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d4730ace |
| 06-Feb-2012 |
Jiri Kosina <jkosina@suse.cz> |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into upstream-fixes
Sync with Linus' tree. This is necessary to have a base for patch that fixes commit 35b4c01e
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into upstream-fixes
Sync with Linus' tree. This is necessary to have a base for patch that fixes commit 35b4c01e29b ("power_supply: add "powers" links to self-powered HID devices") which went in through Anton's tree.
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#
9fa73472 |
| 06-Feb-2012 |
Shaohua Li <shaohua.li@intel.com> |
block: fix ioc locking warning
Meelis reported a warning:
WARNING: at kernel/timer.c:1122 run_timer_softirq+0x199/0x1ec() Hardware name: 939Dual-SATA2 timer: cfq_idle_slice_timer+0x0/0xaa preempt l
block: fix ioc locking warning
Meelis reported a warning:
WARNING: at kernel/timer.c:1122 run_timer_softirq+0x199/0x1ec() Hardware name: 939Dual-SATA2 timer: cfq_idle_slice_timer+0x0/0xaa preempt leak: 00000102 -> 00000103 Modules linked in: sr_mod cdrom videodev media drm_kms_helper ohci_hcd ehci_hcd v4l2_compat_ioctl32 usbcore i2c_ali15x3 snd_seq drm snd_timer snd_seq Pid: 0, comm: swapper Not tainted 3.3.0-rc2-00110-gd125666 #176 Call Trace: <IRQ> [<ffffffff81022aaa>] warn_slowpath_common+0x7e/0x96 [<ffffffff8114c485>] ? cfq_slice_expired+0x1d/0x1d [<ffffffff81022b56>] warn_slowpath_fmt+0x41/0x43 [<ffffffff8114c526>] ? cfq_idle_slice_timer+0xa1/0xaa [<ffffffff8114c485>] ? cfq_slice_expired+0x1d/0x1d [<ffffffff8102c124>] run_timer_softirq+0x199/0x1ec [<ffffffff81047a53>] ? timekeeping_get_ns+0x12/0x31 [<ffffffff810145fd>] ? apic_write+0x11/0x13 [<ffffffff81027475>] __do_softirq+0x74/0xfa [<ffffffff812f337a>] call_softirq+0x1a/0x30 [<ffffffff81002ff9>] do_softirq+0x31/0x68 [<ffffffff810276cf>] irq_exit+0x3d/0xa3 [<ffffffff81014aca>] smp_apic_timer_interrupt+0x6b/0x77 [<ffffffff812f2de9>] apic_timer_interrupt+0x69/0x70 <EOI> [<ffffffff81040136>] ? sched_clock_cpu+0x73/0x7d [<ffffffff81040136>] ? sched_clock_cpu+0x73/0x7d [<ffffffff8100801f>] ? default_idle+0x1e/0x32 [<ffffffff81008019>] ? default_idle+0x18/0x32 [<ffffffff810008b1>] cpu_idle+0x87/0xd1 [<ffffffff812de861>] rest_init+0x85/0x89 [<ffffffff81659a4d>] start_kernel+0x2eb/0x2f8 [<ffffffff8165926e>] x86_64_start_reservations+0x7e/0x82 [<ffffffff81659362>] x86_64_start_kernel+0xf0/0xf7
this_q == locked_q is possible. There are two problems here: 1. In UP case, there is preemption counter issue as spin_trylock always successes. 2. In SMP case, the loop breaks too earlier.
Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reported-by: Meelis Roos <mroos@linux.ee> Reported-by: Knut Petersen <Knut_Petersen@t-online.de> Tested-by: Knut Petersen <Knut_Petersen@t-online.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
972c5ae9 |
| 03-Feb-2012 |
Jiri Kosina <jkosina@suse.cz> |
Merge branch 'master' into for-next
Sync with Linus' tree to be able to apply patch to a newer code (namely drivers/gpu/drm/gma500/psb_intel_lvds.c)
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Revision tags: v3.3-rc2 |
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ea51e504 |
| 31-Jan-2012 |
Takashi Iwai <tiwai@suse.de> |
Merge branch 'fix/asoc' into for-linus
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b20f8662 |
| 28-Jan-2012 |
Florian Tobias Schandinat <FlorianSchandinat@gmx.de> |
Merge commit 'v3.3-rc1' into fbdev-next
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#
6c02b7b1 |
| 27-Jan-2012 |
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
Merge commit 'v3.3-rc1' into stable/for-linus-fixes-3.3
* commit 'v3.3-rc1': (9775 commits) Linux 3.3-rc1 x86, syscall: Need __ARCH_WANT_SYS_IPC for 32 bits qnx4: don't leak ->BitMap on late f
Merge commit 'v3.3-rc1' into stable/for-linus-fixes-3.3
* commit 'v3.3-rc1': (9775 commits) Linux 3.3-rc1 x86, syscall: Need __ARCH_WANT_SYS_IPC for 32 bits qnx4: don't leak ->BitMap on late failure exits qnx4: reduce the insane nesting in qnx4_checkroot() qnx4: di_fname is an array, for crying out loud... KEYS: Permit key_serial() to be called with a const key pointer keys: fix user_defined key sparse messages ima: fix cred sparse warning uml: fix compile for x86-64 MPILIB: Add a missing ENOMEM check tpm: fix (ACPI S3) suspend regression nvme: fix merge error due to change of 'make_request_fn' fn type xen: using EXPORT_SYMBOL requires including export.h gpio: tps65910: Use correct offset for gpio initialization acpi/apei/einj: Add extensions to EINJ from rev 5.0 of acpi spec intel_idle: Split up and provide per CPU initialization func ACPI processor: Remove unneeded variable passed by acpi_processor_hotadd_init V2 tg3: Fix single-vector MSI-X code openvswitch: Fix multipart datapath dumps. ipv6: fix per device IP snmp counters ...
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19c22c34 |
| 21-Jan-2012 |
Mauro Carvalho Chehab <mchehab@redhat.com> |
Merge tag 'v3.3-rc1' into staging/for_v3.3
* tag 'v3.3-rc1': (8187 commits) Linux 3.3-rc1 x86, syscall: Need __ARCH_WANT_SYS_IPC for 32 bits qnx4: don't leak ->BitMap on late failure exits q
Merge tag 'v3.3-rc1' into staging/for_v3.3
* tag 'v3.3-rc1': (8187 commits) Linux 3.3-rc1 x86, syscall: Need __ARCH_WANT_SYS_IPC for 32 bits qnx4: don't leak ->BitMap on late failure exits qnx4: reduce the insane nesting in qnx4_checkroot() qnx4: di_fname is an array, for crying out loud... KEYS: Permit key_serial() to be called with a const key pointer keys: fix user_defined key sparse messages ima: fix cred sparse warning uml: fix compile for x86-64 MPILIB: Add a missing ENOMEM check tpm: fix (ACPI S3) suspend regression nvme: fix merge error due to change of 'make_request_fn' fn type xen: using EXPORT_SYMBOL requires including export.h gpio: tps65910: Use correct offset for gpio initialization acpi/apei/einj: Add extensions to EINJ from rev 5.0 of acpi spec intel_idle: Split up and provide per CPU initialization func ACPI processor: Remove unneeded variable passed by acpi_processor_hotadd_init V2 tg3: Fix single-vector MSI-X code openvswitch: Fix multipart datapath dumps. ipv6: fix per device IP snmp counters ...
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eefad7fd |
| 20-Jan-2012 |
Takashi Iwai <tiwai@suse.de> |
Merge branch 'topic/convert-bint' into topic/hda
Merge the conversions to bint module option type.
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Revision tags: v3.3-rc1 |
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#
282f445a |
| 19-Jan-2012 |
H. Peter Anvin <hpa@linux.intel.com> |
Merge remote-tracking branch 'linus/master' into x86/urgent
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#
0c929238 |
| 17-Jan-2012 |
Paul Mundt <lethal@linux-sh.org> |
Merge branch 'sh/platform-updates' into sh-latest
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#
b3c9dd18 |
| 15-Jan-2012 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge branch 'for-3.3/core' of git://git.kernel.dk/linux-block
* 'for-3.3/core' of git://git.kernel.dk/linux-block: (37 commits) Revert "block: recursive merge requests" block: Stop using macro
Merge branch 'for-3.3/core' of git://git.kernel.dk/linux-block
* 'for-3.3/core' of git://git.kernel.dk/linux-block: (37 commits) Revert "block: recursive merge requests" block: Stop using macro stubs for the bio data integrity calls blockdev: convert some macros to static inlines fs: remove unneeded plug in mpage_readpages() block: Add BLKROTATIONAL ioctl block: Introduce blk_set_stacking_limits function block: remove WARN_ON_ONCE() in exit_io_context() block: an exiting task should be allowed to create io_context block: ioc_cgroup_changed() needs to be exported block: recursive merge requests block, cfq: fix empty queue crash caused by request merge block, cfq: move icq creation and rq->elv.icq association to block core block, cfq: restructure io_cq creation path for io_context interface cleanup block, cfq: move io_cq exit/release to blk-ioc.c block, cfq: move icq cache management to block core block, cfq: move io_cq lookup to blk-ioc.c block, cfq: move cfqd->icq_list to request_queue and add request->elv.icq block, cfq: reorganize cfq_io_context into generic and cfq specific parts block: remove elevator_queue->ops block: reorder elevator switch sequence ...
