Commit Graph

90 Commits

Author SHA1 Message Date
Jan Kara e589f46445 block: fix default IO priority handling again
Commit e70344c059 ("block: fix default IO priority handling")
introduced an inconsistency in get_current_ioprio() that tasks without
IO context return IOPRIO_DEFAULT priority while tasks with freshly
allocated IO context will return 0 (IOPRIO_CLASS_NONE/0) IO priority.
Tasks without IO context used to be rare before 5a9d041ba2 ("block:
move io_context creation into where it's needed") but after this commit
they became common because now only BFQ IO scheduler setups task's IO
context. Similar inconsistency is there for get_task_ioprio() so this
inconsistency is now exposed to userspace and userspace will see
different IO priority for tasks operating on devices with BFQ compared
to devices without BFQ. Furthemore the changes done by commit
e70344c059 change the behavior when no IO priority is set for BFQ IO
scheduler which is also documented in ioprio_set(2) manpage:

"If no I/O scheduler has been set for a thread, then by default the I/O
priority will follow the CPU nice value (setpriority(2)).  In Linux
kernels before version 2.6.24, once an I/O priority had been set using
ioprio_set(), there was no way to reset the I/O scheduling behavior to
the default. Since Linux 2.6.24, specifying ioprio as 0 can be used to
reset to the default I/O scheduling behavior."

So make sure we default to IOPRIO_CLASS_NONE as used to be the case
before commit e70344c059. Also cleanup alloc_io_context() to
explicitely set this IO priority for the allocated IO context to avoid
future surprises. Note that we tweak ioprio_best() to maintain
ioprio_get(2) behavior and make this commit easily backportable.

CC: stable@vger.kernel.org
Fixes: e70344c059 ("block: fix default IO priority handling")
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220623074840.5960-1-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-27 06:29:12 -06:00
Jiri Slaby 15583a563c block: restore the old set_task_ioprio() behaviour wrt PF_EXITING
PF_EXITING tasks were silently ignored before the below commits.
Continue doing so. Otherwise python-psutil tests fail:
  ERROR: psutil.tests.test_process.TestProcess.test_zombie_process
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/_pslinux.py", line 1661, in wrapper
      return fun(self, *args, **kwargs)
    File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/_pslinux.py", line 2133, in ionice_set
      return cext.proc_ioprio_set(self.pid, ioclass, value)
  ProcessLookupError: [Errno 3] No such process

  During handling of the above exception, another exception occurred:

  Traceback (most recent call last):
    File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/psutil/tests/test_process.py", line 1313, in test_zombie_process
      succeed_or_zombie_p_exc(fun)
    File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/psutil/tests/test_process.py", line 1288, in succeed_or_zombie_p_exc
      return fun()
    File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/__init__.py", line 792, in ionice
      return self._proc.ionice_set(ioclass, value)
    File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/_pslinux.py", line 1665, in wrapper
      raise NoSuchProcess(self.pid, self._name)
  psutil.NoSuchProcess: process no longer exists (pid=2057)

Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Fixes: 5fc11eebb4 (block: open code create_task_io_context in set_task_ioprio)
Fixes: a957b61254 (block: fix error in handling dead task for ioprio setting)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220328085928.7899-1-jslaby@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-28 06:34:11 -06:00
Lukas Bulwahn 669a064625 block: drop needless assignment in set_task_ioprio()
Commit 5fc11eebb4 ("block: open code create_task_io_context in
set_task_ioprio") introduces a needless assignment
'ioc = task->io_context', as the local variable ioc is not further
used before returning.

Even after the further fix, commit a957b61254 ("block: fix error in
handling dead task for ioprio setting"), the assignment still remains
needless.

Drop this needless assignment in set_task_ioprio().

This code smell was identified with 'make clang-analyzer'.

