177
  7. 19 May, 2015 5 commits
  8. 08 May, 2015 6 commits
    • Shaohua Li's avatar
      blk-mq: make plug work for mutiple disks and queues · 5b3f341f
      Shaohua Li authored
      
      
      Last patch makes plug work for multiple queue case. However it only
      works for single disk case, because it assumes only one request in the
      plug list. If a task is accessing multiple disks, eg MD/DM, the
      assumption is wrong. Let blk_attempt_plug_merge() record request from
      the same queue.
      
      V2: use NULL parameter in !mq case. Fix a bug. Add comments in
      blk_attempt_plug_merge to make it less (hopefully) confusion.
      
      Cc: Jens Axboe <axboe@fb.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      5b3f341f
    • Shaohua Li's avatar
      blk-mq: do limited block plug for multiple queue case · f984df1f
      Shaohua Li authored
      
      
      plug is still helpful for workload with IO merge, but it can be harmful
      otherwise especially with multiple hardware queues, as there is
      (supposed) no lock contention in this case and plug can introduce
      latency. For multiple queues, we do limited plug, eg plug only if there
      is request merge. If a request doesn't have merge with following
      request, the requet will be dispatched immediately.
      
      V2: check blk_queue_nomerges() as suggested by Jeff.
      
      Cc: Jens Axboe <axboe@fb.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      f984df1f
    • Shaohua Li's avatar
      blk-mq: avoid re-initialize request which is failed in direct dispatch · 239ad215
      Shaohua Li authored
      
      
      If we directly issue a request and it fails, we use
      blk_mq_merge_queue_io(). But we already assigned bio to a request in
      blk_mq_bio_to_request. blk_mq_merge_queue_io shouldn't run
      blk_mq_bio_to_request again.
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      239ad215
    • Jeff Moyer's avatar
      blk-mq: fix plugging in blk_sq_make_request · e6c4438b
      Jeff Moyer authored
      The following appears in blk_sq_make_request:
      
      	/*
      	 * If we have multiple hardware queues, just go directly to
      	 * one of those for sync IO.
      	 */
      
      We clearly don't have multiple hardware queues, here!  This comment was
      introduced with this commit 07068d5b
      
       (blk-mq: split make request
      handler for multi and single queue):
      
          We want slightly different behavior from them:
      
          - On single queue devices, we currently use the per-process plug
            for deferred IO and for merging.
      
          - On multi queue devices, we don't use the per-process plug, but
            we want to go straight to hardware for SYNC IO.
      
      The old code had this:
      
              use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
      
      and that was converted to:
      
      	use_plug = !is_flush_fua && !is_sync;
      
      which is not equivalent.  For the single queue case, that second half of
      the && expression is always true.  So, what I think was actually inteded
      follows (and this more closely matches what is done in blk_queue_bio).
      
      V2: delete the 'likely', which should not be a big deal
      Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      e6c4438b
    • Shaohua Li's avatar
      sched: always use blk_schedule_flush_plug in io_schedule_out · 5596d0d5
      Shaohua Li authored
      
      
      block plug callback could sleep, so we introduce a parameter
      'from_schedule' and corresponding drivers can use it to destinguish a
      schedule plug flush or a plug finish. Unfortunately io_schedule_out
      still uses blk_flush_plug(). This causes below output (Note, I added a
      might_sleep() in raid1_unplug to make it trigger faster, but the whole
      thing doesn't matter if I add might_sleep). In raid1/10, this can cause
      deadlock.
      
      This patch makes io_schedule_out always uses blk_schedule_flush_plug.
      This should only impact drivers (as far as I know, raid 1/10) which are
      sensitive to the 'from_schedule' parameter.
      
