Pull ARM cpufreq updates for 5.10-rc1 from Viresh Kumar:
"- STI cpufreq driver updates to allow new hardware (Alain Volmat).
- Minor tegra driver fixes around initial frequency mismatch warnings (Jon
Hunter).
- dev_err simplification for s5pv210 driver (Krzysztof Kozlowski).
- Qcom driver updates to allow new hardware and minor cleanup (Manivannan
Sadhasivam and Matthias Kaehlcke).
- Add missing MODULE_DEVICE_TABLE for armada driver (Pali Rohár).
- Improved defer-probe handling in cpufreq-dt driver (Stephan Gerhold).
- Call dev_pm_opp_of_remove_table() unconditionally for imx driver (Viresh
Kumar)."
* 'cpufreq/arm/linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm:
cpufreq: qcom: Don't add frequencies without an OPP
cpufreq: qcom-hw: Add cpufreq support for SM8250 SoC
cpufreq: qcom-hw: Use of_device_get_match_data for offsets and row size
cpufreq: qcom-hw: Use devm_platform_ioremap_resource() to simplify code
dt-bindings: cpufreq: cpufreq-qcom-hw: Document Qcom EPSS compatible
cpufreq: qcom-hw: Make use of cpufreq driver_data for passing pdev
cpufreq: armada-37xx: Add missing MODULE_DEVICE_TABLE
cpufreq: arm: Kconfig: add CPUFREQ_DT depend for STI CPUFREQ
cpufreq: dt-platdev: Blacklist st,stih418 SoC
cpufreq: sti-cpufreq: add stih418 support
cpufreq: s5pv210: Use dev_err instead of pr_err in probe
cpufreq: s5pv210: Simplify with dev_err_probe()
cpufreq: tegra186: Fix initial frequency
cpufreq: dt: Refactor initialization to handle probe deferral properly
opp: Handle multiple calls for same OPP table in _of_add_opp_table_v1()
cpufreq: imx6q: Unconditionally call dev_pm_opp_of_remove_table()
opp: Allow dev_pm_opp_get_opp_table() to return -EPROBE_DEFER
Split out all the bits that are purely for dma_map_ops implementations
and related code into a new <linux/dma-map-ops.h> header so that they
don't get pulled into all the drivers. That also means the architecture
specific <asm/dma-mapping.h> is not pulled in by <linux/dma-mapping.h>
any more, which leads to a missing includes that were pulled in by the
x86 or arm versions in a few not overly portable drivers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
To perform partial reads, callers of kernel_read_file*() must have a
non-NULL file_size argument and a preallocated buffer. The new "offset"
argument can then be used to seek to specific locations in the file to
fill the buffer to, at most, "buf_size" per call.
Where possible, the LSM hooks can report whether a full file has been
read or not so that the contents can be reasoned about.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that security_post_load_data() is wired up, use it instead
of the NULL file argument style of security_post_read_file(),
and update the security_kernel_load_data() call to indicate that a
security_kernel_post_load_data() call is expected.
Wire up the IMA check to match earlier logic. Perhaps a generalized
change to ima_post_load_data() might look something like this:
return process_buffer_measurement(buf, size,
kernel_load_data_id_str(load_id),
read_idmap[load_id] ?: FILE_CHECK,
0, NULL);
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-10-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are a few places in the kernel where LSMs would like to have
visibility into the contents of a kernel buffer that has been loaded or
read. While security_kernel_post_read_file() (which includes the
buffer) exists as a pairing for security_kernel_read_file(), no such
hook exists to pair with security_kernel_load_data().
Earlier proposals for just using security_kernel_post_read_file() with a
NULL file argument were rejected (i.e. "file" should always be valid for
the security_..._file hooks, but it appears at least one case was
left in the kernel during earlier refactoring. (This will be fixed in
a subsequent patch.)
Since not all cases of security_kernel_load_data() can have a single
contiguous buffer made available to the LSM hook (e.g. kexec image
segments are separately loaded), there needs to be a way for the LSM to
reason about its expectations of the hook coverage. In order to handle
this, add a "contents" argument to the "kernel_load_data" hook that
indicates if the newly added "kernel_post_load_data" hook will be called
with the full contents once loaded. That way, LSMs requiring full contents
can choose to unilaterally reject "kernel_load_data" with contents=false
(which is effectively the existing hook coverage), but when contents=true
they can allow it and later evaluate the "kernel_post_load_data" hook
once the buffer is loaded.
With this change, LSMs can gain coverage over non-file-backed data loads
(e.g. init_module(2) and firmware userspace helper), which will happen
in subsequent patches.