Fixes: 5fc11eebb4 ("block: open code create_task_io_context in set_task_ioprio")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211223125300.20691-1-lukas.bulwahn@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-23 07:10:07 -07:00
Jens Axboe a957b61254 block: fix error in handling dead task for ioprio setting
Don't combine the task exiting and "already have io_context" case, we
need to just abort if the task is marked as dead. Return -ESRCH, which
is the documented value for ioprio_set() if the specified task could not
be found.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: syzbot+8836466a79f4175961b0@syzkaller.appspotmail.com
Fixes: 5fc11eebb4 ("block: open code create_task_io_context in set_task_ioprio")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-20 20:32:24 -07:00
Christoph Hellwig 5ef1630586 block: only build the icq tracking code when needed
Only bfq needs to code to track icq, so make it conditional.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:02 -07:00
Christoph Hellwig 90b627f542 block: fold create_task_io_context into ioc_find_get_icq
Fold create_task_io_context into the only remaining caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:02 -07:00
Christoph Hellwig 5fc11eebb4 block: open code create_task_io_context in set_task_ioprio
The flow in set_task_ioprio can be simplified by simply open coding
create_task_io_context, which removes a refcount roundtrip on the I/O
context.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:02 -07:00
Christoph Hellwig 8472161b77 block: fold get_task_io_context into set_task_ioprio
Fold get_task_io_context into its only caller, and simplify the code
as no reference to the I/O context is required to just set the ioprio
field.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:02 -07:00
Christoph Hellwig a411cd3cfd block: move set_task_ioprio to blk-ioc.c
Keep set_task_ioprio with the other low-level code that accesses the
io_context structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Christoph Hellwig 091abcb3ef block: cleanup ioc_clear_queue
Fold __ioc_clear_queue into ioc_clear_queue and switch to always
use plain _irq locking instead of the more expensive _irqsave that
is not needed here.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Christoph Hellwig edf70ff5a1 block: refactor put_io_context
Move the code to delay freeing the icqs into a separate helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Christoph Hellwig 8a20c0c7e0 block: remove the NULL ioc check in put_io_context
No caller passes in a NULL pointer, so remove the check.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Christoph Hellwig 4be8a2eaff block: refactor put_iocontext_active
Factor out a ioc_exit_icqs helper to tear down the icqs and the fold
the rest of put_iocontext_active into exit_io_context.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Christoph Hellwig 0aed2f162b block: simplify struct io_context refcounting
Don't hold a reference to ->refcount for each active reference, but
just one for all active references.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Christoph Hellwig 8a2ba1785c block: remove the nr_task field from struct io_context
Nothing ever looks at ->nr_tasks, so remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Christoph Hellwig eca5892a5d block: simplify ioc_lookup_icq
Remove the ioc argument as it always points to current->io_context.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 18b74c4dca block: simplify ioc_create_icq
Remove the ioc and gfp_mask argument, which are hard coded by the caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig d538ea4cb8 block: return the io_context from create_task_io_context
Grab a reference to the newly allocated or existing io_context in
create_task_io_context and return it.  This simplifies the callers and
removes the need for double lookups.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 8ffc13680e block: use alloc_io_context in __copy_io
In __copy_io we know that the newly allocate task_struct does not have
an I/O context yet and is not exiting.  So just allocate the I/O context
struct and install it directly.  There is no need to lock the task
either as it is just being created.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig a0f14d8baa block: factor out a alloc_io_context helper
Factor out a helper that just allocate an I/O context.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 50569c24be block: remove get_io_context_active
Fold it into it's only caller, and remove a lof of the debug checks
that are not needed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 222ee581b8 block: move the remaining elv.icq handling to the I/O scheduler
After the prepare side has been moved to the only I/O scheduler that
cares, do the same for the cleanup and the NULL initialization.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 87dd1d63dc block: move blk_mq_sched_assign_ioc to blk-ioc.c
Move blk_mq_sched_assign_ioc so that many interfaces from the file can
be marked static.  Rename the function to ioc_find_get_icq as well and
return the icq to simplify the interface.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 3304742562 block: mark put_io_context_active static
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 88c9a2ce52 fork: move copy_io to block/blk-ioc.c
Move the copying of the I/O context to the block layer as that is where
we can use the proper low-level interfaces.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:41:29 -07:00
Christoph Hellwig 2aa7745bf6 block: don't include blk-mq-sched.h in blk.h
No needed, shift it into the source files that need it instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29 06:38:44 -07:00
John Ogness ab96bbab46 block: remove retry loop in ioc_release_fn()
The reverse-order double lock dance in ioc_release_fn() is using a
retry loop. This is a problem on PREEMPT_RT because it could preempt
the task that would release q->queue_lock and thus live lock in the
retry loop.