Fix up conflicts in: - block/blk-cgroup.c Switch from can_attach_task to can_attach - block/cfq-iosched.c conflict with now removed cic index changes (we now use q->id instead)
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Revision tags: v3.2 |
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#
c98b2cc2 |
| 27-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block: remove WARN_ON_ONCE() in exit_io_context()
6e736be7 "block: make ioc get/put interface more conventional and fix race on alloction" added WARN_ON_ONCE() in exit_io_context() which triggers if
block: remove WARN_ON_ONCE() in exit_io_context()
6e736be7 "block: make ioc get/put interface more conventional and fix race on alloction" added WARN_ON_ONCE() in exit_io_context() which triggers if !PF_EXITING. All tasks hitting exit_io_context() from task exit should have PF_EXITING set but task struct tearing down after fork failure calls into the function without PF_EXITING, triggering the condition.
WARNING: at block/blk-ioc.c:234 exit_io_context+0x40/0x92() Pid: 17090, comm: trinity Not tainted 3.2.0-rc6-next-20111222-sasha-dirty #77 Call Trace: [<ffffffff810b69a3>] warn_slowpath_common+0x8f/0xb2 [<ffffffff810b6a77>] warn_slowpath_null+0x18/0x1a [<ffffffff8181a7a2>] exit_io_context+0x40/0x92 [<ffffffff810b58c9>] copy_process+0x126f/0x1453 [<ffffffff810b5c1b>] do_fork+0x120/0x3e9 [<ffffffff8106242f>] sys_clone+0x26/0x28 [<ffffffff82425803>] stub_clone+0x13/0x20 ---[ end trace a2e4eb670b375238 ]---
Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
fd638368 |
| 25-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block: an exiting task should be allowed to create io_context
While fixing io_context creation / task exit race condition, 6e736be7f2 "block: make ioc get/put interface more conventional and fix rac
block: an exiting task should be allowed to create io_context
While fixing io_context creation / task exit race condition, 6e736be7f2 "block: make ioc get/put interface more conventional and fix race on alloction" also prevented an exiting (%PF_EXITING) task from creating its own io_context. This is incorrect as exit path may issue IOs, e.g. from exit_files(), and if those IOs are the first ones issued by the task, io_context needs to be created to process the IOs.
Combined with the existing problem of io_context / io_cq creation failure having the possibility of stalling IO, this problem results in deterministic full IO lockup with certain workloads.
Fix it by allowing io_context creation regardless of %PF_EXITING for %current.
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Andrew Morton <akpm@linux-foundation.org> Reported-by: Hugh Dickins <hughd@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Revision tags: v3.2-rc7 |
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#
64c42998 |
| 19-Dec-2011 |
Jens Axboe <axboe@kernel.dk> |
block: ioc_cgroup_changed() needs to be exported
With the ioc changed, ioc_cgroup_changed() can be used by modular code. So ensure that it is exported.
Reported-by: Stephen Rothwell <sfr@canb.auug.
block: ioc_cgroup_changed() needs to be exported
With the ioc changed, ioc_cgroup_changed() can be used by modular code. So ensure that it is exported.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Revision tags: v3.2-rc6 |
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#
f1f8cc94 |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block, cfq: move icq creation and rq->elv.icq association to block core
Now block layer knows everything necessary to create and associate icq's with requests. Move ioc_create_icq() to blk-ioc.c an
block, cfq: move icq creation and rq->elv.icq association to block core
Now block layer knows everything necessary to create and associate icq's with requests. Move ioc_create_icq() to blk-ioc.c and update get_request() such that, if elevator_type->icq_size is set, requests are automatically associated with their matching icq's before elv_set_request(). io_context reference is also managed by block core on request alloc/free.
* Only ioprio/cgroup changed handling remains from cfq_get_cic(). Collapsed into cfq_set_request().
