linux-toradex.git/block, branch v4.1-rc4

blk-mq: don't lose requests if a stopped queue restarts

2015-05-04T20:32:48+00:00

Normally if driver is busy to dispatch a request the logic is like below:
block layer:					driver:
	__blk_mq_run_hw_queue
a.						blk_mq_stop_hw_queue
b.	rq add to ctx->dispatch

later:
1.						blk_mq_start_hw_queue
2.	__blk_mq_run_hw_queue

But it's possible step 1-2 runs between a and b. And since rq isn't in
ctx->dispatch yet, step 2 will not run rq. The rq might get lost if
there are no subsequent requests kick in.

Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

block: destroy bdi before blockdev is unregistered.

2015-04-27T16:27:20+00:00

Because of the peculiar way that md devices are created (automatically
when the device node is opened), a new device can be created and
registered immediately after the
	blk_unregister_region(disk_devt(disk), disk->minors);
call in del_gendisk().

Therefore it is important that all visible artifacts of the previous
device are removed before this call.  In particular, the 'bdi'.

Since:
commit c4db59d31e39ea067c32163ac961e9c80198fd37
Author: Christoph Hellwig 
    fs: don't reassign dirty inodes to default_backing_dev_info

moved the
   device_unregister(bdi->dev);
call from bdi_unregister() to bdi_destroy() it has been quite easy to
lose a race and have a new (e.g.) "md127" be created after the
blk_unregister_region() call and before bdi_destroy() is ultimately
called by the final 'put_disk', which must come after del_gendisk().

The new device finds that the bdi name is already registered in sysfs
and complains

> [ 9627.630029] WARNING: CPU: 18 PID: 3330 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x5a/0x70()
> [ 9627.630032] sysfs: cannot create duplicate filename '/devices/virtual/bdi/9:127'

We can fix this by moving the bdi_destroy() call out of
blk_release_queue() (which can happen very late when a refcount
reaches zero) and into blk_cleanup_queue() - which happens exactly when the md
device driver calls it.

Then it is only necessary for md to call blk_cleanup_queue() before
del_gendisk().  As loop.c devices are also created on demand by
opening the device node, we make the same change there.

Fixes: c4db59d31e39ea067c32163ac961e9c80198fd37
Reported-by: Azat Khuzhin 
Cc: Christoph Hellwig 
Cc: stable@vger.kernel.org (v4.0)
Signed-off-by: NeilBrown 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block:bounce: fix call inc_|dec_zone_page_state on different pages confuse value of NR_BOUNCE

2015-04-27T15:24:07+00:00

Commit d2c5e30c9a1420902262aa923794d2ae4e0bc391
("[PATCH] zoned vm counters: conversion of nr_bounce to per zone counter")
convert statistic of nr_bounce to per zone and one global value in vm_stat,
but it call inc_|dec_zone_page_state on different pages, then different
zones, and cause us to get unexpected value of NR_BOUNCE.

