14 Jan, 2012
1 commit
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For compressed image, the space required is not known until
we finish compressing and writing all pages.
This patch drops the check, and if swap space is not enough
finally, system can still restore to normal after writing
swap fails for compressed images.Signed-off-by: Barry Song
Acked-by: Pavel Machek
Signed-off-by: Rafael J. Wysocki
11 Jan, 2012
1 commit
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When debugging with CONFIG_DEBUG_PAGEALLOC and debug_guardpage_minorder >
0, we have lot of free pages that are not marked so. Snapshot code
account them as savable, what cause hibernate memory preallocation
failure.It is pretty hard to make hibernate allocation succeed with
debug_guardpage_minorder=1. This change at least make it possible when
system has relatively big amount of RAM.Signed-off-by: Stanislaw Gruszka
Acked-by: Rafael J. Wysocki
Cc: Andrea Arcangeli
Cc: Christoph Lameter
Cc: Mel Gorman
Cc: Pekka Enberg
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Jan, 2012
1 commit
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* 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (76 commits)
PM / Hibernate: Implement compat_ioctl for /dev/snapshot
PM / Freezer: fix return value of freezable_schedule_timeout_killable()
PM / shmobile: Allow the A4R domain to be turned off at run time
PM / input / touchscreen: Make st1232 use device PM QoS constraints
PM / QoS: Introduce dev_pm_qos_add_ancestor_request()
PM / shmobile: Remove the stay_on flag from SH7372's PM domains
PM / shmobile: Don't include SH7372's INTCS in syscore suspend/resume
PM / shmobile: Add support for the sh7372 A4S power domain / sleep mode
PM: Drop generic_subsys_pm_ops
PM / Sleep: Remove forward-only callbacks from AMBA bus type
PM / Sleep: Remove forward-only callbacks from platform bus type
PM: Run the driver callback directly if the subsystem one is not there
PM / Sleep: Make pm_op() and pm_noirq_op() return callback pointers
PM/Devfreq: Add Exynos4-bus device DVFS driver for Exynos4210/4212/4412.
PM / Sleep: Merge internal functions in generic_ops.c
PM / Sleep: Simplify generic system suspend callbacks
PM / Hibernate: Remove deprecated hibernation snapshot ioctls
PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled()
ARM: S3C64XX: Implement basic power domain support
PM / shmobile: Use common always on power domain governor
...Fix up trivial conflict in fs/xfs/xfs_buf.c due to removal of unused
XBT_FORCE_SLEEP bit
05 Jan, 2012
1 commit
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This allows uswsusp built for i386 to run on an x86_64 kernel (tested
with Debian package version 1.0+20110509-2).References: http://bugs.debian.org/502816
Signed-off-by: Ben Hutchings
Signed-off-by: Rafael J. Wysocki
04 Jan, 2012
1 commit
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Move invalidate_bdev, block_sync_page into fs/block_dev.c. Export
kill_bdev as well, so brd doesn't have to open code it. Reduce
buffer_head.h requirement accordingly.Removed a rather large comment from invalidate_bdev, as it looked a bit
obsolete to bother moving. The small comment replacing it says enough.Signed-off-by: Nick Piggin
Cc: Al Viro
Cc: Christoph Hellwig
Signed-off-by: Andrew Morton
Signed-off-by: Al Viro
10 Dec, 2011
1 commit
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Several snapshot ioctls were marked for removal quite some time ago,
since they were deprecated. Remove them.Suggested-by: Rafael J. Wysocki
Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki
09 Dec, 2011
1 commit
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Using [un]lock_system_sleep() is safer than directly using mutex_[un]lock()
on 'pm_mutex', since the latter could lead to freezing failures. Hence convert
all the present users of mutex_[un]lock(&pm_mutex) to use these safe APIs
instead.Suggested-by: Tejun Heo
Signed-off-by: Srivatsa S. Bhat
Reviewed-by: Simon Horman
Signed-off-by: Rafael J. Wysocki
07 Dec, 2011
5 commits
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In the snapshot_ioctl() function, under SNAPSHOT_FREEZE, the code below
freeze_processes() is a bit unintuitive. Improve it by replacing the
second 'if' condition with an 'else' clause.Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki -
* pm-freezer: (26 commits)
Freezer / sunrpc / NFS: don't allow TASK_KILLABLE sleeps to block the freezer
Freezer: fix more fallout from the thaw_process rename
freezer: fix wait_event_freezable/__thaw_task races
freezer: kill unused set_freezable_with_signal()
dmatest: don't use set_freezable_with_signal()
usb_storage: don't use set_freezable_with_signal()
freezer: remove unused @sig_only from freeze_task()