      [  370.817949] ------------[ cut here ]------------
      [  370.817960] WARNING: CPU: 7 PID: 145 at ../kernel/sched/core.c:7306 __might_sleep+0x7f/0x90()
      [  370.817969] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff81092fcf>] prepare_to_wait+0x2f/0x90
      [  370.817971] Modules linked in: raid1
      [  370.817976] CPU: 7 PID: 145 Comm: kworker/u16:9 Tainted: G        W       4.0.0+ #361
      [  370.817977] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153802- 04/01/2014
      [  370.817983] Workqueue: writeback bdi_writeback_workfn (flush-9:1)
      [  370.817985]  ffffffff81cd83be ffff8800ba8cb298 ffffffff819dd7af 0000000000000001
      [  370.817988]  ffff8800ba8cb2e8 ffff8800ba8cb2d8 ffffffff81051afc ffff8800ba8cb2c8
      [  370.817990]  ffffffffa00061a8 000000000000041e 0000000000000000 ffff8800ba8cba28
      [  370.817993] Call Trace:
      [  370.817999]  [<ffffffff819dd7af>] dump_stack+0x4f/0x7b
      [  370.818002]  [<ffffffff81051afc>] warn_slowpath_common+0x8c/0xd0
      [  370.818004]  [<ffffffff81051b86>] warn_slowpath_fmt+0x46/0x50
      [  370.818006]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
      [  370.818008]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
      [  370.818010]  [<ffffffff810776ef>] __might_sleep+0x7f/0x90
      [  370.818014]  [<ffffffffa0000c03>] raid1_unplug+0xd3/0x170 [raid1]
      [  370.818024]  [<ffffffff81421d9a>] blk_flush_plug_list+0x8a/0x1e0
      [  370.818028]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
      [  370.818031]  [<ffffffff819e21b0>] io_schedule_timeout+0x130/0x140
      [  370.818033]  [<ffffffff819e3586>] bit_wait_io+0x36/0x50
      [  370.818034]  [<ffffffff819e31b5>] __wait_on_bit+0x65/0x90
      [  370.818041]  [<ffffffff8125b67c>] ? ext4_read_block_bitmap_nowait+0xbc/0x630
      [  370.818043]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
      [  370.818045]  [<ffffffff819e3302>] out_of_line_wait_on_bit+0x72/0x80
      [  370.818047]  [<ffffffff810935e0>] ? autoremove_wake_function+0x40/0x40
      [  370.818050]  [<ffffffff811de744>] __wait_on_buffer+0x44/0x50
      [  370.818053]  [<ffffffff8125ae80>] ext4_wait_block_bitmap+0xe0/0xf0
      [  370.818058]  [<ffffffff812975d6>] ext4_mb_init_cache+0x206/0x790
      [  370.818062]  [<ffffffff8114bc6c>] ? lru_cache_add+0x1c/0x50
      [  370.818064]  [<ffffffff81297c7e>] ext4_mb_init_group+0x11e/0x200
      [  370.818066]  [<ffffffff81298231>] ext4_mb_load_buddy+0x341/0x360
      [  370.818068]  [<ffffffff8129a1a3>] ext4_mb_find_by_goal+0x93/0x2f0
      [  370.818070]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
      [  370.818072]  [<ffffffff8129ab67>] ext4_mb_regular_allocator+0x67/0x460
      [  370.818074]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
      [  370.818076]  [<ffffffff8129ca4b>] ext4_mb_new_blocks+0x4cb/0x620
      [  370.818079]  [<ffffffff81290956>] ext4_ext_map_blocks+0x4c6/0x14d0
      [  370.818081]  [<ffffffff812a4d4e>] ? ext4_es_lookup_extent+0x4e/0x290
      [  370.818085]  [<ffffffff8126399d>] ext4_map_blocks+0x14d/0x4f0
      [  370.818088]  [<ffffffff81266fbd>] ext4_writepages+0x76d/0xe50
      [  370.818094]  [<ffffffff81149691>] do_writepages+0x21/0x50
      [  370.818097]  [<ffffffff811d5c00>] __writeback_single_inode+0x60/0x490
      [  370.818099]  [<ffffffff811d630a>] writeback_sb_inodes+0x2da/0x590
      [  370.818103]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
      [  370.818105]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
      [  370.818107]  [<ffffffff811d665f>] __writeback_inodes_wb+0x9f/0xd0
      [  370.818109]  [<ffffffff811d69db>] wb_writeback+0x34b/0x3c0
      [  370.818111]  [<ffffffff811d70df>] bdi_writeback_workfn+0x23f/0x550
      [  370.818116]  [<ffffffff8106bbd8>] process_one_work+0x1c8/0x570
      [  370.818117]  [<ffffffff8106bb5b>] ? process_one_work+0x14b/0x570
      [  370.818119]  [<ffffffff8106c09b>] worker_thread+0x11b/0x470
      [  370.818121]  [<ffffffff8106bf80>] ? process_one_work+0x570/0x570
      [  370.818124]  [<ffffffff81071868>] kthread+0xf8/0x110
      [  370.818126]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
      [  370.818129]  [<ffffffff819e9322>] ret_from_fork+0x42/0x70
      [  370.818131]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
      [  370.818132] ---[ end trace 7b4deb71e68b6605 ]---
      
      V2: don't change ->in_iowait
      
      Cc: NeilBrown <neilb@suse.de>
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      5596d0d5
    • Shaohua Li's avatar
      blk: clean up plug · dd6cf3e1
      Shaohua Li authored
      