* This removes queue kicking on icq allocation failure (for now). As icq allocation failure is rare and the only effect of queue kicking achieved was possibily accelerating queue processing, this change shouldn't be noticeable.
There is a larger underlying problem. Unlike request allocation, icq allocation is not guaranteed to succeed eventually after retries. The number of icq is unbound and thus mempool can't be the solution either. This effectively adds allocation dependency on memory free path and thus possibility of deadlock.
This usually wouldn't happen because icq allocation is not a hot path and, even when the condition triggers, it's highly unlikely that none of the writeback workers already has icq.
However, this is still possible especially if elevator is being switched under high memory pressure, so we better get it fixed. Probably the only solution is just bypassing elevator and appending to dispatch queue on any elevator allocation failure.
* Comment added to explain how icq's are managed and synchronized.
This completes cleanup of io_context interface.
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
7e5a8794 |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block, cfq: move io_cq exit/release to blk-ioc.c
With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to blk-ioc too. The odd ->io_cq->exit/release() callbacks are replaced with elev
block, cfq: move io_cq exit/release to blk-ioc.c
With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to blk-ioc too. The odd ->io_cq->exit/release() callbacks are replaced with elevator_ops->elevator_exit_icq_fn() with unlinking from both ioc and q, and freeing automatically handled by blk-ioc. The elevator operation only need to perform exit operation specific to the elevator - in cfq's case, exiting the cfqq's.
Also, clearing of io_cq's on q detach is moved to block core and automatically performed on elevator switch and q release.
Because the q io_cq points to might be freed before RCU callback for the io_cq runs, blk-ioc code should remember to which cache the io_cq needs to be freed when the io_cq is released. New field io_cq->__rcu_icq_cache is added for this purpose. As both the new field and rcu_head are used only after io_cq is released and the q/ioc_node fields aren't, they are put into unions.
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
47fdd4ca |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block, cfq: move io_cq lookup to blk-ioc.c
Now that all io_cq related data structures are in block core layer, io_cq lookup can be moved from cfq-iosched.c to blk-ioc.c.
Lookup logic from cfq_cic_l
block, cfq: move io_cq lookup to blk-ioc.c
Now that all io_cq related data structures are in block core layer, io_cq lookup can be moved from cfq-iosched.c to blk-ioc.c.
Lookup logic from cfq_cic_lookup() is moved to ioc_lookup_icq() with parameter return type changes (cfqd -> request_queue, cfq_io_cq -> io_cq) and cfq_cic_lookup() becomes thin wrapper around cfq_cic_lookup().
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
c5869807 |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block, cfq: reorganize cfq_io_context into generic and cfq specific parts
Currently io_context and cfq logics are mixed without clear boundary. Most of io_context is independent from cfq but cfq_io_
block, cfq: reorganize cfq_io_context into generic and cfq specific parts
Currently io_context and cfq logics are mixed without clear boundary. Most of io_context is independent from cfq but cfq_io_context handling logic is dispersed between generic ioc code and cfq.
cfq_io_context represents association between an io_context and a request_queue, which is a concept useful outside of cfq, but it also contains fields which are useful only to cfq.
This patch takes out generic part and put it into io_cq (io context-queue) and the rest into cfq_io_cq (cic moniker remains the same) which contains io_cq. The following changes are made together.
* cfq_ttime and cfq_io_cq now live in cfq-iosched.c.
* All related fields, functions and constants are renamed accordingly.
* ioc->ioc_data is now "struct io_cq *" instead of "void *" and renamed to icq_hint.
This prepares for io_context API cleanup. Documentation is currently sparse. It will be added later.
Changes in this patch are mechanical and don't cause functional change.
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
f2dbd76a |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block, cfq: replace current_io_context() with create_io_context()
When called under queue_lock, current_io_context() triggers lockdep warning if it hits allocation path. This is because io_context
block, cfq: replace current_io_context() with create_io_context()
When called under queue_lock, current_io_context() triggers lockdep warning if it hits allocation path. This is because io_context installation is protected by task_lock which is not IRQ safe, so it triggers irq-unsafe-lock -> irq -> irq-safe-lock -> irq-unsafe-lock deadlock warning.
Given the restriction, accessor + creator rolled into one doesn't work too well. Drop current_io_context() and let the users access task->io_context directly inside queue_lock combined with explicit creation using create_io_context().
Future ioc updates will further consolidate ioc access and the create interface will be unexported.
While at it, relocate ioc internal interface declarations in blk.h and add section comments before and after.
This patch does not introduce functional change.