freezer: use lock_task_sighand() in fake_signal_wake_up()
freezer: restructure __refrigerator()
freezer: fix set_freezable[_with_signal]() race
freezer: remove should_send_signal() and update frozen()
freezer: remove now unused TIF_FREEZE
freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE
cgroup_freezer: prepare for removal of TIF_FREEZE
freezer: clean up freeze_processes() failure path
freezer: kill PF_FREEZING
freezer: test freezable conditions while holding freezer_lock
freezer: make freezing indicate freeze condition in effect
freezer: use dedicated lock instead of task_lock() + memory barrier
freezer: don't distinguish nosig tasks on thaw
... -
The hibernation test modes 'test' and 'testproc' are deprecated, because
the 'pm_test' framework offers much more fine-grained control for debugging
suspend and hibernation related problems.So, remove the deprecated 'test' and 'testproc' hibernation test modes.
Suggested-by: Rafael J. Wysocki
Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki -
Commit 2aede851ddf08666f68ffc17be446420e9d2a056 (PM / Hibernate: Freeze
kernel threads after preallocating memory) moved the freezing of kernel
threads to hibernation_snapshot() function.So now, if the call to hibernation_snapshot() returns early due to a
successful hibernation test, the caller has to thaw processes to ensure
that the system gets back to its original state.But in SNAPSHOT_CREATE_IMAGE hibernation ioctl, the caller does not thaw
processes in case hibernation_snapshot() returned due to a successful
freezer test. Fix this issue. But note we still send the value of 'in_suspend'
(which is now 0) to userspace, because we are not in an error path per-se,
and moreover, the value of in_suspend correctly depicts the situation here.Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki -
In the software_resume() function defined in kernel/power/hibernate.c,
if the call to create_basic_memory_bitmaps() fails, the usermodehelpers
are not enabled (which had been disabled in the previous step). Fix it.Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki
24 Nov, 2011
4 commits
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The goto statements in hibernation_snapshot() are a bit complex.
Refactor the code to remove some of them, thereby simplifying the
implementation.Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki -
Lack of proper indentation of the goto statement decreases the readability
of code significantly. In fact, this made me look twice at the code to check
whether it really does what it should be doing. Fix this.And in the same file, there are some extra whitespaces. Get rid of them too.
Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki -
* 'pm-freezer' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc: (24 commits)
freezer: fix wait_event_freezable/__thaw_task races
freezer: kill unused set_freezable_with_signal()
dmatest: don't use set_freezable_with_signal()
usb_storage: don't use set_freezable_with_signal()
freezer: remove unused @sig_only from freeze_task()
freezer: use lock_task_sighand() in fake_signal_wake_up()
freezer: restructure __refrigerator()
freezer: fix set_freezable[_with_signal]() race
freezer: remove should_send_signal() and update frozen()
freezer: remove now unused TIF_FREEZE
freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE
cgroup_freezer: prepare for removal of TIF_FREEZE
freezer: clean up freeze_processes() failure path
freezer: kill PF_FREEZING
freezer: test freezable conditions while holding freezer_lock
freezer: make freezing indicate freeze condition in effect
freezer: use dedicated lock instead of task_lock() + memory barrier
freezer: don't distinguish nosig tasks on thaw
freezer: remove racy clear_freeze_flag() and set PF_NOFREEZE on dead tasks
freezer: rename thaw_process() to __thaw_task() and simplify the implementation
... -
The hibernation core code forgets to release memory preallocated
for hibernation if there's an error in its early stages or if test
modes causing hibernation_snapshot() to return early are used. This
causes the system to be hardly usable, because the amount of
preallocated memory is usually huge. Fix this problem.Reported-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki
Acked-by: Srivatsa S. Bhat
22 Nov, 2011
10 commits
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After "freezer: make freezing() test freeze conditions in effect
instead of TIF_FREEZE", freezing() returns authoritative answer on
whether the current task should freeze or not and freeze_task()
doesn't need or use @sig_only. Remove it.While at it, rewrite function comment for freeze_task() and rename
@sig_only to @user_only in try_to_freeze_tasks().This patch doesn't cause any functional change.