RCU is already managing the freeing of the request queue and icq. If
the trylock fails, use RCU to guarantee that the request queue and
icq are not freed and re-acquire the locks in the correct order,
allowing forward progress.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-16 10:22:15 -06:00
John Ogness a43f085f87 block: remove unnecessary ioc nested locking
The legacy CFQ IO scheduler could call put_io_context() in its exit_icq()
elevator callback. This led to a lockdep warning, which was fixed in
commit d8c66c5d59 ("block: fix lockdep warning on io_context release
put_io_context()") by using a nested subclass for the ioc spinlock.
However, with commit f382fb0bce ("block: remove legacy IO schedulers")
the CFQ IO scheduler no longer exists.

The BFQ IO scheduler also implements the exit_icq() elevator callback but
does not call put_io_context().

The nested subclass for the ioc spinlock is no longer needed. Since it
existed as an exception and no longer applies, remove the nested subclass
usage.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-16 10:22:15 -06:00
Sahitya Tummala 30a2da7b7e block: Fix use-after-free issue accessing struct io_cq
There is a potential race between ioc_release_fn() and
ioc_clear_queue() as shown below, due to which below kernel
crash is observed. It also can result into use-after-free
issue.

context#1:				context#2:
ioc_release_fn()			__ioc_clear_queue() gets the same icq
->spin_lock(&ioc->lock);		->spin_lock(&ioc->lock);
->ioc_destroy_icq(icq);
  ->list_del_init(&icq->q_node);
  ->call_rcu(&icq->__rcu_head,
  	icq_free_icq_rcu);
->spin_unlock(&ioc->lock);
					->ioc_destroy_icq(icq);
					  ->hlist_del_init(&icq->ioc_node);
					  This results into below crash as this memory
					  is now used by icq->__rcu_head in context#1.
					  There is a chance that icq could be free'd
					  as well.

22150.386550:   <6> Unable to handle kernel write to read-only memory
at virtual address ffffffaa8d31ca50
...
Call trace:
22150.607350:   <2>  ioc_destroy_icq+0x44/0x110
22150.611202:   <2>  ioc_clear_queue+0xac/0x148
22150.615056:   <2>  blk_cleanup_queue+0x11c/0x1a0
22150.619174:   <2>  __scsi_remove_device+0xdc/0x128
22150.623465:   <2>  scsi_forget_host+0x2c/0x78
22150.627315:   <2>  scsi_remove_host+0x7c/0x2a0
22150.631257:   <2>  usb_stor_disconnect+0x74/0xc8
22150.635371:   <2>  usb_unbind_interface+0xc8/0x278
22150.639665:   <2>  device_release_driver_internal+0x198/0x250
22150.644897:   <2>  device_release_driver+0x24/0x30
22150.649176:   <2>  bus_remove_device+0xec/0x140
22150.653204:   <2>  device_del+0x270/0x460
22150.656712:   <2>  usb_disable_device+0x120/0x390
22150.660918:   <2>  usb_disconnect+0xf4/0x2e0
22150.664684:   <2>  hub_event+0xd70/0x17e8
22150.668197:   <2>  process_one_work+0x210/0x480
22150.672222:   <2>  worker_thread+0x32c/0x4c8

Fix this by adding a new ICQ_DESTROYED flag in ioc_destroy_icq() to
indicate this icq is once marked as destroyed. Also, ensure
__ioc_clear_queue() is accessing icq within rcu_read_lock/unlock so
that icq doesn't get free'd up while it is still using it.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Co-developed-by: Pradeep P V K <ppvk@codeaurora.org>
Signed-off-by: Pradeep P V K <ppvk@codeaurora.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-03-12 07:07:38 -06:00
Christoph Hellwig 0d945c1f96 block: remove the queue_lock indirection
With the legacy request path gone there is no good reason to keep
queue_lock as a pointer, we can always use the embedded lock now.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Fixed floppy and blk-cgroup missing conversions and half done edits.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:17:28 -07:00
Christoph Hellwig b6676f653f block: remove a few unused exports
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:25 -07:00
YueHaibing e41128cfd9 block: remove set but not used variable 'et'
Fixes gcc '-Wunused-but-set-variable' warning:

block/blk-ioc.c: In function 'put_io_context_active':
block/blk-ioc.c:174:24: warning:
 variable 'et' set but not used [-Wunused-but-set-variable]