      
      Current code looks like inner plug gets flushed with a
      blk_finish_plug(). Actually it's a nop. All requests/callbacks are added
      to current->plug, while only outmost plug is assigned to current->plug.
      So inner plug always has empty request/callback list, which makes
      blk_flush_plug_list() a nop. This tries to make the code more clear.
      Signed-off-by: default avatarShaohua Li <shli@fb.com>
      Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
      Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      dd6cf3e1
  9. 05 May, 2015 10 commits
  10. 04 May, 2015 2 commits
    • Álvaro Fernández Rojas's avatar
      hwrng: bcm63xx - Fix driver compilation · f440c4ee
      Álvaro Fernández Rojas authored
      - s/clk_didsable_unprepare/clk_disable_unprepare
      - s/prov/priv
      - s/error/ret (bcm63xx_rng_probe)
      
      Fixes: 6229c160
      
       ("hwrng: bcm63xx - make use of devm_hwrng_register")
      Signed-off-by: default avatarÁlvaro Fernández Rojas <noltari@gmail.com>
      Acked-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
      Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      f440c4ee
    • Daniel Borkmann's avatar
      lib: make memzero_explicit more robust against dead store elimination · 7829fb09
      Daniel Borkmann authored
      In commit 0b053c95 ("lib: memzero_explicit: use barrier instead
      of OPTIMIZER_HIDE_VAR"), we made memzero_explicit() more robust in
      case LTO would decide to inline memzero_explicit() and eventually
      find out it could be elimiated as dead store.
      
      While using barrier() works well for the case of gcc, recent efforts
      from LLVMLinux people suggest to use llvm as an alternative to gcc,
      and there, Stephan found in a simple stand-alone user space example
      that llvm could nevertheless optimize and thus elimitate the memset().
      A similar issue has been observed in the referenced llvm bug report,
      which is regarded as not-a-bug.
      
      Based on some experiments, icc is a bit special on its own, while it
      doesn't seem to eliminate the memset(), it could do so with an own
      implementation, and then result in similar findings as with llvm.
      
      The fix in this patch now works for all three compilers (also tested
      with more aggressive optimization levels). Arguably, in the current
      kernel tree it's more of a theoretical issue, but imho, it's better
      to be pedantic about it.
      
      It's clearly visible with gcc/llvm though, with the below code: if we
      would have used barrier() only here, llvm would have omitted clearing,
      not so with barrier_data() variant:
      
        static inline void memzero_explicit(void *s, size_t count)
        {
          memset(s, 0, count);
          barrier_data(s);
        }
      
        int main(void)
        {
          char buff[20];
          memzero_explicit(buff, sizeof(buff));
          return 0;
        }
      
        $ gcc -O2 test.c
        $ gdb a.out
        (gdb) disassemble main
        Dump of assembler code for function main:
         0x0000000000400400  <+0>: lea   -0x28(%rsp),%rax
         0x0000000000400405  <+5>: movq  $0x0,-0x28(%rsp)
         0x000000000040040e <+14>: movq  $0x0,-0x20(%rsp)
         0x0000000000400417 <+23>: movl  $0x0,-0x18(%rsp)
         0x000000000040041f <+31>: xor   %eax,%eax
         0x0000000000400421 <+33>: retq
        End of assembler dump.
      
        $ clang -O2 test.c
        $ gdb a.out
        (gdb) disassemble main
        Dump of assembler code for function main:
         0x00000000004004f0  <+0>: xorps  %xmm0,%xmm0
         0x00000000004004f3  <+3>: movaps %xmm0,-0x18(%rsp)
         0x00000000004004f8  <+8>: movl   $0x0,-0x8(%rsp)
         0x0000000000400500 <+16>: lea    -0x18(%rsp),%rax
         0x0000000000400505 <+21>: xor    %eax,%eax
         0x0000000000400507 <+23>: retq
        End of assembler dump.
      
      As gcc, clang, but also icc defines __GNUC__, it's sufficient to define
      this in compiler-gcc.h only to be picked up. For a fallback or otherwise
      unsupported compiler, we define it as a barrier. Similarly, for ecc which
      does not support gcc inline asm.
      
      Reference: https://llvm.org/bugs/show_bug.cgi?id=15495
      
      Reported-by: default avatarStephan Mueller <smueller@chronox.de>
      Tested-by: default avatarStephan Mueller <smueller@chronox.de>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: Stephan Mueller <smueller@chronox.de>
      Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
      Cc: mancha security <mancha1@zoho.com>
      Cc: Mark Charlebois <charlebm@gmail.com>
      Cc: Behan Webster <behanw@converseincode.com>
      Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      7829fb09