Signed-off-by: Tejun Heo
Acked-by: Oleg Nesterov -
Using TIF_FREEZE for freezing worked when there was only single
freezing condition (the PM one); however, now there is also the
cgroup_freezer and single bit flag is getting clumsy.
thaw_processes() is already testing whether cgroup freezing in in
effect to avoid thawing tasks which were frozen by both PM and cgroup
freezers.This is racy (nothing prevents race against cgroup freezing) and
fragile. A much simpler way is to test actual freeze conditions from
freezing() - ie. directly test whether PM or cgroup freezing is in
effect.This patch adds variables to indicate whether and what type of
freezing conditions are in effect and reimplements freezing() such
that it directly tests whether any of the two freezing conditions is
active and the task should freeze. On fast path, freezing() is still
very cheap - it only tests system_freezing_cnt.This makes the clumsy dancing aroung TIF_FREEZE unnecessary and
freeze/thaw operations more usual - updating state variables for the
new state and nudging target tasks so that they notice the new state
and comply. As long as the nudging happens after state update, it's
race-free.* This allows use of freezing() in freeze_task(). Replace the open
coded tests with freezing().* p != current test is added to warning printing conditions in
try_to_freeze_tasks() failure path. This is necessary as freezing()
is now true for the task which initiated freezing too.-v2: Oleg pointed out that re-freezing FROZEN cgroup could increment
system_freezing_cnt. Fixed.Signed-off-by: Tejun Heo
Acked-by: Paul Menage (for the cgroup portions) -
TIF_FREEZE will be removed soon and freezing() will directly test
whether any freezing condition is in effect. Make the following
changes in preparation.* Rename cgroup_freezing_or_frozen() to cgroup_freezing() and make it
return bool.* Make cgroup_freezing() access task_freezer() under rcu read lock
instead of task_lock(). This makes the state dereferencing racy
against task moving to another cgroup; however, it was already racy
without this change as ->state dereference wasn't synchronized.
This will be later dealt with using attach hooks.* freezer->state is now set before trying to push tasks into the
target state.-v2: Oleg pointed out that freeze_change_state() was setting
freeze->state incorrectly to CGROUP_FROZEN instead of
CGROUP_FREEZING. Fixed.-v3: Matt pointed out that setting CGROUP_FROZEN used to always invoke
try_to_freeze_cgroup() regardless of the current state. Patch
updated such that the actual freeze/thaw operations are always
performed on invocation. This shouldn't make any difference
unless something is broken.Signed-off-by: Tejun Heo
Acked-by: Paul Menage
Cc: Li Zefan
Cc: Oleg Nesterov -
freeze_processes() failure path is rather messy. Freezing is canceled
for workqueues and tasks which aren't frozen yet but frozen tasks are
left alone and should be thawed by the caller and of course some
callers (xen and kexec) didn't do it.This patch updates __thaw_task() to handle cancelation correctly and
makes freeze_processes() and freeze_kernel_threads() call
thaw_processes() on failure instead so that the system is fully thawed
on failure. Unnecessary [suspend_]thaw_processes() calls are removed
from kernel/power/hibernate.c, suspend.c and user.c.While at it, restructure error checking if clause in suspend_prepare()
to be less weird.-v2: Srivatsa spotted missing removal of suspend_thaw_processes() in
suspend_prepare() and error in commit message. Updated.Signed-off-by: Tejun Heo
Acked-by: Srivatsa S. Bhat -
try_to_freeze_tasks() and thaw_processes() use freezable() and
frozen() as preliminary tests before initiating operations on a task.