It not used any more after commit
a1ce35fa49 ("block: remove dead elevator code")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-09 20:08:00 -07:00
Jens Axboe f9cd4bfe96 block: get rid of MQ scheduler ops union
This is a remnant of when we had ops for both SQ and MQ
schedulers. Now it's just MQ, so get rid of the union.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:32 -07:00
Jens Axboe a1ce35fa49 block: remove dead elevator code
This removes a bunch of core and elevator related code. On the core
front, we remove anything related to queue running, draining,
initialization, plugging, and congestions. We also kill anything
related to request allocation, merging, retrieval, and completion.

Remove any checking for single queue IO schedulers, as they no
longer exist. This means we can also delete a bunch of code related
to request issue, adding, completion, etc - and all the SQ related
ops and helpers.

Also kill the load_default_modules(), as all that did was provide
for a way to load the default single queue elevator.

Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:32 -07:00
Shakeel Butt c137969bd4 block, mm: remove unnecessary __GFP_HIGH flag
The flag GFP_ATOMIC already contains __GFP_HIGH. There is no need to
explicitly or __GFP_HIGH again. So, just remove unnecessary __GFP_HIGH.

Signed-off-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:54 -06:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Linus Torvalds e0d072250a Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull block layer fixes from Jens Axboe:
 "A collection of fixes for this merge window, either fixes for existing
  issues, or parts that were waiting for acks to come in. This pull
  request contains:

   - Allocation of nvme queues on the right node from Shaohua.

     This was ready long before the merge window, but waiting on an ack
     from Bjorn on the PCI bit. Now that we have that, the three patches
     can go in.

   - Two fixes for blk-mq-sched with nvmeof, which uses hctx specific
     request allocations. This caused an oops. One part from Sagi, one
     part from Omar.

   - A loop partition scan deadlock fix from Omar, fixing a regression
     in this merge window.

   - A three-patch series from Keith, closing up a hole on clearing out
     requests on shutdown/resume.

   - A stable fix for nbd from Josef, fixing a leak of sockets.

   - Two fixes for a regression in this window from Jan, fixing a
     problem with one of his earlier patches dealing with queue vs bdi
     life times.

   - A fix for a regression with virtio-blk, causing an IO stall if
     scheduling is used. From me.

   - A fix for an io context lock ordering problem. From me"

* 'for-linus' of git://git.kernel.dk/linux-block:
  block: Move bdi_unregister() to del_gendisk()
  blk-mq: ensure that bd->last is always set correctly
  block: don't call ioc_exit_icq() with the queue lock held for blk-mq
  block: Initialize bd_bdi on inode initialization
  loop: fix LO_FLAGS_PARTSCAN hang
  nvme: Complete all stuck requests
  blk-mq: Provide freeze queue timeout
  blk-mq: Export blk_mq_freeze_queue_wait
  nbd: stop leaking sockets
  blk-mq: move update of tags->rqs to __blk_mq_alloc_request()
  blk-mq: kill blk_mq_set_alloc_data()
  blk-mq: make blk_mq_alloc_request_hctx() allocate a scheduler request
  blk-mq-sched: Allocate sched reserved tags as specified in the original queue tagset
  nvme: allocate nvme_queue in correct node
  PCI: add an API to get node from vector
  blk-mq: allocate blk_mq_tags and requests in correct node
2017-03-03 10:53:35 -08:00
Jens Axboe 7b36a7189f block: don't call ioc_exit_icq() with the queue lock held for blk-mq
For legacy scheduling, we always call ioc_exit_icq() with both the
ioc and queue lock held. This poses a problem for blk-mq with
scheduling, since the queue lock isn't what we use in the scheduler.
And since we don't need the queue lock held for ioc exit there,
don't grab it and leave any extra locking up to the blk-mq scheduler.