Additionally prepare IMA to start processing these cases.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In genpd_power_off() we may decide to abort the power off of the PM domain,
even beyond the point when the governor would accept it. The abort is done
if it turns out that a child domain has been requested to be powered on,
which means it's waiting for the lock of the parent to be released.
However, the abort is currently only considered if the genpd in question
has a ->power_off() callback assigned. This is unnecessary limiting,
especially if the genpd would have a parent of its own. Let's remove the
limitation and make the behaviour consistent.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
To clarify the code a bit, let's rename GPD_STATE_ACTIVE into
GENPD_STATE_ON and GPD_STATE_POWER_OFF to GENPD_STATE_OFF.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Generic Initiators are a new ACPI concept that allows for the
description of proximity domains that contain a device which
performs memory access (such as a network card) but neither
host CPU nor Memory.
This patch has the parsing code and provides the infrastructure
for an architecture to associate these new domains with their
nearest memory processing node.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Change additional instances that could use sysfs_emit and sysfs_emit_at
that the coccinelle script could not convert.
o macros creating show functions with ## concatenation
o unbound sprintf uses with buf+len for start of output to sysfs_emit_at
o returns with ?: tests and sprintf to sysfs_emit
o sysfs output with struct class * not struct device * arguments
Miscellanea:
o remove unnecessary initializations around these changes
o consistently use int len for return length of show functions
o use octal permissions and not S_<FOO>
o rename a few show function names so DEVICE_ATTR_<FOO> can be used
o use DEVICE_ATTR_ADMIN_RO where appropriate
o consistently use const char *output for strings
o checkpatch/style neatening
Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/8bc24444fe2049a9b2de6127389b57edfdfe324d.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In register_mem_sect_under_node() the system_state's value is checked to
detect whether the call is made during boot time or during an hot-plug
operation. Unfortunately, that check against SYSTEM_BOOTING is wrong
because regular memory is registered at SYSTEM_SCHEDULING state. In
addition, memory hot-plug operation can be triggered at this system
state by the ACPI [1]. So checking against the system state is not
enough.
The consequence is that on system with interleaved node's ranges like this:
Early memory node ranges
node 1: [mem 0x0000000000000000-0x000000011fffffff]
node 2: [mem 0x0000000120000000-0x000000014fffffff]
node 1: [mem 0x0000000150000000-0x00000001ffffffff]
node 0: [mem 0x0000000200000000-0x000000048fffffff]
node 2: [mem 0x0000000490000000-0x00000007ffffffff]
This can be seen on PowerPC LPAR after multiple memory hot-plug and
hot-unplug operations are done. At the next reboot the node's memory
ranges can be interleaved and since the call to link_mem_sections() is
made in topology_init() while the system is in the SYSTEM_SCHEDULING
state, the node's id is not checked, and the sections registered to
multiple nodes:
$ ls -l /sys/devices/system/memory/memory21/node*
total 0
lrwxrwxrwx 1 root root 0 Aug 24 05:27 node1 -> ../../node/node1
lrwxrwxrwx 1 root root 0 Aug 24 05:27 node2 -> ../../node/node2
In that case, the system is able to boot but if later one of theses
memory blocks is hot-unplugged and then hot-plugged, the sysfs
inconsistency is detected and this is triggering a BUG_ON():
kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084!
Oops: Exception in kernel mode, sig: 5 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4
CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25
Call Trace:
add_memory_resource+0x23c/0x340 (unreliable)
__add_memory+0x5c/0xf0
dlpar_add_lmb+0x1b4/0x500
dlpar_memory+0x1f8/0xb80
handle_dlpar_errorlog+0xc0/0x190
dlpar_store+0x198/0x4a0
kobj_attr_store+0x30/0x50
sysfs_kf_write+0x64/0x90
kernfs_fop_write+0x1b0/0x290
vfs_write+0xe8/0x290
ksys_write+0xdc/0x130
system_call_exception+0x160/0x270
system_call_common+0xf0/0x27c
This patch addresses the root cause by not relying on the system_state
value to detect whether the call is due to a hot-plug operation. An
extra parameter is added to link_mem_sections() detailing whether the
operation is due to a hot-plug operation.