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
b2efa052 |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block, cfq: unlink cfq_io_context's immediately
cic is association between io_context and request_queue. A cic is linked from both ioc and q and should be destroyed when either one goes away. As i
block, cfq: unlink cfq_io_context's immediately
cic is association between io_context and request_queue. A cic is linked from both ioc and q and should be destroyed when either one goes away. As ioc and q both have their own locks, locking becomes a bit complex - both orders work for removal from one but not from the other.
Currently, cfq tries to circumvent this locking order issue with RCU. ioc->lock nests inside queue_lock but the radix tree and cic's are also protected by RCU allowing either side to walk their lists without grabbing lock.
This rather unconventional use of RCU quickly devolves into extremely fragile convolution. e.g. The following is from cfqd going away too soon after ioc and q exits raced.
general protection fault: 0000 [#1] PREEMPT SMP CPU 2 Modules linked in: [ 88.503444] Pid: 599, comm: hexdump Not tainted 3.1.0-rc10-work+ #158 Bochs Bochs RIP: 0010:[<ffffffff81397628>] [<ffffffff81397628>] cfq_exit_single_io_context+0x58/0xf0 ... Call Trace: [<ffffffff81395a4a>] call_for_each_cic+0x5a/0x90 [<ffffffff81395ab5>] cfq_exit_io_context+0x15/0x20 [<ffffffff81389130>] exit_io_context+0x100/0x140 [<ffffffff81098a29>] do_exit+0x579/0x850 [<ffffffff81098d5b>] do_group_exit+0x5b/0xd0 [<ffffffff81098de7>] sys_exit_group+0x17/0x20 [<ffffffff81b02f2b>] system_call_fastpath+0x16/0x1b
The only real hot path here is cic lookup during request initialization and avoiding extra locking requires very confined use of RCU. This patch makes cic removal from both ioc and request_queue perform double-locking and unlink immediately.
* From q side, the change is almost trivial as ioc->lock nests inside queue_lock. It just needs to grab each ioc->lock as it walks cic_list and unlink it.
* From ioc side, it's a bit more difficult because of inversed lock order. ioc needs its lock to walk its cic_list but can't grab the matching queue_lock and needs to perform unlock-relock dancing.
Unlinking is now wholly done from put_io_context() and fast path is optimized by using the queue_lock the caller already holds, which is by far the most common case. If the ioc accessed multiple devices, it tries with trylock. In unlikely cases of fast path failure, it falls back to full double-locking dance from workqueue.
Double-locking isn't the prettiest thing in the world but it's *far* simpler and more understandable than RCU trick without adding any meaningful overhead.
This still leaves a lot of now unnecessary RCU logics. Future patches will trim them.
-v2: Vivek pointed out that cic->q was being dereferenced after cic->release() was called. Updated to use local variable @this_q instead.
Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
dc86900e |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block, cfq: move ioc ioprio/cgroup changed handling to cic
ioprio/cgroup change was handled by marking the changed state in ioc and, on the following access to the ioc, performing RCU-protected iter
block, cfq: move ioc ioprio/cgroup changed handling to cic
ioprio/cgroup change was handled by marking the changed state in ioc and, on the following access to the ioc, performing RCU-protected iteration through all cic's grabbing the matching queue_lock.
This patch moves the changed state to each cic. When ioprio or cgroup changes, the respective bit is set on all cic's of the ioc and when each of those cic (not ioc) is accessed, change is applied for that specific ioc-queue pair.
This also fixes the following two race conditions between setting and clearing of changed states.
* Missing barrier between assign/load of ioprio and ioprio_changed allowed applying old ioprio.
* Change requests could happen between application of change and clearing of changed variables.
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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#
6e736be7 |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block: make ioc get/put interface more conventional and fix race on alloction
Ignoring copy_io() during fork, io_context can be allocated from two places - current_io_context() and set_task_ioprio()
block: make ioc get/put interface more conventional and fix race on alloction
Ignoring copy_io() during fork, io_context can be allocated from two places - current_io_context() and set_task_ioprio(). The former is always called from local task while the latter can be called from different task. The synchornization between them are peculiar and dubious.
* current_io_context() doesn't grab task_lock() and assumes that if it saw %NULL ->io_context, it would stay that way until allocation and assignment is complete. It has smp_wmb() between alloc/init and assignment.
* set_task_ioprio() grabs task_lock() for assignment and does smp_read_barrier_depends() between "ioc = task->io_context" and "if (ioc)". Unfortunately, this doesn't achieve anything - the latter is not a dependent load of the former. ie, if ioc itself were being dereferenced "ioc->xxx", it would mean something (not sure what tho) but as the code currently stands, the dependent read barrier is noop.