Reported-by: Paolo Valente <paolo.valente@linaro.org>
Tested-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-03-02 13:59:08 -07:00
Ingo Molnar f719ff9bce sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h>
But first update the code that uses these facilities with the
new header.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:38 +01:00
Omar Sandoval 3d492c2e01 blk-mq-sched: don't hold queue_lock when calling exit_icq
None of the other blk-mq elevator hooks are called with this lock held.
Additionally, it can lead to circular locking dependencies between
queue_lock and the private scheduler lock.

Reported-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-10 11:34:47 -07:00
Jens Axboe bd166ef183 blk-mq-sched: add framework for MQ capable IO schedulers
This adds a set of hooks that intercepts the blk-mq path of
allocating/inserting/issuing/completing requests, allowing
us to develop a scheduler within that framework.

We reuse the existing elevator scheduler API on the registration
side, but augment that with the scheduler flagging support for
the blk-mq interfce, and with a separate set of ops hooks for MQ
devices.

We split driver and scheduler tags, so we can run the scheduling
independently of device queue depth.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-17 10:04:20 -07:00
Jens Axboe c51ca6cf54 block: move existing elevator ops to union
Prep patch for adding MQ ops as well, since doing anon unions with
named initializers doesn't work on older compilers.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-17 10:03:33 -07:00
Mel Gorman d0164adc89 mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
Paul E. McKenney ec6c676a08 block: Substitute rcu_access_pointer() for rcu_dereference_raw()
(Trivial patch.)

If the code is looking at the RCU-protected pointer itself, but not
dereferencing it, the rcu_dereference() functions can be downgraded to
rcu_access_pointer().  This commit makes this downgrade in blkg_destroy()
and ioc_destroy_icq(), both of which simply compare the RCU-protected
pointer against another pointer with no dereferencing.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>
2014-02-18 12:21:26 -08:00
Grygorii Strashko d17ab45927 block: cleanup removing dependency on bootmem headers
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-11-08 19:43:48 -07:00
Jan Kara 5e4c0d9741 lib/radix-tree.c: make radix_tree_node_alloc() work correctly within interrupt
With users of radix_tree_preload() run from interrupt (block/blk-ioc.c is
one such possible user), the following race can happen:

radix_tree_preload()
...
radix_tree_insert()
  radix_tree_node_alloc()
    if (rtp->nr) {
      ret = rtp->nodes[rtp->nr - 1];
<interrupt>
...
radix_tree_preload()
...
radix_tree_insert()
  radix_tree_node_alloc()
    if (rtp->nr) {
      ret = rtp->nodes[rtp->nr - 1];

And we give out one radix tree node twice.  That clearly results in radix
tree corruption with different results (usually OOPS) depending on which
two users of radix tree race.

We fix the problem by making radix_tree_node_alloc() always allocate fresh
radix tree nodes when in interrupt.  Using preloading when in interrupt
doesn't make sense since all the allocations have to be atomic anyway and
we cannot steal nodes from process-context users because some users rely
on radix_tree_insert() succeeding after radix_tree_preload().
in_interrupt() check is somewhat ugly but we cannot simply key off passed
gfp_mask as that is acquired from root_gfp_mask() and thus the same for
all preload users.

Another part of the fix is to avoid node preallocation in
radix_tree_preload() when passed gfp_mask doesn't allow waiting.  Again,
preallocation in such case doesn't make sense and when preallocation would
happen in interrupt we could possibly leak some allocated nodes.  However,
some users of radix_tree_preload() require following radix_tree_insert()
to succeed.  To avoid unexpected effects for these users,
radix_tree_preload() only warns if passed gfp mask doesn't allow waiting
and we provide a new function radix_tree_maybe_preload() for those users
which get different gfp mask from different call sites and which are
prepared to handle radix_tree_insert() failure.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11 15:59:36 -07:00
Viresh Kumar 695588f945 block: queue work on power efficient wq
Block layer uses workqueues for multiple purposes. There is no real dependency
of scheduling these on the cpu which scheduled them.

On a idle system, it is observed that and idle cpu wakes up many times just to
service this work. It would be better if we can schedule it on a cpu which the
scheduler believes to be the most appropriate one.