[1] According to Oscar Salvador, using this qemu command line, ACPI
memory hotplug operations are raised at SYSTEM_SCHEDULING state:
$QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
-m size=$MEM,slots=255,maxmem=4294967296k \
-numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
-object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
-object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
-object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
-object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
-object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
-object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
-object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \
Fixes: 4fbce63391 ("mm/memory_hotplug.c: make register_mem_sect_under_node() a callback of walk_memory_range()")
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200915094143.79181-3-ldufour@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull regmap fixes from Mark Brown:
"Two issues here - one is a fix for use after free issues in the case
where a regmap overrides its name using something dynamically
generated, the other is that we weren't handling access checks
non-incrementing I/O on registers within paged register regions
correctly resulting in spurious errors.
Both of these are quite rare but serious if they occur"
* tag 'regmap-fix-v5.9-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
regmap: fix page selection for noinc writes
regmap: fix page selection for noinc reads
regmap: debugfs: Add back in erroneously removed initialisation of ret
regmap: debugfs: Fix handling of name string for debugfs init delays
To support runtime PM for hisi SAS driver (the driver is in directory
drivers/scsi/hisi_sas), we add device link between scsi_device->sdev_gendev
(consumer device) and hisi_hba->dev(supplier device) with flags
DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE.
After runtime suspended consumers and supplier, unload the dirver which
causes a hung.
We found that it called function device_release_driver_internal() to
release the supplier device (hisi_hba->dev), as the device link was
busy, it set the device link state to DL_STATE_SUPPLIER_UNBIND, and
then it called device_release_driver_internal() to release the consumer
device (scsi_device->sdev_gendev).
Then it would try to call pm_runtime_get_sync() to resume the consumer
device, but because consumer-supplier relation existed, it would try
to resume the supplier first, but as the link state was already
DL_STATE_SUPPLIER_UNBIND, so it skipped resuming the supplier and only
resumed the consumer which hanged (it sends IOs to resume scsi_device
while the SAS controller is suspended).
Simple flow is as follows:
device_release_driver_internal -> (supplier device)
if device_links_busy ->
device_links_unbind_consumers ->
...
WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND)
device_release_driver_internal (consumer device)
pm_runtime_get_sync -> (consumer device)
...
__rpm_callback ->
rpm_get_suppliers ->
if link->state == DL_STATE_SUPPLIER_UNBIND -> skip the action of resuming the supplier
...
pm_runtime_clean_up_links
...
Correct suspend/resume ordering between a supplier device and its consumer
devices (resume the supplier device before resuming consumer devices, and
suspend consumer devices before suspending the supplier device) should be
guaranteed by runtime PM, but the state checks in rpm_get_supplier() and
rpm_put_supplier() break this rule, so remove them.
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
[ rjw: Subject and changelog edits ]
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Dictionaries are only used for SUBSYSTEM and DEVICE properties. The
current implementation stores the property names each time they are
used. This requires more space than otherwise necessary. Also,
because the dictionary entries are currently considered optional,
it cannot be relied upon that they are always available, even if the
writer wanted to store them. These issues will increase should new
dictionary properties be introduced.
Rather than storing the subsystem and device properties in the
dict ring, introduce a struct dev_printk_info with separate fields
to store only the property values. Embed this struct within the
struct printk_info to provide guaranteed availability.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/87mu1jl6ne.fsf@jogness.linutronix.de
arch_scale_freq_invariant() is used by schedutil to determine whether
the scheduler's load-tracking signals are frequency invariant. Its
definition is overridable, though by default it is hardcoded to 'true'
if arch_scale_freq_capacity() is defined ('false' otherwise).
This behaviour is not overridden on arm, arm64 and other users of the
generic arch topology driver, which is somewhat precarious:
arch_scale_freq_capacity() will always be defined, yet not all cpufreq
drivers are guaranteed to drive the frequency invariance scale factor
setting. In other words, the load-tracking signals may very well *not*
be frequency invariant.
Now that cpufreq can be queried on whether the current driver is driving
the Frequency Invariance (FI) scale setting, the current situation can
be improved. This combines the query of whether cpufreq supports the
setting of the frequency scale factor, with whether all online CPUs are
counter-based FI enabled.
While cpufreq FI enablement applies at system level, for all CPUs,
counter-based FI support could also be used for only a subset of CPUs to
set the invariance scale factor. Therefore, if cpufreq-based FI support
is present, we consider the system to be invariant. If missing, we
require all online CPUs to be counter-based FI enabled in order for the
full system to be considered invariant.
If the system ends up not being invariant, a new condition is needed in
the counter initialization code that disables all scale factor setting
based on counters.