As only one of the the two test-assignment sequences is task_lock() protected, the task_lock() can't do much about race between the two. Nothing prevents current_io_context() and set_task_ioprio() allocating its own ioc for the same task and overwriting the other's.
Also, set_task_ioprio() can race with exiting task and create a new ioc after exit_io_context() is finished.
ioc get/put doesn't have any reason to be complex. The only hot path is accessing the existing ioc of %current, which is simple to achieve given that ->io_context is never destroyed as long as the task is alive. All other paths can happily go through task_lock() like all other task sub structures without impacting anything.
This patch updates ioc get/put so that it becomes more conventional.
* alloc_io_context() is replaced with get_task_io_context(). This is the only interface which can acquire access to ioc of another task. On return, the caller has an explicit reference to the object which should be put using put_io_context() afterwards.
* The functionality of current_io_context() remains the same but when creating a new ioc, it shares the code path with get_task_io_context() and always goes through task_lock().
* get_io_context() now means incrementing ref on an ioc which the caller already has access to (be that an explicit refcnt or implicit %current one).
* PF_EXITING inhibits creation of new io_context and once exit_io_context() is finished, it's guaranteed that both ioc acquisition functions return %NULL.
* All users are updated. Most are trivial but smp_read_barrier_depends() removal from cfq_get_io_context() needs a bit of explanation. I suppose the original intention was to ensure ioc->ioprio is visible when set_task_ioprio() allocates new io_context and installs it; however, this wouldn't have worked because set_task_ioprio() doesn't have wmb between init and install. There are other problems with this which will be fixed in another patch.
* While at it, use NUMA_NO_NODE instead of -1 for wildcard node specification.
-v2: Vivek spotted contamination from debug patch. Removed.
Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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42ec57a8 |
| 13-Dec-2011 |
Tejun Heo <tj@kernel.org> |
block: misc ioc cleanups
* int return from put_io_context() wasn't used by anybody. Make it return void like other put functions and docbook-fy the function comment.
* Reorder dummy declaratio
block: misc ioc cleanups
* int return from put_io_context() wasn't used by anybody. Make it return void like other put functions and docbook-fy the function comment.
* Reorder dummy declarations for !CONFIG_BLOCK case a bit.
* Make alloc_ioc_context() use __GFP_ZERO allocation, take init out of if block and drop 0'ing.
* Docbook-fy current_io_context() comment.
This patch doesn't introduce any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Revision tags: v3.2-rc5, v3.2-rc4 |
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d4bbf7e7 |
| 28-Nov-2011 |
Tejun Heo <tj@kernel.org> |
Merge branch 'master' into x86/memblock
Conflicts & resolutions:
* arch/x86/xen/setup.c
dc91c728fd "xen: allow extra memory to be in multiple regions" 24aa07882b "memblock, x86: Replace memblock
Merge branch 'master' into x86/memblock
Conflicts & resolutions:
* arch/x86/xen/setup.c
dc91c728fd "xen: allow extra memory to be in multiple regions" 24aa07882b "memblock, x86: Replace memblock_x86_reserve/free..."
conflicted on xen_add_extra_mem() updates. The resolution is trivial as the latter just want to replace memblock_x86_reserve_range() with memblock_reserve().
* drivers/pci/intel-iommu.c
166e9278a3f "x86/ia64: intel-iommu: move to drivers/iommu/" 5dfe8660a3d "bootmem: Replace work_with_active_regions() with..."
conflicted as the former moved the file under drivers/iommu/. Resolved by applying the chnages from the latter on the moved file.
* mm/Kconfig
6661672053a "memblock: add NO_BOOTMEM config symbol" c378ddd53f9 "memblock, x86: Make ARCH_DISCARD_MEMBLOCK a config option"
conflicted trivially. Both added config options. Just letting both add their own options resolves the conflict.
* mm/memblock.c
d1f0ece6cdc "mm/memblock.c: small function definition fixes" ed7b56a799c "memblock: Remove memblock_memory_can_coalesce()"
confliected. The former updates function removed by the latter. Resolution is trivial.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Revision tags: v3.2-rc3, v3.2-rc2, v3.2-rc1 |
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6ad390a2 |
| 26-Oct-2011 |
Dmitry Torokhov <dmitry.torokhov@gmail.com> |
Merge branch 'next' into for-linus
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