Below is the result on my machine:
Mar  2 09:26:08 udknight kernel: [144766.778265] Mem-Info:
Mar  2 09:26:08 udknight kernel: [144766.778266] DMA per-cpu:
Mar  2 09:26:08 udknight kernel: [144766.778268] CPU    0: hi:    0, btch:   1 usd:   0
Mar  2 09:26:08 udknight kernel: [144766.778269] CPU    1: hi:    0, btch:   1 usd:   0
Mar  2 09:26:08 udknight kernel: [144766.778270] Normal per-cpu:
Mar  2 09:26:08 udknight kernel: [144766.778271] CPU    0: hi:  186, btch:  31 usd:   0
Mar  2 09:26:08 udknight kernel: [144766.778273] CPU    1: hi:  186, btch:  31 usd:   0
Mar  2 09:26:08 udknight kernel: [144766.778274] HighMem per-cpu:
Mar  2 09:26:08 udknight kernel: [144766.778275] CPU    0: hi:  186, btch:  31 usd:   0
Mar  2 09:26:08 udknight kernel: [144766.778276] CPU    1: hi:  186, btch:  31 usd:   0
Mar  2 09:26:08 udknight kernel: [144766.778279] active_anon:46926 inactive_anon:287406 isolated_anon:0
Mar  2 09:26:08 udknight kernel: [144766.778279]  active_file:105085 inactive_file:139432 isolated_file:0
Mar  2 09:26:08 udknight kernel: [144766.778279]  unevictable:653 dirty:0 writeback:0 unstable:0
Mar  2 09:26:08 udknight kernel: [144766.778279]  free:178957 slab_reclaimable:6419 slab_unreclaimable:9966
Mar  2 09:26:08 udknight kernel: [144766.778279]  mapped:4426 shmem:305277 pagetables:784 bounce:0
Mar  2 09:26:08 udknight kernel: [144766.778279]  free_cma:0
Mar  2 09:26:08 udknight kernel: [144766.778286] DMA free:3324kB min:68kB low:84kB high:100kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15976kB managed:15900kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
Mar  2 09:26:08 udknight kernel: [144766.778287] lowmem_reserve[]: 0 822 3754 3754
Mar  2 09:26:08 udknight kernel: [144766.778293] Normal free:26828kB min:3632kB low:4540kB high:5448kB active_anon:4872kB inactive_anon:68kB active_file:1796kB inactive_file:1796kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:892920kB managed:842560kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:4144kB slab_reclaimable:25676kB slab_unreclaimable:39864kB kernel_stack:1944kB pagetables:3136kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:2412612 all_unreclaimable? yes
Mar  2 09:26:08 udknight kernel: [144766.778294] lowmem_reserve[]: 0 0 23451 23451
Mar  2 09:26:08 udknight kernel: [144766.778299] HighMem free:685676kB min:512kB low:3748kB high:6984kB active_anon:182832kB inactive_anon:1149556kB active_file:418544kB inactive_file:555932kB unevictable:2612kB isolated(anon):0kB isolated(file):0kB present:3001732kB managed:3001732kB mlocked:0kB dirty:0kB writeback:0kB mapped:17704kB shmem:1216964kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:75771152kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
Mar  2 09:26:08 udknight kernel: [144766.778300] lowmem_reserve[]: 0 0 0 0

You can see bounce:75771152kB for HighMem, but bounce:0 for lowmem and global.

This patch fix it.

Signed-off-by: Wang YanQing 
Signed-off-by: Jens Axboe

elevator: fix double release of elevator module

2015-04-23T16:47:44+00:00

Our issue is descripted in below call path:
->elevator_init
 ->elevator_init_fn
  ->{cfq,deadline,noop}_init_queue
   ->elevator_alloc
    ->kzalloc_node
   fail to call kzalloc_node and then put module in elevator_alloc;
fail to call elevator_init_fn and then put module again in elevator_init.

Remove elevator_put invoking in error path of elevator_alloc to avoid
double release issue.

Signed-off-by: Chao Yu 
Reviewed-by: Jeff Moyer 
Signed-off-by: Jens Axboe

blk-mq: fix CPU hotplug handling

2015-04-23T16:27:38+00:00

hctx->tags has to be set as NULL in case that it is to be unmapped
no matter if set->tags[hctx->queue_num] is NULL or not in blk_mq_map_swqueue()
because shared tags can be freed already from another request queue.

The same situation has to be considered during handling CPU online too.
Unmapped hw queue can be remapped after CPU topo is changed, so we need
to allocate tags for the hw queue in blk_mq_map_swqueue(). Then tags
allocation for hw queue can be removed in hctx cpu online notifier, and it
is reasonable to do that after mapping is updated.

Cc: 
Reported-by: Dongsu Park 
Tested-by: Dongsu Park 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

blk-mq: fix race between timeout and CPU hotplug

2015-04-23T16:27:35+00:00

Firstly during CPU hotplug, even queue is freezed, timeout
handler still may come and access hctx->tags, which may cause
use after free, so this patch deactivates timeout handler
inside CPU hotplug notifier.

Secondly, tags can be shared by more than one queues, so we
have to check if the hctx has been unmapped, otherwise
still use-after-free on tags can be triggered.

Cc: 
Reported-by: Dongsu Park 
Tested-by: Dongsu Park 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

blk-mq: fix iteration of busy bitmap

2015-04-17T14:31:12+00:00

Commit 889fa31f00b2 was a bit too eager in reducing the loop count,
so we ended up missing queues in some configurations. Ensure that
our division rounds up, so that's not the case.

Reported-by: Guenter Roeck 
Fixes: 889fa31f00b2 ("blk-mq: reduce unnecessary software queue looping")
Signed-off-by: Jens Axboe

Merge branch 'for-4.1/core' of git://git.kernel.dk/linux-block

2015-04-17T01:49:16+00:00

Pull block layer core bits from Jens Axboe:
 "This is the core pull request for 4.1.  Not a lot of stuff in here for
  this round, mostly little fixes or optimizations.  This pull request
  contains:

   - An optimization that speeds up queue runs on blk-mq, especially for
     the case where there's a large difference between nr_cpu_ids and
     the actual mapped software queues on a hardware queue.  From Chong
     Yuan.