These are done without any synchronization and hinder with
synchronization cleanup without any real performance benefits.In try_to_freeze_tasks(), open code self test and move PF_NOFREEZE and
frozen() tests inside freezer_lock in freeze_task().thaw_processes() can simply drop freezable() test as frozen() test in
__thaw_task() is enough.Note: This used to be a part of larger patch to fix set_freezable()
race. Separated out to satisfy ordering among dependent fixes.Signed-off-by: Tejun Heo
Cc: Oleg Nesterov -
Currently freezing (TIF_FREEZE) and frozen (PF_FROZEN) states are
interlocked - freezing is set to request freeze and when the task
actually freezes, it clears freezing and sets frozen.This interlocking makes things more complex than necessary - freezing
doesn't mean there's freezing condition in effect and frozen doesn't
match the task actually entering and leaving frozen state (it's
cleared by the thawing task).This patch makes freezing indicate that freeze condition is in effect.
A task enters and stays frozen if freezing. This makes PF_FROZEN
manipulation done only by the task itself and prevents wakeup from
__thaw_task() leaking outside of refrigerator.The only place which needs to tell freezing && !frozen is
try_to_freeze_task() to whine about tasks which don't enter frozen.
It's updated to test the condition explicitly.With the change, frozen() state my linger after __thaw_task() until
the task wakes up and exits fridge. This can trigger BUG_ON() in
update_if_frozen(). Work it around by testing freezing() && frozen()
instead of frozen().-v2: Oleg pointed out missing re-check of freezing() when trying to
clear FROZEN and possible spurious BUG_ON() trigger in
update_if_frozen(). Both fixed.Signed-off-by: Tejun Heo
Cc: Oleg Nesterov
Cc: Paul Menage -
Freezer synchronization is needlessly complicated - it's by no means a
hot path and the priority is staying unintrusive and safe. This patch
makes it simply use a dedicated lock instead of piggy-backing on
task_lock() and playing with memory barriers.On the failure path of try_to_freeze_tasks(), locking is moved from it
to cancel_freezing(). This makes the frozen() test racy but the race
here is a non-issue as the warning is printed for tasks which failed
to enter frozen for 20 seconds and race on PF_FROZEN at the last
moment doesn't change anything.This simplifies freezer implementation and eases further changes
including some race fixes.Signed-off-by: Tejun Heo
-
There's no point in thawing nosig tasks before others. There's no
ordering requirement between the two groups on thaw, which the staged
thawing can't guarantee anyway. Simplify thaw_processes() by removing
the distinction and collapsing thaw_tasks() into thaw_processes().
This will help further updates to freezer.Signed-off-by: Tejun Heo
-
clear_freeze_flag() in exit_mm() is racy. Freezing can start
afterwards. Remove it. Skipping freezer for exiting task will be
properly implemented later.Also, freezable() was testing exit_state directly to make system
freezer ignore dead tasks. Let the exiting task set PF_NOFREEZE after
entering TASK_DEAD instead.Signed-off-by: Tejun Heo
Cc: Oleg Nesterov -
thaw_process() now has only internal users - system and cgroup
freezers. Remove the unnecessary return value, rename, unexport and
collapse __thaw_process() into it. This will help further updates to
the freezer code.-v3: oom_kill grew a use of thaw_process() while this patch was
pending. Convert it to use __thaw_task() for now. In the longer
term, this should be handled by allowing tasks to die if killed
even if it's frozen.-v2: minor style update as suggested by Matt.
Signed-off-by: Tejun Heo
Cc: Paul Menage
Cc: Matt Helsley
19 Nov, 2011
2 commits
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After commit 2a77c46de1e3dace73745015635ebbc648eca69c
(PM / Suspend: Add statistics debugfs file for suspend to RAM)
a missing pair of braces inside the state_store() function causes even
invalid arguments to suspend to be wrongly treated as failed suspend
attempts. Fix this.[rjw: Put the hash/subject of the buggy commit into the changelog.]
Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki -
Commit 2aede851ddf08666f68ffc17be446420e9d2a056
(PM / Hibernate: Freeze kernel threads after preallocating memory)
postponed the freezing of kernel threads to after preallocating memory
for hibernation. But while doing that, the hibernation test TEST_FREEZER
and the test mode HIBERNATION_TESTPROC were not moved accordingly.As a result, when using these test modes, it only goes upto the freezing of
userspace and exits, when in fact it should go till the complete end of task
freezing stage, namely the freezing of kernel threads as well.So, move these points of exit to appropriate places so that freezing of
kernel threads is also tested while using these test harnesses.Signed-off-by: Srivatsa S. Bhat
Signed-off-by: Rafael J. Wysocki
08 Nov, 2011
1 commit
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Since commit 4a31a334, the name of this misc device is not initialized,
which leads to a funny device named /dev/(null) being created and
/proc/misc containing an entry with just a number but no name. The latter
leads to complaints by cryptsetup, which caused me to investigate this
matter.Signed-off-by: Dominik Brodowski
Signed-off-by: Rafael J. Wysocki
07 Nov, 2011
1 commit
-
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
Revert "tracing: Include module.h in define_trace.h"
irq: don't put module.h into irq.h for tracking irqgen modules.
bluetooth: macroize two small inlines to avoid module.h
ip_vs.h: fix implicit use of module_get/module_put from module.h
nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
include: replace linux/module.h with "struct module" wherever possible
include: convert various register fcns to macros to avoid include chaining
crypto.h: remove unused crypto_tfm_alg_modname() inline
uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
pm_runtime.h: explicitly requires notifier.h
linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
miscdevice.h: fix up implicit use of lists and types
stop_machine.h: fix implicit use of smp.h for smp_processor_id
of: fix implicit use of errno.h in include/linux/of.h
of_platform.h: delete needless include
acpi: remove module.h include from platform/aclinux.h
miscdevice.h: delete unnecessary inclusion of module.h
device_cgroup.h: delete needless include
net: sch_generic remove redundant use of
net: inet_timewait_sock doesnt need
...Fix up trivial conflicts (other header files, and removal of the ab3550 mfd driver) in
- drivers/media/dvb/frontends/dibx000_common.c
- drivers/media/video/{mt9m111.c,ov6650.c}
- drivers/mfd/ab3550-core.c
- include/linux/dmaengine.h
05 Nov, 2011
1 commit
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Remove an "if" check, that repeats an equivalent one 6 lines above.
Signed-off-by: Guennadi Liakhovetski
Signed-off-by: Rafael J. Wysocki
01 Nov, 2011
1 commit
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These files were getting via an implicit non-obvious
path, but we want to crush those out of existence since they cost
time during compiles of processing thousands of lines of headers
for no reason. Give them the lightweight header that just contains
the EXPORT_SYMBOL infrastructure.Signed-off-by: Paul Gortmaker
31 Oct, 2011
1 commit
-
These files were implicitly relying on coming in via
module.h, as without it we get things like:kernel/power/suspend.c:100: error: implicit declaration of function ‘usermodehelper_disable’
kernel/power/suspend.c:109: error: implicit declaration of function ‘usermodehelper_enable’
kernel/power/user.c:254: error: implicit declaration of function ‘usermodehelper_disable’
kernel/power/user.c:261: error: implicit declaration of function ‘usermodehelper_enable’kernel/sys.c:317: error: implicit declaration of function ‘usermodehelper_disable’
kernel/sys.c:1816: error: implicit declaration of function ‘call_usermodehelper_setup’
kernel/sys.c:1822: error: implicit declaration of function ‘call_usermodehelper_setfns’
kernel/sys.c:1824: error: implicit declaration of function ‘call_usermodehelper_exec’Signed-off-by: Paul Gortmaker
29 Oct, 2011
1 commit
-
…git-cur/linux-2.6-arm
* 'devel-stable' of http://ftp.arm.linux.org.uk/pub/linux/arm/kernel/git-cur/linux-2.6-arm: (178 commits)
ARM: 7139/1: fix compilation with CONFIG_ARM_ATAG_DTB_COMPAT and large TEXT_OFFSET