Precedence of counters over cpufreq use is not important here. The
invariant status is only given to the system if all CPUs have at least
one method of setting the frequency scale factor.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The passed cpumask arguments to arch_set_freq_scale() and
arch_freq_counters_available() are only iterated over, so reflect this
in the prototype. This also allows to pass system cpumasks like
cpu_online_mask without getting a warning.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The current frequency passed to arch_set_freq_scale() could end up
being 0, signaling an error in setting a new frequency. Also, if the
maximum frequency in 0, this will result in a division by 0 error.
Therefore, validate these input values before using them for the
setting of the frequency scale factor.
Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In regmap_debugfs_init the initialisation of the debugfs is delayed
if the root node isn't ready yet. Most callers of regmap_debugfs_init
pass the name from the regmap_config, which is considered temporary
ie. may be unallocated after the regmap_init call returns. This leads
to a potential use after free, where config->name has been freed by
the time it is used in regmap_debugfs_initcall.
This situation can be seen on Zynq, where the architecture init_irq
callback registers a syscon device, using a local variable for the
regmap_config. As init_irq is very early in the platform bring up the
regmap debugfs root isn't ready yet. Although this doesn't crash it
does result in the debugfs entry not having the correct name.
Regmap already sets map->name from config->name on the regmap_init
path and the fact that a separate field is used to pass the name
to regmap_debugfs_init appears to be an artifact of the debugfs
name being added before the map name. As such this patch updates
regmap_debugfs_init to use map->name, which is already duplicated from
the config avoiding the issue.
This does however leave two lose ends, both regmap_attach_dev and
regmap_reinit_cache can be called after a regmap is registered and
would have had the effect of applying a new name to the debugfs
entries. In both of these cases it was chosen to update the map
name. In the case of regmap_attach_dev there are 3 users that
currently use this function to update the name, thus doing so avoids
changes for those users and it seems reasonable that attaching
a device would want to set the name of the map. In the case of
regmap_reinit_cache the primary use-case appears to be devices that
need some register access to identify the device (for example devices
in the same family) and then update the cache to match the exact
hardware. Whilst no users do currently update the name here, given the
use-case it seemed reasonable the name might want to be updated once
the device is better identified.
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20200917120828.12987-1-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Devices such as the AD5628 require 32 bits of data divided in 12 bits
for dummy, command and address, and 20 for data and dummy. Eg:
XXXXCCCCAAAADDDDDDDDDDDDDDDDXXXX
Where X is dont care, C is command, A is address and D is data bits.
Which would requierd the following regmap_config:
static const struct regmap_config config_dac = {
.reg_bits = 12,
.val_bits = 20,
.max_register = 0xff,
};
Signed-off-by: Ricardo Ribalda <ribalda@kernel.org>
Link: https://lore.kernel.org/r/20200917114727.1120373-1-ribalda@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
The new field 'dma_range_map' in struct device is used to facilitate the
use of single or multiple offsets between mapping regions of cpu addrs and
dma addrs. It subsumes the role of "dev->dma_pfn_offset" which was only
capable of holding a single uniform offset and had no region bounds
checking.
The function of_dma_get_range() has been modified so that it takes a single
argument -- the device node -- and returns a map, NULL, or an error code.
The map is an array that holds the information regarding the DMA regions.
Each range entry contains the address offset, the cpu_start address, the
dma_start address, and the size of the region.
of_dma_configure() is the typical manner to set range offsets but there are
a number of ad hoc assignments to "dev->dma_pfn_offset" in the kernel
driver code. These cases now invoke the function
dma_direct_set_offset(dev, cpu_addr, dma_addr, size).
Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
[hch: various interface cleanups]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
There is one overlooked situation under which a driver must not do IO to
allocate memory. You cannot do that while disconnecting a device. A
device being disconnected is no longer functional in most cases, yet IO
may fail only when the handler runs.
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20200916191544.5104-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull driver core fixes from Greg KH:
"Here are some small driver core and debugfs fixes for 5.9-rc5
Included in here are:
- firmware loader memory leak fix
- firmware loader testing fixes for non-EFI systems
- device link locking fixes found by lockdep
- kobject_del() bugfix that has been affecting some callers
- debugfs minor fix
All of these have been in linux-next for a while with no reported
issues"
* tag 'driver-core-5.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
test_firmware: Test platform fw loading on non-EFI systems
PM: <linux/device.h>: fix @em_pd kernel-doc warning
kobject: Drop unneeded conditional in __kobject_del()
driver core: Fix device_pm_lock() locking for device links
MAINTAINERS: Add the security document to SECURITY CONTACT
driver code: print symbolic error code
debugfs: Fix module state check condition
kobject: Restore old behaviour of kobject_del(NULL)
firmware_loader: fix memory leak for paged buffer