This patch replaces normal workqueues with power efficient versions.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2013-05-14 10:50:07 -07:00
Sasha Levin b67bfe0d42 hlist: drop the node parameter from iterators
I'm not sure why, but the hlist for each entry iterators were conceived

        list_for_each_entry(pos, head, member)

The hlist ones were greedy and wanted an extra parameter:

        hlist_for_each_entry(tpos, pos, head, member)

Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.

Besides the semantic patch, there was some manual work required:

 - Fix up the actual hlist iterators in linux/list.h
 - Fix up the declaration of other iterators based on the hlist ones.
 - A very small amount of places were using the 'node' parameter, this
 was modified to use 'obj->member' instead.
 - Coccinelle didn't handle the hlist_for_each_entry_safe iterator
 properly, so those had to be fixed up manually.

The semantic patch which is mostly the work of Peter Senna Tschudin is here:

@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;

type T;
expression a,c,d,e;
identifier b;
statement S;
@@

-T b;
    <+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
    ...+>

[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 19:10:24 -08:00
Olof Johansson 4638a83e86 block: uninitialized ioc->nr_tasks triggers WARN_ON
Hi,

I'm using the old-fashioned 'dump' backup tool, and I noticed that it spews the
below warning as of 3.5-rc1 and later (3.4 is fine):

[   10.886893] ------------[ cut here ]------------
[   10.886904] WARNING: at include/linux/iocontext.h:140 copy_process+0x1488/0x1560()
[   10.886905] Hardware name: Bochs
[   10.886906] Modules linked in:
[   10.886908] Pid: 2430, comm: dump Not tainted 3.5.0-rc7+ #27
[   10.886908] Call Trace:
[   10.886911]  [<ffffffff8107ce8a>] warn_slowpath_common+0x7a/0xb0
[   10.886912]  [<ffffffff8107ced5>] warn_slowpath_null+0x15/0x20
[   10.886913]  [<ffffffff8107c088>] copy_process+0x1488/0x1560
[   10.886914]  [<ffffffff8107c244>] do_fork+0xb4/0x340
[   10.886918]  [<ffffffff8108effa>] ? recalc_sigpending+0x1a/0x50
[   10.886919]  [<ffffffff8108f6b2>] ? __set_task_blocked+0x32/0x80
[   10.886920]  [<ffffffff81091afa>] ? __set_current_blocked+0x3a/0x60
[   10.886923]  [<ffffffff81051db3>] sys_clone+0x23/0x30
[   10.886925]  [<ffffffff8179bd73>] stub_clone+0x13/0x20
[   10.886927]  [<ffffffff8179baa2>] ? system_call_fastpath+0x16/0x1b
[   10.886928] ---[ end trace 32a14af7ee6a590b ]---

Reproducing is easy, I can hit it on a KVM system with a very basic
config (x86_64 make defconfig + enable the drivers needed). To hit it,
just install dump (on debian/ubuntu, not sure what the package might be
called on Fedora), and:

dump -o -f /tmp/foo /

You'll see the warning in dmesg once it forks off the I/O process and
starts dumping filesystem contents.

I bisected it down to the following commit:

commit f6e8d01bee
Author: Tejun Heo <tj@kernel.org>
Date:   Mon Mar 5 13:15:26 2012 -0800

    block: add io_context->active_ref

    Currently ioc->nr_tasks is used to decide two things - whether an ioc
    is done issuing IOs and whether it's shared by multiple tasks.  This
    patch separate out the first into ioc->active_ref, which is acquired
    and released using {get|put}_io_context_active() respectively.

    This will be used to associate bio's with a given task.  This patch
    doesn't introduce any visible behavior change.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>

It seems like the init of ioc->nr_tasks was removed in that patch,
so it starts out at 0 instead of 1.

Tejun, is the right thing here to add back the init, or should something else
be done?

The below patch removes the warning, but I haven't done any more extensive
testing on it.

Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-08-01 12:17:27 +02:00
Eric Dumazet 3c9c708c9f block: avoid infinite loop in get_task_io_context()
Calling get_task_io_context() on a exiting task which isn't %current can
loop forever. This triggers at boot time on my dev machine.

BUG: soft lockup - CPU#3 stuck for 22s ! [mountall.1603]

Fix this by making create_task_io_context() returns -EBUSY in this case
to break the loop.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-05-31 13:39:05 +02:00