ARM: gic, local timers: use the request_percpu_irq() interface
ARM: gic: consolidate PPI handling
ARM: switch from NO_MACH_MEMORY_H to NEED_MACH_MEMORY_H
ARM: mach-s5p64x0: remove mach/memory.h
ARM: mach-s3c64xx: remove mach/memory.h
ARM: plat-mxc: remove mach/memory.h
ARM: mach-prima2: remove mach/memory.h
ARM: mach-zynq: remove mach/memory.h
ARM: mach-bcmring: remove mach/memory.h
ARM: mach-davinci: remove mach/memory.h
ARM: mach-pxa: remove mach/memory.h
ARM: mach-ixp4xx: remove mach/memory.h
ARM: mach-h720x: remove mach/memory.h
ARM: mach-vt8500: remove mach/memory.h
ARM: mach-s5pc100: remove mach/memory.h
ARM: mach-tegra: remove mach/memory.h
ARM: plat-tcc: remove mach/memory.h
ARM: mach-mmp: remove mach/memory.h
ARM: mach-cns3xxx: remove mach/memory.h
...Fix up mostly pretty trivial conflicts in:
- arch/arm/Kconfig
- arch/arm/include/asm/localtimer.h
- arch/arm/kernel/Makefile
- arch/arm/mach-shmobile/board-ap4evb.c
- arch/arm/mach-u300/core.c
- arch/arm/mm/dma-mapping.c
- arch/arm/mm/proc-v7.S
- arch/arm/plat-omap/Kconfig
largely due to some CONFIG option renaming (ie CONFIG_PM_SLEEP ->
CONFIG_ARM_CPU_SUSPEND for the arm-specific suspend code etc) and
addition of NEED_MACH_MEMORY_H next to HAVE_IDE.
17 Oct, 2011
6 commits
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Use threads for LZO compression/decompression on hibernate/thaw.
Improve buffering on hibernate/thaw.
Calculate/verify CRC32 of the image pages on hibernate/thaw.In my testing, this improved write/read speed by a factor of about two.
Signed-off-by: Bojan Smojver
Signed-off-by: Rafael J. Wysocki -
Static and extern variables in kernel/power/hibernate.c need not be
initialized to 0 explicitly, so remove those initializations.[rjw: Modified subject, added changelog.]
Signed-off-by: Barry Song
Signed-off-by: Rafael J. Wysocki -
Patch "PM / Hibernate: Add resumewait param to support MMC-like
devices as resume file" added the resumewait kernel command line
option. The present patch adds resumedelay so that
resumewait/delay were analogous to rootwait/delay.[rjw: Modified the subject and changelog slightly.]
Signed-off-by: Barry Song
Acked-by: Pavel Machek
Signed-off-by: Rafael J. Wysocki -
Some devices like MMC are async detected very slow. For example,
drivers/mmc/host/sdhci.c launches a 200ms delayed work to detect
MMC partitions then add disk.We have wait_for_device_probe() and scsi_complete_async_scans()
before calling swsusp_check(), but it is not enough to wait for MMC.This patch adds resumewait kernel param just like rootwait so
that we have enough time to wait until MMC is ready. The difference is
that we wait for resume partition whereas rootwait waits for rootfs
partition (which may be on a different device).This patch will make hibernation support many embedded products
without SCSI devices, but with devices like MMC.[rjw: Modified the changelog slightly.]
Signed-off-by: Barry Song
Reviewed-by: Valdis Kletnieks
Signed-off-by: Rafael J. Wysocki -
Fix a typo in a function name in the kerneldoc comment next to
resume_target_kernel().[rjw: Changed the subject slightly, added the changelog.]
Signed-off-by: Barry Song
Signed-off-by: Rafael J. Wysocki -
There is a problem with the current ordering of hibernate code which
leads to deadlocks in some filesystems' memory shrinkers. Namely,
some filesystems use freezable kernel threads that are inactive when
the hibernate memory preallocation is carried out. Those same
filesystems use memory shrinkers that may be triggered by the
hibernate memory preallocation. If those memory shrinkers wait for
the frozen kernel threads, the hibernate process deadlocks (this
happens with XFS, for one example).Apparently, it is not technically viable to redesign the filesystems
in question to avoid the situation described above, so the only
possible solution of this issue is to defer the freezing of kernel
threads until the hibernate memory preallocation is done, which is
implemented by this change.Unfortunately, this requires the memory preallocation to be done
before the "prepare" stage of device freeze, so after this change the
only way drivers can allocate additional memory for their freeze
routines in a clean way is to use PM notifiers.Reported-by: Christoph
Signed-off-by: Rafael J. Wysocki