   - Honor node local allocations for requests on legacy devices.  From
     David Rientjes.

   - Cleanup of blk_mq_rq_to_pdu() from me.

   - exit_aio() fixup from me, greatly speeding up exiting multiple IO
     contexts off exit_group().  For my particular test case, fio exit
     took ~6 seconds.  A typical case of both exposing RCU grace periods
     to user space, and serializing exit of them.

   - Make blk_mq_queue_enter() honor the gfp mask passed in, so we only
     wait if __GFP_WAIT is set.  From Keith Busch.

   - blk-mq exports and two added helpers from Mike Snitzer, which will
     be used by the dm-mq code.

   - Cleanups of blk-mq queue init from Wei Fang and Xiaoguang Wang"

* 'for-4.1/core' of git://git.kernel.dk/linux-block:
  blk-mq: reduce unnecessary software queue looping
  aio: fix serial draining in exit_aio()
  blk-mq: cleanup blk_mq_rq_to_pdu()
  blk-mq: put blk_queue_rq_timeout together in blk_mq_init_queue()
  block: remove redundant check about 'set->nr_hw_queues' in blk_mq_alloc_tag_set()
  block: allocate request memory local to request queue
  blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set
  blk-mq: export blk_mq_run_hw_queues
  blk-mq: add blk_mq_init_allocated_queue and export blk_mq_register_disk

blk-mq: reduce unnecessary software queue looping

2015-04-15T17:39:29+00:00

In flush_busy_ctxs() and blk_mq_hctx_has_pending(), regardless of how many
ctxs assigned to one hctx, they will all loop hctx->ctx_map.map_size
times. Here hctx->ctx_map.map_size is a const ALIGN(nr_cpu_ids, 8) / 8.
Especially, flush_busy_ctxs() is in hot code path. And it's unnecessary.
Change ->map_size to contain the actually mapped software queues, so we
only loop for as many iterations as we have to.

And remove cpumask setting and nr_ctx count in blk_mq_init_cpu_queues()
since they are all re-done in blk_mq_map_swqueue().
blk_mq_map_swqueue().

Signed-off-by: Chong Yuan 
Reviewed-by: Wenbo Wang 

Updated by me for formatting and commenting.

Signed-off-by: Jens Axboe

Merge branch 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2015-04-14T22:31:03+00:00

Pull vfs update from Al Viro:
 "Part one:

   - struct filename-related cleanups

   - saner iov_iter_init() replacements (and switching the syscalls to
     use of those)

   - ntfs switch to ->write_iter() (Anton)

   - aio cleanups and splitting iocb into common and async parts
     (Christoph)

   - assorted fixes (me, bfields, Andrew Elble)

  There's a lot more, including the completion of switchover to
  ->{read,write}_iter(), d_inode/d_backing_inode annotations, f_flags
  race fixes, etc, but that goes after #for-davem merge.  David has
  pulled it, and once it's in I'll send the next vfs pull request"

* 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (35 commits)
  sg_start_req(): use import_iovec()
  sg_start_req(): make sure that there's not too many elements in iovec
  blk_rq_map_user(): use import_single_range()
  sg_io(): use import_iovec()
  process_vm_access: switch to {compat_,}import_iovec()
  switch keyctl_instantiate_key_common() to iov_iter
  switch {compat_,}do_readv_writev() to {compat_,}import_iovec()
  aio_setup_vectored_rw(): switch to {compat_,}import_iovec()
  vmsplice_to_user(): switch to import_iovec()
  kill aio_setup_single_vector()
  aio: simplify arguments of aio_setup_..._rw()
  aio: lift iov_iter_init() into aio_setup_..._rw()
  lift iov_iter into {compat_,}do_readv_writev()
  NFS: fix BUG() crash in notify_change() with patch to chown_common()
  dcache: return -ESTALE not -EBUSY on distributed fs race
  NTFS: Version 2.1.32 - Update file write from aio_write to write_iter.
  VFS: Add iov_iter_fault_in_multipages_readable()
  drop bogus check in file_open_root()
  switch security_inode_getattr() to struct path *
  constify tomoyo_realpath_from_path()
  ...